Commit 046199ca authored by Wu Zhangjin's avatar Wu Zhangjin Committed by Ralf Baechle
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MIPS: Tracing: Make ftrace for MIPS work without -fno-omit-frame-pointer 



When remove the -fno-omit-frame-pointer, gcc will not save the frame
pointer for us, we need to save one ourselves.

Signed-off-by: default avatarWu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/679/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent e17ff5fe

arch/mips/include/asm/ftrace.h

+57 −0
Original line number Diff line number Diff line
@@ -19,6 +19,62 @@ 
extern void _mcount(void);

#define mcount _mcount



#define safe_load(load, src, dst, error)		\

do {							\

	asm volatile (					\

		"1: " load " %[" STR(dst) "], 0(%[" STR(src) "])\n"\

		"   li %[" STR(error) "], 0\n"		\

		"2:\n"					\

							\

		".section .fixup, \"ax\"\n"		\

		"3: li %[" STR(error) "], 1\n"		\

		"   j 2b\n"				\

		".previous\n"				\

							\

		".section\t__ex_table,\"a\"\n\t"	\

		STR(PTR) "\t1b, 3b\n\t"			\

		".previous\n"				\

							\

		: [dst] "=&r" (dst), [error] "=r" (error)\

		: [src] "r" (src)			\

		: "memory"				\

	);						\

} while (0)



#define safe_store(store, src, dst, error)	\

do {						\

	asm volatile (				\

		"1: " store " %[" STR(src) "], 0(%[" STR(dst) "])\n"\

		"   li %[" STR(error) "], 0\n"	\

		"2:\n"				\

						\

		".section .fixup, \"ax\"\n"	\

		"3: li %[" STR(error) "], 1\n"	\

		"   j 2b\n"			\

		".previous\n"			\

						\

		".section\t__ex_table,\"a\"\n\t"\

		STR(PTR) "\t1b, 3b\n\t"		\

		".previous\n"			\

						\

		: [error] "=r" (error)		\

		: [dst] "r" (dst), [src] "r" (src)\

		: "memory"			\

	);					\

} while (0)



#define safe_load_code(dst, src, error) \

	safe_load(STR(lw), src, dst, error)

#define safe_store_code(src, dst, error) \

	safe_store(STR(sw), src, dst, error)



#define safe_load_stack(dst, src, error) \

	safe_load(STR(PTR_L), src, dst, error)



#define safe_store_stack(src, dst, error) \

	safe_store(STR(PTR_S), src, dst, error)





#ifdef CONFIG_DYNAMIC_FTRACE

static inline unsigned long ftrace_call_adjust(unsigned long addr)

{
@@ -27,6 +83,7 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) 


struct dyn_arch_ftrace {

};



#endif /*  CONFIG_DYNAMIC_FTRACE */

#endif /* __ASSEMBLY__ */

#endif /* CONFIG_FUNCTION_TRACER */

arch/mips/kernel/ftrace.c

+41 −15
Original line number Diff line number Diff line
@@ -27,7 +27,13 @@ static unsigned int ftrace_nop = 0x00000000; 


static int ftrace_modify_code(unsigned long ip, unsigned int new_code)

{

	*(unsigned int *)ip = new_code;

	int faulted;



	/* *(unsigned int *)ip = new_code; */

	safe_store_code(new_code, ip, faulted);



	if (unlikely(faulted))

		return -EFAULT;



	flush_icache_range(ip, ip + 8);
@@ -41,14 +47,20 @@ int ftrace_make_nop(struct module *mod, 
		    struct dyn_ftrace *rec, unsigned long addr)

{

	unsigned int new;

	int faulted;

	unsigned long ip = rec->ip;



	/* We have compiled module with -mlong-calls, but compiled the kernel

	 * without it, we need to cope with them respectively. */

	if (ip & 0x40000000) {

		/* record it for ftrace_make_call */

		if (lui_v1 == 0)

			lui_v1 = *(unsigned int *)ip;

		if (lui_v1 == 0) {

			/* lui_v1 = *(unsigned int *)ip; */

			safe_load_code(lui_v1, ip, faulted);



			if (unlikely(faulted))

				return -EFAULT;

		}



		/* lui v1, hi_16bit_of_mcount        --> b 1f (0x10000004)

		 * addiu v1, v1, low_16bit_of_mcount
@@ -147,6 +159,7 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr, 
{

	unsigned long sp, ip, ra;

	unsigned int code;

	int faulted;



	/* in module or kernel? */

	if (self_addr & 0x40000000) {
@@ -162,8 +175,11 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr, 
	do {

		ip -= 4;



		/* get the code at "ip" */

		code = *(unsigned int *)ip;

		/* get the code at "ip": code = *(unsigned int *)ip; */

		safe_load_code(code, ip, faulted);



		if (unlikely(faulted))

			return 0;



		/* If we hit the non-store instruction before finding where the

		 * ra is stored, then this is a leaf function and it does not
@@ -174,11 +190,14 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr, 
	} while (((code & S_RA_SP) != S_RA_SP));



	sp = fp + (code & OFFSET_MASK);

	ra = *(unsigned long *)sp;



	/* ra = *(unsigned long *)sp; */

	safe_load_stack(ra, sp, faulted);

	if (unlikely(faulted))

		return 0;



	if (ra == parent)

		return sp;



	return 0;

}
@@ -193,6 +212,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, 
	struct ftrace_graph_ent trace;

	unsigned long return_hooker = (unsigned long)

	    &return_to_handler;

	int faulted;



	if (unlikely(atomic_read(&current->tracing_graph_pause)))

		return;
@@ -206,21 +226,23 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, 
	 * ftrace_get_parent_addr() does it!

	 */



	old = *parent;

	/* old = *parent; */

	safe_load_stack(old, parent, faulted);

	if (unlikely(faulted))

		goto out;



	parent = (unsigned long *)ftrace_get_parent_addr(self_addr, old,

							 (unsigned long)parent,

							 fp);



	/* If fails when getting the stack address of the non-leaf function's

	 * ra, stop function graph tracer and return */

	if (parent == 0) {

		ftrace_graph_stop();

		WARN_ON(1);

		return;

	}

	if (parent == 0)

		goto out;



	*parent = return_hooker;

	/* *parent = return_hooker; */

	safe_store_stack(return_hooker, parent, faulted);

	if (unlikely(faulted))

		goto out;



	if (ftrace_push_return_trace(old, self_addr, &trace.depth, fp) ==

	    -EBUSY) {
@@ -235,5 +257,9 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, 
		current->curr_ret_stack--;

		*parent = old;

	}

	return;

out:

	ftrace_graph_stop();

	WARN_ON(1);

}

#endif				/* CONFIG_FUNCTION_GRAPH_TRACER */

arch/mips/kernel/mcount.S

+8 −0
Original line number Diff line number Diff line
@@ -139,7 +139,15 @@ NESTED(ftrace_graph_caller, PT_SIZE, ra) 
#endif

	PTR_LA	a0, PT_R1(sp)	/* arg1: &AT -> a0 */

	jal	prepare_ftrace_return

#ifdef CONFIG_FRAME_POINTER

	 move	a2, fp		/* arg3: frame pointer */

#else

#ifdef CONFIG_64BIT

	 PTR_LA	a2, PT_SIZE(sp)

#else

	 PTR_LA	a2, (PT_SIZE+8)(sp)

#endif

#endif



	MCOUNT_RESTORE_REGS

	RETURN_BACK

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