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| author | D Scott Phillips <scott@os.amperecomputing.com> | 2022-11-02 09:01:06 -0700 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2022-11-09 09:51:39 +0000 |
| commit | 8ec8490a1950efeccb00967698cf7cb2fcd25ca7 (patch) | |
| tree | 173c2eee88787a3f9337343bed02892316fd01d7 /arch | |
| parent | 2081b3bd0c11757725dcab9ba5d38e1bddb03459 (diff) | |
| download | linux-8ec8490a1950efeccb00967698cf7cb2fcd25ca7.tar.gz | |
arm64: Fix bit-shifting UB in the MIDR_CPU_MODEL() macro
CONFIG_UBSAN_SHIFT with gcc-5 complains that the shifting of
ARM_CPU_IMP_AMPERE (0xC0) into bits [31:24] by MIDR_CPU_MODEL() is
undefined behavior. Well, sort of, it actually spells the error as:
arch/arm64/kernel/proton-pack.c: In function 'spectre_bhb_loop_affected':
arch/arm64/include/asm/cputype.h:44:2: error: initializer element is not constant
(((imp) << MIDR_IMPLEMENTOR_SHIFT) | \
^
This isn't an issue for other Implementor codes, as all the other codes
have zero in the top bit and so are representable as a signed int.
Cast the implementor code to unsigned in MIDR_CPU_MODEL to remove the
undefined behavior.
Fixes: 0e5d5ae837c8 ("arm64: Add AMPERE1 to the Spectre-BHB affected list")
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: D Scott Phillips <scott@os.amperecomputing.com>
Link: https://lore.kernel.org/r/20221102160106.1096948-1-scott@os.amperecomputing.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/include/asm/cputype.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h index abc418650fec..65e53ef5a396 100644 --- a/arch/arm64/include/asm/cputype.h +++ b/arch/arm64/include/asm/cputype.h @@ -41,7 +41,7 @@ (((midr) & MIDR_IMPLEMENTOR_MASK) >> MIDR_IMPLEMENTOR_SHIFT) #define MIDR_CPU_MODEL(imp, partnum) \ - (((imp) << MIDR_IMPLEMENTOR_SHIFT) | \ + ((_AT(u32, imp) << MIDR_IMPLEMENTOR_SHIFT) | \ (0xf << MIDR_ARCHITECTURE_SHIFT) | \ ((partnum) << MIDR_PARTNUM_SHIFT)) |