BTI issues with allmodconfig on mainline with LLVM 11 #1428

nickdesaulniers · 2021-07-07T18:23:30Z

https://github.com/ClangBuiltLinux/continuous-integration2/runs/3010034514?check_suite_focus=true

nickdesaulniers · 2021-07-07T18:24:34Z

warning: some functions compiled with BTI and some compiled without BTI
warning: not setting BTI in feature flags

nickdesaulniers · 2021-07-07T18:24:57Z

I wonder if that's in -next or not, perhaps a cherry pick is necessary for mainline.

nathanchance · 2021-07-07T18:26:29Z

Same issue in -next: https://builds.tuxbuild.com/1uzDbJpD7lJ3Wvr5k8yHjL8ouNT/build.log

nathanchance · 2021-07-07T19:10:14Z

51c2ee6d121ceb31ab8d35aff4ce53007aefb455 is the first bad commit
commit 51c2ee6d121ceb31ab8d35aff4ce53007aefb455
Author: Nick Desaulniers <ndesaulniers@google.com>
Date:   Mon Jun 21 16:18:22 2021 -0700

    Kconfig: Introduce ARCH_WANTS_NO_INSTR and CC_HAS_NO_PROFILE_FN_ATTR

    We don't want compiler instrumentation to touch noinstr functions,
    which are annotated with the no_profile_instrument_function function
    attribute. Add a Kconfig test for this and make GCOV depend on it, and
    in the future, PGO.

    If an architecture is using noinstr, it should denote that via this
    Kconfig value. That makes Kconfigs that depend on noinstr able to express
    dependencies in an architecturally agnostic way.

    Cc: Masahiro Yamada <masahiroy@kernel.org>
    Link: https://lore.kernel.org/lkml/YMTn9yjuemKFLbws@hirez.programming.kicks-ass.net/
    Link: https://lore.kernel.org/lkml/YMcssV%2Fn5IBGv4f0@hirez.programming.kicks-ass.net/
    Suggested-by: Nathan Chancellor <nathan@kernel.org>
    Suggested-by: Peter Zijlstra <peterz@infradead.org>
    Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
    Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
    Reviewed-by: Nathan Chancellor <nathan@kernel.org>
    Acked-by: Mark Rutland <mark.rutland@arm.com>
    Acked-by: Heiko Carstens <hca@linux.ibm.com>
    Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Signed-off-by: Kees Cook <keescook@chromium.org>
    Link: https://lore.kernel.org/r/20210621231822.2848305-4-ndesaulniers@google.com

 arch/Kconfig        | 7 +++++++
 arch/arm64/Kconfig  | 1 +
 arch/s390/Kconfig   | 1 +
 arch/x86/Kconfig    | 1 +
 init/Kconfig        | 3 +++
 kernel/gcov/Kconfig | 1 +
 6 files changed, 14 insertions(+)
bisect run success

Let me see if I can reverse bisect LLVM to see what commit in 12.0.0 resolved this...

nathanchance · 2021-07-07T20:09:16Z

llvm/llvm-project@a88c722 resolved this in LLVM. However, I do not understand why we are getting these warnings from Nick's commit in Linux... All that commit does is prevent CONFIG_GCOV_KERNEL from being selected by an architecture that wants noinstr to work, which should actually prevent generation of certain LLVM synthesized functions?

nathanchance · 2021-07-09T00:10:06Z

Patch submitted: https://lore.kernel.org/r/20210709000627.3183718-1-nathan@kernel.org/

Commit 97fed77 ("arm64: bti: Provide Kconfig for kernel mode BTI") disabled CONFIG_ARM64_BTI_KERNEL when CONFIG_GCOV_KERNEL was enabled and compilign with clang because of warnings that occur because LLVM was not emitting PAC/BTI instructions for compiler generated functions. This was an adequate fix to avoid the warnings with allmodconfig until commit 51c2ee6 ("Kconfig: Introduce ARCH_WANTS_NO_INSTR and CC_HAS_NO_PROFILE_FN_ATTR"), which prevented CONFIG_GCOV_KERNEL from being selected with clang 12.0.0 and older because it does not support the no_profile_instrument_function attribute. As a result, CONFIG_ARM64_BTI_KERNEL gets enabled and there are more warnings of this nature. Rather than play whack-a-mole with the config options, just update this condition to require clang 12.0.0, which should have all of the issues ironed out. Link: ClangBuiltLinux#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 Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Commit 97fed77 ("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 51c2ee6 ("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: ClangBuiltLinux#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: llvm/llvm-project@a88c722 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>

nathanchance · 2021-07-17T03:45:05Z

Merged into mainline: https://git.kernel.org/linus/8cdd23c23c3d481a43b4aa03dcb5738812831115

[ Upstream commit 8cdd23c ] Commit 97fed77 ("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 51c2ee6 ("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: ClangBuiltLinux/linux#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: llvm/llvm-project@a88c722 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> Stable-dep-of: c0a454b ("arm64/bti: Disable in kernel BTI when cross section thunks are broken") Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 8cdd23c ] Commit 97fed77 ("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 51c2ee6 ("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: ClangBuiltLinux#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: llvm/llvm-project@a88c722 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> Stable-dep-of: c0a454b ("arm64/bti: Disable in kernel BTI when cross section thunks are broken") Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 8cdd23c ] Commit 97fed77 ("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 51c2ee6 ("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: ClangBuiltLinux/linux#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: llvm/llvm-project@a88c722 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> Stable-dep-of: c0a454b ("arm64/bti: Disable in kernel BTI when cross section thunks are broken") Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 8cdd23c ] Commit 97fed77 ("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 51c2ee6 ("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: ClangBuiltLinux#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: llvm/llvm-project@a88c722 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> Stable-dep-of: c0a454b ("arm64/bti: Disable in kernel BTI when cross section thunks are broken") Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 8cdd23c ] Commit 97fed77 ("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 51c2ee6 ("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: ClangBuiltLinux/linux#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: llvm/llvm-project@a88c722 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> Stable-dep-of: c0a454b ("arm64/bti: Disable in kernel BTI when cross section thunks are broken") Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 8cdd23c ] Commit 97fed77 ("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 51c2ee6 ("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: ClangBuiltLinux#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: llvm/llvm-project@a88c722 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> Stable-dep-of: c0a454b ("arm64/bti: Disable in kernel BTI when cross section thunks are broken") Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 8cdd23c ] Commit 97fed77 ("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 51c2ee6 ("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: ClangBuiltLinux/linux#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: llvm/llvm-project@a88c722 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> Stable-dep-of: c0a454b ("arm64/bti: Disable in kernel BTI when cross section thunks are broken") Signed-off-by: Sasha Levin <sashal@kernel.org>

Source: Kernel.org MR: 123058 Type: Integration Disposition: Backport from git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable linux-5.10.y ChangeID: 050de2898039560060dc2edca3d032ef62132fc1 Description: [ Upstream commit 8cdd23c ] Commit 97fed77 ("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 51c2ee6 ("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: ClangBuiltLinux/linux#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: llvm/llvm-project@a88c722 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> Stable-dep-of: c0a454b ("arm64/bti: Disable in kernel BTI when cross section thunks are broken") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Armin Kuster <akuster@mvista.com>

[ Upstream commit 8cdd23c23c3d481a43b4aa03dcb5738812831115 ] 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: ClangBuiltLinux/linux#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: llvm/llvm-project@a88c722 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> Stable-dep-of: c0a454b9044f ("arm64/bti: Disable in kernel BTI when cross section thunks are broken") Signed-off-by: Sasha Levin <sashal@kernel.org>

stable inclusion from stable-v5.10.146 commit 050de2898039560060dc2edca3d032ef62132fc1 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6D0VX Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=050de2898039560060dc2edca3d032ef62132fc1 -------------------------------- [ Upstream commit 8cdd23c ] Commit 97fed77 ("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 51c2ee6 ("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: ClangBuiltLinux/linux#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: llvm/llvm-project@a88c722 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> Stable-dep-of: c0a454b ("arm64/bti: Disable in kernel BTI when cross section thunks are broken") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com> Reviewed-by: Zheng Zengkai <zhengzengkai@huawei.com>

[ Upstream commit 8cdd23c23c3d481a43b4aa03dcb5738812831115 ] 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: ClangBuiltLinux/linux#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: llvm/llvm-project@a88c722 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> Stable-dep-of: c0a454b9044f ("arm64/bti: Disable in kernel BTI when cross section thunks are broken") Signed-off-by: Sasha Levin <sashal@kernel.org>

nathanchance changed the title ~~BTF issues with allmodconfig on mainline with LLVM 11~~ BTI issues with allmodconfig on mainline with LLVM 11 Jul 7, 2021

nathanchance transferred this issue from ClangBuiltLinux/continuous-integration2 Jul 8, 2021

nathanchance closed this as completed Jul 9, 2021

nathanchance reopened this Jul 9, 2021

nathanchance self-assigned this Jul 9, 2021

nathanchance added [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LLVM] 12 This bug was fixed in LLVM 12.0 [PATCH] Submitted A patch has been submitted for review [ARCH] arm64 This bug impacts ARCH=arm64 labels Jul 9, 2021

nathanchance closed this as completed Jul 17, 2021

nathanchance added [FIXED][LINUX] 5.14 This bug was fixed in Linux 5.14 and removed [PATCH] Submitted A patch has been submitted for review labels Jul 17, 2021

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BTI issues with allmodconfig on mainline with LLVM 11 #1428

BTI issues with allmodconfig on mainline with LLVM 11 #1428

nickdesaulniers commented Jul 7, 2021

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nathanchance commented Jul 17, 2021

BTI issues with allmodconfig on mainline with LLVM 11 #1428

BTI issues with allmodconfig on mainline with LLVM 11 #1428

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nickdesaulniers commented Jul 7, 2021

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nathanchance commented Jul 17, 2021