Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.19 29/57] arm64: alternatives: Move length validation in alternative_{insn, endif} | Date | Mon, 26 Apr 2021 09:29:26 +0200 |
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From: Nathan Chancellor <nathan@kernel.org>
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> --- arch/arm64/include/asm/alternative.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/arch/arm64/include/asm/alternative.h +++ b/arch/arm64/include/asm/alternative.h @@ -119,9 +119,9 @@ static inline void apply_alternatives_mo .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_mo */ .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 /*
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