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Commit 327933f5 authored by Matt Fleming's avatar Matt Fleming Committed by Paul Mundt
Browse files

sh: Function graph tracer support 



Add both dynamic and static function graph tracer support for sh.

Signed-off-by: default avatarMatt Fleming <matt@console-pimps.org>
Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent b99610fb

arch/sh/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ config SUPERH32 
	select HAVE_DYNAMIC_FTRACE

	select HAVE_FUNCTION_TRACE_MCOUNT_TEST

	select HAVE_FTRACE_SYSCALLS

	select HAVE_FUNCTION_GRAPH_TRACER

	select HAVE_ARCH_KGDB

	select ARCH_HIBERNATION_POSSIBLE if MMU

arch/sh/include/asm/ftrace.h

+3 −0
Original line number Diff line number Diff line
@@ -13,8 +13,11 @@ extern void mcount(void); 
#ifdef CONFIG_DYNAMIC_FTRACE

#define CALL_ADDR		((long)(ftrace_call))

#define STUB_ADDR		((long)(ftrace_stub))

#define GRAPH_ADDR		((long)(ftrace_graph_call))

#define CALLER_ADDR		((long)(ftrace_caller))



#define MCOUNT_INSN_OFFSET	((STUB_ADDR - CALL_ADDR) - 4)

#define GRAPH_INSN_OFFSET	((CALLER_ADDR - GRAPH_ADDR) - 4)



struct dyn_arch_ftrace {

	/* No extra data needed on sh */

arch/sh/kernel/Makefile_32

+1 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ obj-$(CONFIG_KPROBES) += kprobes.o 
obj-$(CONFIG_GENERIC_GPIO)	+= gpio.o

obj-$(CONFIG_DYNAMIC_FTRACE)	+= ftrace.o

obj-$(CONFIG_FTRACE_SYSCALLS)	+= ftrace.o

obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o

obj-$(CONFIG_DUMP_CODE)		+= disassemble.o

obj-$(CONFIG_HIBERNATION)	+= swsusp.o

arch/sh/kernel/ftrace.c

+122 −0
Original line number Diff line number Diff line
@@ -16,11 +16,13 @@ 
#include <linux/string.h>

#include <linux/init.h>

#include <linux/io.h>

#include <linux/kernel.h>

#include <asm/ftrace.h>

#include <asm/cacheflush.h>

#include <asm/unistd.h>

#include <trace/syscall.h>



#ifdef CONFIG_DYNAMIC_FTRACE

static unsigned char ftrace_replaced_code[MCOUNT_INSN_SIZE];



static unsigned char ftrace_nop[4];
@@ -133,6 +135,126 @@ int __init ftrace_dyn_arch_init(void *data) 


	return 0;

}

#endif /* CONFIG_DYNAMIC_FTRACE */



#ifdef CONFIG_FUNCTION_GRAPH_TRACER

#ifdef CONFIG_DYNAMIC_FTRACE

extern void ftrace_graph_call(void);



static int ftrace_mod(unsigned long ip, unsigned long old_addr,

		      unsigned long new_addr)

{

	unsigned char code[MCOUNT_INSN_SIZE];



	if (probe_kernel_read(code, (void *)ip, MCOUNT_INSN_SIZE))

		return -EFAULT;



	if (old_addr != __raw_readl((unsigned long *)code))

		return -EINVAL;



	__raw_writel(new_addr, ip);

	return 0;

}



int ftrace_enable_ftrace_graph_caller(void)

{

	unsigned long ip, old_addr, new_addr;



	ip = (unsigned long)(&ftrace_graph_call) + GRAPH_INSN_OFFSET;

	old_addr = (unsigned long)(&skip_trace);

	new_addr = (unsigned long)(&ftrace_graph_caller);



	return ftrace_mod(ip, old_addr, new_addr);

}



int ftrace_disable_ftrace_graph_caller(void)

{

	unsigned long ip, old_addr, new_addr;



	ip = (unsigned long)(&ftrace_graph_call) + GRAPH_INSN_OFFSET;

	old_addr = (unsigned long)(&ftrace_graph_caller);

	new_addr = (unsigned long)(&skip_trace);



	return ftrace_mod(ip, old_addr, new_addr);

}

#endif /* CONFIG_DYNAMIC_FTRACE */



/*

 * Hook the return address and push it in the stack of return addrs

 * in the current thread info.

 *

 * This is the main routine for the function graph tracer. The function

 * graph tracer essentially works like this:

 *

 * parent is the stack address containing self_addr's return address.

 * We pull the real return address out of parent and store it in

 * current's ret_stack. Then, we replace the return address on the stack

 * with the address of return_to_handler. self_addr is the function that

 * called mcount.

 *

 * When self_addr returns, it will jump to return_to_handler which calls

 * ftrace_return_to_handler. ftrace_return_to_handler will pull the real

 * return address off of current's ret_stack and jump to it.

 */

void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)

{

	unsigned long old;

	int faulted, err;

	struct ftrace_graph_ent trace;

	unsigned long return_hooker = (unsigned long)&return_to_handler;



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

		return;



	/*

	 * Protect against fault, even if it shouldn't

	 * happen. This tool is too much intrusive to

	 * ignore such a protection.

	 */

	__asm__ __volatile__(

		"1:						\n\t"

		"mov.l		@%2, %0				\n\t"

		"2:						\n\t"

		"mov.l		%3, @%2				\n\t"

		"mov		#0, %1				\n\t"

		"3:						\n\t"

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

		"4:						\n\t"

		"mov.l		5f, %0				\n\t"

		"jmp		@%0				\n\t"

		" mov		#1, %1				\n\t"

		".balign 4					\n\t"

		"5:	.long 3b				\n\t"

		".previous					\n\t"

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

		".long 1b, 4b					\n\t"

		".long 2b, 4b					\n\t"

		".previous					\n\t"

		: "=&r" (old), "=r" (faulted)

		: "r" (parent), "r" (return_hooker)

	);



	if (unlikely(faulted)) {

		ftrace_graph_stop();

		WARN_ON(1);

		return;

	}



	err = ftrace_push_return_trace(old, self_addr, &trace.depth, 0);

	if (err == -EBUSY) {

		__raw_writel(old, parent);

		return;

	}



	trace.func = self_addr;



	/* Only trace if the calling function expects to */

	if (!ftrace_graph_entry(&trace)) {

		current->curr_ret_stack--;

		__raw_writel(old, parent);

	}

}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */



#ifdef CONFIG_FTRACE_SYSCALLS

arch/sh/kernel/vmlinux_64.lds.S

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