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Subject[PATCH 2/3] MIPS: ftrace: Combine ftrace_modify_code* into one function
Date
Behavior of ftrace_modify_code_2r() is similar to ftrace_modify_code_2(),
just the order of modification changed. Add a new struct ftrace_insn
to combine ftrace_modify_code with above two functions. The function is
same with the original ftrace_modify_code when ftrace_insn.code[1]
is DONT_SET.

Signed-off-by: Jinyang He <hejinyang@loongson.cn>
---
arch/mips/include/asm/ftrace.h | 3 +
arch/mips/kernel/ftrace.c | 157 +++++++++++++++++------------------------
2 files changed, 68 insertions(+), 92 deletions(-)

diff --git a/arch/mips/include/asm/ftrace.h b/arch/mips/include/asm/ftrace.h
index b463f2a..636c640 100644
--- a/arch/mips/include/asm/ftrace.h
+++ b/arch/mips/include/asm/ftrace.h
@@ -84,6 +84,9 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
struct dyn_arch_ftrace {
};

+struct ftrace_insn {
+ unsigned int code[2];
+};
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* __ASSEMBLY__ */
#endif /* CONFIG_FUNCTION_TRACER */
diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c
index f57e68f..fd6d1da 100644
--- a/arch/mips/kernel/ftrace.c
+++ b/arch/mips/kernel/ftrace.c
@@ -44,89 +44,70 @@ void arch_ftrace_update_code(int command)
#define INSN_NOP 0x00000000 /* nop */
#define INSN_JAL(addr) \
((unsigned int)(JAL | (((addr) >> 2) & ADDR_MASK)))
+#define INSN_B_1F (0x10000000 | MCOUNT_OFFSET_INSNS)
+
+#define DONT_SET 0xffffffff
+
+static struct ftrace_insn jal_ftrace_caller __read_mostly;
+static struct ftrace_insn la_mcount __read_mostly;
+static struct ftrace_insn nop_kernel __read_mostly;
+static struct ftrace_insn nop_module __read_mostly;

-static unsigned int insn_jal_ftrace_caller __read_mostly;
-static unsigned int insn_la_mcount[2] __read_mostly;
-static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly;
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+static struct ftrace_insn j_ftrace_graph_caller __read_mostly;
+#endif

static inline void ftrace_dyn_arch_init_insns(void)
{
u32 *buf;
- unsigned int v1;
+ unsigned int v1 = 3;

/* la v1, _mcount */
- v1 = 3;
- buf = (u32 *)&insn_la_mcount[0];
+ buf = (u32 *)&la_mcount;
UASM_i_LA(&buf, v1, MCOUNT_ADDR);
+#ifdef CONFIG_64BIT
+ la_mcount.code[1] = DONT_SET;
+#endif

/* jal (ftrace_caller + 8), jump over the first two instruction */
- buf = (u32 *)&insn_jal_ftrace_caller;
+ buf = (u32 *)&jal_ftrace_caller;
uasm_i_jal(&buf, (FTRACE_ADDR + 8) & JUMP_RANGE_MASK);
+ jal_ftrace_caller.code[1] = DONT_SET;
+
+ nop_kernel.code[0] = INSN_NOP;
+ nop_module.code[0] = INSN_B_1F;
+
+#ifdef CONFIG_64BIT
+ nop_kernel.code[1] = DONT_SET;
+ nop_module.code[1] = DONT_SET;
+#else
+ nop_kernel.code[1] = INSN_NOP;
+ nop_module.code[1] = INSN_NOP;
+#endif

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/* j ftrace_graph_caller */
- buf = (u32 *)&insn_j_ftrace_graph_caller;
+ buf = (u32 *)&j_ftrace_graph_caller;
uasm_i_j(&buf, (unsigned long)ftrace_graph_caller & JUMP_RANGE_MASK);
+ j_ftrace_graph_caller.code[1] = DONT_SET;
#endif
}

-static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
-{
- int faulted;
- mm_segment_t old_fs;
-
- /* *(unsigned int *)ip = new_code; */
- safe_store_code(new_code, ip, faulted);
-
- if (unlikely(faulted))
- return -EFAULT;
-
- old_fs = get_fs();
- set_fs(KERNEL_DS);
- flush_icache_range(ip, ip + 8);
- set_fs(old_fs);
-
- return 0;
-}
-
-#ifndef CONFIG_64BIT
-static int ftrace_modify_code_2(unsigned long ip, unsigned int new_code1,
- unsigned int new_code2)
-{
- int faulted;
- mm_segment_t old_fs;
-
- safe_store_code(new_code1, ip, faulted);
- if (unlikely(faulted))
- return -EFAULT;
-
- ip += 4;
- safe_store_code(new_code2, ip, faulted);
- if (unlikely(faulted))
- return -EFAULT;
-
- ip -= 4;
- old_fs = get_fs();
- set_fs(KERNEL_DS);
- flush_icache_range(ip, ip + 8);
- set_fs(old_fs);
-
- return 0;
-}
-
-static int ftrace_modify_code_2r(unsigned long ip, unsigned int new_code1,
- unsigned int new_code2)
+static int ftrace_modify_code(unsigned long ip, struct ftrace_insn insns)
{
int faulted;
mm_segment_t old_fs;

- ip += 4;
- safe_store_code(new_code2, ip, faulted);
- if (unlikely(faulted))
- return -EFAULT;
+ if (insns.code[1] != DONT_SET) {
+ ip += 4;
+ safe_store_code(insns.code[1], ip, faulted);
+ if (unlikely(faulted))
+ return -EFAULT;
+ ip -= 4;
+ }

- ip -= 4;
- safe_store_code(new_code1, ip, faulted);
+ /* *(unsigned int *)ip = insns.code[0]; */
+ safe_store_code(insns.code[0], ip, faulted);
if (unlikely(faulted))
return -EFAULT;

@@ -137,7 +118,6 @@ static int ftrace_modify_code_2r(unsigned long ip, unsigned int new_code1,

return 0;
}
-#endif

/*
* The details about the calling site of mcount on MIPS
@@ -169,66 +149,55 @@ static int ftrace_modify_code_2r(unsigned long ip, unsigned int new_code1,
* 1: offset = 4 instructions
*/

-#define INSN_B_1F (0x10000000 | MCOUNT_OFFSET_INSNS)
-
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
- unsigned int new;
+ struct ftrace_insn insns;
unsigned long ip = rec->ip;

/*
* If ip is in kernel space, no long call, otherwise, long call is
* needed.
*/
- new = core_kernel_text(ip) ? INSN_NOP : INSN_B_1F;
-#ifdef CONFIG_64BIT
- return ftrace_modify_code(ip, new);
-#else
- /*
- * On 32 bit MIPS platforms, gcc adds a stack adjust
- * instruction in the delay slot after the branch to
- * mcount and expects mcount to restore the sp on return.
- * This is based on a legacy API and does nothing but
- * waste instructions so it's being removed at runtime.
- */
- return ftrace_modify_code_2(ip, new, INSN_NOP);
-#endif
+ insns = core_kernel_text(ip) ? nop_kernel : nop_module;
+
+ return ftrace_modify_code(ip, insns);
}

int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
- unsigned int new;
+ struct ftrace_insn insns;
unsigned long ip = rec->ip;

- new = core_kernel_text(ip) ? insn_jal_ftrace_caller : insn_la_mcount[0];
+ insns = core_kernel_text(ip) ? jal_ftrace_caller : la_mcount;

-#ifdef CONFIG_64BIT
- return ftrace_modify_code(ip, new);
-#else
- return ftrace_modify_code_2r(ip, new, core_kernel_text(ip) ?
- INSN_NOP : insn_la_mcount[1]);
-#endif
+ return ftrace_modify_code(ip, insns);
}

#define FTRACE_CALL_IP ((unsigned long)(&ftrace_call))

int ftrace_update_ftrace_func(ftrace_func_t func)
{
- unsigned int new;
+ struct ftrace_insn insns;

- new = INSN_JAL((unsigned long)func);
+ insns.code[0] = INSN_JAL((unsigned long)func);
+ insns.code[1] = DONT_SET;

- return ftrace_modify_code(FTRACE_CALL_IP, new);
+ return ftrace_modify_code(FTRACE_CALL_IP, insns);
}

int __init ftrace_dyn_arch_init(void)
{
+ struct ftrace_insn insns;
+
+ insns.code[0] = INSN_NOP;
+ insns.code[1] = DONT_SET;
+
/* Encode the instructions when booting */
ftrace_dyn_arch_init_insns();

/* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */
- ftrace_modify_code(MCOUNT_ADDR, INSN_NOP);
+ ftrace_modify_code(MCOUNT_ADDR, insns);

return 0;
}
@@ -243,13 +212,17 @@ extern void ftrace_graph_call(void);

int ftrace_enable_ftrace_graph_caller(void)
{
- return ftrace_modify_code(FTRACE_GRAPH_CALL_IP,
- insn_j_ftrace_graph_caller);
+ return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, j_ftrace_graph_caller);
}

int ftrace_disable_ftrace_graph_caller(void)
{
- return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, INSN_NOP);
+ struct ftrace_insn insns;
+
+ insns.code[0] = INSN_NOP;
+ insns.code[1] = DONT_SET;
+
+ return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, insns);
}

#endif /* CONFIG_DYNAMIC_FTRACE */
--
2.1.0
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