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author | Nathan Chancellor <nathan@kernel.org> | 2021-07-13 00:46:37 +0300 |
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committer | Will Deacon <will@kernel.org> | 2021-07-13 18:31:31 +0300 |
commit | 8cdd23c23c3d481a43b4aa03dcb5738812831115 (patch) | |
tree | 42880cdc96c3cca8f652b6e76bcba4cefd390f6c /arch/arm64/lib/copy_in_user.S | |
parent | c1132702c71f4b95db9435bac5fdc912881563e0 (diff) | |
download | linux-8cdd23c23c3d481a43b4aa03dcb5738812831115.tar.xz |
arm64: Restrict ARM64_BTI_KERNEL to clang 12.0.0 and newer
Commit 97fed779f2a6 ("arm64: bti: Provide Kconfig for kernel mode BTI")
disabled CONFIG_ARM64_BTI_KERNEL when CONFIG_GCOV_KERNEL was enabled and
compiling with clang because of warnings that were seen with
allmodconfig because LLVM was not emitting PAC/BTI instructions for
compiler generated functions:
| warning: some functions compiled with BTI and some compiled without BTI
| warning: not setting BTI in feature flags
This dependency was fine for avoiding the warnings with allmodconfig
until commit 51c2ee6d121c ("Kconfig: Introduce ARCH_WANTS_NO_INSTR and
CC_HAS_NO_PROFILE_FN_ATTR"), which prevents CONFIG_GCOV_KERNEL from
being enabled with clang 12.0.0 or older because those versions do not
support the no_profile_instrument_function attribute.
As a result, CONFIG_ARM64_BTI_KERNEL gets enabled with allmodconfig and
there are more warnings like the ones above due to CONFIG_KASAN, which
suffers from the same problem as CONFIG_GCOV_KERNEL. This was most
likely not noticed at the time because allmodconfig +
CONFIG_GCOV_KERNEL=n was not tested. defconfig + CONFIG_KASAN=y is
enough to reproduce the same warnings as above.
The root cause of the warnings was resolved in LLVM during the 12.0.0
release so rather than play whack-a-mole with the dependencies, just
update CONFIG_ARM64_BTI_KERNEL to require clang 12.0.0, which will have
all of the issues ironed out.
Link: https://github.com/ClangBuiltLinux/linux/issues/1428
Link: https://github.com/ClangBuiltLinux/continuous-integration2/runs/3010034706?check_suite_focus=true
Link: https://github.com/ClangBuiltLinux/continuous-integration2/runs/3010035725?check_suite_focus=true
Link: https://github.com/llvm/llvm-project/commit/a88c722e687e6780dcd6a58718350dc76fcc4cc9
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20210712214636.3134425-1-nathan@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/lib/copy_in_user.S')
0 files changed, 0 insertions, 0 deletions