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x86/ftrace: Use text_gen_insn()

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Replace the ftrace_code_union with the generic text_gen_insn() helper,
which does exactly this.

Tested-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191111132457.932808000@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2019-10-09 12:44:14 +02:00 committed by Ingo Molnar
parent 254d2c0451
commit 67c1d4a280
3 changed files with 36 additions and 52 deletions
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30
arch/x86/include/asm/text-patching.h
View File

@ -80,7 +80,35 @@ static inline int text_opcode_size(u8 opcode)
return size;
}
extern void *text_gen_insn(u8 opcode, const void *addr, const void *dest);
union text_poke_insn {
u8 text[POKE_MAX_OPCODE_SIZE];
struct {
u8 opcode;
s32 disp;
} __attribute__((packed));
};
static __always_inline
void *text_gen_insn(u8 opcode, const void *addr, const void *dest)
{
static union text_poke_insn insn; /* per instance */
int size = text_opcode_size(opcode);
insn.opcode = opcode;
if (size > 1) {
insn.disp = (long)dest - (long)(addr + size);
if (size == 2) {
/*
* Ensure that for JMP9 the displacement
* actually fits the signed byte.
*/
BUG_ON((insn.disp >> 31) != (insn.disp >> 7));
}
}
return &insn.text;
}
extern int after_bootmem;
extern __ro_after_init struct mm_struct *poking_mm;

26
arch/x86/kernel/alternative.c
View File

@ -1247,29 +1247,3 @@ void __ref text_poke_bp(void *addr, const void *opcode, size_t len, const void *
text_poke_loc_init(&tp, addr, opcode, len, emulate);
text_poke_bp_batch(&tp, 1);
}
union text_poke_insn {
u8 text[POKE_MAX_OPCODE_SIZE];
struct {
u8 opcode;
s32 disp;
} __attribute__((packed));
};
void *text_gen_insn(u8 opcode, const void *addr, const void *dest)
{
static union text_poke_insn insn; /* text_mutex */
int size = text_opcode_size(opcode);
lockdep_assert_held(&text_mutex);
insn.opcode = opcode;
if (size > 1) {
insn.disp = (long)dest - (long)(addr + size);
if (size == 2)
BUG_ON((insn.disp >> 31) != (insn.disp >> 7));
}
return &insn.text;
}

32
arch/x86/kernel/ftrace.c
View File

@ -63,24 +63,6 @@ int ftrace_arch_code_modify_post_process(void)
return 0;
}
union ftrace_code_union {
char code[MCOUNT_INSN_SIZE];
struct {
char op;
int offset;
} __attribute__((packed));
};
static const char *ftrace_text_replace(char op, unsigned long ip, unsigned long addr)
{
static union ftrace_code_union calc;
calc.op = op;
calc.offset = (int)(addr - (ip + MCOUNT_INSN_SIZE));
return calc.code;
}
static const char *ftrace_nop_replace(void)
{
return ideal_nops[NOP_ATOMIC5];
@ -88,7 +70,7 @@ static const char *ftrace_nop_replace(void)
static const char *ftrace_call_replace(unsigned long ip, unsigned long addr)
{
return ftrace_text_replace(CALL_INSN_OPCODE, ip, addr);
return text_gen_insn(CALL_INSN_OPCODE, (void *)ip, (void *)addr);
}
static int ftrace_verify_code(unsigned long ip, const char *old_code)
@ -480,20 +462,20 @@ void arch_ftrace_update_trampoline(struct ftrace_ops *ops)
/* Return the address of the function the trampoline calls */
static void *addr_from_call(void *ptr)
{
union ftrace_code_union calc;
union text_poke_insn call;
int ret;
ret = probe_kernel_read(&calc, ptr, MCOUNT_INSN_SIZE);
ret = probe_kernel_read(&call, ptr, CALL_INSN_SIZE);
if (WARN_ON_ONCE(ret < 0))
return NULL;
/* Make sure this is a call */
if (WARN_ON_ONCE(calc.op != 0xe8)) {
pr_warn("Expected e8, got %x\n", calc.op);
if (WARN_ON_ONCE(call.opcode != CALL_INSN_OPCODE)) {
pr_warn("Expected E8, got %x\n", call.opcode);
return NULL;
}
return ptr + MCOUNT_INSN_SIZE + calc.offset;
return ptr + CALL_INSN_SIZE + call.disp;
}
void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
@ -562,7 +544,7 @@ extern void ftrace_graph_call(void);
static const char *ftrace_jmp_replace(unsigned long ip, unsigned long addr)
{
return ftrace_text_replace(JMP32_INSN_OPCODE, ip, addr);
return text_gen_insn(JMP32_INSN_OPCODE, (void *)ip, (void *)addr);
}
static int ftrace_mod_jmp(unsigned long ip, void *func)