[PATCH -v5 11/17] x86/kprobes: Convert to text-patching.h

From: Peter Zijlstra
Date: Mon Nov 11 2019 - 09:47:18 EST

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Convert kprobes to the new text-poke naming.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
arch/x86/include/asm/kprobes.h | 14 +++--------
arch/x86/include/asm/text-patching.h | 2 +
arch/x86/kernel/kprobes/core.c | 18 +++++++-------
arch/x86/kernel/kprobes/opt.c | 44 ++++++++++++++++-------------------
4 files changed, 37 insertions(+), 41 deletions(-)

--- a/arch/x86/include/asm/kprobes.h
+++ b/arch/x86/include/asm/kprobes.h
@@ -11,12 +11,11 @@

#include <asm-generic/kprobes.h>

-#define BREAKPOINT_INSTRUCTION 0xcc
-
#ifdef CONFIG_KPROBES
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/percpu.h>
+#include <asm/text-patching.h>
#include <asm/insn.h>

#define __ARCH_WANT_KPROBES_INSN_SLOT
@@ -25,10 +24,7 @@ struct pt_regs;
struct kprobe;

typedef u8 kprobe_opcode_t;
-#define RELATIVEJUMP_OPCODE 0xe9
-#define RELATIVEJUMP_SIZE 5
-#define RELATIVECALL_OPCODE 0xe8
-#define RELATIVE_ADDR_SIZE 4
+
#define MAX_STACK_SIZE 64
#define CUR_STACK_SIZE(ADDR) \
(current_top_of_stack() - (unsigned long)(ADDR))
@@ -43,11 +39,11 @@ extern __visible kprobe_opcode_t optprob
extern __visible kprobe_opcode_t optprobe_template_val[];
extern __visible kprobe_opcode_t optprobe_template_call[];
extern __visible kprobe_opcode_t optprobe_template_end[];
-#define MAX_OPTIMIZED_LENGTH (MAX_INSN_SIZE + RELATIVE_ADDR_SIZE)
+#define MAX_OPTIMIZED_LENGTH (MAX_INSN_SIZE + DISP32_SIZE)
#define MAX_OPTINSN_SIZE \
(((unsigned long)optprobe_template_end - \
(unsigned long)optprobe_template_entry) + \
- MAX_OPTIMIZED_LENGTH + RELATIVEJUMP_SIZE)
+ MAX_OPTIMIZED_LENGTH + JMP32_INSN_SIZE)

extern const int kretprobe_blacklist_size;

@@ -73,7 +69,7 @@ struct arch_specific_insn {

struct arch_optimized_insn {
/* copy of the original instructions */
- kprobe_opcode_t copied_insn[RELATIVE_ADDR_SIZE];
+ kprobe_opcode_t copied_insn[DISP32_SIZE];
/* detour code buffer */
kprobe_opcode_t *insn;
/* the size of instructions copied to detour code buffer */
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -61,6 +61,8 @@ extern void text_poke_finish(void);
#define JMP8_INSN_SIZE 2
#define JMP8_INSN_OPCODE 0xEB

+#define DISP32_SIZE 4
+
static inline int text_opcode_size(u8 opcode)
{
int size = 0;
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -119,14 +119,14 @@ __synthesize_relative_insn(void *dest, v
/* Insert a jump instruction at address 'from', which jumps to address 'to'.*/
void synthesize_reljump(void *dest, void *from, void *to)
{
- __synthesize_relative_insn(dest, from, to, RELATIVEJUMP_OPCODE);
+ __synthesize_relative_insn(dest, from, to, JMP32_INSN_OPCODE);
}
NOKPROBE_SYMBOL(synthesize_reljump);

/* Insert a call instruction at address 'from', which calls address 'to'.*/
void synthesize_relcall(void *dest, void *from, void *to)
{
- __synthesize_relative_insn(dest, from, to, RELATIVECALL_OPCODE);
+ __synthesize_relative_insn(dest, from, to, CALL_INSN_OPCODE);
}
NOKPROBE_SYMBOL(synthesize_relcall);

@@ -301,7 +301,7 @@ static int can_probe(unsigned long paddr
* Another debugging subsystem might insert this breakpoint.
* In that case, we can't recover it.
*/
- if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
+ if (insn.opcode.bytes[0] == INT3_INSN_OPCODE)
return 0;
addr += insn.length;
}
@@ -356,7 +356,7 @@ int __copy_instruction(u8 *dest, u8 *src
return 0;

/* Another subsystem puts a breakpoint, failed to recover */
- if (insn->opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
+ if (insn->opcode.bytes[0] == INT3_INSN_OPCODE)
return 0;

/* We should not singlestep on the exception masking instructions */
@@ -400,14 +400,14 @@ static int prepare_boost(kprobe_opcode_t
int len = insn->length;

if (can_boost(insn, p->addr) &&
- MAX_INSN_SIZE - len >= RELATIVEJUMP_SIZE) {
+ MAX_INSN_SIZE - len >= JMP32_INSN_SIZE) {
/*
* These instructions can be executed directly if it
* jumps back to correct address.
*/
synthesize_reljump(buf + len, p->ainsn.insn + len,
p->addr + insn->length);
- len += RELATIVEJUMP_SIZE;
+ len += JMP32_INSN_SIZE;
p->ainsn.boostable = true;
} else {
p->ainsn.boostable = false;
@@ -501,7 +501,7 @@ int arch_prepare_kprobe(struct kprobe *p

void arch_arm_kprobe(struct kprobe *p)
{
- text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1);
+ text_poke(p->addr, ((unsigned char []){INT3_INSN_OPCODE}), 1);
}

void arch_disarm_kprobe(struct kprobe *p)
@@ -609,7 +609,7 @@ static void setup_singlestep(struct kpro
regs->flags |= X86_EFLAGS_TF;
regs->flags &= ~X86_EFLAGS_IF;
/* single step inline if the instruction is an int3 */
- if (p->opcode == BREAKPOINT_INSTRUCTION)
+ if (p->opcode == INT3_INSN_OPCODE)
regs->ip = (unsigned long)p->addr;
else
regs->ip = (unsigned long)p->ainsn.insn;
@@ -695,7 +695,7 @@ int kprobe_int3_handler(struct pt_regs *
reset_current_kprobe();
return 1;
}
- } else if (*addr != BREAKPOINT_INSTRUCTION) {
+ } else if (*addr != INT3_INSN_OPCODE) {
/*
* The breakpoint instruction was removed right
* after we hit it. Another cpu has removed
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -38,7 +38,7 @@ unsigned long __recover_optprobed_insn(k
long offs;
int i;

- for (i = 0; i < RELATIVEJUMP_SIZE; i++) {
+ for (i = 0; i < JMP32_INSN_SIZE; i++) {
kp = get_kprobe((void *)addr - i);
/* This function only handles jump-optimized kprobe */
if (kp && kprobe_optimized(kp)) {
@@ -62,10 +62,10 @@ unsigned long __recover_optprobed_insn(k

if (addr == (unsigned long)kp->addr) {
buf[0] = kp->opcode;
- memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
+ memcpy(buf + 1, op->optinsn.copied_insn, DISP32_SIZE);
} else {
offs = addr - (unsigned long)kp->addr - 1;
- memcpy(buf, op->optinsn.copied_insn + offs, RELATIVE_ADDR_SIZE - offs);
+ memcpy(buf, op->optinsn.copied_insn + offs, DISP32_SIZE - offs);
}

return (unsigned long)buf;
@@ -141,8 +141,6 @@ STACK_FRAME_NON_STANDARD(optprobe_templa
#define TMPL_END_IDX \
((long)optprobe_template_end - (long)optprobe_template_entry)

-#define INT3_SIZE sizeof(kprobe_opcode_t)
-
/* Optimized kprobe call back function: called from optinsn */
static void
optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
@@ -162,7 +160,7 @@ optimized_callback(struct optimized_kpro
regs->cs |= get_kernel_rpl();
regs->gs = 0;
#endif
- regs->ip = (unsigned long)op->kp.addr + INT3_SIZE;
+ regs->ip = (unsigned long)op->kp.addr + INT3_INSN_SIZE;
regs->orig_ax = ~0UL;

__this_cpu_write(current_kprobe, &op->kp);
@@ -179,7 +177,7 @@ static int copy_optimized_instructions(u
struct insn insn;
int len = 0, ret;

- while (len < RELATIVEJUMP_SIZE) {
+ while (len < JMP32_INSN_SIZE) {
ret = __copy_instruction(dest + len, src + len, real + len, &insn);
if (!ret || !can_boost(&insn, src + len))
return -EINVAL;
@@ -271,7 +269,7 @@ static int can_optimize(unsigned long pa
return 0;

/* Check there is enough space for a relative jump. */
- if (size - offset < RELATIVEJUMP_SIZE)
+ if (size - offset < JMP32_INSN_SIZE)
return 0;

/* Decode instructions */
@@ -290,15 +288,15 @@ static int can_optimize(unsigned long pa
kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);
insn_get_length(&insn);
/* Another subsystem puts a breakpoint */
- if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
+ if (insn.opcode.bytes[0] == INT3_INSN_OPCODE)
return 0;
/* Recover address */
insn.kaddr = (void *)addr;
insn.next_byte = (void *)(addr + insn.length);
/* Check any instructions don't jump into target */
if (insn_is_indirect_jump(&insn) ||
- insn_jump_into_range(&insn, paddr + INT3_SIZE,
- RELATIVE_ADDR_SIZE))
+ insn_jump_into_range(&insn, paddr + INT3_INSN_SIZE,
+ DISP32_SIZE))
return 0;
addr += insn.length;
}
@@ -374,7 +372,7 @@ int arch_prepare_optimized_kprobe(struct
* Verify if the address gap is in 2GB range, because this uses
* a relative jump.
*/
- rel = (long)slot - (long)op->kp.addr + RELATIVEJUMP_SIZE;
+ rel = (long)slot - (long)op->kp.addr + JMP32_INSN_SIZE;
if (abs(rel) > 0x7fffffff) {
ret = -ERANGE;
goto err;
@@ -401,7 +399,7 @@ int arch_prepare_optimized_kprobe(struct
/* Set returning jmp instruction at the tail of out-of-line buffer */
synthesize_reljump(buf + len, slot + len,
(u8 *)op->kp.addr + op->optinsn.size);
- len += RELATIVEJUMP_SIZE;
+ len += JMP32_INSN_SIZE;

/* We have to use text_poke() for instruction buffer because it is RO */
text_poke(slot, buf, len);
@@ -422,22 +420,22 @@ int arch_prepare_optimized_kprobe(struct
void arch_optimize_kprobes(struct list_head *oplist)
{
struct optimized_kprobe *op, *tmp;
- u8 insn_buff[RELATIVEJUMP_SIZE];
+ u8 insn_buff[JMP32_INSN_SIZE];

list_for_each_entry_safe(op, tmp, oplist, list) {
s32 rel = (s32)((long)op->optinsn.insn -
- ((long)op->kp.addr + RELATIVEJUMP_SIZE));
+ ((long)op->kp.addr + JMP32_INSN_SIZE));

WARN_ON(kprobe_disabled(&op->kp));

/* Backup instructions which will be replaced by jump address */
- memcpy(op->optinsn.copied_insn, op->kp.addr + INT3_SIZE,
- RELATIVE_ADDR_SIZE);
+ memcpy(op->optinsn.copied_insn, op->kp.addr + INT3_INSN_SIZE,
+ DISP32_SIZE);

- insn_buff[0] = RELATIVEJUMP_OPCODE;
+ insn_buff[0] = JMP32_INSN_OPCODE;
*(s32 *)(&insn_buff[1]) = rel;

- text_poke_bp(op->kp.addr, insn_buff, RELATIVEJUMP_SIZE, NULL);
+ text_poke_bp(op->kp.addr, insn_buff, JMP32_INSN_SIZE, NULL);

list_del_init(&op->list);
}
@@ -446,13 +444,13 @@ void arch_optimize_kprobes(struct list_h
/* Replace a relative jump with a breakpoint (int3). */
void arch_unoptimize_kprobe(struct optimized_kprobe *op)
{
- u8 insn_buff[RELATIVEJUMP_SIZE];
+ u8 insn_buff[JMP32_INSN_SIZE];

/* Set int3 to first byte for kprobes */
- insn_buff[0] = BREAKPOINT_INSTRUCTION;
- memcpy(insn_buff + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE);
+ insn_buff[0] = INT3_INSN_OPCODE;
+ memcpy(insn_buff + 1, op->optinsn.copied_insn, DISP32_SIZE);

- text_poke_bp(op->kp.addr, insn_buff, RELATIVEJUMP_SIZE,
+ text_poke_bp(op->kp.addr, insn_buff, JMP32_INSN_SIZE,
text_gen_insn(JMP32_INSN_OPCODE, op->kp.addr, op->optinsn.insn));
}

Next message: Peter Zijlstra: "[PATCH -v5 16/17] x86/kprobe: Add comments to arch_{,un}optimize_kprobes()"
Previous message: Peter Zijlstra: "Re: [PATCH RFC 1/6] perf/x86: Add perf text poke event"
In reply to: Peter Zijlstra: "[PATCH -v5 00/17] Rewrite x86/ftrace to use text_poke (and more)"
Next in thread: Peter Zijlstra: "[PATCH -v5 16/17] x86/kprobe: Add comments to arch_{,un}optimize_kprobes()"
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