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authorNathan Chancellor <nathan@kernel.org>2021-04-14 03:08:04 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-04-21 14:00:55 +0300
commite6177990e17d0b8126701fc8db877bc921caea16 (patch)
treeee1146c0d12cdac6676d43f94466a44a00bdf45f /arch/arm64/include
parente2931f05eb328e167bd39369dd738f9840bf4f39 (diff)
downloadlinux-e6177990e17d0b8126701fc8db877bc921caea16.tar.xz
arm64: alternatives: Move length validation in alternative_{insn, endif}
commit 22315a2296f4c251fa92aec45fbbae37e9301b6c upstream. After commit 2decad92f473 ("arm64: mte: Ensure TIF_MTE_ASYNC_FAULT is set atomically"), LLVM's integrated assembler fails to build entry.S: <instantiation>:5:7: error: expected assembly-time absolute expression .org . - (664b-663b) + (662b-661b) ^ <instantiation>:6:7: error: expected assembly-time absolute expression .org . - (662b-661b) + (664b-663b) ^ The root cause is LLVM's assembler has a one-pass design, meaning it cannot figure out these instruction lengths when the .org directive is outside of the subsection that they are in, which was changed by the .arch_extension directive added in the above commit. Apply the same fix from commit 966a0acce2fc ("arm64/alternatives: move length validation inside the subsection") to the alternative_endif macro, shuffling the .org directives so that the length validation happen will always happen in the same subsections. alternative_insn has not shown any issue yet but it appears that it could have the same issue in the future so just preemptively change it. Fixes: f7b93d42945c ("arm64/alternatives: use subsections for replacement sequences") Cc: <stable@vger.kernel.org> # 5.8.x Link: https://github.com/ClangBuiltLinux/linux/issues/1347 Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Sami Tolvanen <samitolvanen@google.com> Tested-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Link: https://lore.kernel.org/r/20210414000803.662534-1-nathan@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/arm64/include')
-rw-r--r--arch/arm64/include/asm/alternative.h8
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h
index 619db9b4c9d5..3cb3c4ab3ea5 100644
--- a/arch/arm64/include/asm/alternative.h
+++ b/arch/arm64/include/asm/alternative.h
@@ -119,9 +119,9 @@ static inline void apply_alternatives_module(void *start, size_t length) { }
.popsection
.subsection 1
663: \insn2
-664: .previous
- .org . - (664b-663b) + (662b-661b)
+664: .org . - (664b-663b) + (662b-661b)
.org . - (662b-661b) + (664b-663b)
+ .previous
.endif
.endm
@@ -191,11 +191,11 @@ static inline void apply_alternatives_module(void *start, size_t length) { }
*/
.macro alternative_endif
664:
+ .org . - (664b-663b) + (662b-661b)
+ .org . - (662b-661b) + (664b-663b)
.if .Lasm_alt_mode==0
.previous
.endif
- .org . - (664b-663b) + (662b-661b)
- .org . - (662b-661b) + (664b-663b)
.endm
/*