arch/s390/kernel/ftrace.c - kernel/prism - Git at Google

 /*
  * Dynamic function tracer architecture backend.
  *
  * Copyright IBM Corp. 2009
  *
  *   Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
  *
  */

 #include <linux/hardirq.h>
 #include <linux/uaccess.h>
 #include <linux/ftrace.h>
 #include <linux/kernel.h>
 #include <linux/types.h>
 #include <trace/syscall.h>
 #include <asm/lowcore.h>

 #ifdef CONFIG_DYNAMIC_FTRACE

 void ftrace_disable_code(void);
 void ftrace_disable_return(void);
 void ftrace_call_code(void);
 void ftrace_nop_code(void);

 #define FTRACE_INSN_SIZE 4

 #ifdef CONFIG_64BIT

 asm(
 	"	.align	4\n"
 	"ftrace_disable_code:\n"
 	"	j	0f\n"
 	"	.word	0x0024\n"
 	"	lg	%r1,"__stringify(__LC_FTRACE_FUNC)"\n"
 	"	basr	%r14,%r1\n"
 	"ftrace_disable_return:\n"
 	"	lg	%r14,8(15)\n"
 	"	lgr	%r0,%r0\n"
 	"0:\n");

 asm(
 	"	.align	4\n"
 	"ftrace_nop_code:\n"
 	"	j	.+"__stringify(MCOUNT_INSN_SIZE)"\n");

 asm(
 	"	.align	4\n"
 	"ftrace_call_code:\n"
 	"	stg	%r14,8(%r15)\n");

 #else /* CONFIG_64BIT */

 asm(
 	"	.align	4\n"
 	"ftrace_disable_code:\n"
 	"	j	0f\n"
 	"	l	%r1,"__stringify(__LC_FTRACE_FUNC)"\n"
 	"	basr	%r14,%r1\n"
 	"ftrace_disable_return:\n"
 	"	l	%r14,4(%r15)\n"
 	"	j	0f\n"
 	"	bcr	0,%r7\n"
 	"	bcr	0,%r7\n"
 	"	bcr	0,%r7\n"
 	"	bcr	0,%r7\n"
 	"	bcr	0,%r7\n"
 	"	bcr	0,%r7\n"
 	"0:\n");

 asm(
 	"	.align	4\n"
 	"ftrace_nop_code:\n"
 	"	j	.+"__stringify(MCOUNT_INSN_SIZE)"\n");

 asm(
 	"	.align	4\n"
 	"ftrace_call_code:\n"
 	"	st	%r14,4(%r15)\n");

 #endif /* CONFIG_64BIT */

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

 	/*
 	 * Note: Due to modules 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.
 	 *  This however is just a simple sanity check.
 	 */
 	if (probe_kernel_read(replaced, (void *)ip, old_size))
 		return -EFAULT;
 	if (memcmp(replaced, old_code, old_size) != 0)
 		return -EINVAL;
 	if (probe_kernel_write((void *)ip, new_code, new_size))
 		return -EPERM;
 	return 0;
 }

 static int ftrace_make_initial_nop(struct module *mod, struct dyn_ftrace *rec,
 				   unsigned long addr)
 {
 	return ftrace_modify_code(rec->ip,
 				  ftrace_call_code, FTRACE_INSN_SIZE,
 				  ftrace_disable_code, MCOUNT_INSN_SIZE);
 }

 int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
 		    unsigned long addr)
 {
 	if (addr == MCOUNT_ADDR)
 		return ftrace_make_initial_nop(mod, rec, addr);
 	return ftrace_modify_code(rec->ip,
 				  ftrace_call_code, FTRACE_INSN_SIZE,
 				  ftrace_nop_code, FTRACE_INSN_SIZE);
 }

 int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
 {
 	return ftrace_modify_code(rec->ip,
 				  ftrace_nop_code, FTRACE_INSN_SIZE,
 				  ftrace_call_code, FTRACE_INSN_SIZE);
 }

 int ftrace_update_ftrace_func(ftrace_func_t func)
 {
 	ftrace_dyn_func = (unsigned long)func;
 	return 0;
 }

 int __init ftrace_dyn_arch_init(void *data)
 {
 	*(unsigned long *)data = 0;
 	return 0;
 }

 #endif /* CONFIG_DYNAMIC_FTRACE */

 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 #ifdef CONFIG_DYNAMIC_FTRACE
 /*
  * Patch the kernel code at ftrace_graph_caller location:
  * The instruction there is branch relative on condition. The condition mask
  * is either all ones (always branch aka disable ftrace_graph_caller) or all
  * zeroes (nop aka enable ftrace_graph_caller).
  * Instruction format for brc is a7m4xxxx where m is the condition mask.
  */
 int ftrace_enable_ftrace_graph_caller(void)
 {
 	unsigned short opcode = 0xa704;

 	return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));
 }

 int ftrace_disable_ftrace_graph_caller(void)
 {
 	unsigned short opcode = 0xa7f4;

 	return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));
 }

 static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)
 {
 	return addr - (ftrace_disable_return - ftrace_disable_code);
 }

 #else /* CONFIG_DYNAMIC_FTRACE */

 static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)
 {
 	return addr - MCOUNT_OFFSET_RET;
 }

 #endif /* CONFIG_DYNAMIC_FTRACE */

 /*
  * Hook the return address and push it in the stack of return addresses
  * in current thread info.
  */
 unsigned long prepare_ftrace_return(unsigned long ip, unsigned long parent)
 {
 	struct ftrace_graph_ent trace;

 	if (unlikely(atomic_read(&current->tracing_graph_pause)))
 		goto out;
 	if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY)
 		goto out;
 	trace.func = ftrace_mcount_call_adjust(ip) & PSW_ADDR_INSN;
 	/* Only trace if the calling function expects to. */
 	if (!ftrace_graph_entry(&trace)) {
 		current->curr_ret_stack--;
 		goto out;
 	}
 	parent = (unsigned long)return_to_handler;
 out:
 	return parent;
 }
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */

 #ifdef CONFIG_FTRACE_SYSCALLS

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

 static struct syscall_metadata **syscalls_metadata;

 struct syscall_metadata *syscall_nr_to_meta(int nr)
 {
 	if (!syscalls_metadata || nr >= NR_syscalls || 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 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(syscall, NULL, NULL, NULL, str);

 	for ( ; start < stop; start++) {
 		if (start->name && !strcmp(start->name + 3, str + 3))
 			return start;
 	}
 	return NULL;
 }

 static int __init arch_init_ftrace_syscalls(void)
 {
 	struct syscall_metadata *meta;
 	int i;
 	syscalls_metadata = kzalloc(sizeof(*syscalls_metadata) * NR_syscalls,
 				    GFP_KERNEL);
 	if (!syscalls_metadata)
 		return -ENOMEM;
 	for (i = 0; i < NR_syscalls; i++) {
 		meta = find_syscall_meta((unsigned long)sys_call_table[i]);
 		syscalls_metadata[i] = meta;
 	}
 	return 0;
 }
 arch_initcall(arch_init_ftrace_syscalls);
 #endif
	/*
	* Dynamic function tracer architecture backend.
	*
	* Copyright IBM Corp. 2009
	*
	* Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
	*
	*/

	#include <linux/hardirq.h>
	#include <linux/uaccess.h>
	#include <linux/ftrace.h>
	#include <linux/kernel.h>
	#include <linux/types.h>
	#include <trace/syscall.h>
	#include <asm/lowcore.h>

	#ifdef CONFIG_DYNAMIC_FTRACE

	void ftrace_disable_code(void);
	void ftrace_disable_return(void);
	void ftrace_call_code(void);
	void ftrace_nop_code(void);

	#define FTRACE_INSN_SIZE 4

	#ifdef CONFIG_64BIT

	asm(
	" .align 4\n"
	"ftrace_disable_code:\n"
	" j 0f\n"
	" .word 0x0024\n"
	" lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n"
	" basr %r14,%r1\n"
	"ftrace_disable_return:\n"
	" lg %r14,8(15)\n"
	" lgr %r0,%r0\n"
	"0:\n");

	asm(
	" .align 4\n"
	"ftrace_nop_code:\n"
	" j .+"__stringify(MCOUNT_INSN_SIZE)"\n");

	asm(
	" .align 4\n"
	"ftrace_call_code:\n"
	" stg %r14,8(%r15)\n");

	#else /* CONFIG_64BIT */

	asm(
	" .align 4\n"
	"ftrace_disable_code:\n"
	" j 0f\n"
	" l %r1,"__stringify(__LC_FTRACE_FUNC)"\n"
	" basr %r14,%r1\n"
	"ftrace_disable_return:\n"
	" l %r14,4(%r15)\n"
	" j 0f\n"
	" bcr 0,%r7\n"
	" bcr 0,%r7\n"
	" bcr 0,%r7\n"
	" bcr 0,%r7\n"
	" bcr 0,%r7\n"
	" bcr 0,%r7\n"
	"0:\n");

	asm(
	" .align 4\n"
	"ftrace_nop_code:\n"
	" j .+"__stringify(MCOUNT_INSN_SIZE)"\n");

	asm(
	" .align 4\n"
	"ftrace_call_code:\n"
	" st %r14,4(%r15)\n");

	#endif /* CONFIG_64BIT */

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

	/*
	* Note: Due to modules 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.
	* This however is just a simple sanity check.
	*/
	if (probe_kernel_read(replaced, (void *)ip, old_size))
	return -EFAULT;
	if (memcmp(replaced, old_code, old_size) != 0)
	return -EINVAL;
	if (probe_kernel_write((void *)ip, new_code, new_size))
	return -EPERM;
	return 0;
	}

	static int ftrace_make_initial_nop(struct module mod, struct dyn_ftrace rec,
	unsigned long addr)
	{
	return ftrace_modify_code(rec->ip,
	ftrace_call_code, FTRACE_INSN_SIZE,
	ftrace_disable_code, MCOUNT_INSN_SIZE);
	}

	int ftrace_make_nop(struct module mod, struct dyn_ftrace rec,
	unsigned long addr)
	{
	if (addr == MCOUNT_ADDR)
	return ftrace_make_initial_nop(mod, rec, addr);
	return ftrace_modify_code(rec->ip,
	ftrace_call_code, FTRACE_INSN_SIZE,
	ftrace_nop_code, FTRACE_INSN_SIZE);
	}

	int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
	{
	return ftrace_modify_code(rec->ip,
	ftrace_nop_code, FTRACE_INSN_SIZE,
	ftrace_call_code, FTRACE_INSN_SIZE);
	}

	int ftrace_update_ftrace_func(ftrace_func_t func)
	{
	ftrace_dyn_func = (unsigned long)func;
	return 0;
	}

	int __init ftrace_dyn_arch_init(void *data)
	{
	(unsigned long )data = 0;
	return 0;
	}

	#endif /* CONFIG_DYNAMIC_FTRACE */

	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
	#ifdef CONFIG_DYNAMIC_FTRACE
	/*
	* Patch the kernel code at ftrace_graph_caller location:
	* The instruction there is branch relative on condition. The condition mask
	* is either all ones (always branch aka disable ftrace_graph_caller) or all
	* zeroes (nop aka enable ftrace_graph_caller).
	* Instruction format for brc is a7m4xxxx where m is the condition mask.
	*/
	int ftrace_enable_ftrace_graph_caller(void)
	{
	unsigned short opcode = 0xa704;

	return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));
	}

	int ftrace_disable_ftrace_graph_caller(void)
	{
	unsigned short opcode = 0xa7f4;

	return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));
	}

	static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)
	{
	return addr - (ftrace_disable_return - ftrace_disable_code);
	}

	#else /* CONFIG_DYNAMIC_FTRACE */

	static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)
	{
	return addr - MCOUNT_OFFSET_RET;
	}

	#endif /* CONFIG_DYNAMIC_FTRACE */

	/*
	* Hook the return address and push it in the stack of return addresses
	* in current thread info.
	*/
	unsigned long prepare_ftrace_return(unsigned long ip, unsigned long parent)
	{
	struct ftrace_graph_ent trace;

	if (unlikely(atomic_read(&current->tracing_graph_pause)))
	goto out;
	if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY)
	goto out;
	trace.func = ftrace_mcount_call_adjust(ip) & PSW_ADDR_INSN;
	/* Only trace if the calling function expects to. */
	if (!ftrace_graph_entry(&trace)) {
	current->curr_ret_stack--;
	goto out;
	}
	parent = (unsigned long)return_to_handler;
	out:
	return parent;
	}
	#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

	#ifdef CONFIG_FTRACE_SYSCALLS

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

	static struct syscall_metadata **syscalls_metadata;

	struct syscall_metadata *syscall_nr_to_meta(int nr)
	{
	if (!syscalls_metadata \|\| nr >= NR_syscalls \|\| 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 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(syscall, NULL, NULL, NULL, str);

	for ( ; start < stop; start++) {
	if (start->name && !strcmp(start->name + 3, str + 3))
	return start;
	}
	return NULL;
	}

	static int __init arch_init_ftrace_syscalls(void)
	{
	struct syscall_metadata *meta;
	int i;
	syscalls_metadata = kzalloc(sizeof(syscalls_metadata) NR_syscalls,
	GFP_KERNEL);
	if (!syscalls_metadata)
	return -ENOMEM;
	for (i = 0; i < NR_syscalls; i++) {
	meta = find_syscall_meta((unsigned long)sys_call_table[i]);
	syscalls_metadata[i] = meta;
	}
	return 0;
	}
	arch_initcall(arch_init_ftrace_syscalls);
	#endif