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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-02 11:44:12 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-08-02 11:44:12 -0700 |
| commit | 8eae6c90b7094481dd8e0d4153fe8269041dcd3e (patch) | |
| tree | d177a69bf25dea05e7dc3ef16b6fd2390db2b9e8 | |
| parent | 65bfd707fd9807586b970bdad85fc23c83b65521 (diff) | |
| parent | 52075128273ace53e6254e37899a47d40d4baf45 (diff) | |
Merge tag 'x86-urgent-2026-08-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull misc x86 fixes from Ingo Molnar:
- Fix the boot-time memcmp() asm implementation's constraints
and optimization properties (Mauricio Faria de Oliveira)
- Move the 0xd0...0xd7 AMD Zen5 model range from the Zen6
range where it mistakenly ended up (Pratik Vishwakarma)
* tag 'x86-urgent-2026-08-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/CPU/AMD: Carve out a Zen5 models range
x86/boot: Add volatile, clobbers and zero-length test in memcmp()
| -rw-r--r-- | arch/x86/boot/string.c | 11 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/amd.c | 4 |
2 files changed, 12 insertions, 3 deletions
diff --git a/arch/x86/boot/string.c b/arch/x86/boot/string.c index ac0f900ebc47..1632d40e1f54 100644 --- a/arch/x86/boot/string.c +++ b/arch/x86/boot/string.c @@ -32,8 +32,15 @@ int memcmp(const void *s1, const void *s2, size_t len) { bool diff; - asm("repe cmpsb" - : "=@ccnz" (diff), "+D" (s1), "+S" (s2), "+c" (len)); + + /* + * Make sure ZF is properly set in the len==0 case because in it, + * RCX==0 and the REPE; CMPSB won't get executed. + */ + asm volatile("test %3, %3\n\t" + "repe cmpsb" + : "=@ccnz" (diff), "+D" (s1), "+S" (s2), "+c" (len) + : : "cc", "memory"); return diff; } diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index 487ac147e11f..d61df70d6875 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -515,11 +515,13 @@ static void bsp_init_amd(struct cpuinfo_x86 *c) case 0x00 ... 0x2f: case 0x40 ... 0x4f: case 0x60 ... 0x7f: + case 0xd0 ... 0xd7: setup_force_cpu_cap(X86_FEATURE_ZEN5); break; case 0x50 ... 0x5f: case 0x80 ... 0xaf: - case 0xc0 ... 0xef: + case 0xc0 ... 0xcf: + case 0xd8 ... 0xef: setup_force_cpu_cap(X86_FEATURE_ZEN6); break; default: |