x86/asm: Cleanup prefetch primitives
This is based on a patch originally by hpa.
With the current improvements to the alternatives, we can simply use %P1
as a mem8 operand constraint and rely on the toolchain to generate the
proper instruction sizes. For example, on 32-bit, where we use an empty
old instruction we get:
apply_alternatives: feat: 6*32+8, old: (c104648b, len: 4), repl: (c195566c, len: 4)
c104648b: alt_insn: 90 90 90 90
c195566c: rpl_insn: 0f 0d 4b 5c
...
apply_alternatives: feat: 6*32+8, old: (c18e09b4, len: 3), repl: (c1955948, len: 3)
c18e09b4: alt_insn: 90 90 90
c1955948: rpl_insn: 0f 0d 08
...
apply_alternatives: feat: 6*32+8, old: (c1190cf9, len: 7), repl: (c1955a79, len: 7)
c1190cf9: alt_insn: 90 90 90 90 90 90 90
c1955a79: rpl_insn: 0f 0d 0d a0 d4 85 c1
all with the proper padding done depending on the size of the
replacement instruction the compiler generates.
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index efc3b22..8118e94 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -91,7 +91,7 @@
{
volatile u32 *addr = (volatile u32 *)(APIC_BASE + reg);
- alternative_io("movl %0, %1", "xchgl %0, %1", X86_BUG_11AP,
+ alternative_io("movl %0, %P1", "xchgl %0, %P1", X86_BUG_11AP,
ASM_OUTPUT2("=r" (v), "=m" (*addr)),
ASM_OUTPUT2("0" (v), "m" (*addr)));
}
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index ec1c935..7be2c9a 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -761,10 +761,10 @@
#define ARCH_HAS_SPINLOCK_PREFETCH
#ifdef CONFIG_X86_32
-# define BASE_PREFETCH ASM_NOP4
+# define BASE_PREFETCH ""
# define ARCH_HAS_PREFETCH
#else
-# define BASE_PREFETCH "prefetcht0 (%1)"
+# define BASE_PREFETCH "prefetcht0 %P1"
#endif
/*
@@ -775,10 +775,9 @@
*/
static inline void prefetch(const void *x)
{
- alternative_input(BASE_PREFETCH,
- "prefetchnta (%1)",
+ alternative_input(BASE_PREFETCH, "prefetchnta %P1",
X86_FEATURE_XMM,
- "r" (x));
+ "m" (*(const char *)x));
}
/*
@@ -788,10 +787,9 @@
*/
static inline void prefetchw(const void *x)
{
- alternative_input(BASE_PREFETCH,
- "prefetchw (%1)",
- X86_FEATURE_3DNOW,
- "r" (x));
+ alternative_input(BASE_PREFETCH, "prefetchw %P1",
+ X86_FEATURE_3DNOWPREFETCH,
+ "m" (*(const char *)x));
}
static inline void spin_lock_prefetch(const void *x)
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index a220239..dd9e505 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -711,6 +711,11 @@
set_cpu_bug(c, X86_BUG_AMD_APIC_C1E);
rdmsr_safe(MSR_AMD64_PATCH_LEVEL, &c->microcode, &dummy);
+
+ /* 3DNow or LM implies PREFETCHW */
+ if (!cpu_has(c, X86_FEATURE_3DNOWPREFETCH))
+ if (cpu_has(c, X86_FEATURE_3DNOW) || cpu_has(c, X86_FEATURE_LM))
+ set_cpu_cap(c, X86_FEATURE_3DNOWPREFETCH);
}
#ifdef CONFIG_X86_32