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Ard Biesheuvel 69216a545c crypto: sha256/arm - fix crash bug in Thumb2 build
The SHA256 code we adopted from the OpenSSL project uses a rather
peculiar way to take the address of the round constant table: it
takes the address of the sha256_block_data_order() routine, and
substracts a constant known quantity to arrive at the base of the
table, which is emitted by the same assembler code right before
the routine's entry point.

However, recent versions of binutils have helpfully changed the
behavior of references emitted via an ADR instruction when running
in Thumb2 mode: it now takes the Thumb execution mode bit into
account, which is bit 0 af the address. This means the produced
table address also has bit 0 set, and so we end up with an address
value pointing 1 byte past the start of the table, which results
in crashes such as

  Unable to handle kernel paging request at virtual address bf825000
  pgd = 42f44b11
  [bf825000] *pgd=80000040206003, *pmd=5f1bd003, *pte=00000000
  Internal error: Oops: 207 [#1] PREEMPT SMP THUMB2
  Modules linked in: sha256_arm(+) sha1_arm_ce sha1_arm ...
  CPU: 7 PID: 396 Comm: cryptomgr_test Not tainted 5.0.0-rc6+ #144
  Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
  PC is at sha256_block_data_order+0xaaa/0xb30 [sha256_arm]
  LR is at __this_module+0x17fd/0xffffe800 [sha256_arm]
  pc : [<bf820bca>]    lr : [<bf824ffd>]    psr: 800b0033
  sp : ebc8bbe8  ip : faaabe1c  fp : 2fdd3433
  r10: 4c5f1692  r9 : e43037df  r8 : b04b0a5a
  r7 : c369d722  r6 : 39c3693e  r5 : 7a013189  r4 : 1580d26b
  r3 : 8762a9b0  r2 : eea9c2cd  r1 : 3e9ab536  r0 : 1dea4ae7
  Flags: Nzcv  IRQs on  FIQs on  Mode SVC_32  ISA Thumb  Segment user
  Control: 70c5383d  Table: 6b8467c0  DAC: dbadc0de
  Process cryptomgr_test (pid: 396, stack limit = 0x69e1fe23)
  Stack: (0xebc8bbe8 to 0xebc8c000)
  ...
  unwind: Unknown symbol address bf820bca
  unwind: Index not found bf820bca
  Code: 441a ea80 40f9 440a (f85e) 3b04
  ---[ end trace e560cce92700ef8a ]---

Given that this affects older kernels as well, in case they are built
with a recent toolchain, apply a minimal backportable fix, which is
to emit another non-code label at the start of the routine, and
reference that instead. (This is similar to the current upstream state
of this file in OpenSSL)

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2019-02-22 12:40:56 +08:00
Documentation Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
LICENSES This is a fairly typical cycle for documentation. There's some welcome 2018-10-24 18:01:11 +01:00
arch crypto: sha256/arm - fix crash bug in Thumb2 build 2019-02-22 12:40:56 +08:00
block for-4.21/block-20190102 2019-01-02 18:49:58 -08:00
certs kbuild: remove redundant target cleaning on failure 2019-01-06 09:46:51 +09:00
crypto crypto: sm3 - fix undefined shift by >= width of value 2019-01-10 21:37:32 +08:00
drivers crypto: ccree - add missing inline qualifier 2019-02-22 12:40:56 +08:00
firmware kbuild: change filechk to surround the given command with { } 2019-01-06 09:46:51 +09:00
fs Add Adiantum support for fscrypt 2019-01-06 12:21:11 -08:00
include Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
init jump_label: move 'asm goto' support test to Kconfig 2019-01-06 09:46:51 +09:00
ipc ipc: IPCMNI limit check for semmni 2018-10-31 08:54:14 -07:00
kernel Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
lib Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
mm Change mincore() to count "mapped" pages rather than "cached" pages 2019-01-06 13:43:02 -08:00
net jump_label: move 'asm goto' support test to Kconfig 2019-01-06 09:46:51 +09:00
samples Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid 2019-01-05 17:53:40 -08:00
scripts kconfig: rename generated .*conf-cfg to *conf-cfg 2019-01-06 10:47:09 +09:00
security Merge branch 'mount.part1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-01-05 13:25:58 -08:00
sound Remove 'type' argument from access_ok() function 2019-01-03 18:57:57 -08:00
tools Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt Merge branch 'akpm' (patches from Andrew) 2019-01-05 09:16:18 -08:00
.clang-format page cache: Convert find_get_pages_contig to XArray 2018-10-21 10:46:34 -04:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support for DT binding schema checks 2018-12-13 09:41:32 -06:00
.mailmap A few early MIPS fixes for 4.21: 2019-01-05 12:48:25 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Add CREDITS entry for Shaohua Li 2019-01-04 14:27:09 -07:00
Kbuild kbuild: use assignment instead of define ... endef for filechk_* rules 2019-01-06 10:22:35 +09:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS chrome platform changes for v4.21 2019-01-06 11:40:06 -08:00
Makefile Linux 5.0-rc1 2019-01-06 17:08:20 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.