Commit Graph

279 Commits

Author SHA1 Message Date
Linus Torvalds b2c3dda6f8 Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull time fixes from Ingo Molnar:
 "A TIA adjtimex interface extension, and a POSIX compliance ABI fix for
  timespec64 users"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  ntp: Allow TAI-UTC offset to be set to zero
  y2038: Make CONFIG_64BIT_TIME unconditional
2019-05-16 11:00:20 -07:00
Christoph Hellwig d8ae8a3765 initramfs: move the legacy keepinitrd parameter to core code
No need to handle the freeing disable in arch code when we already have a
core hook (and a different name for the option) for it.

Link: http://lkml.kernel.org/r/20190213174621.29297-7-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>	[arm64]
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>	[m68k]
Cc: Steven Price <steven.price@arm.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-05-14 09:47:47 -07:00
Linus Torvalds 0bc40e549a Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 mm updates from Ingo Molnar:
 "The changes in here are:

   - text_poke() fixes and an extensive set of executability lockdowns,
     to (hopefully) eliminate the last residual circumstances under
     which we are using W|X mappings even temporarily on x86 kernels.
     This required a broad range of surgery in text patching facilities,
     module loading, trampoline handling and other bits.

   - tweak page fault messages to be more informative and more
     structured.

   - remove DISCONTIGMEM support on x86-32 and make SPARSEMEM the
     default.

   - reduce KASLR granularity on 5-level paging kernels from 512 GB to
     1 GB.

   - misc other changes and updates"

* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
  x86/mm: Initialize PGD cache during mm initialization
  x86/alternatives: Add comment about module removal races
  x86/kprobes: Use vmalloc special flag
  x86/ftrace: Use vmalloc special flag
  bpf: Use vmalloc special flag
  modules: Use vmalloc special flag
  mm/vmalloc: Add flag for freeing of special permsissions
  mm/hibernation: Make hibernation handle unmapped pages
  x86/mm/cpa: Add set_direct_map_*() functions
  x86/alternatives: Remove the return value of text_poke_*()
  x86/jump-label: Remove support for custom text poker
  x86/modules: Avoid breaking W^X while loading modules
  x86/kprobes: Set instruction page as executable
  x86/ftrace: Set trampoline pages as executable
  x86/kgdb: Avoid redundant comparison of patched code
  x86/alternatives: Use temporary mm for text poking
  x86/alternatives: Initialize temporary mm for patching
  fork: Provide a function for copying init_mm
  uprobes: Initialize uprobes earlier
  x86/mm: Save debug registers when loading a temporary mm
  ...
2019-05-06 16:13:31 -07:00
Linus Torvalds 007dc78fea Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
 "Here are the locking changes in this cycle:

   - rwsem unification and simpler micro-optimizations to prepare for
     more intrusive (and more lucrative) scalability improvements in
     v5.3 (Waiman Long)

   - Lockdep irq state tracking flag usage cleanups (Frederic
     Weisbecker)

   - static key improvements (Jakub Kicinski, Peter Zijlstra)

   - misc updates, cleanups and smaller fixes"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (26 commits)
  locking/lockdep: Remove unnecessary unlikely()
  locking/static_key: Don't take sleeping locks in __static_key_slow_dec_deferred()
  locking/static_key: Factor out the fast path of static_key_slow_dec()
  locking/static_key: Add support for deferred static branches
  locking/lockdep: Test all incompatible scenarios at once in check_irq_usage()
  locking/lockdep: Avoid bogus Clang warning
  locking/lockdep: Generate LOCKF_ bit composites
  locking/lockdep: Use expanded masks on find_usage_*() functions
  locking/lockdep: Map remaining magic numbers to lock usage mask names
  locking/lockdep: Move valid_state() inside CONFIG_TRACE_IRQFLAGS && CONFIG_PROVE_LOCKING
  locking/rwsem: Prevent unneeded warning during locking selftest
  locking/rwsem: Optimize rwsem structure for uncontended lock acquisition
  locking/rwsem: Enable lock event counting
  locking/lock_events: Don't show pvqspinlock events on bare metal
  locking/lock_events: Make lock_events available for all archs & other locks
  locking/qspinlock_stat: Introduce generic lockevent_*() counting APIs
  locking/rwsem: Enhance DEBUG_RWSEMS_WARN_ON() macro
  locking/rwsem: Add debug check for __down_read*()
  locking/rwsem: Micro-optimize rwsem_try_read_lock_unqueued()
  locking/rwsem: Move rwsem internal function declarations to rwsem-xadd.h
  ...
2019-05-06 13:50:15 -07:00
Rick Edgecombe d253ca0c38 x86/mm/cpa: Add set_direct_map_*() functions
Add two new functions set_direct_map_default_noflush() and
set_direct_map_invalid_noflush() for setting the direct map alias for the
page to its default valid permissions and to an invalid state that cannot
be cached in a TLB, respectively. These functions do not flush the TLB.

Note, __kernel_map_pages() does something similar but flushes the TLB and
doesn't reset the permission bits to default on all architectures.

Also add an ARCH config ARCH_HAS_SET_DIRECT_MAP for specifying whether
these have an actual implementation or a default empty one.

Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <akpm@linux-foundation.org>
Cc: <ard.biesheuvel@linaro.org>
Cc: <deneen.t.dock@intel.com>
Cc: <kernel-hardening@lists.openwall.com>
Cc: <kristen@linux.intel.com>
Cc: <linux_dti@icloud.com>
Cc: <will.deacon@arm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190426001143.4983-15-namit@vmware.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-30 12:37:56 +02:00
Arnd Bergmann f3d964673b y2038: Make CONFIG_64BIT_TIME unconditional
As Stepan Golosunov points out, there is a small mistake in the
get_timespec64() function in the kernel. It was originally added under the
assumption that CONFIG_64BIT_TIME would get enabled on all 32-bit and
64-bit architectures, but when the conversion was done, it was only turned
on for 32-bit ones.

The effect is that the get_timespec64() function never clears the upper
half of the tv_nsec field for 32-bit tasks in compat mode. Clearing this is
required for POSIX compliant behavior of functions that pass a 'timespec'
structure with a 64-bit tv_sec and a 32-bit tv_nsec, plus uninitialized
padding.

The easiest fix for linux-5.1 is to just make the Kconfig symbol
unconditional, as it was originally intended. As a follow-up, the #ifdef
CONFIG_64BIT_TIME can be removed completely..

Note: for native 32-bit mode, no change is needed, this works as
designed and user space should never need to clear the upper 32
bits of the tv_nsec field, in or out of the kernel.

Fixes: 00bf25d693 ("y2038: use time32 syscall names on 32-bit")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Joseph Myers <joseph@codesourcery.com>
Cc: libc-alpha@sourceware.org
Cc: linux-api@vger.kernel.org
Cc: Deepa Dinamani <deepa.kernel@gmail.com>
Cc: Lukasz Majewski <lukma@denx.de>
Cc: Stepan Golosunov <stepan@golosunov.pp.ru>
Link: https://lore.kernel.org/lkml/20190422090710.bmxdhhankurhafxq@sghpc.golosunov.pp.ru/
Link: https://lkml.kernel.org/r/20190429131951.471701-1-arnd@arndb.de
2019-04-29 21:07:10 +02:00
Waiman Long a8654596f0 locking/rwsem: Enable lock event counting
Add lock event counting calls so that we can track the number of lock
events happening in the rwsem code.

With CONFIG_LOCK_EVENT_COUNTS on and booting a 4-socket 112-thread x86-64
system, the rwsem counts after system bootup were as follows:

  rwsem_opt_fail=261
  rwsem_opt_wlock=50636
  rwsem_rlock=445
  rwsem_rlock_fail=0
  rwsem_rlock_fast=22
  rwsem_rtrylock=810144
  rwsem_sleep_reader=441
  rwsem_sleep_writer=310
  rwsem_wake_reader=355
  rwsem_wake_writer=2335
  rwsem_wlock=261
  rwsem_wlock_fail=0
  rwsem_wtrylock=20583

It can be seen that most of the lock acquisitions in the slowpath were
write-locks in the optimistic spinning code path with no sleeping at
all. For this system, over 97% of the locks are acquired via optimistic
spinning. It illustrates the importance of optimistic spinning in
improving the performance of rwsem.

Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20190404174320.22416-11-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-10 10:56:06 +02:00
Waiman Long fb346fd9fc locking/lock_events: Make lock_events available for all archs & other locks
The QUEUED_LOCK_STAT option to report queued spinlocks event counts
was previously allowed only on x86 architecture. To make the locking
event counting code more useful, it is now renamed to a more generic
LOCK_EVENT_COUNTS config option. This new option will be available to
all the architectures that use qspinlock at the moment.

Other locking code can now start to use the generic locking event
counting code by including lock_events.h and put the new locking event
names into the lock_events_list.h header file.

My experience with lock event counting is that it gives valuable insight
on how the locking code works and what can be done to make it better. I
would like to extend this benefit to other locking code like mutex and
rwsem in the near future.

The PV qspinlock specific code will stay in qspinlock_stat.h. The
locking event counters will now reside in the <debugfs>/lock_event_counts
directory.

Signed-off-by: Waiman Long <longman@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Link: http://lkml.kernel.org/r/20190404174320.22416-9-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-10 10:56:04 +02:00
Martin Schwidefsky 952a31c9e6 asm-generic/tlb: Introduce CONFIG_HAVE_MMU_GATHER_NO_GATHER=y
Add the Kconfig option HAVE_MMU_GATHER_NO_GATHER to the generic
mmu_gather code. If the option is set the mmu_gather will not
track individual pages for delayed page free anymore. A platform
that enables the option needs to provide its own implementation
of the __tlb_remove_page_size() function to free pages.

No change in behavior intended.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: aneesh.kumar@linux.vnet.ibm.com
Cc: heiko.carstens@de.ibm.com
Cc: linux@armlinux.org.uk
Cc: npiggin@gmail.com
Link: http://lkml.kernel.org/r/20180918125151.31744-2-schwidefsky@de.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-03 10:32:55 +02:00
Peter Zijlstra 96bc9567cb asm-generic/tlb, arch: Invert CONFIG_HAVE_RCU_TABLE_INVALIDATE
Make issuing a TLB invalidate for page-table pages the normal case.

The reason is twofold:

 - too many invalidates is safer than too few,
 - most architectures use the linux page-tables natively
   and would thus require this.

Make it an opt-out, instead of an opt-in.

No change in behavior intended.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-03 10:32:47 +02:00
Peter Zijlstra ed6a79352c asm-generic/tlb, arch: Provide CONFIG_HAVE_MMU_GATHER_PAGE_SIZE
Move the mmu_gather::page_size things into the generic code instead of
PowerPC specific bits.

No change in behavior intended.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-04-03 10:32:40 +02:00
Linus Torvalds 45763bf4bc Char/Misc driver patches for 5.1-rc1
Here is the big char/misc driver patch pull request for 5.1-rc1.
 
 The largest thing by far is the new habanalabs driver for their AI
 accelerator chip.  For now it is in the drivers/misc directory but will
 probably move to a new directory soon along with other drivers of this
 type.
 
 Other than that, just the usual set of individual driver updates and
 fixes.  There's an "odd" merge in here from the DRM tree that they asked
 me to do as the MEI driver is starting to interact with the i915 driver,
 and it needed some coordination.  All of those patches have been
 properly acked by the relevant subsystem maintainers.
 
 All of these have been in linux-next with no reported issues, most for
 quite some time.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'char-misc-5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

Pull char/misc driver updates from Greg KH:
 "Here is the big char/misc driver patch pull request for 5.1-rc1.

  The largest thing by far is the new habanalabs driver for their AI
  accelerator chip. For now it is in the drivers/misc directory but will
  probably move to a new directory soon along with other drivers of this
  type.

  Other than that, just the usual set of individual driver updates and
  fixes. There's an "odd" merge in here from the DRM tree that they
  asked me to do as the MEI driver is starting to interact with the i915
  driver, and it needed some coordination. All of those patches have
  been properly acked by the relevant subsystem maintainers.

  All of these have been in linux-next with no reported issues, most for
  quite some time"

* tag 'char-misc-5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (219 commits)
  habanalabs: adjust Kconfig to fix build errors
  habanalabs: use %px instead of %p in error print
  habanalabs: use do_div for 64-bit divisions
  intel_th: gth: Fix an off-by-one in output unassigning
  habanalabs: fix little-endian<->cpu conversion warnings
  habanalabs: use NULL to initialize array of pointers
  habanalabs: fix little-endian<->cpu conversion warnings
  habanalabs: soft-reset device if context-switch fails
  habanalabs: print pointer using %p
  habanalabs: fix memory leak with CBs with unaligned size
  habanalabs: return correct error code on MMU mapping failure
  habanalabs: add comments in uapi/misc/habanalabs.h
  habanalabs: extend QMAN0 job timeout
  habanalabs: set DMA0 completion to SOB 1007
  habanalabs: fix validation of WREG32 to DMA completion
  habanalabs: fix mmu cache registers init
  habanalabs: disable CPU access on timeouts
  habanalabs: add MMU DRAM default page mapping
  habanalabs: Dissociate RAZWI info from event types
  misc/habanalabs: adjust Kconfig to fix build errors
  ...
2019-03-06 14:18:59 -08:00
Linus Torvalds c8f5ed6ef9 Merge branch 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull EFI updates from Ingo Molnar:
 "The main EFI changes in this cycle were:

   - Use 32-bit alignment for efi_guid_t

   - Allow the SetVirtualAddressMap() call to be omitted

   - Implement earlycon=efifb based on existing earlyprintk code

   - Various minor fixes and code cleanups from Sai, Ard and me"

* 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi: Fix build error due to enum collision between efi.h and ima.h
  efi/x86: Convert x86 EFI earlyprintk into generic earlycon implementation
  x86: Make ARCH_USE_MEMREMAP_PROT a generic Kconfig symbol
  efi/arm/arm64: Allow SetVirtualAddressMap() to be omitted
  efi: Replace GPL license boilerplate with SPDX headers
  efi/fdt: Apply more cleanups
  efi: Use 32-bit alignment for efi_guid_t
  efi/memattr: Don't bail on zero VA if it equals the region's PA
  x86/efi: Mark can_free_region() as an __init function
2019-03-06 07:13:56 -08:00
Yury Norov 942fa985e9 32-bit userspace ABI: introduce ARCH_32BIT_OFF_T config option
All new 32-bit architectures should have 64-bit userspace off_t type, but
existing architectures has 32-bit ones.

To enforce the rule, new config option is added to arch/Kconfig that defaults
ARCH_32BIT_OFF_T to be disabled for new 32-bit architectures. All existing
32-bit architectures enable it explicitly.

New option affects force_o_largefile() behaviour. Namely, if userspace
off_t is 64-bits long, we have no reason to reject user to open big files.

Note that even if architectures has only 64-bit off_t in the kernel
(arc, c6x, h8300, hexagon, nios2, openrisc, and unicore32),
a libc may use 32-bit off_t, and therefore want to limit the file size
to 4GB unless specified differently in the open flags.

Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Yury Norov <ynorov@marvell.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2019-02-19 10:10:05 +01:00
Arnd Bergmann 00bf25d693 y2038: use time32 syscall names on 32-bit
This is the big flip, where all 32-bit architectures set COMPAT_32BIT_TIME
and use the _time32 system calls from the former compat layer instead
of the system calls that take __kernel_timespec and similar arguments.

The temporary redirects for __kernel_timespec, __kernel_itimerspec
and __kernel_timex can get removed with this.

It would be easy to split this commit by architecture, but with the new
generated system call tables, it's easy enough to do it all at once,
which makes it a little easier to check that the changes are the same
in each table.

Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
2019-02-07 00:13:28 +01:00
Ard Biesheuvel ce9084ba0d x86: Make ARCH_USE_MEMREMAP_PROT a generic Kconfig symbol
Turn ARCH_USE_MEMREMAP_PROT into a generic Kconfig symbol, and fix the
dependency expression to reflect that AMD_MEM_ENCRYPT depends on it,
instead of the other way around. This will permit ARCH_USE_MEMREMAP_PROT
to be selected by other architectures.

Note that the encryption related early memremap routines in
arch/x86/mm/ioremap.c cannot be built for 32-bit x86 without triggering
the following warning:

     arch/x86//mm/ioremap.c: In function 'early_memremap_encrypted':
  >> arch/x86/include/asm/pgtable_types.h:193:27: warning: conversion from
                     'long long unsigned int' to 'long unsigned int' changes
                     value from '9223372036854776163' to '355' [-Woverflow]
      #define __PAGE_KERNEL_ENC (__PAGE_KERNEL | _PAGE_ENC)
                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~
     arch/x86//mm/ioremap.c:713:46: note: in expansion of macro '__PAGE_KERNEL_ENC'
       return early_memremap_prot(phys_addr, size, __PAGE_KERNEL_ENC);

which essentially means they are 64-bit only anyway. However, we cannot
make them dependent on CONFIG_ARCH_HAS_MEM_ENCRYPT, since that is always
defined, even for i386 (and changing that results in a slew of build errors)

So instead, build those routines only if CONFIG_AMD_MEM_ENCRYPT is
defined.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Alexander Graf <agraf@suse.de>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Jeffrey Hugo <jhugo@codeaurora.org>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Jones <pjones@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20190202094119.13230-9-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-02-04 08:27:29 +01:00
Finn Thain 666047fe2a m68k/atari: Implement arch_nvram_ops methods and enable CONFIG_HAVE_ARCH_NVRAM_OPS
Atari RTC NVRAM uses a checksum so implement the remaining arch_nvram_ops
methods for the set_checksum and initialize ioctls. Enable
CONFIG_HAVE_ARCH_NVRAM_OPS.

Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-01-22 10:21:44 +01:00
Masahiro Yamada e9666d10a5 jump_label: move 'asm goto' support test to Kconfig
Currently, CONFIG_JUMP_LABEL just means "I _want_ to use jump label".

The jump label is controlled by HAVE_JUMP_LABEL, which is defined
like this:

  #if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
  # define HAVE_JUMP_LABEL
  #endif

We can improve this by testing 'asm goto' support in Kconfig, then
make JUMP_LABEL depend on CC_HAS_ASM_GOTO.

Ugly #ifdef HAVE_JUMP_LABEL will go away, and CONFIG_JUMP_LABEL will
match to the real kernel capability.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
2019-01-06 09:46:51 +09:00
Joel Fernandes (Google) 2c91bd4a4e mm: speed up mremap by 20x on large regions
Android needs to mremap large regions of memory during memory management
related operations.  The mremap system call can be really slow if THP is
not enabled.  The bottleneck is move_page_tables, which is copying each
pte at a time, and can be really slow across a large map.  Turning on
THP may not be a viable option, and is not for us.  This patch speeds up
the performance for non-THP system by copying at the PMD level when
possible.

The speedup is an order of magnitude on x86 (~20x).  On a 1GB mremap,
the mremap completion times drops from 3.4-3.6 milliseconds to 144-160
microseconds.

Before:
Total mremap time for 1GB data: 3521942 nanoseconds.
Total mremap time for 1GB data: 3449229 nanoseconds.
Total mremap time for 1GB data: 3488230 nanoseconds.

After:
Total mremap time for 1GB data: 150279 nanoseconds.
Total mremap time for 1GB data: 144665 nanoseconds.
Total mremap time for 1GB data: 158708 nanoseconds.

If THP is enabled the optimization is mostly skipped except in certain
situations.

[joel@joelfernandes.org: fix 'move_normal_pmd' unused function warning]
  Link: http://lkml.kernel.org/r/20181108224457.GB209347@google.com
Link: http://lkml.kernel.org/r/20181108181201.88826-3-joelaf@google.com
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Cc: Julia Lawall <Julia.Lawall@lip6.fr>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-01-04 13:13:48 -08:00
Linus Torvalds 2d6bb6adb7 New gcc plugin: stackleak
- Introduces the stackleak gcc plugin ported from grsecurity by Alexander
   Popov, with x86 and arm64 support.
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Merge tag 'stackleak-v4.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull stackleak gcc plugin from Kees Cook:
 "Please pull this new GCC plugin, stackleak, for v4.20-rc1. This plugin
  was ported from grsecurity by Alexander Popov. It provides efficient
  stack content poisoning at syscall exit. This creates a defense
  against at least two classes of flaws:

   - Uninitialized stack usage. (We continue to work on improving the
     compiler to do this in other ways: e.g. unconditional zero init was
     proposed to GCC and Clang, and more plugin work has started too).

   - Stack content exposure. By greatly reducing the lifetime of valid
     stack contents, exposures via either direct read bugs or unknown
     cache side-channels become much more difficult to exploit. This
     complements the existing buddy and heap poisoning options, but
     provides the coverage for stacks.

  The x86 hooks are included in this series (which have been reviewed by
  Ingo, Dave Hansen, and Thomas Gleixner). The arm64 hooks have already
  been merged through the arm64 tree (written by Laura Abbott and
  reviewed by Mark Rutland and Will Deacon).

  With VLAs having been removed this release, there is no need for
  alloca() protection, so it has been removed from the plugin"

* tag 'stackleak-v4.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  arm64: Drop unneeded stackleak_check_alloca()
  stackleak: Allow runtime disabling of kernel stack erasing
  doc: self-protection: Add information about STACKLEAK feature
  fs/proc: Show STACKLEAK metrics in the /proc file system
  lkdtm: Add a test for STACKLEAK
  gcc-plugins: Add STACKLEAK plugin for tracking the kernel stack
  x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls
2018-11-01 11:46:27 -07:00
Linus Torvalds 343a9f3540 The biggest change here is the updates to kprobes
Back in January I posted patches to create function based events. These were
 the events that you suggested I make to allow developers to easily create
 events in code where no trace event exists. After posting those changes for
 review, it was suggested that we implement this instead with kprobes.
 
 The problem with kprobes is that the interface is too complex and needs to
 be simplified. Masami Hiramatsu posted patches in March and I've been
 playing with them a bit. There's been a bit of clean up in the kprobe code
 that was inspired by the function based event patches, and a couple of
 enhancements to the kprobe event interface.
 
  - If the arch supports it (we added support for x86), you can place a
    kprobe event at the start of a function and use $arg1, $arg2, etc
    to reference the arguments of a function. (Before you needed to know
    what register or where on the stack the argument was).
 
  - The second is a way to see array of events. For example, if you reference
    a mac address, you can add:
 
    echo 'p:mac ip_rcv perm_addr=+574($arg2):x8[6]' > kprobe_events
 
    And this will produce:
 
    mac: (ip_rcv+0x0/0x140) perm_addr={0x52,0x54,0x0,0xc0,0x76,0xec}
 
 Other changes include
 
  - Exporting trace_dump_stack to modules
 
  - Have the stack tracer trace the entire stack (stop trying to remove
    tracing itself, as we keep removing too much).
 
  - Added support for SDT in uprobes
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Merge tag 'trace-v4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "The biggest change here is the updates to kprobes

  Back in January I posted patches to create function based events.
  These were the events that you suggested I make to allow developers to
  easily create events in code where no trace event exists. After
  posting those changes for review, it was suggested that we implement
  this instead with kprobes.

  The problem with kprobes is that the interface is too complex and
  needs to be simplified. Masami Hiramatsu posted patches in March and
  I've been playing with them a bit. There's been a bit of clean up in
  the kprobe code that was inspired by the function based event patches,
  and a couple of enhancements to the kprobe event interface.

   - If the arch supports it (we added support for x86), you can place a
     kprobe event at the start of a function and use $arg1, $arg2, etc
     to reference the arguments of a function. (Before you needed to
     know what register or where on the stack the argument was).

   - The second is a way to see array of events. For example, if you
     reference a mac address, you can add:

	echo 'p:mac ip_rcv perm_addr=+574($arg2):x8[6]' > kprobe_events

     And this will produce:

	mac: (ip_rcv+0x0/0x140) perm_addr={0x52,0x54,0x0,0xc0,0x76,0xec}

  Other changes include

   - Exporting trace_dump_stack to modules

   - Have the stack tracer trace the entire stack (stop trying to remove
     tracing itself, as we keep removing too much).

   - Added support for SDT in uprobes"

[ SDT - "Statically Defined Tracing" are userspace markers for tracing.
  Let's not use random TLA's in explanations unless they are fairly
  well-established as generic (at least for kernel people) - Linus ]

* tag 'trace-v4.20' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (24 commits)
  tracing: Have stack tracer trace full stack
  tracing: Export trace_dump_stack to modules
  tracing: probeevent: Fix uninitialized used of offset in parse args
  tracing/kprobes: Allow kprobe-events to record module symbol
  tracing/kprobes: Check the probe on unloaded module correctly
  tracing/uprobes: Fix to return -EFAULT if copy_from_user failed
  tracing: probeevent: Add $argN for accessing function args
  x86: ptrace: Add function argument access API
  tracing: probeevent: Add array type support
  tracing: probeevent: Add symbol type
  tracing: probeevent: Unify fetch_insn processing common part
  tracing: probeevent: Append traceprobe_ for exported function
  tracing: probeevent: Return consumed bytes of dynamic area
  tracing: probeevent: Unify fetch type tables
  tracing: probeevent: Introduce new argument fetching code
  tracing: probeevent: Remove NOKPROBE_SYMBOL from print functions
  tracing: probeevent: Cleanup argument field definition
  tracing: probeevent: Cleanup print argument functions
  trace_uprobe: support reference counter in fd-based uprobe
  perf probe: Support SDT markers having reference counter (semaphore)
  ...
2018-10-30 09:49:56 -07:00
Masami Hiramatsu 3c88ee194c x86: ptrace: Add function argument access API
Add regs_get_argument() which returns N th argument of the
function call.
Note that this chooses most probably assignment, in some case
it can be incorrect (e.g. passing data structure or floating
point etc.)

This is expected to be called from kprobes or ftrace with regs
where the top of stack is the return address.

Link: http://lkml.kernel.org/r/152465885737.26224.2822487520472783854.stgit@devbox

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2018-10-10 22:19:11 -04:00
Ard Biesheuvel 50ff18ab49 jump_label: Implement generic support for relative references
To reduce the size taken up by absolute references in jump label
entries themselves and the associated relocation records in the
.init segment, add support for emitting them as relative references
instead.

Note that this requires some extra care in the sorting routine, given
that the offsets change when entries are moved around in the jump_entry
table.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jessica Yu <jeyu@kernel.org>
Link: https://lkml.kernel.org/r/20180919065144.25010-3-ard.biesheuvel@linaro.org
2018-09-27 17:56:47 +02:00
Alexander Popov afaef01c00 x86/entry: Add STACKLEAK erasing the kernel stack at the end of syscalls
The STACKLEAK feature (initially developed by PaX Team) has the following
benefits:

1. Reduces the information that can be revealed through kernel stack leak
   bugs. The idea of erasing the thread stack at the end of syscalls is
   similar to CONFIG_PAGE_POISONING and memzero_explicit() in kernel
   crypto, which all comply with FDP_RIP.2 (Full Residual Information
   Protection) of the Common Criteria standard.

2. Blocks some uninitialized stack variable attacks (e.g. CVE-2017-17712,
   CVE-2010-2963). That kind of bugs should be killed by improving C
   compilers in future, which might take a long time.

This commit introduces the code filling the used part of the kernel
stack with a poison value before returning to userspace. Full
STACKLEAK feature also contains the gcc plugin which comes in a
separate commit.

The STACKLEAK feature is ported from grsecurity/PaX. More information at:
  https://grsecurity.net/
  https://pax.grsecurity.net/

This code is modified from Brad Spengler/PaX Team's code in the last
public patch of grsecurity/PaX based on our understanding of the code.
Changes or omissions from the original code are ours and don't reflect
the original grsecurity/PaX code.

Performance impact:

Hardware: Intel Core i7-4770, 16 GB RAM

Test #1: building the Linux kernel on a single core
        0.91% slowdown

Test #2: hackbench -s 4096 -l 2000 -g 15 -f 25 -P
        4.2% slowdown

So the STACKLEAK description in Kconfig includes: "The tradeoff is the
performance impact: on a single CPU system kernel compilation sees a 1%
slowdown, other systems and workloads may vary and you are advised to
test this feature on your expected workload before deploying it".

Signed-off-by: Alexander Popov <alex.popov@linux.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
2018-09-04 10:35:47 -07:00
Linus Torvalds 706a1ea65e Merge branch 'tlb-fixes'
Merge fixes for missing TLB shootdowns.

This fixes a couple of cases that involved us possibly freeing page
table structures before the required TLB shootdown had been done.

There are a few cleanup patches to make the code easier to follow, and
to avoid some of the more problematic cases entirely when not necessary.

To make this easier for backports, it undoes the recent lazy TLB
patches, because the cleanups and fixes are more important, and Rik is
ok with re-doing them later when things have calmed down.

The missing TLB flush was only delayed, and the wrong ordering only
happened under memory pressure (and in theory under a couple of other
fairly theoretical situations), so this may have been all very unlikely
to have hit people in practice.

But getting the TLB shootdown wrong is _so_ hard to debug and see that I
consider this a crticial fix.

Many thanks to Jann Horn for having debugged this.

* tlb-fixes:
  x86/mm: Only use tlb_remove_table() for paravirt
  mm: mmu_notifier fix for tlb_end_vma
  mm/tlb, x86/mm: Support invalidating TLB caches for RCU_TABLE_FREE
  mm/tlb: Remove tlb_remove_table() non-concurrent condition
  mm: move tlb_table_flush to tlb_flush_mmu_free
  x86/mm/tlb: Revert the recent lazy TLB patches
2018-08-23 14:55:01 -07:00
Linus Torvalds 0c4b0f815f A few MIPS fixes for 4.19:
- Fix microMIPS build failures by adding a .insn directive to the
     barrier_before_unreachable() asm statement in order to convince the
     toolchain that the asm statement is a valid branch target rather
     than a bogus attempt to switch ISA.
 
   - Clean up our declarations of TLB functions that we overwrite with
     generated code in order to prevent the compiler making assumptions
     about alignment that cause microMIPS kernels built with GCC 7 &
     above to die early during boot.
 
   - Fix up a regression for MIPS32 kernels which slipped into the main
     MIPS pull for 4.19, causing CONFIG_32BIT=y kernels to contain
     inappropriate MIPS64 instructions.
 
   - Extend our existing workaround for MIPSr6 builds that end up using
     the __multi3 intrinsic to GCC 7 & below, rather than just GCC 7.
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Merge tag 'mips_4.19_2' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux

Pull MIPS fixes from Paul Burton:

  - Fix microMIPS build failures by adding a .insn directive to the
    barrier_before_unreachable() asm statement in order to convince the
    toolchain that the asm statement is a valid branch target rather
    than a bogus attempt to switch ISA.

  - Clean up our declarations of TLB functions that we overwrite with
    generated code in order to prevent the compiler making assumptions
    about alignment that cause microMIPS kernels built with GCC 7 &
    above to die early during boot.

  - Fix up a regression for MIPS32 kernels which slipped into the main
    MIPS pull for 4.19, causing CONFIG_32BIT=y kernels to contain
    inappropriate MIPS64 instructions.

  - Extend our existing workaround for MIPSr6 builds that end up using
    the __multi3 intrinsic to GCC 7 & below, rather than just GCC 7.

* tag 'mips_4.19_2' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux:
  MIPS: lib: Provide MIPS64r6 __multi3() for GCC < 7
  MIPS: Workaround GCC __builtin_unreachable reordering bug
  compiler.h: Allow arch-specific asm/compiler.h
  MIPS: Avoid move psuedo-instruction whilst using MIPS_ISA_LEVEL
  MIPS: Consistently declare TLB functions
  MIPS: Export tlbmiss_handler_setup_pgd near its definition
2018-08-23 14:23:08 -07:00
Peter Zijlstra d86564a2f0 mm/tlb, x86/mm: Support invalidating TLB caches for RCU_TABLE_FREE
Jann reported that x86 was missing required TLB invalidates when he
hit the !*batch slow path in tlb_remove_table().

This is indeed the case; RCU_TABLE_FREE does not provide TLB (cache)
invalidates, the PowerPC-hash where this code originated and the
Sparc-hash where this was subsequently used did not need that. ARM
which later used this put an explicit TLB invalidate in their
__p*_free_tlb() functions, and PowerPC-radix followed that example.

But when we hooked up x86 we failed to consider this. Fix this by
(optionally) hooking tlb_remove_table() into the TLB invalidate code.

NOTE: s390 was also needing something like this and might now
      be able to use the generic code again.

[ Modified to be on top of Nick's cleanups, which simplified this patch
  now that tlb_flush_mmu_tlbonly() really only flushes the TLB - Linus ]

Fixes: 9e52fc2b50 ("x86/mm: Enable RCU based page table freeing (CONFIG_HAVE_RCU_TABLE_FREE=y)")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Rik van Riel <riel@surriel.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: David Miller <davem@davemloft.net>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-23 11:55:58 -07:00
Ard Biesheuvel 271ca78877 arch: enable relative relocations for arm64, power and x86
Patch series "add support for relative references in special sections", v10.

This adds support for emitting special sections such as initcall arrays,
PCI fixups and tracepoints as relative references rather than absolute
references.  This reduces the size by 50% on 64-bit architectures, but
more importantly, it removes the need for carrying relocation metadata for
these sections in relocatable kernels (e.g., for KASLR) that needs to be
fixed up at boot time.  On arm64, this reduces the vmlinux footprint of
such a reference by 8x (8 byte absolute reference + 24 byte RELA entry vs
4 byte relative reference)

Patch #3 was sent out before as a single patch.  This series supersedes
the previous submission.  This version makes relative ksymtab entries
dependent on the new Kconfig symbol HAVE_ARCH_PREL32_RELOCATIONS rather
than trying to infer from kbuild test robot replies for which
architectures it should be blacklisted.

Patch #1 introduces the new Kconfig symbol HAVE_ARCH_PREL32_RELOCATIONS,
and sets it for the main architectures that are expected to benefit the
most from this feature, i.e., 64-bit architectures or ones that use
runtime relocations.

Patch #2 add support for #define'ing __DISABLE_EXPORTS to get rid of
ksymtab/kcrctab sections in decompressor and EFI stub objects when
rebuilding existing C files to run in a different context.

Patches #4 - #6 implement relative references for initcalls, PCI fixups
and tracepoints, respectively, all of which produce sections with order
~1000 entries on an arm64 defconfig kernel with tracing enabled.  This
means we save about 28 KB of vmlinux space for each of these patches.

[From the v7 series blurb, which included the jump_label patches as well]:

  For the arm64 kernel, all patches combined reduce the memory footprint
  of vmlinux by about 1.3 MB (using a config copied from Ubuntu that has
  KASLR enabled), of which ~1 MB is the size reduction of the RELA section
  in .init, and the remaining 300 KB is reduction of .text/.data.

This patch (of 6):

Before updating certain subsystems to use place relative 32-bit
relocations in special sections, to save space and reduce the number of
absolute relocations that need to be processed at runtime by relocatable
kernels, introduce the Kconfig symbol and define it for some architectures
that should be able to support and benefit from it.

Link: http://lkml.kernel.org/r/20180704083651.24360-2-ard.biesheuvel@linaro.org
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Thomas Garnier <thgarnie@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: James Morris <jmorris@namei.org>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Cc: James Morris <james.morris@microsoft.com>
Cc: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:47 -07:00
Paul Burton 04f264d3a8
compiler.h: Allow arch-specific asm/compiler.h
We have a need to override the definition of
barrier_before_unreachable() for MIPS, which means we either need to add
architecture-specific code into linux/compiler-gcc.h or we need to allow
the architecture to provide a header that can define the macro before
the generic definition. The latter seems like the better approach.

A straightforward approach to the per-arch header is to make use of
asm-generic to provide a default empty header & adjust architectures
which don't need anything specific to make use of that by adding the
header to generic-y. Unfortunately this doesn't work so well due to
commit 28128c61e0 ("kconfig.h: Include compiler types to avoid missed
struct attributes") which caused linux/compiler_types.h to be included
in the compilation of every C file via the -include linux/kconfig.h flag
in c_flags.

Because the -include flag is present for all C files we compile, we need
the architecture-provided header to be present before any C files are
compiled. If any C files can be compiled prior to the asm-generic header
wrappers being generated then we hit a build failure due to missing
header. Such cases do exist - one pointed out by the kbuild test robot
is the compilation of arch/ia64/kernel/nr-irqs.c, which occurs as part
of the archprepare target [1].

This leaves us with a few options:

  1) Use generic-y & fix any build failures we find by enforcing
     ordering such that the asm-generic target occurs before any C
     compilation, such that linux/compiler_types.h can always include
     the generated asm-generic wrapper which in turn includes the empty
     asm-generic header. This would rely on us finding all the
     problematic cases - I don't know for sure that the ia64 issue is
     the only one.

  2) Add an actual empty header to each architecture, so that we don't
     need the generated asm-generic wrapper. This seems messy.

  3) Give up & add #ifdef CONFIG_MIPS or similar to
     linux/compiler_types.h. This seems messy too.

  4) Include the arch header only when it's actually needed, removing
     the need for the asm-generic wrapper for all other architectures.

This patch allows us to use approach 4, by including an asm/compiler.h
header from linux/compiler_types.h after the inclusion of the
compiler-specific linux/compiler-*.h header(s). We do this
conditionally, only when CONFIG_HAVE_ARCH_COMPILER_H is selected, in
order to avoid the need for asm-generic wrappers & the associated build
ordering issue described above. The asm/compiler.h header is included
after the generic linux/compiler-*.h header(s) for consistency with the
way linux/compiler-intel.h & linux/compiler-clang.h are included after
the linux/compiler-gcc.h header that they override.

[1] https://lists.01.org/pipermail/kbuild-all/2018-August/051175.html

Signed-off-by: Paul Burton <paul.burton@mips.com>
Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Patchwork: https://patchwork.linux-mips.org/patch/20269/
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: James Hogan <jhogan@kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-arch@vger.kernel.org
Cc: linux-kbuild@vger.kernel.org
Cc: linux-mips@linux-mips.org
2018-08-21 10:05:45 -07:00
Linus Torvalds fa1b5d09d0 Consolidation of Kconfig files by Christoph Hellwig.
Move the source statements of arch-independent Kconfig files instead of
 duplicating the includes in every arch/$(SRCARCH)/Kconfig.
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Merge tag 'kconfig-v4.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kconfig consolidation from Masahiro Yamada:
 "Consolidation of Kconfig files by Christoph Hellwig.

  Move the source statements of arch-independent Kconfig files instead
  of duplicating the includes in every arch/$(SRCARCH)/Kconfig"

* tag 'kconfig-v4.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kconfig: add a Memory Management options" menu
  kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt
  kconfig: use a menu in arch/Kconfig to reduce clutter
  kconfig: include kernel/Kconfig.preempt from init/Kconfig
  Kconfig: consolidate the "Kernel hacking" menu
  kconfig: include common Kconfig files from top-level Kconfig
  kconfig: remove duplicate SWAP symbol defintions
  um: create a proper drivers Kconfig
  um: cleanup Kconfig files
  um: stop abusing KBUILD_KCONFIG
2018-08-15 13:05:12 -07:00
Linus Torvalds 7c7b562c6f - Kconfig and Makefile clean-ups (Masahiro Yamada, Kees Cook)
- gcc-common.h definition clean-ups (Alexander Popov)
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Merge tag 'gcc-plugin-cleanup-v4.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull gcc plugin cleanups from Kees Cook:

 - Kconfig and Makefile clean-ups (Masahiro Yamada, Kees Cook)

 - gcc-common.h definition clean-ups (Alexander Popov)

* tag 'gcc-plugin-cleanup-v4.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  gcc-plugins: Clean up the cgraph_create_edge* macros
  gcc-plugins: Regularize Makefile.gcc-plugins
  gcc-plugins: split out Kconfig entries to scripts/gcc-plugins/Kconfig
  gcc-plugins: remove unused GCC_PLUGIN_SUBDIR
2018-08-15 12:06:16 -07:00
Randy Dunlap 22471e1313 kconfig: use a menu in arch/Kconfig to reduce clutter
Put everything in arch/Kconfig into a General options menu
so that they don't clutter up the main/major/primary list of
menu options.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-08-02 08:06:54 +09:00
Christoph Hellwig 87a4c37599 kconfig: include kernel/Kconfig.preempt from init/Kconfig
Almost all architectures include it.  Add a ARCH_NO_PREEMPT symbol to
disable preempt support for alpha, hexagon, non-coldfire m68k and
user mode Linux.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-08-02 08:06:54 +09:00
Christoph Hellwig 1572497cb0 kconfig: include common Kconfig files from top-level Kconfig
Instead of duplicating the source statements in every architecture just
do it once in the toplevel Kconfig file.

Note that with this the inclusion of arch/$(SRCARCH/Kconfig moves out of
the top-level Kconfig into arch/Kconfig so that don't violate ordering
constraits while keeping a sensible menu structure.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-08-02 08:03:23 +09:00
Masahiro Yamada 45332b1bdf gcc-plugins: split out Kconfig entries to scripts/gcc-plugins/Kconfig
Collect relevant code into the scripts/gcc-plugins directory.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
2018-07-24 16:11:07 -07:00
Thomas Gleixner 05736e4ac1 cpu/hotplug: Provide knobs to control SMT
Provide a command line and a sysfs knob to control SMT.

The command line options are:

 'nosmt':	Enumerate secondary threads, but do not online them
 		
 'nosmt=force': Ignore secondary threads completely during enumeration
 		via MP table and ACPI/MADT.

The sysfs control file has the following states (read/write):

 'on':		 SMT is enabled. Secondary threads can be freely onlined
 'off':		 SMT is disabled. Secondary threads, even if enumerated
 		 cannot be onlined
 'forceoff':	 SMT is permanentely disabled. Writes to the control
 		 file are rejected.
 'notsupported': SMT is not supported by the CPU

The command line option 'nosmt' sets the sysfs control to 'off'. This
can be changed to 'on' to reenable SMT during runtime.

The command line option 'nosmt=force' sets the sysfs control to
'forceoff'. This cannot be changed during runtime.

When SMT is 'on' and the control file is changed to 'off' then all online
secondary threads are offlined and attempts to online a secondary thread
later on are rejected.

When SMT is 'off' and the control file is changed to 'on' then secondary
threads can be onlined again. The 'off' -> 'on' transition does not
automatically online the secondary threads.

When the control file is set to 'forceoff', the behaviour is the same as
setting it to 'off', but the operation is irreversible and later writes to
the control file are rejected.

When the control status is 'notsupported' then writes to the control file
are rejected.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
2018-06-21 14:20:58 +02:00
Mauro Carvalho Chehab 5fb94e9ca3 docs: Fix some broken references
As we move stuff around, some doc references are broken. Fix some of
them via this script:
	./scripts/documentation-file-ref-check --fix

Manually checked if the produced result is valid, removing a few
false-positives.

Acked-by: Takashi Iwai <tiwai@suse.de>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Stephen Boyd <sboyd@kernel.org>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Coly Li <colyli@suse.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Jonathan Corbet <corbet@lwn.net>
2018-06-15 18:10:01 -03:00
Masahiro Yamada d148eac0e7 Kbuild: rename HAVE_CC_STACKPROTECTOR config variable
HAVE_CC_STACKPROTECTOR should be selected by architectures with stack
canary implementation.  It is not about the compiler support.

For the consistency with commit 050e9baa9d ("Kbuild: rename
CC_STACKPROTECTOR[_STRONG] config variables"), remove 'CC_' from the
config symbol.

I moved the 'select' lines to keep the alphabetical sorting.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-15 07:15:28 +09:00
Linus Torvalds 050e9baa9d Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables
The changes to automatically test for working stack protector compiler
support in the Kconfig files removed the special STACKPROTECTOR_AUTO
option that picked the strongest stack protector that the compiler
supported.

That was all a nice cleanup - it makes no sense to have the AUTO case
now that the Kconfig phase can just determine the compiler support
directly.

HOWEVER.

It also meant that doing "make oldconfig" would now _disable_ the strong
stackprotector if you had AUTO enabled, because in a legacy config file,
the sane stack protector configuration would look like

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  # CONFIG_CC_STACKPROTECTOR_NONE is not set
  # CONFIG_CC_STACKPROTECTOR_REGULAR is not set
  # CONFIG_CC_STACKPROTECTOR_STRONG is not set
  CONFIG_CC_STACKPROTECTOR_AUTO=y

and when you ran this through "make oldconfig" with the Kbuild changes,
it would ask you about the regular CONFIG_CC_STACKPROTECTOR (that had
been renamed from CONFIG_CC_STACKPROTECTOR_REGULAR to just
CONFIG_CC_STACKPROTECTOR), but it would think that the STRONG version
used to be disabled (because it was really enabled by AUTO), and would
disable it in the new config, resulting in:

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
  CONFIG_CC_STACKPROTECTOR=y
  # CONFIG_CC_STACKPROTECTOR_STRONG is not set
  CONFIG_CC_HAS_SANE_STACKPROTECTOR=y

That's dangerously subtle - people could suddenly find themselves with
the weaker stack protector setup without even realizing.

The solution here is to just rename not just the old RECULAR stack
protector option, but also the strong one.  This does that by just
removing the CC_ prefix entirely for the user choices, because it really
is not about the compiler support (the compiler support now instead
automatially impacts _visibility_ of the options to users).

This results in "make oldconfig" actually asking the user for their
choice, so that we don't have any silent subtle security model changes.
The end result would generally look like this:

  CONFIG_HAVE_CC_STACKPROTECTOR=y
  CONFIG_CC_HAS_STACKPROTECTOR_NONE=y
  CONFIG_STACKPROTECTOR=y
  CONFIG_STACKPROTECTOR_STRONG=y
  CONFIG_CC_HAS_SANE_STACKPROTECTOR=y

where the "CC_" versions really are about internal compiler
infrastructure, not the user selections.

Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-06-14 12:21:18 +09:00
Linus Torvalds be779f03d5 Kbuild updates for v4.18 (2nd)
- fix some bugs introduced by the recent Kconfig syntax extension
 
  - add some symbols about compiler information in Kconfig, such as
    CC_IS_GCC, CC_IS_CLANG, GCC_VERSION, etc.
 
  - test compiler capability for the stack protector in Kconfig, and
    clean-up Makefile
 
  - test compiler capability for GCC-plugins in Kconfig, and clean-up
    Makefile
 
  - allow to enable GCC-plugins for COMPILE_TEST
 
  - test compiler capability for KCOV in Kconfig and correct dependency
 
  - remove auto-detect mode of the GCOV format, which is now more nicely
    handled in Kconfig
 
  - test compiler capability for mprofile-kernel on PowerPC, and
    clean-up Makefile
 
  - misc cleanups
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Merge tag 'kbuild-v4.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull more Kbuild updates from Masahiro Yamada:

 - fix some bugs introduced by the recent Kconfig syntax extension

 - add some symbols about compiler information in Kconfig, such as
   CC_IS_GCC, CC_IS_CLANG, GCC_VERSION, etc.

 - test compiler capability for the stack protector in Kconfig, and
   clean-up Makefile

 - test compiler capability for GCC-plugins in Kconfig, and clean-up
   Makefile

 - allow to enable GCC-plugins for COMPILE_TEST

 - test compiler capability for KCOV in Kconfig and correct dependency

 - remove auto-detect mode of the GCOV format, which is now more nicely
   handled in Kconfig

 - test compiler capability for mprofile-kernel on PowerPC, and clean-up
   Makefile

 - misc cleanups

* tag 'kbuild-v4.18-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  linux/linkage.h: replace VMLINUX_SYMBOL_STR() with __stringify()
  kconfig: fix localmodconfig
  sh: remove no-op macro VMLINUX_SYMBOL()
  powerpc/kbuild: move -mprofile-kernel check to Kconfig
  Documentation: kconfig: add recommended way to describe compiler support
  gcc-plugins: disable GCC_PLUGIN_STRUCTLEAK_BYREF_ALL for COMPILE_TEST
  gcc-plugins: allow to enable GCC_PLUGINS for COMPILE_TEST
  gcc-plugins: test plugin support in Kconfig and clean up Makefile
  gcc-plugins: move GCC version check for PowerPC to Kconfig
  kcov: test compiler capability in Kconfig and correct dependency
  gcov: remove CONFIG_GCOV_FORMAT_AUTODETECT
  arm64: move GCC version check for ARCH_SUPPORTS_INT128 to Kconfig
  kconfig: add CC_IS_CLANG and CLANG_VERSION
  kconfig: add CC_IS_GCC and GCC_VERSION
  stack-protector: test compiler capability in Kconfig and drop AUTO mode
  kbuild: fix endless syncconfig in case arch Makefile sets CROSS_COMPILE
2018-06-13 08:40:34 -07:00
Masahiro Yamada caa91ba53e gcc-plugins: disable GCC_PLUGIN_STRUCTLEAK_BYREF_ALL for COMPILE_TEST
We have enabled GCC_PLUGINS for COMPILE_TEST, but allmodconfig now
produces new warnings.

  CC [M]  drivers/net/wireless/broadcom/brcm80211/brcmsmac/phy/phy_n.o
drivers/net/wireless/broadcom/brcm80211/brcmsmac/phy/phy_n.c: In function ‘wlc_phy_workarounds_nphy_rev7’:
drivers/net/wireless/broadcom/brcm80211/brcmsmac/phy/phy_n.c:16563:1: warning: the frame size of 3128 bytes is larger than 2048 bytes [-Wframe-larger-than=]
 }
 ^
drivers/net/wireless/broadcom/brcm80211/brcmsmac/phy/phy_n.c: In function ‘wlc_phy_workarounds_nphy_rev3’:
drivers/net/wireless/broadcom/brcm80211/brcmsmac/phy/phy_n.c:16905:1: warning: the frame size of 2800 bytes is larger than 2048 bytes [-Wframe-larger-than=]
 }
 ^
drivers/net/wireless/broadcom/brcm80211/brcmsmac/phy/phy_n.c: In function ‘wlc_phy_cal_txiqlo_nphy’:
drivers/net/wireless/broadcom/brcm80211/brcmsmac/phy/phy_n.c:26033:1: warning: the frame size of 2488 bytes is larger than 2048 bytes [-Wframe-larger-than=]
 }
 ^

It looks like GCC_PLUGIN_STRUCTLEAK_BYREF_ALL is causing this.
Add "depends on !COMPILE_TEST" to not dirturb the compile test.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-06-11 09:16:28 +09:00
Masahiro Yamada 1658dcee3d gcc-plugins: allow to enable GCC_PLUGINS for COMPILE_TEST
Now that the compiler's plugin support is checked in Kconfig,
all{yes,mod}config will not be bothered.

Remove 'depends on !COMPILE_TEST' for GCC_PLUGINS.

'depends on !COMPILE_TEST' for the following three are still kept:
  GCC_PLUGIN_CYC_COMPLEXITY
  GCC_PLUGIN_STRUCTLEAK_VERBOSE
  GCC_PLUGIN_RANDSTRUCT_PERFORMANCE

Kees suggested to do so because the first two are too noisy, and the
last one would reduce the compile test coverage.  I commented the
reasons in arch/Kconfig.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kees Cook <keescook@chromium.org>
2018-06-11 09:16:27 +09:00
Masahiro Yamada 59f53855ba gcc-plugins: test plugin support in Kconfig and clean up Makefile
Run scripts/gcc-plugin.sh from Kconfig so that users can enable
GCC_PLUGINS only when the compiler supports building plugins.

Kconfig defines a new symbol, PLUGIN_HOSTCC.  This will contain
the compiler (g++ or gcc) used for building plugins, or empty
if the plugin can not be supported at all.

This allows us to remove all ugly testing in Makefile.gcc-plugins.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kees Cook <keescook@chromium.org>
2018-06-11 09:16:22 +09:00
Linus Torvalds d82991a868 Merge branch 'core-rseq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull restartable sequence support from Thomas Gleixner:
 "The restartable sequences syscall (finally):

  After a lot of back and forth discussion and massive delays caused by
  the speculative distraction of maintainers, the core set of
  restartable sequences has finally reached a consensus.

  It comes with the basic non disputed core implementation along with
  support for arm, powerpc and x86 and a full set of selftests

  It was exposed to linux-next earlier this week, so it does not fully
  comply with the merge window requirements, but there is really no
  point to drag it out for yet another cycle"

* 'core-rseq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rseq/selftests: Provide Makefile, scripts, gitignore
  rseq/selftests: Provide parametrized tests
  rseq/selftests: Provide basic percpu ops test
  rseq/selftests: Provide basic test
  rseq/selftests: Provide rseq library
  selftests/lib.mk: Introduce OVERRIDE_TARGETS
  powerpc: Wire up restartable sequences system call
  powerpc: Add syscall detection for restartable sequences
  powerpc: Add support for restartable sequences
  x86: Wire up restartable sequence system call
  x86: Add support for restartable sequences
  arm: Wire up restartable sequences system call
  arm: Add syscall detection for restartable sequences
  arm: Add restartable sequences support
  rseq: Introduce restartable sequences system call
  uapi/headers: Provide types_32_64.h
2018-06-10 10:17:09 -07:00
Masahiro Yamada 2a61f4747e stack-protector: test compiler capability in Kconfig and drop AUTO mode
Move the test for -fstack-protector(-strong) option to Kconfig.

If the compiler does not support the option, the corresponding menu
is automatically hidden.  If STRONG is not supported, it will fall
back to REGULAR.  If REGULAR is not supported, it will be disabled.
This means, AUTO is implicitly handled by the dependency solver of
Kconfig, hence removed.

I also turned the 'choice' into only two boolean symbols.  The use of
'choice' is not a good idea here, because all of all{yes,mod,no}config
would choose the first visible value, while we want allnoconfig to
disable as many features as possible.

X86 has additional shell scripts in case the compiler supports those
options, but generates broken code.  I added CC_HAS_SANE_STACKPROTECTOR
to test this.  I had to add -m32 to gcc-x86_32-has-stack-protector.sh
to make it work correctly.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Kees Cook <keescook@chromium.org>
2018-06-08 18:56:00 +09:00
Linus Torvalds 8715ee75fe Kbuild updates for v4.18
- improve fixdep to coalesce consecutive slashes in dep-files
 
 - fix some issues of the maintainer string generation in deb-pkg script
 
 - remove unused CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX and clean-up
   several tools and linker scripts
 
 - clean-up modpost
 
 - allow to enable the dead code/data elimination for PowerPC in EXPERT mode
 
 - improve two coccinelle scripts for better performance
 
 - pass endianness and machine size flags to sparse for all architecture
 
 - misc fixes
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Merge tag 'kbuild-v4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

 - improve fixdep to coalesce consecutive slashes in dep-files

 - fix some issues of the maintainer string generation in deb-pkg script

 - remove unused CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX and clean-up
   several tools and linker scripts

 - clean-up modpost

 - allow to enable the dead code/data elimination for PowerPC in EXPERT
   mode

 - improve two coccinelle scripts for better performance

 - pass endianness and machine size flags to sparse for all architecture

 - misc fixes

* tag 'kbuild-v4.18' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (25 commits)
  kbuild: add machine size to CHECKFLAGS
  kbuild: add endianness flag to CHEKCFLAGS
  kbuild: $(CHECK) doesnt need NOSTDINC_FLAGS twice
  scripts: Fixed printf format mismatch
  scripts/tags.sh: use `find` for $ALLSOURCE_ARCHS generation
  coccinelle: deref_null: improve performance
  coccinelle: mini_lock: improve performance
  powerpc: Allow LD_DEAD_CODE_DATA_ELIMINATION to be selected
  kbuild: Allow LD_DEAD_CODE_DATA_ELIMINATION to be selectable if enabled
  kbuild: LD_DEAD_CODE_DATA_ELIMINATION no -ffunction-sections/-fdata-sections for module build
  kbuild: Fix asm-generic/vmlinux.lds.h for LD_DEAD_CODE_DATA_ELIMINATION
  modpost: constify *modname function argument where possible
  modpost: remove redundant is_vmlinux() test
  modpost: use strstarts() helper more widely
  modpost: pass struct elf_info pointer to get_modinfo()
  checkpatch: remove VMLINUX_SYMBOL() check
  vmlinux.lds.h: remove no-op macro VMLINUX_SYMBOL()
  kbuild: remove CONFIG_HAVE_UNDERSCORE_SYMBOL_PREFIX
  export.h: remove code for prefixing symbols with underscore
  depmod.sh: remove symbol prefix support
  ...
2018-06-06 11:00:15 -07:00
Mathieu Desnoyers d7822b1e24 rseq: Introduce restartable sequences system call
Expose a new system call allowing each thread to register one userspace
memory area to be used as an ABI between kernel and user-space for two
purposes: user-space restartable sequences and quick access to read the
current CPU number value from user-space.

* Restartable sequences (per-cpu atomics)

Restartables sequences allow user-space to perform update operations on
per-cpu data without requiring heavy-weight atomic operations.

The restartable critical sections (percpu atomics) work has been started
by Paul Turner and Andrew Hunter. It lets the kernel handle restart of
critical sections. [1] [2] The re-implementation proposed here brings a
few simplifications to the ABI which facilitates porting to other
architectures and speeds up the user-space fast path.

Here are benchmarks of various rseq use-cases.

Test hardware:

arm32: ARMv7 Processor rev 4 (v7l) "Cubietruck", 2-core
x86-64: Intel E5-2630 v3@2.40GHz, 16-core, hyperthreading

The following benchmarks were all performed on a single thread.

* Per-CPU statistic counter increment

                getcpu+atomic (ns/op)    rseq (ns/op)    speedup
arm32:                344.0                 31.4          11.0
x86-64:                15.3                  2.0           7.7

* LTTng-UST: write event 32-bit header, 32-bit payload into tracer
             per-cpu buffer

                getcpu+atomic (ns/op)    rseq (ns/op)    speedup
arm32:               2502.0                 2250.0         1.1
x86-64:               117.4                   98.0         1.2

* liburcu percpu: lock-unlock pair, dereference, read/compare word

                getcpu+atomic (ns/op)    rseq (ns/op)    speedup
arm32:                751.0                 128.5          5.8
x86-64:                53.4                  28.6          1.9

* jemalloc memory allocator adapted to use rseq

Using rseq with per-cpu memory pools in jemalloc at Facebook (based on
rseq 2016 implementation):

The production workload response-time has 1-2% gain avg. latency, and
the P99 overall latency drops by 2-3%.

* Reading the current CPU number

Speeding up reading the current CPU number on which the caller thread is
running is done by keeping the current CPU number up do date within the
cpu_id field of the memory area registered by the thread. This is done
by making scheduler preemption set the TIF_NOTIFY_RESUME flag on the
current thread. Upon return to user-space, a notify-resume handler
updates the current CPU value within the registered user-space memory
area. User-space can then read the current CPU number directly from
memory.

Keeping the current cpu id in a memory area shared between kernel and
user-space is an improvement over current mechanisms available to read
the current CPU number, which has the following benefits over
alternative approaches:

- 35x speedup on ARM vs system call through glibc
- 20x speedup on x86 compared to calling glibc, which calls vdso
  executing a "lsl" instruction,
- 14x speedup on x86 compared to inlined "lsl" instruction,
- Unlike vdso approaches, this cpu_id value can be read from an inline
  assembly, which makes it a useful building block for restartable
  sequences.
- The approach of reading the cpu id through memory mapping shared
  between kernel and user-space is portable (e.g. ARM), which is not the
  case for the lsl-based x86 vdso.

On x86, yet another possible approach would be to use the gs segment
selector to point to user-space per-cpu data. This approach performs
similarly to the cpu id cache, but it has two disadvantages: it is
not portable, and it is incompatible with existing applications already
using the gs segment selector for other purposes.

Benchmarking various approaches for reading the current CPU number:

ARMv7 Processor rev 4 (v7l)
Machine model: Cubietruck
- Baseline (empty loop):                                    8.4 ns
- Read CPU from rseq cpu_id:                               16.7 ns
- Read CPU from rseq cpu_id (lazy register):               19.8 ns
- glibc 2.19-0ubuntu6.6 getcpu:                           301.8 ns
- getcpu system call:                                     234.9 ns

x86-64 Intel(R) Xeon(R) CPU E5-2630 v3 @ 2.40GHz:
- Baseline (empty loop):                                    0.8 ns
- Read CPU from rseq cpu_id:                                0.8 ns
- Read CPU from rseq cpu_id (lazy register):                0.8 ns
- Read using gs segment selector:                           0.8 ns
- "lsl" inline assembly:                                   13.0 ns
- glibc 2.19-0ubuntu6 getcpu:                              16.6 ns
- getcpu system call:                                      53.9 ns

- Speed (benchmark taken on v8 of patchset)

Running 10 runs of hackbench -l 100000 seems to indicate, contrary to
expectations, that enabling CONFIG_RSEQ slightly accelerates the
scheduler:

Configuration: 2 sockets * 8-core Intel(R) Xeon(R) CPU E5-2630 v3 @
2.40GHz (directly on hardware, hyperthreading disabled in BIOS, energy
saving disabled in BIOS, turboboost disabled in BIOS, cpuidle.off=1
kernel parameter), with a Linux v4.6 defconfig+localyesconfig,
restartable sequences series applied.

* CONFIG_RSEQ=n

avg.:      41.37 s
std.dev.:   0.36 s

* CONFIG_RSEQ=y

avg.:      40.46 s
std.dev.:   0.33 s

- Size

On x86-64, between CONFIG_RSEQ=n/y, the text size increase of vmlinux is
567 bytes, and the data size increase of vmlinux is 5696 bytes.

[1] https://lwn.net/Articles/650333/
[2] http://www.linuxplumbersconf.org/2013/ocw/system/presentations/1695/original/LPC%20-%20PerCpu%20Atomics.pdf

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Watson <davejwatson@fb.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Chris Lameter <cl@linux.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Andrew Hunter <ahh@google.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Maurer <bmaurer@fb.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-api@vger.kernel.org
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20151027235635.16059.11630.stgit@pjt-glaptop.roam.corp.google.com
Link: http://lkml.kernel.org/r/20150624222609.6116.86035.stgit@kitami.mtv.corp.google.com
Link: https://lkml.kernel.org/r/20180602124408.8430-3-mathieu.desnoyers@efficios.com
2018-06-06 11:58:31 +02:00
Linus Torvalds 0bbcce5d1e Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timers and timekeeping updates from Thomas Gleixner:

 - Core infrastucture work for Y2038 to address the COMPAT interfaces:

     + Add a new Y2038 safe __kernel_timespec and use it in the core
       code

     + Introduce config switches which allow to control the various
       compat mechanisms

     + Use the new config switch in the posix timer code to control the
       32bit compat syscall implementation.

 - Prevent bogus selection of CPU local clocksources which causes an
   endless reselection loop

 - Remove the extra kthread in the clocksource code which has no value
   and just adds another level of indirection

 - The usual bunch of trivial updates, cleanups and fixlets all over the
   place

 - More SPDX conversions

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  clocksource/drivers/mxs_timer: Switch to SPDX identifier
  clocksource/drivers/timer-imx-tpm: Switch to SPDX identifier
  clocksource/drivers/timer-imx-gpt: Switch to SPDX identifier
  clocksource/drivers/timer-imx-gpt: Remove outdated file path
  clocksource/drivers/arc_timer: Add comments about locking while read GFRC
  clocksource/drivers/mips-gic-timer: Add pr_fmt and reword pr_* messages
  clocksource/drivers/sprd: Fix Kconfig dependency
  clocksource: Move inline keyword to the beginning of function declarations
  timer_list: Remove unused function pointer typedef
  timers: Adjust a kernel-doc comment
  tick: Prefer a lower rating device only if it's CPU local device
  clocksource: Remove kthread
  time: Change nanosleep to safe __kernel_* types
  time: Change types to new y2038 safe __kernel_* types
  time: Fix get_timespec64() for y2038 safe compat interfaces
  time: Add new y2038 safe __kernel_timespec
  posix-timers: Make compat syscalls depend on CONFIG_COMPAT_32BIT_TIME
  time: Introduce CONFIG_COMPAT_32BIT_TIME
  time: Introduce CONFIG_64BIT_TIME in architectures
  compat: Enable compat_get/put_timespec64 always
  ...
2018-06-04 20:27:54 -07:00
Linus Torvalds e5a594643a dma-mapping updates for 4.18:
- replaceme the force_dma flag with a dma_configure bus method.
    (Nipun Gupta, although one patch is іncorrectly attributed to me
     due to a git rebase bug)
  - use GFP_DMA32 more agressively in dma-direct. (Takashi Iwai)
  - remove PCI_DMA_BUS_IS_PHYS and rely on the dma-mapping API to do the
    right thing for bounce buffering.
  - move dma-debug initialization to common code, and apply a few cleanups
    to the dma-debug code.
  - cleanup the Kconfig mess around swiotlb selection
  - swiotlb comment fixup (Yisheng Xie)
  - a trivial swiotlb fix. (Dan Carpenter)
  - support swiotlb on RISC-V. (based on a patch from Palmer Dabbelt)
  - add a new generic dma-noncoherent dma_map_ops implementation and use
    it for arc, c6x and nds32.
  - improve scatterlist validity checking in dma-debug. (Robin Murphy)
  - add a struct device quirk to limit the dma-mask to 32-bit due to
    bridge/system issues, and switch x86 to use it instead of a local
    hack for VIA bridges.
  - handle devices without a dma_mask more gracefully in the dma-direct
    code.
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Merge tag 'dma-mapping-4.18' of git://git.infradead.org/users/hch/dma-mapping

Pull dma-mapping updates from Christoph Hellwig:

 - replace the force_dma flag with a dma_configure bus method. (Nipun
   Gupta, although one patch is іncorrectly attributed to me due to a
   git rebase bug)

 - use GFP_DMA32 more agressively in dma-direct. (Takashi Iwai)

 - remove PCI_DMA_BUS_IS_PHYS and rely on the dma-mapping API to do the
   right thing for bounce buffering.

 - move dma-debug initialization to common code, and apply a few
   cleanups to the dma-debug code.

 - cleanup the Kconfig mess around swiotlb selection

 - swiotlb comment fixup (Yisheng Xie)

 - a trivial swiotlb fix. (Dan Carpenter)

 - support swiotlb on RISC-V. (based on a patch from Palmer Dabbelt)

 - add a new generic dma-noncoherent dma_map_ops implementation and use
   it for arc, c6x and nds32.

 - improve scatterlist validity checking in dma-debug. (Robin Murphy)

 - add a struct device quirk to limit the dma-mask to 32-bit due to
   bridge/system issues, and switch x86 to use it instead of a local
   hack for VIA bridges.

 - handle devices without a dma_mask more gracefully in the dma-direct
   code.

* tag 'dma-mapping-4.18' of git://git.infradead.org/users/hch/dma-mapping: (48 commits)
  dma-direct: don't crash on device without dma_mask
  nds32: use generic dma_noncoherent_ops
  nds32: implement the unmap_sg DMA operation
  nds32: consolidate DMA cache maintainance routines
  x86/pci-dma: switch the VIA 32-bit DMA quirk to use the struct device flag
  x86/pci-dma: remove the explicit nodac and allowdac option
  x86/pci-dma: remove the experimental forcesac boot option
  Documentation/x86: remove a stray reference to pci-nommu.c
  core, dma-direct: add a flag 32-bit dma limits
  dma-mapping: remove unused gfp_t parameter to arch_dma_alloc_attrs
  dma-debug: check scatterlist segments
  c6x: use generic dma_noncoherent_ops
  arc: use generic dma_noncoherent_ops
  arc: fix arc_dma_{map,unmap}_page
  arc: fix arc_dma_sync_sg_for_{cpu,device}
  arc: simplify arc_dma_sync_single_for_{cpu,device}
  dma-mapping: provide a generic dma-noncoherent implementation
  dma-mapping: simplify Kconfig dependencies
  riscv: add swiotlb support
  riscv: only enable ZONE_DMA32 for 64-bit
  ...
2018-06-04 10:58:12 -07:00
Nicholas Piggin 5d20ee3192 kbuild: Allow LD_DEAD_CODE_DATA_ELIMINATION to be selectable if enabled
Architectures that are capable can select
HAVE_LD_DEAD_CODE_DATA_ELIMINATION to enable selection of that
option (as an EXPERT kernel option).

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-05-17 22:45:01 +09:00