arch/sh/kernel/ftrace.c - kernel/prism - Git at Google

 /*
  * Copyright (C) 2008 Matt Fleming <matt@console-pimps.org>
  * Copyright (C) 2008 Paul Mundt <lethal@linux-sh.org>
  *
  * Code for replacing ftrace calls with jumps.
  *
  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
  *
  * Thanks goes to Ingo Molnar, for suggesting the idea.
  * Mathieu Desnoyers, for suggesting postponing the modifications.
  * Arjan van de Ven, for keeping me straight, and explaining to me
  * the dangers of modifying code on the run.
  */
 #include <linux/uaccess.h>
 #include <linux/ftrace.h>
 #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];
 /*
  * If we're trying to nop out a call to a function, we instead
  * place a call to the address after the memory table.
  *
  * 8c011060 <a>:
  * 8c011060:       02 d1           mov.l   8c01106c <a+0xc>,r1
  * 8c011062:       22 4f           sts.l   pr,@-r15
  * 8c011064:       02 c7           mova    8c011070 <a+0x10>,r0
  * 8c011066:       2b 41           jmp     @r1
  * 8c011068:       2a 40           lds     r0,pr
  * 8c01106a:       09 00           nop
  * 8c01106c:       68 24           .word 0x2468     <--- ip
  * 8c01106e:       1d 8c           .word 0x8c1d
  * 8c011070:       26 4f           lds.l   @r15+,pr <--- ip + MCOUNT_INSN_SIZE
  *
  * We write 0x8c011070 to 0x8c01106c so that on entry to a() we branch
  * past the _mcount call and continue executing code like normal.
  */
 static unsigned char *ftrace_nop_replace(unsigned long ip)
 {
 	__raw_writel(ip + MCOUNT_INSN_SIZE, ftrace_nop);
 	return ftrace_nop;
 }

 static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
 {
 	/* Place the address in the memory table. */
 	__raw_writel(addr, ftrace_replaced_code);

 	/*
 	 * No locking needed, this must be called via kstop_machine
 	 * which in essence is like running on a uniprocessor machine.
 	 */
 	return ftrace_replaced_code;
 }

 static int ftrace_modify_code(unsigned long ip, unsigned char *old_code,
 		       unsigned char *new_code)
 {
 	unsigned char replaced[MCOUNT_INSN_SIZE];

 	/*
 	 * Note: Due to modules and __init, code can
 	 *  disappear and change, we need to protect against faulting
 	 *  as well as code changing. We do this by using the
 	 *  probe_kernel_* functions.
 	 *
 	 * No real locking needed, this code is run through
 	 * kstop_machine, or before SMP starts.
 	 */

 	/* read the text we want to modify */
 	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
 		return -EFAULT;

 	/* Make sure it is what we expect it to be */
 	if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
 		return -EINVAL;

 	/* replace the text with the new text */
 	if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE))
 		return -EPERM;

 	flush_icache_range(ip, ip + MCOUNT_INSN_SIZE);

 	return 0;
 }

 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
 	unsigned long ip = (unsigned long)(&ftrace_call) + MCOUNT_INSN_OFFSET;
 	unsigned char old[MCOUNT_INSN_SIZE], *new;

 	memcpy(old, (unsigned char *)ip, MCOUNT_INSN_SIZE);
 	new = ftrace_call_replace(ip, (unsigned long)func);

 	return ftrace_modify_code(ip, old, new);
 }

 int ftrace_make_nop(struct module *mod,
 		    struct dyn_ftrace *rec, unsigned long addr)
 {
 	unsigned char *new, *old;
 	unsigned long ip = rec->ip;

 	old = ftrace_call_replace(ip, addr);
 	new = ftrace_nop_replace(ip);

 	return ftrace_modify_code(rec->ip, old, new);
 }

 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 {
 	unsigned char *new, *old;
 	unsigned long ip = rec->ip;

 	old = ftrace_nop_replace(ip);
 	new = ftrace_call_replace(ip, addr);

 	return ftrace_modify_code(rec->ip, old, new);
 }

 int __init ftrace_dyn_arch_init(void *data)
 {
 	/* The return code is retured via data */
 	__raw_writel(0, (unsigned long)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

 extern unsigned long __start_syscalls_metadata[];
 extern unsigned long __stop_syscalls_metadata[];
 extern unsigned long *sys_call_table;

 static struct syscall_metadata **syscalls_metadata;

 static struct syscall_metadata *find_syscall_meta(unsigned long *syscall)
 {
 	struct syscall_metadata *start;
 	struct syscall_metadata *stop;
 	char str[KSYM_SYMBOL_LEN];


 	start = (struct syscall_metadata *)__start_syscalls_metadata;
 	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
 	kallsyms_lookup((unsigned long) syscall, NULL, NULL, NULL, str);

 	for ( ; start < stop; start++) {
 		if (start->name && !strcmp(start->name, str))
 			return start;
 	}

 	return NULL;
 }

 struct syscall_metadata *syscall_nr_to_meta(int nr)
 {
 	if (!syscalls_metadata || nr >= FTRACE_SYSCALL_MAX || nr < 0)
 		return NULL;

 	return syscalls_metadata[nr];
 }

 int syscall_name_to_nr(char *name)
 {
 	int i;

 	if (!syscalls_metadata)
 		return -1;
 	for (i = 0; i < NR_syscalls; i++)
 		if (syscalls_metadata[i])
 			if (!strcmp(syscalls_metadata[i]->name, name))
 				return i;
 	return -1;
 }

 void set_syscall_enter_id(int num, int id)
 {
 	syscalls_metadata[num]->enter_id = id;
 }

 void set_syscall_exit_id(int num, int id)
 {
 	syscalls_metadata[num]->exit_id = id;
 }

 static int __init arch_init_ftrace_syscalls(void)
 {
 	int i;
 	struct syscall_metadata *meta;
 	unsigned long **psys_syscall_table = &sys_call_table;

 	syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) *
 					FTRACE_SYSCALL_MAX, GFP_KERNEL);
 	if (!syscalls_metadata) {
 		WARN_ON(1);
 		return -ENOMEM;
 	}

 	for (i = 0; i < FTRACE_SYSCALL_MAX; i++) {
 		meta = find_syscall_meta(psys_syscall_table[i]);
 		syscalls_metadata[i] = meta;
 	}

 	return 0;
 }
 arch_initcall(arch_init_ftrace_syscalls);
 #endif /* CONFIG_FTRACE_SYSCALLS */
	/*
	* Copyright (C) 2008 Matt Fleming <matt@console-pimps.org>
	* Copyright (C) 2008 Paul Mundt <lethal@linux-sh.org>
	*
	* Code for replacing ftrace calls with jumps.
	*
	* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
	*
	* Thanks goes to Ingo Molnar, for suggesting the idea.
	* Mathieu Desnoyers, for suggesting postponing the modifications.
	* Arjan van de Ven, for keeping me straight, and explaining to me
	* the dangers of modifying code on the run.
	*/
	#include <linux/uaccess.h>
	#include <linux/ftrace.h>
	#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];
	/*
	* If we're trying to nop out a call to a function, we instead
	* place a call to the address after the memory table.
	*
	* 8c011060 <a>:
	* 8c011060: 02 d1 mov.l 8c01106c <a+0xc>,r1
	* 8c011062: 22 4f sts.l pr,@-r15
	* 8c011064: 02 c7 mova 8c011070 <a+0x10>,r0
	* 8c011066: 2b 41 jmp @r1
	* 8c011068: 2a 40 lds r0,pr
	* 8c01106a: 09 00 nop
	* 8c01106c: 68 24 .word 0x2468 <--- ip
	* 8c01106e: 1d 8c .word 0x8c1d
	* 8c011070: 26 4f lds.l @r15+,pr <--- ip + MCOUNT_INSN_SIZE
	*
	* We write 0x8c011070 to 0x8c01106c so that on entry to a() we branch
	* past the _mcount call and continue executing code like normal.
	*/
	static unsigned char *ftrace_nop_replace(unsigned long ip)
	{
	__raw_writel(ip + MCOUNT_INSN_SIZE, ftrace_nop);
	return ftrace_nop;
	}

	static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
	{
	/* Place the address in the memory table. */
	__raw_writel(addr, ftrace_replaced_code);

	/*
	* No locking needed, this must be called via kstop_machine
	* which in essence is like running on a uniprocessor machine.
	*/
	return ftrace_replaced_code;
	}

	static int ftrace_modify_code(unsigned long ip, unsigned char *old_code,
	unsigned char *new_code)
	{
	unsigned char replaced[MCOUNT_INSN_SIZE];

	/*
	* Note: Due to modules and __init, code can
	* disappear and change, we need to protect against faulting
	* as well as code changing. We do this by using the
	* probe_kernel_* functions.
	*
	* No real locking needed, this code is run through
	* kstop_machine, or before SMP starts.
	*/

	/* read the text we want to modify */
	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
	return -EFAULT;

	/* Make sure it is what we expect it to be */
	if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
	return -EINVAL;

	/* replace the text with the new text */
	if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE))
	return -EPERM;

	flush_icache_range(ip, ip + MCOUNT_INSN_SIZE);

	return 0;
	}

	int ftrace_update_ftrace_func(ftrace_func_t func)
	{
	unsigned long ip = (unsigned long)(&ftrace_call) + MCOUNT_INSN_OFFSET;
	unsigned char old[MCOUNT_INSN_SIZE], *new;

	memcpy(old, (unsigned char *)ip, MCOUNT_INSN_SIZE);
	new = ftrace_call_replace(ip, (unsigned long)func);

	return ftrace_modify_code(ip, old, new);
	}

	int ftrace_make_nop(struct module *mod,
	struct dyn_ftrace *rec, unsigned long addr)
	{
	unsigned char new, old;
	unsigned long ip = rec->ip;

	old = ftrace_call_replace(ip, addr);
	new = ftrace_nop_replace(ip);

	return ftrace_modify_code(rec->ip, old, new);
	}

	int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
	{
	unsigned char new, old;
	unsigned long ip = rec->ip;

	old = ftrace_nop_replace(ip);
	new = ftrace_call_replace(ip, addr);

	return ftrace_modify_code(rec->ip, old, new);
	}

	int __init ftrace_dyn_arch_init(void *data)
	{
	/* The return code is retured via data */
	__raw_writel(0, (unsigned long)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

	extern unsigned long __start_syscalls_metadata[];
	extern unsigned long __stop_syscalls_metadata[];
	extern unsigned long *sys_call_table;

	static struct syscall_metadata **syscalls_metadata;

	static struct syscall_metadata find_syscall_meta(unsigned long syscall)
	{
	struct syscall_metadata *start;
	struct syscall_metadata *stop;
	char str[KSYM_SYMBOL_LEN];


	start = (struct syscall_metadata *)__start_syscalls_metadata;
	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
	kallsyms_lookup((unsigned long) syscall, NULL, NULL, NULL, str);

	for ( ; start < stop; start++) {
	if (start->name && !strcmp(start->name, str))
	return start;
	}

	return NULL;
	}

	struct syscall_metadata *syscall_nr_to_meta(int nr)
	{
	if (!syscalls_metadata \|\| nr >= FTRACE_SYSCALL_MAX \|\| nr < 0)
	return NULL;

	return syscalls_metadata[nr];
	}

	int syscall_name_to_nr(char *name)
	{
	int i;

	if (!syscalls_metadata)
	return -1;
	for (i = 0; i < NR_syscalls; i++)
	if (syscalls_metadata[i])
	if (!strcmp(syscalls_metadata[i]->name, name))
	return i;
	return -1;
	}

	void set_syscall_enter_id(int num, int id)
	{
	syscalls_metadata[num]->enter_id = id;
	}

	void set_syscall_exit_id(int num, int id)
	{
	syscalls_metadata[num]->exit_id = id;
	}

	static int __init arch_init_ftrace_syscalls(void)
	{
	int i;
	struct syscall_metadata *meta;
	unsigned long **psys_syscall_table = &sys_call_table;

	syscalls_metadata = kzalloc(sizeof(syscalls_metadata)
	FTRACE_SYSCALL_MAX, GFP_KERNEL);
	if (!syscalls_metadata) {
	WARN_ON(1);
	return -ENOMEM;
	}

	for (i = 0; i < FTRACE_SYSCALL_MAX; i++) {
	meta = find_syscall_meta(psys_syscall_table[i]);
	syscalls_metadata[i] = meta;
	}

	return 0;
	}
	arch_initcall(arch_init_ftrace_syscalls);
	#endif /* CONFIG_FTRACE_SYSCALLS */