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authorLinus Torvalds <torvalds@linux-foundation.org>2023-02-21 19:27:47 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2023-02-21 19:27:47 +0300
commit1adce1b9440cdf0c427419b99bc9db756b5ad931 (patch)
treec51091a2ed88c28a284bacec2d822018efd3d820
parentd9de5ce8a5ec8f97c9468244fd85ff1a10363b60 (diff)
parent923510c88d2b7d947c4217835fd9ca6bd65cc56c (diff)
downloadlinux-1adce1b9440cdf0c427419b99bc9db756b5ad931.tar.xz
Merge tag 'x86_alternatives_for_v6.3_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm alternatives updates from Borislav Petkov: - Teach the static_call patching infrastructure to handle conditional tall calls properly which can be static calls too - Add proper struct alt_instr.flags which controls different aspects of insn patching behavior * tag 'x86_alternatives_for_v6.3_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/static_call: Add support for Jcc tail-calls x86/alternatives: Teach text_poke_bp() to patch Jcc.d32 instructions x86/alternatives: Introduce int3_emulate_jcc() x86/alternatives: Add alt_instr.flags
-rw-r--r--arch/x86/include/asm/alternative.h132
-rw-r--r--arch/x86/include/asm/text-patching.h31
-rw-r--r--arch/x86/kernel/alternative.c76
-rw-r--r--arch/x86/kernel/kprobes/core.c38
-rw-r--r--arch/x86/kernel/static_call.c50
-rw-r--r--tools/objtool/arch/x86/include/arch/special.h6
6 files changed, 218 insertions, 115 deletions
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 7659217f4d49..e2975a32d443 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -6,8 +6,10 @@
#include <linux/stringify.h>
#include <asm/asm.h>
-#define ALTINSTR_FLAG_INV (1 << 15)
-#define ALT_NOT(feat) ((feat) | ALTINSTR_FLAG_INV)
+#define ALT_FLAGS_SHIFT 16
+
+#define ALT_FLAG_NOT BIT(0)
+#define ALT_NOT(feature) ((ALT_FLAG_NOT << ALT_FLAGS_SHIFT) | (feature))
#ifndef __ASSEMBLY__
@@ -59,10 +61,27 @@
".long 999b - .\n\t" \
".popsection\n\t"
+/*
+ * The patching flags are part of the upper bits of the @ft_flags parameter when
+ * specifying them. The split is currently like this:
+ *
+ * [31... flags ...16][15... CPUID feature bit ...0]
+ *
+ * but since this is all hidden in the macros argument being split, those fields can be
+ * extended in the future to fit in a u64 or however the need arises.
+ */
struct alt_instr {
s32 instr_offset; /* original instruction */
s32 repl_offset; /* offset to replacement instruction */
- u16 cpuid; /* cpuid bit set for replacement */
+
+ union {
+ struct {
+ u32 cpuid: 16; /* CPUID bit set for replacement */
+ u32 flags: 16; /* patching control flags */
+ };
+ u32 ft_flags;
+ };
+
u8 instrlen; /* length of original instruction */
u8 replacementlen; /* length of new instruction */
} __packed;
@@ -182,10 +201,10 @@ static inline int alternatives_text_reserved(void *start, void *end)
" - (" alt_slen ")), 0x90\n" \
alt_end_marker ":\n"
-#define ALTINSTR_ENTRY(feature, num) \
+#define ALTINSTR_ENTRY(ft_flags, num) \
" .long 661b - .\n" /* label */ \
" .long " b_replacement(num)"f - .\n" /* new instruction */ \
- " .word " __stringify(feature) "\n" /* feature bit */ \
+ " .4byte " __stringify(ft_flags) "\n" /* feature + flags */ \
" .byte " alt_total_slen "\n" /* source len */ \
" .byte " alt_rlen(num) "\n" /* replacement len */
@@ -194,20 +213,20 @@ static inline int alternatives_text_reserved(void *start, void *end)
b_replacement(num)":\n\t" newinstr "\n" e_replacement(num) ":\n"
/* alternative assembly primitive: */
-#define ALTERNATIVE(oldinstr, newinstr, feature) \
+#define ALTERNATIVE(oldinstr, newinstr, ft_flags) \
OLDINSTR(oldinstr, 1) \
".pushsection .altinstructions,\"a\"\n" \
- ALTINSTR_ENTRY(feature, 1) \
+ ALTINSTR_ENTRY(ft_flags, 1) \
".popsection\n" \
".pushsection .altinstr_replacement, \"ax\"\n" \
ALTINSTR_REPLACEMENT(newinstr, 1) \
".popsection\n"
-#define ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2)\
+#define ALTERNATIVE_2(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2) \
OLDINSTR_2(oldinstr, 1, 2) \
".pushsection .altinstructions,\"a\"\n" \
- ALTINSTR_ENTRY(feature1, 1) \
- ALTINSTR_ENTRY(feature2, 2) \
+ ALTINSTR_ENTRY(ft_flags1, 1) \
+ ALTINSTR_ENTRY(ft_flags2, 2) \
".popsection\n" \
".pushsection .altinstr_replacement, \"ax\"\n" \
ALTINSTR_REPLACEMENT(newinstr1, 1) \
@@ -215,21 +234,22 @@ static inline int alternatives_text_reserved(void *start, void *end)
".popsection\n"
/* If @feature is set, patch in @newinstr_yes, otherwise @newinstr_no. */
-#define ALTERNATIVE_TERNARY(oldinstr, feature, newinstr_yes, newinstr_no) \
+#define ALTERNATIVE_TERNARY(oldinstr, ft_flags, newinstr_yes, newinstr_no) \
ALTERNATIVE_2(oldinstr, newinstr_no, X86_FEATURE_ALWAYS, \
- newinstr_yes, feature)
-
-#define ALTERNATIVE_3(oldinsn, newinsn1, feat1, newinsn2, feat2, newinsn3, feat3) \
- OLDINSTR_3(oldinsn, 1, 2, 3) \
- ".pushsection .altinstructions,\"a\"\n" \
- ALTINSTR_ENTRY(feat1, 1) \
- ALTINSTR_ENTRY(feat2, 2) \
- ALTINSTR_ENTRY(feat3, 3) \
- ".popsection\n" \
- ".pushsection .altinstr_replacement, \"ax\"\n" \
- ALTINSTR_REPLACEMENT(newinsn1, 1) \
- ALTINSTR_REPLACEMENT(newinsn2, 2) \
- ALTINSTR_REPLACEMENT(newinsn3, 3) \
+ newinstr_yes, ft_flags)
+
+#define ALTERNATIVE_3(oldinsn, newinsn1, ft_flags1, newinsn2, ft_flags2, \
+ newinsn3, ft_flags3) \
+ OLDINSTR_3(oldinsn, 1, 2, 3) \
+ ".pushsection .altinstructions,\"a\"\n" \
+ ALTINSTR_ENTRY(ft_flags1, 1) \
+ ALTINSTR_ENTRY(ft_flags2, 2) \
+ ALTINSTR_ENTRY(ft_flags3, 3) \
+ ".popsection\n" \
+ ".pushsection .altinstr_replacement, \"ax\"\n" \
+ ALTINSTR_REPLACEMENT(newinsn1, 1) \
+ ALTINSTR_REPLACEMENT(newinsn2, 2) \
+ ALTINSTR_REPLACEMENT(newinsn3, 3) \
".popsection\n"
/*
@@ -244,14 +264,14 @@ static inline int alternatives_text_reserved(void *start, void *end)
* For non barrier like inlines please define new variants
* without volatile and memory clobber.
*/
-#define alternative(oldinstr, newinstr, feature) \
- asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, feature) : : : "memory")
+#define alternative(oldinstr, newinstr, ft_flags) \
+ asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, ft_flags) : : : "memory")
-#define alternative_2(oldinstr, newinstr1, feature1, newinstr2, feature2) \
- asm_inline volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2) ::: "memory")
+#define alternative_2(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2) \
+ asm_inline volatile(ALTERNATIVE_2(oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2) ::: "memory")
-#define alternative_ternary(oldinstr, feature, newinstr_yes, newinstr_no) \
- asm_inline volatile(ALTERNATIVE_TERNARY(oldinstr, feature, newinstr_yes, newinstr_no) ::: "memory")
+#define alternative_ternary(oldinstr, ft_flags, newinstr_yes, newinstr_no) \
+ asm_inline volatile(ALTERNATIVE_TERNARY(oldinstr, ft_flags, newinstr_yes, newinstr_no) ::: "memory")
/*
* Alternative inline assembly with input.
@@ -261,8 +281,8 @@ static inline int alternatives_text_reserved(void *start, void *end)
* Argument numbers start with 1.
* Leaving an unused argument 0 to keep API compatibility.
*/
-#define alternative_input(oldinstr, newinstr, feature, input...) \
- asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
+#define alternative_input(oldinstr, newinstr, ft_flags, input...) \
+ asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, ft_flags) \
: : "i" (0), ## input)
/*
@@ -273,20 +293,20 @@ static inline int alternatives_text_reserved(void *start, void *end)
* Otherwise, if CPU has feature1, newinstr1 is used.
* Otherwise, oldinstr is used.
*/
-#define alternative_input_2(oldinstr, newinstr1, feature1, newinstr2, \
- feature2, input...) \
- asm_inline volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, \
- newinstr2, feature2) \
+#define alternative_input_2(oldinstr, newinstr1, ft_flags1, newinstr2, \
+ ft_flags2, input...) \
+ asm_inline volatile(ALTERNATIVE_2(oldinstr, newinstr1, ft_flags1, \
+ newinstr2, ft_flags2) \
: : "i" (0), ## input)
/* Like alternative_input, but with a single output argument */
-#define alternative_io(oldinstr, newinstr, feature, output, input...) \
- asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
+#define alternative_io(oldinstr, newinstr, ft_flags, output, input...) \
+ asm_inline volatile (ALTERNATIVE(oldinstr, newinstr, ft_flags) \
: output : "i" (0), ## input)
/* Like alternative_io, but for replacing a direct call with another one. */
-#define alternative_call(oldfunc, newfunc, feature, output, input...) \
- asm_inline volatile (ALTERNATIVE("call %P[old]", "call %P[new]", feature) \
+#define alternative_call(oldfunc, newfunc, ft_flags, output, input...) \
+ asm_inline volatile (ALTERNATIVE("call %P[old]", "call %P[new]", ft_flags) \
: output : [old] "i" (oldfunc), [new] "i" (newfunc), ## input)
/*
@@ -295,10 +315,10 @@ static inline int alternatives_text_reserved(void *start, void *end)
* Otherwise, if CPU has feature1, function1 is used.
* Otherwise, old function is used.
*/
-#define alternative_call_2(oldfunc, newfunc1, feature1, newfunc2, feature2, \
+#define alternative_call_2(oldfunc, newfunc1, ft_flags1, newfunc2, ft_flags2, \
output, input...) \
- asm_inline volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\
- "call %P[new2]", feature2) \
+ asm_inline volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", ft_flags1,\
+ "call %P[new2]", ft_flags2) \
: output, ASM_CALL_CONSTRAINT \
: [old] "i" (oldfunc), [new1] "i" (newfunc1), \
[new2] "i" (newfunc2), ## input)
@@ -347,10 +367,10 @@ static inline int alternatives_text_reserved(void *start, void *end)
* enough information for the alternatives patching code to patch an
* instruction. See apply_alternatives().
*/
-.macro altinstruction_entry orig alt feature orig_len alt_len
+.macro altinstr_entry orig alt ft_flags orig_len alt_len
.long \orig - .
.long \alt - .
- .word \feature
+ .4byte \ft_flags
.byte \orig_len
.byte \alt_len
.endm
@@ -361,7 +381,7 @@ static inline int alternatives_text_reserved(void *start, void *end)
* @newinstr. ".skip" directive takes care of proper instruction padding
* in case @newinstr is longer than @oldinstr.
*/
-.macro ALTERNATIVE oldinstr, newinstr, feature
+.macro ALTERNATIVE oldinstr, newinstr, ft_flags
140:
\oldinstr
141:
@@ -369,7 +389,7 @@ static inline int alternatives_text_reserved(void *start, void *end)
142:
.pushsection .altinstructions,"a"
- altinstruction_entry 140b,143f,\feature,142b-140b,144f-143f
+ altinstr_entry 140b,143f,\ft_flags,142b-140b,144f-143f
.popsection
.pushsection .altinstr_replacement,"ax"
@@ -399,7 +419,7 @@ static inline int alternatives_text_reserved(void *start, void *end)
* has @feature1, it replaces @oldinstr with @newinstr1. If CPU has
* @feature2, it replaces @oldinstr with @feature2.
*/
-.macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2
+.macro ALTERNATIVE_2 oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2
140:
\oldinstr
141:
@@ -408,8 +428,8 @@ static inline int alternatives_text_reserved(void *start, void *end)
142:
.pushsection .altinstructions,"a"
- altinstruction_entry 140b,143f,\feature1,142b-140b,144f-143f
- altinstruction_entry 140b,144f,\feature2,142b-140b,145f-144f
+ altinstr_entry 140b,143f,\ft_flags1,142b-140b,144f-143f
+ altinstr_entry 140b,144f,\ft_flags2,142b-140b,145f-144f
.popsection
.pushsection .altinstr_replacement,"ax"
@@ -421,7 +441,7 @@ static inline int alternatives_text_reserved(void *start, void *end)
.popsection
.endm
-.macro ALTERNATIVE_3 oldinstr, newinstr1, feature1, newinstr2, feature2, newinstr3, feature3
+.macro ALTERNATIVE_3 oldinstr, newinstr1, ft_flags1, newinstr2, ft_flags2, newinstr3, ft_flags3
140:
\oldinstr
141:
@@ -430,9 +450,9 @@ static inline int alternatives_text_reserved(void *start, void *end)
142:
.pushsection .altinstructions,"a"
- altinstruction_entry 140b,143f,\feature1,142b-140b,144f-143f
- altinstruction_entry 140b,144f,\feature2,142b-140b,145f-144f
- altinstruction_entry 140b,145f,\feature3,142b-140b,146f-145f
+ altinstr_entry 140b,143f,\ft_flags1,142b-140b,144f-143f
+ altinstr_entry 140b,144f,\ft_flags2,142b-140b,145f-144f
+ altinstr_entry 140b,145f,\ft_flags3,142b-140b,146f-145f
.popsection
.pushsection .altinstr_replacement,"ax"
@@ -447,9 +467,9 @@ static inline int alternatives_text_reserved(void *start, void *end)
.endm
/* If @feature is set, patch in @newinstr_yes, otherwise @newinstr_no. */
-#define ALTERNATIVE_TERNARY(oldinstr, feature, newinstr_yes, newinstr_no) \
+#define ALTERNATIVE_TERNARY(oldinstr, ft_flags, newinstr_yes, newinstr_no) \
ALTERNATIVE_2 oldinstr, newinstr_no, X86_FEATURE_ALWAYS, \
- newinstr_yes, feature
+ newinstr_yes, ft_flags
#endif /* __ASSEMBLY__ */
diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index f4b87f08f5c5..29832c338cdc 100644
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -184,6 +184,37 @@ void int3_emulate_ret(struct pt_regs *regs)
unsigned long ip = int3_emulate_pop(regs);
int3_emulate_jmp(regs, ip);
}
+
+static __always_inline
+void int3_emulate_jcc(struct pt_regs *regs, u8 cc, unsigned long ip, unsigned long disp)
+{
+ static const unsigned long jcc_mask[6] = {
+ [0] = X86_EFLAGS_OF,
+ [1] = X86_EFLAGS_CF,
+ [2] = X86_EFLAGS_ZF,
+ [3] = X86_EFLAGS_CF | X86_EFLAGS_ZF,
+ [4] = X86_EFLAGS_SF,
+ [5] = X86_EFLAGS_PF,
+ };
+
+ bool invert = cc & 1;
+ bool match;
+
+ if (cc < 0xc) {
+ match = regs->flags & jcc_mask[cc >> 1];
+ } else {
+ match = ((regs->flags & X86_EFLAGS_SF) >> X86_EFLAGS_SF_BIT) ^
+ ((regs->flags & X86_EFLAGS_OF) >> X86_EFLAGS_OF_BIT);
+ if (cc >= 0xe)
+ match = match || (regs->flags & X86_EFLAGS_ZF);
+ }
+
+ if ((match && !invert) || (!match && invert))
+ ip += disp;
+
+ int3_emulate_jmp(regs, ip);
+}
+
#endif /* !CONFIG_UML_X86 */
#endif /* _ASM_X86_TEXT_PATCHING_H */
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 7d8c3cbde368..f615e0cb6d93 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -282,27 +282,25 @@ void __init_or_module noinline apply_alternatives(struct alt_instr *start,
*/
for (a = start; a < end; a++) {
int insn_buff_sz = 0;
- /* Mask away "NOT" flag bit for feature to test. */
- u16 feature = a->cpuid & ~ALTINSTR_FLAG_INV;
instr = (u8 *)&a->instr_offset + a->instr_offset;
replacement = (u8 *)&a->repl_offset + a->repl_offset;
BUG_ON(a->instrlen > sizeof(insn_buff));
- BUG_ON(feature >= (NCAPINTS + NBUGINTS) * 32);
+ BUG_ON(a->cpuid >= (NCAPINTS + NBUGINTS) * 32);
/*
* Patch if either:
* - feature is present
- * - feature not present but ALTINSTR_FLAG_INV is set to mean,
+ * - feature not present but ALT_FLAG_NOT is set to mean,
* patch if feature is *NOT* present.
*/
- if (!boot_cpu_has(feature) == !(a->cpuid & ALTINSTR_FLAG_INV))
+ if (!boot_cpu_has(a->cpuid) == !(a->flags & ALT_FLAG_NOT))
goto next;
DPRINTK("feat: %s%d*32+%d, old: (%pS (%px) len: %d), repl: (%px, len: %d)",
- (a->cpuid & ALTINSTR_FLAG_INV) ? "!" : "",
- feature >> 5,
- feature & 0x1f,
+ (a->flags & ALT_FLAG_NOT) ? "!" : "",
+ a->cpuid >> 5,
+ a->cpuid & 0x1f,
instr, instr, a->instrlen,
replacement, a->replacementlen);
@@ -340,6 +338,12 @@ next:
}
}
+static inline bool is_jcc32(struct insn *insn)
+{
+ /* Jcc.d32 second opcode byte is in the range: 0x80-0x8f */
+ return insn->opcode.bytes[0] == 0x0f && (insn->opcode.bytes[1] & 0xf0) == 0x80;
+}
+
#if defined(CONFIG_RETPOLINE) && defined(CONFIG_OBJTOOL)
/*
@@ -378,12 +382,6 @@ static int emit_indirect(int op, int reg, u8 *bytes)
return i;
}
-static inline bool is_jcc32(struct insn *insn)
-{
- /* Jcc.d32 second opcode byte is in the range: 0x80-0x8f */
- return insn->opcode.bytes[0] == 0x0f && (insn->opcode.bytes[1] & 0xf0) == 0x80;
-}
-
static int emit_call_track_retpoline(void *addr, struct insn *insn, int reg, u8 *bytes)
{
u8 op = insn->opcode.bytes[0];
@@ -1772,6 +1770,11 @@ void text_poke_sync(void)
on_each_cpu(do_sync_core, NULL, 1);
}
+/*
+ * NOTE: crazy scheme to allow patching Jcc.d32 but not increase the size of
+ * this thing. When len == 6 everything is prefixed with 0x0f and we map
+ * opcode to Jcc.d8, using len to distinguish.
+ */
struct text_poke_loc {
/* addr := _stext + rel_addr */
s32 rel_addr;
@@ -1893,6 +1896,10 @@ noinstr int poke_int3_handler(struct pt_regs *regs)
int3_emulate_jmp(regs, (long)ip + tp->disp);
break;
+ case 0x70 ... 0x7f: /* Jcc */
+ int3_emulate_jcc(regs, tp->opcode & 0xf, (long)ip, tp->disp);
+ break;
+
default:
BUG();
}
@@ -1966,16 +1973,26 @@ static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries
* Second step: update all but the first byte of the patched range.
*/
for (do_sync = 0, i = 0; i < nr_entries; i++) {
- u8 old[POKE_MAX_OPCODE_SIZE] = { tp[i].old, };
+ u8 old[POKE_MAX_OPCODE_SIZE+1] = { tp[i].old, };
+ u8 _new[POKE_MAX_OPCODE_SIZE+1];
+ const u8 *new = tp[i].text;
int len = tp[i].len;
if (len - INT3_INSN_SIZE > 0) {
memcpy(old + INT3_INSN_SIZE,
text_poke_addr(&tp[i]) + INT3_INSN_SIZE,
len - INT3_INSN_SIZE);
+
+ if (len == 6) {
+ _new[0] = 0x0f;
+ memcpy(_new + 1, new, 5);
+ new = _new;
+ }
+
text_poke(text_poke_addr(&tp[i]) + INT3_INSN_SIZE,
- (const char *)tp[i].text + INT3_INSN_SIZE,
+ new + INT3_INSN_SIZE,
len - INT3_INSN_SIZE);
+
do_sync++;
}
@@ -2003,8 +2020,7 @@ static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries
* The old instruction is recorded so that the event can be
* processed forwards or backwards.
*/
- perf_event_text_poke(text_poke_addr(&tp[i]), old, len,
- tp[i].text, len);
+ perf_event_text_poke(text_poke_addr(&tp[i]), old, len, new, len);
}
if (do_sync) {
@@ -2021,10 +2037,15 @@ static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries
* replacing opcode.
*/
for (do_sync = 0, i = 0; i < nr_entries; i++) {
- if (tp[i].text[0] == INT3_INSN_OPCODE)
+ u8 byte = tp[i].text[0];
+
+ if (tp[i].len == 6)
+ byte = 0x0f;
+
+ if (byte == INT3_INSN_OPCODE)
continue;
- text_poke(text_poke_addr(&tp[i]), tp[i].text, INT3_INSN_SIZE);
+ text_poke(text_poke_addr(&tp[i]), &byte, INT3_INSN_SIZE);
do_sync++;
}
@@ -2042,9 +2063,11 @@ static void text_poke_loc_init(struct text_poke_loc *tp, void *addr,
const void *opcode, size_t len, const void *emulate)
{
struct insn insn;
- int ret, i;
+ int ret, i = 0;
- memcpy((void *)tp->text, opcode, len);
+ if (len == 6)
+ i = 1;
+ memcpy((void *)tp->text, opcode+i, len-i);
if (!emulate)
emulate = opcode;
@@ -2055,6 +2078,13 @@ static void text_poke_loc_init(struct text_poke_loc *tp, void *addr,
tp->len = len;
tp->opcode = insn.opcode.bytes[0];
+ if (is_jcc32(&insn)) {
+ /*
+ * Map Jcc.d32 onto Jcc.d8 and use len to distinguish.
+ */
+ tp->opcode = insn.opcode.bytes[1] - 0x10;
+ }
+
switch (tp->opcode) {
case RET_INSN_OPCODE:
case JMP32_INSN_OPCODE:
@@ -2071,7 +2101,6 @@ static void text_poke_loc_init(struct text_poke_loc *tp, void *addr,
BUG_ON(len != insn.length);
}
-
switch (tp->opcode) {
case INT3_INSN_OPCODE:
case RET_INSN_OPCODE:
@@ -2080,6 +2109,7 @@ static void text_poke_loc_init(struct text_poke_loc *tp, void *addr,
case CALL_INSN_OPCODE:
case JMP32_INSN_OPCODE:
case JMP8_INSN_OPCODE:
+ case 0x70 ... 0x7f: /* Jcc */
tp->disp = insn.immediate.value;
break;
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 754da3b226f9..f7f6042eb7e6 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -464,50 +464,26 @@ static void kprobe_emulate_call(struct kprobe *p, struct pt_regs *regs)
}
NOKPROBE_SYMBOL(kprobe_emulate_call);
-static nokprobe_inline
-void __kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs, bool cond)
+static void kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs)
{
unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size;
- if (cond)
- ip += p->ainsn.rel32;
+ ip += p->ainsn.rel32;
int3_emulate_jmp(regs, ip);
}
-
-static void kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs)
-{
- __kprobe_emulate_jmp(p, regs, true);
-}
NOKPROBE_SYMBOL(kprobe_emulate_jmp);
-static const unsigned long jcc_mask[6] = {
- [0] = X86_EFLAGS_OF,
- [1] = X86_EFLAGS_CF,
- [2] = X86_EFLAGS_ZF,
- [3] = X86_EFLAGS_CF | X86_EFLAGS_ZF,
- [4] = X86_EFLAGS_SF,
- [5] = X86_EFLAGS_PF,
-};
-
static void kprobe_emulate_jcc(struct kprobe *p, struct pt_regs *regs)
{
- bool invert = p->ainsn.jcc.type & 1;
- bool match;
+ unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size;
- if (p->ainsn.jcc.type < 0xc) {
- match = regs->flags & jcc_mask[p->ainsn.jcc.type >> 1];
- } else {
- match = ((regs->flags & X86_EFLAGS_SF) >> X86_EFLAGS_SF_BIT) ^
- ((regs->flags & X86_EFLAGS_OF) >> X86_EFLAGS_OF_BIT);
- if (p->ainsn.jcc.type >= 0xe)
- match = match || (regs->flags & X86_EFLAGS_ZF);
- }
- __kprobe_emulate_jmp(p, regs, (match && !invert) || (!match && invert));
+ int3_emulate_jcc(regs, p->ainsn.jcc.type, ip, p->ainsn.rel32);
}
NOKPROBE_SYMBOL(kprobe_emulate_jcc);
static void kprobe_emulate_loop(struct kprobe *p, struct pt_regs *regs)
{
+ unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size;
bool match;
if (p->ainsn.loop.type != 3) { /* LOOP* */
@@ -535,7 +511,9 @@ static void kprobe_emulate_loop(struct kprobe *p, struct pt_regs *regs)
else if (p->ainsn.loop.type == 1) /* LOOPE */
match = match && (regs->flags & X86_EFLAGS_ZF);
- __kprobe_emulate_jmp(p, regs, match);
+ if (match)
+ ip += p->ainsn.rel32;
+ int3_emulate_jmp(regs, ip);
}
NOKPROBE_SYMBOL(kprobe_emulate_loop);
diff --git a/arch/x86/kernel/static_call.c b/arch/x86/kernel/static_call.c
index 2ebc338980bc..b70670a98597 100644
--- a/arch/x86/kernel/static_call.c
+++ b/arch/x86/kernel/static_call.c
@@ -9,6 +9,7 @@ enum insn_type {
NOP = 1, /* site cond-call */
JMP = 2, /* tramp / site tail-call */
RET = 3, /* tramp / site cond-tail-call */
+ JCC = 4,
};
/*
@@ -25,12 +26,40 @@ static const u8 xor5rax[] = { 0x2e, 0x2e, 0x2e, 0x31, 0xc0 };
static const u8 retinsn[] = { RET_INSN_OPCODE, 0xcc, 0xcc, 0xcc, 0xcc };
+static u8 __is_Jcc(u8 *insn) /* Jcc.d32 */
+{
+ u8 ret = 0;
+
+ if (insn[0] == 0x0f) {
+ u8 tmp = insn[1];
+ if ((tmp & 0xf0) == 0x80)
+ ret = tmp;
+ }
+
+ return ret;
+}
+
+extern void __static_call_return(void);
+
+asm (".global __static_call_return\n\t"
+ ".type __static_call_return, @function\n\t"
+ ASM_FUNC_ALIGN "\n\t"
+ "__static_call_return:\n\t"
+ ANNOTATE_NOENDBR
+ ANNOTATE_RETPOLINE_SAFE
+ "ret; int3\n\t"
+ ".size __static_call_return, . - __static_call_return \n\t");
+
static void __ref __static_call_transform(void *insn, enum insn_type type,
void *func, bool modinit)
{
const void *emulate = NULL;
int size = CALL_INSN_SIZE;
const void *code;
+ u8 op, buf[6];
+
+ if ((type == JMP || type == RET) && (op = __is_Jcc(insn)))
+ type = JCC;
switch (type) {
case CALL:
@@ -57,6 +86,20 @@ static void __ref __static_call_transform(void *insn, enum insn_type type,
else
code = &retinsn;
break;
+
+ case JCC:
+ if (!func) {
+ func = __static_call_return;
+ if (cpu_feature_enabled(X86_FEATURE_RETHUNK))
+ func = x86_return_thunk;
+ }
+
+ buf[0] = 0x0f;
+ __text_gen_insn(buf+1, op, insn+1, func, 5);
+ code = buf;
+ size = 6;
+
+ break;
}
if (memcmp(insn, code, size) == 0)
@@ -68,9 +111,9 @@ static void __ref __static_call_transform(void *insn, enum insn_type type,
text_poke_bp(insn, code, size, emulate);
}
-static void __static_call_validate(void *insn, bool tail, bool tramp)
+static void __static_call_validate(u8 *insn, bool tail, bool tramp)
{
- u8 opcode = *(u8 *)insn;
+ u8 opcode = insn[0];
if (tramp && memcmp(insn+5, tramp_ud, 3)) {
pr_err("trampoline signature fail");
@@ -79,7 +122,8 @@ static void __static_call_validate(void *insn, bool tail, bool tramp)
if (tail) {
if (opcode == JMP32_INSN_OPCODE ||
- opcode == RET_INSN_OPCODE)
+ opcode == RET_INSN_OPCODE ||
+ __is_Jcc(insn))
return;
} else {
if (opcode == CALL_INSN_OPCODE ||
diff --git a/tools/objtool/arch/x86/include/arch/special.h b/tools/objtool/arch/x86/include/arch/special.h
index f2918f789a0a..ca8131352994 100644
--- a/tools/objtool/arch/x86/include/arch/special.h
+++ b/tools/objtool/arch/x86/include/arch/special.h
@@ -11,11 +11,11 @@
#define JUMP_NEW_OFFSET 4
#define JUMP_KEY_OFFSET 8
-#define ALT_ENTRY_SIZE 12
+#define ALT_ENTRY_SIZE 14
#define ALT_ORIG_OFFSET 0
#define ALT_NEW_OFFSET 4
#define ALT_FEATURE_OFFSET 8
-#define ALT_ORIG_LEN_OFFSET 10
-#define ALT_NEW_LEN_OFFSET 11
+#define ALT_ORIG_LEN_OFFSET 12
+#define ALT_NEW_LEN_OFFSET 13
#endif /* _X86_ARCH_SPECIAL_H */