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x86/insn: Simplify for_each_insn_prefix()

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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@infradead.org>
This commit is contained in:
Peter Zijlstra
2025-09-25 10:19:05 +02:00
parent 8a5c6cbfe4
commit 45e1dccc06
6 changed files with 13 additions and 21 deletions
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3
arch/x86/boot/compressed/sev-handle-vc.c
View File

@@ -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;
}

5
arch/x86/include/asm/insn.h
View File

@@ -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

3
arch/x86/kernel/kprobes/core.c
View File

@@ -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);

6
arch/x86/kernel/uprobes.c
View File

@@ -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;
}

12
arch/x86/lib/insn-eval.c
View File

@@ -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;
}

5
tools/arch/x86/include/asm/insn.h
View File

@@ -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