@@ -109,6 +109,10 @@
.popsection
.endm
+#define ALTERNATIVE_TERNARY(oldinstr, feature, newinstr1, newinstr2) \
+ ALTERNATIVE_2 oldinstr, newinstr2, X86_FEATURE_ALWAYS, \
+ newinstr1, feature
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_ALTERNATIVE_ASM_H */
@@ -59,6 +59,7 @@ struct alt_instr {
s32 instr_offset; /* original instruction */
s32 repl_offset; /* offset to replacement instruction */
u16 cpuid; /* cpuid bit set for replacement */
+#define ALT_INSTR_CPUID_INV 0x8000 /* patch if ~cpuid bit is NOT set */
u8 instrlen; /* length of original instruction */
u8 replacementlen; /* length of new instruction */
u8 padlen; /* length of build-time padding */
@@ -175,6 +176,9 @@ static inline int alternatives_text_reserved(void *start, void *end)
ALTINSTR_REPLACEMENT(newinstr2, feature2, 2) \
".popsection\n"
+#define ALTERNATIVE_TERNARY(oldinstr, feature, newinstr1, newinstr2) \
+ ALTERNATIVE_2(oldinstr, newinstr2, X86_FEATURE_ALWAYS, newinstr1, feature)
+
#define ALTERNATIVE_3(oldinsn, newinsn1, feat1, newinsn2, feat2, newinsn3, feat3) \
OLDINSTR_3(oldinsn, 1, 2, 3) \
".pushsection .altinstructions,\"a\"\n" \
@@ -206,6 +210,9 @@ static inline int alternatives_text_reserved(void *start, void *end)
#define alternative_2(oldinstr, newinstr1, feature1, newinstr2, feature2) \
asm_inline volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2) ::: "memory")
+#define alternative_ternary(oldinstr, feature, newinstr1, newinstr2) \
+ asm_inline volatile(ALTERNATIVE_TERNARY(oldinstr, feature, newinstr1, newinstr2) ::: "memory")
+
/*
* Alternative inline assembly with input.
*
@@ -388,21 +388,28 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start,
*/
for (a = start; a < end; a++) {
int insn_buff_sz = 0;
+ u16 feature;
+ bool not_feature;
instr = (u8 *)&a->instr_offset + a->instr_offset;
replacement = (u8 *)&a->repl_offset + a->repl_offset;
+ feature = a->cpuid;
+ not_feature = feature & ALT_INSTR_CPUID_INV;
+ if (not_feature)
+ feature = ~feature;
BUG_ON(a->instrlen > sizeof(insn_buff));
- BUG_ON(a->cpuid >= (NCAPINTS + NBUGINTS) * 32);
- if (!boot_cpu_has(a->cpuid)) {
+ BUG_ON(feature >= (NCAPINTS + NBUGINTS) * 32);
+ if (!!boot_cpu_has(feature) == not_feature) {
if (a->padlen > 1)
optimize_nops(a, instr);
continue;
}
- DPRINTK("feat: %d*32+%d, old: (%pS (%px) len: %d), repl: (%px, len: %d), pad: %d",
- a->cpuid >> 5,
- a->cpuid & 0x1f,
+ DPRINTK("feat: %s%d*32+%d, old: (%pS (%px) len: %d), repl: (%px, len: %d), pad: %d",
+ not_feature ? "~" : "",
+ feature >> 5,
+ feature & 0x1f,
instr, instr, a->instrlen,
replacement, a->replacementlen, a->padlen);
Instead of only supporting to modify instructions when a specific feature is set, support doing so for the case a feature is not set. Add ALTERNATIVE_TERNARY support for replacing an initial instruction with either of two instructions depending on a feature: ALTERNATIVE_TERNARY "default_instr", FEATURE_NR, "feature_on_instr", "feature_off_instr" which will start with "default_instr" and at patch time will, depending on FEATURE_NR being set or not, patch that with either "feature_on_instr" or "feature_off_instr". Signed-off-by: Juergen Gross <jgross@suse.com> --- V3: - new patch V4: - use X86_FEATURE_ALWAYS instead of negated feature (Boris Petkov) - unfortunately this isn't enough to get rid of the "not feature" support, as this is needed in the patch "x86/paravirt: switch functions with custom code to ALTERNATIVE", too --- arch/x86/include/asm/alternative-asm.h | 4 ++++ arch/x86/include/asm/alternative.h | 7 +++++++ arch/x86/kernel/alternative.c | 17 ++++++++++++----- 3 files changed, 23 insertions(+), 5 deletions(-)