Commit Graph

15 Commits

Author SHA1 Message Date
Andy Lutomirski 3ae36655b9 x86-64: Rework vsyscall emulation and add vsyscall= parameter
There are three choices:

vsyscall=native: Vsyscalls are native code that issues the
corresponding syscalls.

vsyscall=emulate (default): Vsyscalls are emulated by instruction
fault traps, tested in the bad_area path.  The actual contents of
the vsyscall page is the same as the vsyscall=native case except
that it's marked NX.  This way programs that make assumptions about
what the code in the page does will not be confused when they read
that code.

vsyscall=none: Trying to execute a vsyscall will segfault.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/8449fb3abf89851fd6b2260972666a6f82542284.1312988155.git.luto@mit.edu
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2011-08-10 19:26:46 -05:00
Andy Lutomirski 5cec93c216 x86-64: Emulate legacy vsyscalls
There's a fair amount of code in the vsyscall page.  It contains
a syscall instruction (in the gettimeofday fallback) and who
knows what will happen if an exploit jumps into the middle of
some other code.

Reduce the risk by replacing the vsyscalls with short magic
incantations that cause the kernel to emulate the real
vsyscalls. These incantations are useless if entered in the
middle.

This causes vsyscalls to be a little more expensive than real
syscalls.  Fortunately sensible programs don't use them.
The only exception is time() which is still called by glibc
through the vsyscall - but calling time() millions of times
per second is not sensible. glibc has this fixed in the
development tree.

This patch is not perfect: the vread_tsc and vread_hpet
functions are still at a fixed address.  Fixing that might
involve making alternative patching work in the vDSO.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jesper Juhl <jj@chaosbits.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Jan Beulich <JBeulich@novell.com>
Cc: richard -rw- weinberger <richard.weinberger@gmail.com>
Cc: Mikael Pettersson <mikpe@it.uu.se>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Louis Rilling <Louis.Rilling@kerlabs.com>
Cc: Valdis.Kletnieks@vt.edu
Cc: pageexec@freemail.hu
Link: http://lkml.kernel.org/r/e64e1b3c64858820d12c48fa739efbd1485e79d5.1307292171.git.luto@mit.edu
[ Removed the CONFIG option - it's simpler to just do it unconditionally. Tidied up the code as well. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-06-07 10:02:35 +02:00
Gleb Natapov 631bc48782 KVM: Handle async PF in a guest.
When async PF capability is detected hook up special page fault handler
that will handle async page fault events and bypass other page faults to
regular page fault handler. Also add async PF handling to nested SVM
emulation. Async PF always generates exit to L1 where vcpu thread will
be scheduled out until page is available.

Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
2011-01-12 11:23:16 +02:00
Brian Gerst 9b6dba9e07 x86: Merge simd_math_error() into math_error()
The only difference between FPU and SIMD exceptions is where the
status bits are read from (cwd/swd vs. mxcsr).  This also fixes
the discrepency introduced by commit adf77bac, which fixed FPU
but not SIMD.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <1269176446-2489-3-git-send-email-brgerst@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2010-05-03 13:39:29 -07:00
Akinobu Mita fde0312d01 x86: Remove unused patch_espfix_desc()
patch_espfix_desc() is not used after commit
dc4c2a0aed

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
LKML-Reference: <20090718150955.GB11294@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-07-19 18:27:52 +02:00
Linus Torvalds be15f9d63b Merge branch 'x86-xen-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-xen-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (42 commits)
  xen: cache cr0 value to avoid trap'n'emulate for read_cr0
  xen/x86-64: clean up warnings about IST-using traps
  xen/x86-64: fix breakpoints and hardware watchpoints
  xen: reserve Xen start_info rather than e820 reserving
  xen: add FIX_TEXT_POKE to fixmap
  lguest: update lazy mmu changes to match lguest's use of kvm hypercalls
  xen: honour VCPU availability on boot
  xen: add "capabilities" file
  xen: drop kexec bits from /sys/hypervisor since kexec isn't implemented yet
  xen/sys/hypervisor: change writable_pt to features
  xen: add /sys/hypervisor support
  xen/xenbus: export xenbus_dev_changed
  xen: use device model for suspending xenbus devices
  xen: remove suspend_cancel hook
  xen/dev-evtchn: clean up locking in evtchn
  xen: export ioctl headers to userspace
  xen: add /dev/xen/evtchn driver
  xen: add irq_from_evtchn
  xen: clean up gate trap/interrupt constants
  xen: set _PAGE_NX in __supported_pte_mask before pagetable construction
  ...
2009-06-10 16:16:27 -07:00
Linus Torvalds bb7762961d Merge branch 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'x86-mm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (22 commits)
  x86: fix system without memory on node0
  x86, mm: Fix node_possible_map logic
  mm, x86: remove MEMORY_HOTPLUG_RESERVE related code
  x86: make sparse mem work in non-NUMA mode
  x86: process.c, remove useless headers
  x86: merge process.c a bit
  x86: use sparse_memory_present_with_active_regions() on UMA
  x86: unify 64-bit UMA and NUMA paging_init()
  x86: Allow 1MB of slack between the e820 map and SRAT, not 4GB
  x86: Sanity check the e820 against the SRAT table using e820 map only
  x86: clean up and and print out initial max_pfn_mapped
  x86/pci: remove rounding quirk from e820_setup_gap()
  x86, e820, pci: reserve extra free space near end of RAM
  x86: fix typo in address space documentation
  x86: 46 bit physical address support on 64 bits
  x86, mm: fault.c, use printk_once() in is_errata93()
  x86: move per-cpu mmu_gathers to mm/init.c
  x86: move max_pfn_mapped and max_low_pfn_mapped to setup.c
  x86: unify noexec handling
  x86: remove (null) in /sys kernel_page_tables
  ...
2009-06-10 16:13:20 -07:00
Jeremy Fitzhardinge 6cac5a9246 xen/x86-64: fix breakpoints and hardware watchpoints
Native x86-64 uses the IST mechanism to run int3 and debug traps on
an alternative stack.  Xen does not do this, and so the frames were
being misinterpreted by the ptrace code.  This change special-cases
these two exceptions by using Xen variants which run on the normal
kernel stack properly.

Impact: avoid crash or bad data when IST trap is invoked under Xen
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
2009-05-08 15:51:03 -07:00
Jaswinder Singh Rajput e7d43a74cb x86: avoid multiple declaration of kstack_depth_to_print
Impact: cleanup

asm/stacktrace.h is more appropriate so removing other 2 declarations.

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
LKML-Reference: <1239695308.3033.34.camel@ht.satnam>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-04-14 11:45:33 +02:00
Ingo Molnar a2bcd4731f x86/mm: further cleanups of fault.c's include file section
Impact: cleanup

Eliminate more than 20 unnecessary #include lines in fault.c

Also fix include file dependency bug in asm/traps.h. (this was
masked before, by implicit inclusion)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <tip-56aea8468746e673a4bf50b6a13d97b2d1cbe1e8@git.kernel.org>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
2009-03-30 14:02:02 +02:00
Brian Gerst aa78bcfa01 x86: use pt_regs pointer in do_device_not_available()
The generic exception handler (error_code) passes in the pt_regs
pointer and the error code (unused in this case).  The commit
"x86: fix math_emu register frame access" changed this to pass by
value, which doesn't work correctly with stack protector enabled.
Change it back to use the pt_regs pointer.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-11 12:40:44 +01:00
Tejun Heo d315760ffa x86: fix math_emu register frame access
do_device_not_available() is the handler for #NM and it declares that
it takes a unsigned long and calls math_emu(), which takes a long
argument and surprisingly expects the stack frame starting at the zero
argument would match struct math_emu_info, which isn't true regardless
of configuration in the current code.

This patch makes do_device_not_available() take struct pt_regs like
other exception handlers and initialize struct math_emu_info with
pointer to it and pass pointer to the math_emu_info to math_emulate()
like normal C functions do.  This way, unless gcc makes a copy of
struct pt_regs in do_device_not_available(), the register frame is
correctly accessed regardless of kernel configuration or compiler
used.

This doesn't fix all math_emu problems but it at least gets it
somewhat working.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-02-10 00:39:14 +01:00
Jaswinder Singh d1769d5475 x86: traps.c declare functions before they get used
Impact: cleanup

 In asm/traps.h :-
 do_double_fault : added under X86_64
 sync_regs : added under X86_64
 math_error : moved out from X86_32 as it is common for both 32 and 64 bit
 math_emulate : moved from X86_32 as it is common for both 32 and 64 bit
 smp_thermal_interrupt : added under X86_64
 mce_threshold_interrupt : added under X86_64

Signed-off-by: Jaswinder Singh <jaswinder@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-18 22:33:13 +01:00
H. Peter Anvin 1965aae3c9 x86: Fix ASM_X86__ header guards
Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:

a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2008-10-22 22:55:23 -07:00
Al Viro bb8985586b x86, um: ... and asm-x86 move
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2008-10-22 22:55:20 -07:00