linux_dsm_epyc7002/arch/x86/platform
Borislav Petkov d070ccc7ad x86/efi: Remove EFI PGD build time checks
[ Upstream commit 816ef8d7a2c4182e19bc06ab65751cb9e3951e94 ]

With CONFIG_X86_5LEVEL, CONFIG_UBSAN and CONFIG_UBSAN_UNSIGNED_OVERFLOW
enabled, clang fails the build with

  x86_64-linux-ld: arch/x86/platform/efi/efi_64.o: in function `efi_sync_low_kernel_mappings':
  efi_64.c:(.text+0x22c): undefined reference to `__compiletime_assert_354'

which happens due to -fsanitize=unsigned-integer-overflow being enabled:

  -fsanitize=unsigned-integer-overflow: Unsigned integer overflow, where
  the result of an unsigned integer computation cannot be represented
  in its type. Unlike signed integer overflow, this is not undefined
  behavior, but it is often unintentional. This sanitizer does not check
  for lossy implicit conversions performed before such a computation
  (see -fsanitize=implicit-conversion).

and that fires when the (intentional) EFI_VA_START/END defines overflow
an unsigned long, leading to the assertion expressions not getting
optimized away (on GCC they do)...

However, those checks are superfluous: the runtime services mapping
code already makes sure the ranges don't overshoot EFI_VA_END as the
EFI mapping range is hardcoded. On each runtime services call, it is
switched to the EFI-specific PGD and even if mappings manage to escape
that last PGD, this won't remain unnoticed for long.

So rip them out.

See https://github.com/ClangBuiltLinux/linux/issues/256 for more info.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: http://lkml.kernel.org/r/20210107223424.4135538-1-arnd@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
2021-02-17 11:02:24 +01:00
..
atom x86/platform: Convert to new CPU match macros 2020-03-24 21:29:38 +01:00
ce4100 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
efi x86/efi: Remove EFI PGD build time checks 2021-02-17 11:02:24 +01:00
geode Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-07-08 17:49:45 -07:00
goldfish treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282 2019-06-05 17:36:37 +02:00
intel x86: platform: iosf_mbi: Call cpu_latency_qos_*() instead of pm_qos_*() 2020-02-13 11:27:03 +01:00
intel-mid x86/platform/intel-mid: convert to use i2c_new_client_device() 2020-06-19 09:20:25 +02:00
intel-quark x86/platform: Convert to new CPU match macros 2020-03-24 21:29:38 +01:00
iris treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 70 2019-05-24 17:36:47 +02:00
olpc power supply and reset changes for the v5.8 series 2020-06-10 11:28:35 -07:00
pvh treewide: Convert macro and uses of __section(foo) to __section("foo") 2020-10-25 14:51:49 -07:00
scx200 treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
sfi x86: Use pr_warn instead of pr_warning 2019-10-18 15:00:18 +02:00
ts5500 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
uv - Fix the #DE oops message string format which confused tools parsing 2020-10-13 12:02:57 -07:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00