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Subject[PATCH -v5 08/17] x86/ftrace: Use text_gen_insn()
Replace the ftrace_code_union with the generic text_gen_insn() helper,
which does exactly this.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/text-patching.h | 25 ++++++++++++++++++++++++-
arch/x86/kernel/alternative.c | 26 --------------------------
arch/x86/kernel/ftrace.c | 32 +++++++-------------------------
3 files changed, 31 insertions(+), 52 deletions(-)

--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -80,7 +80,30 @@ static inline int text_opcode_size(u8 op
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)
+ BUG_ON((insn.disp >> 31) != (insn.disp >> 7));
+ }
+
+ return &insn.text;
+}

extern int after_bootmem;
extern __ro_after_init struct mm_struct *poking_mm;
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -1247,29 +1247,3 @@ void __ref text_poke_bp(void *addr, cons
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;
-}
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -58,24 +58,6 @@ int ftrace_arch_code_modify_post_process
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];
@@ -83,7 +65,7 @@ static const char *ftrace_nop_replace(vo

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)
@@ -475,20 +457,20 @@ void arch_ftrace_update_trampoline(struc
/* 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,
@@ -557,7 +539,7 @@ 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)

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