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Message-ID: <176060714785.709179.11824506848891961011.tip-bot2@tip-bot2>
Date: Thu, 16 Oct 2025 09:32:27 -0000
From: "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: perf/core] x86/insn: Simplify for_each_insn_prefix()
The following commit has been merged into the perf/core branch of tip:
Commit-ID: 45e1dccc0653c50e377dae57ef086a8d0f71061d
Gitweb: https://git.kernel.org/tip/45e1dccc0653c50e377dae57ef086a8d0f71061d
Author: Peter Zijlstra <peterz@...radead.org>
AuthorDate: Thu, 25 Sep 2025 10:19:05 +02:00
Committer: Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 16 Oct 2025 11:13:48 +02:00
x86/insn: Simplify for_each_insn_prefix()
Use the new-found freedom of allowing variable declarions inside
for() to simplify the for_each_insn_prefix() iterator to no longer
need an external temporary.
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
arch/x86/boot/compressed/sev-handle-vc.c | 3 +--
arch/x86/include/asm/insn.h | 5 ++---
arch/x86/kernel/kprobes/core.c | 3 +--
arch/x86/kernel/uprobes.c | 6 ++----
arch/x86/lib/insn-eval.c | 12 +++++-------
tools/arch/x86/include/asm/insn.h | 5 ++---
6 files changed, 13 insertions(+), 21 deletions(-)
diff --git a/arch/x86/boot/compressed/sev-handle-vc.c b/arch/x86/boot/compressed/sev-handle-vc.c
index 7530ad8..030001b 100644
--- a/arch/x86/boot/compressed/sev-handle-vc.c
+++ b/arch/x86/boot/compressed/sev-handle-vc.c
@@ -29,11 +29,10 @@
bool insn_has_rep_prefix(struct insn *insn)
{
insn_byte_t p;
- int i;
insn_get_prefixes(insn);
- for_each_insn_prefix(insn, i, p) {
+ for_each_insn_prefix(insn, p) {
if (p == 0xf2 || p == 0xf3)
return true;
}
diff --git a/arch/x86/include/asm/insn.h b/arch/x86/include/asm/insn.h
index 091f88c..846d21c 100644
--- a/arch/x86/include/asm/insn.h
+++ b/arch/x86/include/asm/insn.h
@@ -312,7 +312,6 @@ static inline int insn_offset_immediate(struct insn *insn)
/**
* for_each_insn_prefix() -- Iterate prefixes in the instruction
* @insn: Pointer to struct insn.
- * @idx: Index storage.
* @prefix: Prefix byte.
*
* Iterate prefix bytes of given @insn. Each prefix byte is stored in @prefix
@@ -321,8 +320,8 @@ static inline int insn_offset_immediate(struct insn *insn)
* Since prefixes.nbytes can be bigger than 4 if some prefixes
* are repeated, it cannot be used for looping over the prefixes.
*/
-#define for_each_insn_prefix(insn, idx, prefix) \
- for (idx = 0; idx < ARRAY_SIZE(insn->prefixes.bytes) && (prefix = insn->prefixes.bytes[idx]) != 0; idx++)
+#define for_each_insn_prefix(insn, prefix) \
+ for (int idx = 0; idx < ARRAY_SIZE(insn->prefixes.bytes) && (prefix = insn->prefixes.bytes[idx]) != 0; idx++)
#define POP_SS_OPCODE 0x1f
#define MOV_SREG_OPCODE 0x8e
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 3863d77..c1fac3a 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -141,7 +141,6 @@ bool can_boost(struct insn *insn, void *addr)
{
kprobe_opcode_t opcode;
insn_byte_t prefix;
- int i;
if (search_exception_tables((unsigned long)addr))
return false; /* Page fault may occur on this address. */
@@ -154,7 +153,7 @@ bool can_boost(struct insn *insn, void *addr)
if (insn->opcode.nbytes != 1)
return false;
- for_each_insn_prefix(insn, i, prefix) {
+ for_each_insn_prefix(insn, prefix) {
insn_attr_t attr;
attr = inat_get_opcode_attribute(prefix);
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 6318898..a563e90 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -259,9 +259,8 @@ static volatile u32 good_2byte_insns[256 / 32] = {
static bool is_prefix_bad(struct insn *insn)
{
insn_byte_t p;
- int i;
- for_each_insn_prefix(insn, i, p) {
+ for_each_insn_prefix(insn, p) {
insn_attr_t attr;
attr = inat_get_opcode_attribute(p);
@@ -1404,7 +1403,6 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
{
u8 opc1 = OPCODE1(insn);
insn_byte_t p;
- int i;
if (insn_is_nop(insn))
goto setup;
@@ -1437,7 +1435,7 @@ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn)
* Intel and AMD behavior differ in 64-bit mode: Intel ignores 66 prefix.
* No one uses these insns, reject any branch insns with such prefix.
*/
- for_each_insn_prefix(insn, i, p) {
+ for_each_insn_prefix(insn, p) {
if (p == 0x66)
return -ENOTSUPP;
}
diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c
index c991dac..e03eeec 100644
--- a/arch/x86/lib/insn-eval.c
+++ b/arch/x86/lib/insn-eval.c
@@ -63,11 +63,10 @@ static bool is_string_insn(struct insn *insn)
bool insn_has_rep_prefix(struct insn *insn)
{
insn_byte_t p;
- int i;
insn_get_prefixes(insn);
- for_each_insn_prefix(insn, i, p) {
+ for_each_insn_prefix(insn, p) {
if (p == 0xf2 || p == 0xf3)
return true;
}
@@ -92,13 +91,13 @@ bool insn_has_rep_prefix(struct insn *insn)
static int get_seg_reg_override_idx(struct insn *insn)
{
int idx = INAT_SEG_REG_DEFAULT;
- int num_overrides = 0, i;
+ int num_overrides = 0;
insn_byte_t p;
insn_get_prefixes(insn);
/* Look for any segment override prefixes. */
- for_each_insn_prefix(insn, i, p) {
+ for_each_insn_prefix(insn, p) {
insn_attr_t attr;
attr = inat_get_opcode_attribute(p);
@@ -1701,7 +1700,6 @@ bool insn_is_nop(struct insn *insn)
u8 sib = 0, sib_scale, sib_index, sib_base;
u8 nrex, rex;
u8 p, rep = 0;
- int i;
if ((nrex = insn->rex_prefix.nbytes)) {
rex = insn->rex_prefix.bytes[nrex-1];
@@ -1741,7 +1739,7 @@ bool insn_is_nop(struct insn *insn)
modrm_rm = sib_base;
}
- for_each_insn_prefix(insn, i, p) {
+ for_each_insn_prefix(insn, p) {
if (p == 0xf3) /* REPE */
rep = 1;
}
@@ -1789,7 +1787,7 @@ bool insn_is_nop(struct insn *insn)
if (sib && (sib_scale != 0 || sib_index != 4)) /* (%reg, %eiz, 1) */
return false;
- for_each_insn_prefix(insn, i, p) {
+ for_each_insn_prefix(insn, p) {
if (p != 0x3e) /* DS */
return false;
}
diff --git a/tools/arch/x86/include/asm/insn.h b/tools/arch/x86/include/asm/insn.h
index c683d60..8f10f29 100644
--- a/tools/arch/x86/include/asm/insn.h
+++ b/tools/arch/x86/include/asm/insn.h
@@ -312,7 +312,6 @@ static inline int insn_offset_immediate(struct insn *insn)
/**
* for_each_insn_prefix() -- Iterate prefixes in the instruction
* @insn: Pointer to struct insn.
- * @idx: Index storage.
* @prefix: Prefix byte.
*
* Iterate prefix bytes of given @insn. Each prefix byte is stored in @prefix
@@ -321,8 +320,8 @@ static inline int insn_offset_immediate(struct insn *insn)
* Since prefixes.nbytes can be bigger than 4 if some prefixes
* are repeated, it cannot be used for looping over the prefixes.
*/
-#define for_each_insn_prefix(insn, idx, prefix) \
- for (idx = 0; idx < ARRAY_SIZE(insn->prefixes.bytes) && (prefix = insn->prefixes.bytes[idx]) != 0; idx++)
+#define for_each_insn_prefix(insn, prefix) \
+ for (int idx = 0; idx < ARRAY_SIZE(insn->prefixes.bytes) && (prefix = insn->prefixes.bytes[idx]) != 0; idx++)
#define POP_SS_OPCODE 0x1f
#define MOV_SREG_OPCODE 0x8e
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