[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / x86 / kernel / ftrace.c

/*
 * 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/spinlock.h>
#include <linux/hardirq.h>
#include <linux/uaccess.h>
#include <linux/ftrace.h>
#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/list.h>

#include <asm/cacheflush.h>
#include <asm/ftrace.h>
#include <asm/nops.h>
#include <asm/nmi.h>


#ifdef CONFIG_DYNAMIC_FTRACE

int ftrace_arch_code_modify_prepare(void)
{
	set_kernel_text_rw();
	return 0;
}

int ftrace_arch_code_modify_post_process(void)
{
	set_kernel_text_ro();
	return 0;
}

union ftrace_code_union {
	char code[MCOUNT_INSN_SIZE];
	struct {
		char e8;
		int offset;
	} __attribute__((packed));
};

static int ftrace_calc_offset(long ip, long addr)
{
	return (int)(addr - ip);
}

static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
{
	static union ftrace_code_union calc;

	calc.e8		= 0xe8;
	calc.offset	= ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr);

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

/*
 * Modifying code must take extra care. On an SMP machine, if
 * the code being modified is also being executed on another CPU
 * that CPU will have undefined results and possibly take a GPF.
 * We use kstop_machine to stop other CPUS from exectuing code.
 * But this does not stop NMIs from happening. We still need
 * to protect against that. We separate out the modification of
 * the code to take care of this.
 *
 * Two buffers are added: An IP buffer and a "code" buffer.
 *
 * 1) Put the instruction pointer into the IP buffer
 *    and the new code into the "code" buffer.
 * 2) Wait for any running NMIs to finish and set a flag that says
 *    we are modifying code, it is done in an atomic operation.
 * 3) Write the code
 * 4) clear the flag.
 * 5) Wait for any running NMIs to finish.
 *
 * If an NMI is executed, the first thing it does is to call
 * "ftrace_nmi_enter". This will check if the flag is set to write
 * and if it is, it will write what is in the IP and "code" buffers.
 *
 * The trick is, it does not matter if everyone is writing the same
 * content to the code location. Also, if a CPU is executing code
 * it is OK to write to that code location if the contents being written
 * are the same as what exists.
 */

#define MOD_CODE_WRITE_FLAG (1 << 31)	/* set when NMI should do the write */
static atomic_t nmi_running = ATOMIC_INIT(0);
static int mod_code_status;		/* holds return value of text write */
static void *mod_code_ip;		/* holds the IP to write to */
static void *mod_code_newcode;		/* holds the text to write to the IP */

static unsigned nmi_wait_count;
static atomic_t nmi_update_count = ATOMIC_INIT(0);

int ftrace_arch_read_dyn_info(char *buf, int size)
{
	int r;

	r = snprintf(buf, size, "%u %u",
		     nmi_wait_count,
		     atomic_read(&nmi_update_count));
	return r;
}

static void clear_mod_flag(void)
{
	int old = atomic_read(&nmi_running);

	for (;;) {
		int new = old & ~MOD_CODE_WRITE_FLAG;

		if (old == new)
			break;

		old = atomic_cmpxchg(&nmi_running, old, new);
	}
}

static void ftrace_mod_code(void)
{
	/*
	 * Yes, more than one CPU process can be writing to mod_code_status.
	 *    (and the code itself)
	 * But if one were to fail, then they all should, and if one were
	 * to succeed, then they all should.
	 */
	mod_code_status = probe_kernel_write(mod_code_ip, mod_code_newcode,
					     MCOUNT_INSN_SIZE);

	/* if we fail, then kill any new writers */
	if (mod_code_status)
		clear_mod_flag();
}

void ftrace_nmi_enter(void)
{
	if (atomic_inc_return(&nmi_running) & MOD_CODE_WRITE_FLAG) {
		smp_rmb();
		ftrace_mod_code();
		atomic_inc(&nmi_update_count);
	}
	/* Must have previous changes seen before executions */
	smp_mb();
}

void ftrace_nmi_exit(void)
{
	/* Finish all executions before clearing nmi_running */
	smp_mb();
	atomic_dec(&nmi_running);
}

static void wait_for_nmi_and_set_mod_flag(void)
{
	if (!atomic_cmpxchg(&nmi_running, 0, MOD_CODE_WRITE_FLAG))
		return;

	do {
		cpu_relax();
	} while (atomic_cmpxchg(&nmi_running, 0, MOD_CODE_WRITE_FLAG));

	nmi_wait_count++;
}

static void wait_for_nmi(void)
{
	if (!atomic_read(&nmi_running))
		return;

	do {
		cpu_relax();
	} while (atomic_read(&nmi_running));

	nmi_wait_count++;
}

static int
do_ftrace_mod_code(unsigned long ip, void *new_code)
{
	mod_code_ip = (void *)ip;
	mod_code_newcode = new_code;

	/* The buffers need to be visible before we let NMIs write them */
	smp_mb();

	wait_for_nmi_and_set_mod_flag();

	/* Make sure all running NMIs have finished before we write the code */
	smp_mb();

	ftrace_mod_code();

	/* Make sure the write happens before clearing the bit */
	smp_mb();

	clear_mod_flag();
	wait_for_nmi();

	return mod_code_status;
}


static unsigned char ftrace_nop[MCOUNT_INSN_SIZE];

static unsigned char *ftrace_nop_replace(void)
{
	return ftrace_nop;
}

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 (do_ftrace_mod_code(ip, new_code))
		return -EPERM;

	sync_core();

	return 0;
}

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();

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

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

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

	memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
	new = ftrace_call_replace(ip, (unsigned long)func);
	ret = ftrace_modify_code(ip, old, new);

	return ret;
}

int __init ftrace_dyn_arch_init(void *data)
{
	extern const unsigned char ftrace_test_p6nop[];
	extern const unsigned char ftrace_test_nop5[];
	extern const unsigned char ftrace_test_jmp[];
	int faulted = 0;

	/*
	 * There is no good nop for all x86 archs.
	 * We will default to using the P6_NOP5, but first we
	 * will test to make sure that the nop will actually
	 * work on this CPU. If it faults, we will then
	 * go to a lesser efficient 5 byte nop. If that fails
	 * we then just use a jmp as our nop. This isn't the most
	 * efficient nop, but we can not use a multi part nop
	 * since we would then risk being preempted in the middle
	 * of that nop, and if we enabled tracing then, it might
	 * cause a system crash.
	 *
	 * TODO: check the cpuid to determine the best nop.
	 */
	asm volatile (
		"ftrace_test_jmp:"
		"jmp ftrace_test_p6nop\n"
		"nop\n"
		"nop\n"
		"nop\n"  /* 2 byte jmp + 3 bytes */
		"ftrace_test_p6nop:"
		P6_NOP5
		"jmp 1f\n"
		"ftrace_test_nop5:"
		".byte 0x66,0x66,0x66,0x66,0x90\n"
		"1:"
		".section .fixup, \"ax\"\n"
		"2:	movl $1, %0\n"
		"	jmp ftrace_test_nop5\n"
		"3:	movl $2, %0\n"
		"	jmp 1b\n"
		".previous\n"
		_ASM_EXTABLE(ftrace_test_p6nop, 2b)
		_ASM_EXTABLE(ftrace_test_nop5, 3b)
		: "=r"(faulted) : "0" (faulted));

	switch (faulted) {
	case 0:
		pr_info("ftrace: converting mcount calls to 0f 1f 44 00 00\n");
		memcpy(ftrace_nop, ftrace_test_p6nop, MCOUNT_INSN_SIZE);
		break;
	case 1:
		pr_info("ftrace: converting mcount calls to 66 66 66 66 90\n");
		memcpy(ftrace_nop, ftrace_test_nop5, MCOUNT_INSN_SIZE);
		break;
	case 2:
		pr_info("ftrace: converting mcount calls to jmp . + 5\n");
		memcpy(ftrace_nop, ftrace_test_jmp, MCOUNT_INSN_SIZE);
		break;
	}

	/* The return code is retured via data */
	*(unsigned long *)data = 0;

	return 0;
}
#endif

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

#ifdef CONFIG_DYNAMIC_FTRACE
extern void ftrace_graph_call(void);

static int ftrace_mod_jmp(unsigned long ip,
			  int old_offset, int new_offset)
{
	unsigned char code[MCOUNT_INSN_SIZE];

	if (probe_kernel_read(code, (void *)ip, MCOUNT_INSN_SIZE))
		return -EFAULT;

	if (code[0] != 0xe9 || old_offset != *(int *)(&code[1]))
		return -EINVAL;

	*(int *)(&code[1]) = new_offset;

	if (do_ftrace_mod_code(ip, &code))
		return -EPERM;

	return 0;
}

int ftrace_enable_ftrace_graph_caller(void)
{
	unsigned long ip = (unsigned long)(&ftrace_graph_call);
	int old_offset, new_offset;

	old_offset = (unsigned long)(&ftrace_stub) - (ip + MCOUNT_INSN_SIZE);
	new_offset = (unsigned long)(&ftrace_graph_caller) - (ip + MCOUNT_INSN_SIZE);

	return ftrace_mod_jmp(ip, old_offset, new_offset);
}

int ftrace_disable_ftrace_graph_caller(void)
{
	unsigned long ip = (unsigned long)(&ftrace_graph_call);
	int old_offset, new_offset;

	old_offset = (unsigned long)(&ftrace_graph_caller) - (ip + MCOUNT_INSN_SIZE);
	new_offset = (unsigned long)(&ftrace_stub) - (ip + MCOUNT_INSN_SIZE);

	return ftrace_mod_jmp(ip, old_offset, new_offset);
}

#endif /* !CONFIG_DYNAMIC_FTRACE */

/*
 * Hook the return address and push it in the stack of return addrs
 * in current thread info.
 */
void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
{
	unsigned long old;
	int faulted;
	struct ftrace_graph_ent trace;
	unsigned long return_hooker = (unsigned long)
				&return_to_handler;

	/* Nmi's are currently unsupported */
	if (unlikely(in_nmi()))
		return;

	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: " _ASM_MOV " (%[parent]), %[old]\n"
		"2: " _ASM_MOV " %[return_hooker], (%[parent])\n"
		"   movl $0, %[faulted]\n"
		"3:\n"

		".section .fixup, \"ax\"\n"
		"4: movl $1, %[faulted]\n"
		"   jmp 3b\n"
		".previous\n"

		_ASM_EXTABLE(1b, 4b)
		_ASM_EXTABLE(2b, 4b)

		: [old] "=r" (old), [faulted] "=r" (faulted)
		: [parent] "r" (parent), [return_hooker] "r" (return_hooker)
		: "memory"
	);

	if (unlikely(faulted)) {
		ftrace_graph_stop();
		WARN_ON(1);
		return;
	}

	if (ftrace_push_return_trace(old, self_addr, &trace.depth) == -EBUSY) {
		*parent = old;
		return;
	}

	trace.func = self_addr;

	/* Only trace if the calling function expects to */
	if (!ftrace_graph_entry(&trace)) {
		current->curr_ret_stack--;
		*parent = old;
	}
}
#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];
}

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

	if (atomic_inc_return(&refs) != 1)
		goto end;

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

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

	/* Paranoid: avoid overflow */
end:
	atomic_dec(&refs);
}
#endif
Commit	Line	Data
3d083395 SR	1	/*
	2	* Code for replacing ftrace calls with jumps.
	3	*
	4	* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
	5	*
	6	* Thanks goes to Ingo Molnar, for suggesting the idea.
	7	* Mathieu Desnoyers, for suggesting postponing the modifications.
	8	* Arjan van de Ven, for keeping me straight, and explaining to me
	9	* the dangers of modifying code on the run.
	10	*/
	11
	12	#include <linux/spinlock.h>
	13	#include <linux/hardirq.h>
6f93fc07	14	#include <linux/uaccess.h>
3d083395 SR	15	#include <linux/ftrace.h>
3d083395 SR	16	#include <linux/percpu.h>
19b3e967	17	#include <linux/sched.h>
3d083395 SR	18	#include <linux/init.h>
	19	#include <linux/list.h>
	20
16239630	21	#include <asm/cacheflush.h>
395a59d0	22	#include <asm/ftrace.h>
732f3ca7	23	#include <asm/nops.h>
caf4b323	24	#include <asm/nmi.h>
3d083395	25
3d083395	26
caf4b323	27	#ifdef CONFIG_DYNAMIC_FTRACE
3d083395	28
16239630 SR	29	int ftrace_arch_code_modify_prepare(void)
	30	{
	31	set_kernel_text_rw();
	32	return 0;
	33	}
	34
	35	int ftrace_arch_code_modify_post_process(void)
	36	{
	37	set_kernel_text_ro();
	38	return 0;
	39	}
	40
3d083395	41	union ftrace_code_union {
395a59d0	42	char code[MCOUNT_INSN_SIZE];
3d083395 SR	43	struct {
	44	char e8;
	45	int offset;
	46	} __attribute__((packed));
	47	};
	48
15adc048	49	static int ftrace_calc_offset(long ip, long addr)
3c1720f0 SR	50	{
	51	return (int)(addr - ip);
	52	}
3d083395	53
31e88909	54	static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
3c1720f0 SR	55	{
3c1720f0 SR	56	static union ftrace_code_union calc;
3d083395	57
3c1720f0	58	calc.e8 = 0xe8;
395a59d0	59	calc.offset = ftrace_calc_offset(ip + MCOUNT_INSN_SIZE, addr);
3c1720f0 SR	60
	61	/*
	62	* No locking needed, this must be called via kstop_machine
	63	* which in essence is like running on a uniprocessor machine.
	64	*/
	65	return calc.code;
3d083395 SR	66	}
3d083395 SR	67
17666f02 SR	68	/*
	69	* Modifying code must take extra care. On an SMP machine, if
	70	* the code being modified is also being executed on another CPU
	71	* that CPU will have undefined results and possibly take a GPF.
	72	* We use kstop_machine to stop other CPUS from exectuing code.
	73	* But this does not stop NMIs from happening. We still need
	74	* to protect against that. We separate out the modification of
	75	* the code to take care of this.
	76	*
	77	* Two buffers are added: An IP buffer and a "code" buffer.
	78	*
a26a2a27	79	* 1) Put the instruction pointer into the IP buffer
17666f02	80	* and the new code into the "code" buffer.
e9d9df44 LJ	81	* 2) Wait for any running NMIs to finish and set a flag that says
	82	* we are modifying code, it is done in an atomic operation.
	83	* 3) Write the code
	84	* 4) clear the flag.
	85	* 5) Wait for any running NMIs to finish.
17666f02 SR	86	*
	87	* If an NMI is executed, the first thing it does is to call
	88	* "ftrace_nmi_enter". This will check if the flag is set to write
	89	* and if it is, it will write what is in the IP and "code" buffers.
	90	*
	91	* The trick is, it does not matter if everyone is writing the same
	92	* content to the code location. Also, if a CPU is executing code
	93	* it is OK to write to that code location if the contents being written
	94	* are the same as what exists.
	95	*/
	96
e9d9df44	97	#define MOD_CODE_WRITE_FLAG (1 << 31) /* set when NMI should do the write */
4e6ea144	98	static atomic_t nmi_running = ATOMIC_INIT(0);
a26a2a27	99	static int mod_code_status; /* holds return value of text write */
a26a2a27 SR	100	static void mod_code_ip; / holds the IP to write to */
a26a2a27 SR	101	static void mod_code_newcode; / holds the text to write to the IP */
17666f02	102
a26a2a27 SR	103	static unsigned nmi_wait_count;
a26a2a27 SR	104	static atomic_t nmi_update_count = ATOMIC_INIT(0);
b807c3d0 SR	105
	106	int ftrace_arch_read_dyn_info(char *buf, int size)
	107	{
	108	int r;
	109
	110	r = snprintf(buf, size, "%u %u",
	111	nmi_wait_count,
	112	atomic_read(&nmi_update_count));
	113	return r;
	114	}
	115
e9d9df44 LJ	116	static void clear_mod_flag(void)
	117	{
	118	int old = atomic_read(&nmi_running);
	119
	120	for (;;) {
	121	int new = old & ~MOD_CODE_WRITE_FLAG;
	122
	123	if (old == new)
	124	break;
	125
	126	old = atomic_cmpxchg(&nmi_running, old, new);
	127	}
	128	}
	129
17666f02 SR	130	static void ftrace_mod_code(void)
	131	{
	132	/*
	133	* Yes, more than one CPU process can be writing to mod_code_status.
	134	* (and the code itself)
	135	* But if one were to fail, then they all should, and if one were
	136	* to succeed, then they all should.
	137	*/
	138	mod_code_status = probe_kernel_write(mod_code_ip, mod_code_newcode,
	139	MCOUNT_INSN_SIZE);
90c7ac49 SR	140
	141	/* if we fail, then kill any new writers */
	142	if (mod_code_status)
e9d9df44	143	clear_mod_flag();
17666f02 SR	144	}
17666f02 SR	145
a81bd80a	146	void ftrace_nmi_enter(void)
17666f02	147	{
e9d9df44 LJ	148	if (atomic_inc_return(&nmi_running) & MOD_CODE_WRITE_FLAG) {
e9d9df44 LJ	149	smp_rmb();
17666f02	150	ftrace_mod_code();
b807c3d0 SR	151	atomic_inc(&nmi_update_count);
b807c3d0 SR	152	}
e9d9df44 LJ	153	/* Must have previous changes seen before executions */
e9d9df44 LJ	154	smp_mb();
17666f02 SR	155	}
17666f02 SR	156
a81bd80a	157	void ftrace_nmi_exit(void)
17666f02	158	{
4e6ea144	159	/* Finish all executions before clearing nmi_running */
e9d9df44	160	smp_mb();
4e6ea144	161	atomic_dec(&nmi_running);
17666f02 SR	162	}
17666f02 SR	163
e9d9df44 LJ	164	static void wait_for_nmi_and_set_mod_flag(void)
	165	{
	166	if (!atomic_cmpxchg(&nmi_running, 0, MOD_CODE_WRITE_FLAG))
	167	return;
	168
	169	do {
	170	cpu_relax();
	171	} while (atomic_cmpxchg(&nmi_running, 0, MOD_CODE_WRITE_FLAG));
	172
	173	nmi_wait_count++;
	174	}
	175
17666f02 SR	176	static void wait_for_nmi(void)
17666f02 SR	177	{
4e6ea144	178	if (!atomic_read(&nmi_running))
89025282	179	return;
b807c3d0	180
89025282	181	do {
17666f02	182	cpu_relax();
4e6ea144	183	} while (atomic_read(&nmi_running));
b807c3d0	184
89025282	185	nmi_wait_count++;
17666f02 SR	186	}
	187
	188	static int
	189	do_ftrace_mod_code(unsigned long ip, void *new_code)
	190	{
	191	mod_code_ip = (void *)ip;
	192	mod_code_newcode = new_code;
	193
	194	/* The buffers need to be visible before we let NMIs write them */
17666f02 SR	195	smp_mb();
17666f02 SR	196
e9d9df44	197	wait_for_nmi_and_set_mod_flag();
17666f02 SR	198
	199	/* Make sure all running NMIs have finished before we write the code */
	200	smp_mb();
	201
	202	ftrace_mod_code();
	203
	204	/* Make sure the write happens before clearing the bit */
17666f02 SR	205	smp_mb();
17666f02 SR	206
e9d9df44	207	clear_mod_flag();
17666f02 SR	208	wait_for_nmi();
	209
	210	return mod_code_status;
	211	}
	212
	213
caf4b323 FW	214
	215
	216	static unsigned char ftrace_nop[MCOUNT_INSN_SIZE];
	217
31e88909	218	static unsigned char *ftrace_nop_replace(void)
caf4b323 FW	219	{
	220	return ftrace_nop;
	221	}
	222
31e88909	223	static int
3d083395 SR	224	ftrace_modify_code(unsigned long ip, unsigned char *old_code,
	225	unsigned char *new_code)
	226	{
6f93fc07	227	unsigned char replaced[MCOUNT_INSN_SIZE];
3d083395 SR	228
	229	/*
	230	* Note: Due to modules and __init, code can
	231	* disappear and change, we need to protect against faulting
76aefee5	232	* as well as code changing. We do this by using the
ab9a0918	233	* probe_kernel_* functions.
3d083395 SR	234	*
3d083395 SR	235	* No real locking needed, this code is run through
6f93fc07	236	* kstop_machine, or before SMP starts.
3d083395	237	*/
76aefee5 SR	238
76aefee5 SR	239	/* read the text we want to modify */
ab9a0918	240	if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
593eb8a2	241	return -EFAULT;
6f93fc07	242
76aefee5	243	/* Make sure it is what we expect it to be */
6f93fc07	244	if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
593eb8a2	245	return -EINVAL;
3d083395	246
76aefee5	247	/* replace the text with the new text */
17666f02	248	if (do_ftrace_mod_code(ip, new_code))
593eb8a2	249	return -EPERM;
6f93fc07 SR	250
6f93fc07 SR	251	sync_core();
3d083395	252
6f93fc07	253	return 0;
3d083395 SR	254	}
3d083395 SR	255
31e88909 SR	256	int ftrace_make_nop(struct module *mod,
	257	struct dyn_ftrace *rec, unsigned long addr)
	258	{
	259	unsigned char new, old;
	260	unsigned long ip = rec->ip;
	261
	262	old = ftrace_call_replace(ip, addr);
	263	new = ftrace_nop_replace();
	264
	265	return ftrace_modify_code(rec->ip, old, new);
	266	}
	267
	268	int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
	269	{
	270	unsigned char new, old;
	271	unsigned long ip = rec->ip;
	272
	273	old = ftrace_nop_replace();
	274	new = ftrace_call_replace(ip, addr);
	275
	276	return ftrace_modify_code(rec->ip, old, new);
	277	}
	278
15adc048	279	int ftrace_update_ftrace_func(ftrace_func_t func)
d61f82d0 SR	280	{
d61f82d0 SR	281	unsigned long ip = (unsigned long)(&ftrace_call);
395a59d0	282	unsigned char old[MCOUNT_INSN_SIZE], *new;
d61f82d0 SR	283	int ret;
d61f82d0 SR	284
395a59d0	285	memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
d61f82d0 SR	286	new = ftrace_call_replace(ip, (unsigned long)func);
	287	ret = ftrace_modify_code(ip, old, new);
	288
	289	return ret;
	290	}
	291
d61f82d0	292	int __init ftrace_dyn_arch_init(void *data)
3d083395	293	{
732f3ca7 SR	294	extern const unsigned char ftrace_test_p6nop[];
	295	extern const unsigned char ftrace_test_nop5[];
	296	extern const unsigned char ftrace_test_jmp[];
	297	int faulted = 0;
d61f82d0	298
732f3ca7 SR	299	/*
	300	* There is no good nop for all x86 archs.
	301	* We will default to using the P6_NOP5, but first we
	302	* will test to make sure that the nop will actually
	303	* work on this CPU. If it faults, we will then
	304	* go to a lesser efficient 5 byte nop. If that fails
	305	* we then just use a jmp as our nop. This isn't the most
	306	* efficient nop, but we can not use a multi part nop
	307	* since we would then risk being preempted in the middle
	308	* of that nop, and if we enabled tracing then, it might
	309	* cause a system crash.
	310	*
	311	* TODO: check the cpuid to determine the best nop.
	312	*/
	313	asm volatile (
732f3ca7 SR	314	"ftrace_test_jmp:"
732f3ca7 SR	315	"jmp ftrace_test_p6nop\n"
8b27386a AK	316	"nop\n"
	317	"nop\n"
	318	"nop\n" /* 2 byte jmp + 3 bytes */
732f3ca7 SR	319	"ftrace_test_p6nop:"
	320	P6_NOP5
	321	"jmp 1f\n"
	322	"ftrace_test_nop5:"
	323	".byte 0x66,0x66,0x66,0x66,0x90\n"
732f3ca7 SR	324	"1:"
	325	".section .fixup, \"ax\"\n"
	326	"2: movl $1, %0\n"
	327	" jmp ftrace_test_nop5\n"
	328	"3: movl $2, %0\n"
	329	" jmp 1b\n"
	330	".previous\n"
	331	_ASM_EXTABLE(ftrace_test_p6nop, 2b)
	332	_ASM_EXTABLE(ftrace_test_nop5, 3b)
	333	: "=r"(faulted) : "0" (faulted));
	334
	335	switch (faulted) {
	336	case 0:
	337	pr_info("ftrace: converting mcount calls to 0f 1f 44 00 00\n");
8115f3f0	338	memcpy(ftrace_nop, ftrace_test_p6nop, MCOUNT_INSN_SIZE);
732f3ca7 SR	339	break;
	340	case 1:
	341	pr_info("ftrace: converting mcount calls to 66 66 66 66 90\n");
8115f3f0	342	memcpy(ftrace_nop, ftrace_test_nop5, MCOUNT_INSN_SIZE);
732f3ca7 SR	343	break;
732f3ca7 SR	344	case 2:
8b27386a	345	pr_info("ftrace: converting mcount calls to jmp . + 5\n");
8115f3f0	346	memcpy(ftrace_nop, ftrace_test_jmp, MCOUNT_INSN_SIZE);
732f3ca7 SR	347	break;
	348	}
	349
	350	/* The return code is retured via data */
	351	(unsigned long )data = 0;
dfa60aba	352
3d083395 SR	353	return 0;
3d083395 SR	354	}
caf4b323	355	#endif
e7d3737e	356
fb52607a	357	#ifdef CONFIG_FUNCTION_GRAPH_TRACER
e7d3737e	358
5a45cfe1 SR	359	#ifdef CONFIG_DYNAMIC_FTRACE
	360	extern void ftrace_graph_call(void);
	361
	362	static int ftrace_mod_jmp(unsigned long ip,
	363	int old_offset, int new_offset)
	364	{
	365	unsigned char code[MCOUNT_INSN_SIZE];
	366
	367	if (probe_kernel_read(code, (void *)ip, MCOUNT_INSN_SIZE))
	368	return -EFAULT;
	369
	370	if (code[0] != 0xe9 \|\| old_offset != (int )(&code[1]))
	371	return -EINVAL;
	372
	373	(int )(&code[1]) = new_offset;
	374
	375	if (do_ftrace_mod_code(ip, &code))
	376	return -EPERM;
	377
	378	return 0;
	379	}
	380
	381	int ftrace_enable_ftrace_graph_caller(void)
	382	{
	383	unsigned long ip = (unsigned long)(&ftrace_graph_call);
	384	int old_offset, new_offset;
	385
	386	old_offset = (unsigned long)(&ftrace_stub) - (ip + MCOUNT_INSN_SIZE);
	387	new_offset = (unsigned long)(&ftrace_graph_caller) - (ip + MCOUNT_INSN_SIZE);
	388
	389	return ftrace_mod_jmp(ip, old_offset, new_offset);
	390	}
	391
	392	int ftrace_disable_ftrace_graph_caller(void)
	393	{
	394	unsigned long ip = (unsigned long)(&ftrace_graph_call);
	395	int old_offset, new_offset;
	396
	397	old_offset = (unsigned long)(&ftrace_graph_caller) - (ip + MCOUNT_INSN_SIZE);
	398	new_offset = (unsigned long)(&ftrace_stub) - (ip + MCOUNT_INSN_SIZE);
	399
	400	return ftrace_mod_jmp(ip, old_offset, new_offset);
	401	}
	402
e7d3737e FW	403	#endif /* !CONFIG_DYNAMIC_FTRACE */
e7d3737e FW	404
e7d3737e FW	405	/*
	406	* Hook the return address and push it in the stack of return addrs
	407	* in current thread info.
	408	*/
	409	void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
	410	{
	411	unsigned long old;
e7d3737e	412	int faulted;
287b6e68	413	struct ftrace_graph_ent trace;
e7d3737e FW	414	unsigned long return_hooker = (unsigned long)
	415	&return_to_handler;
	416
	417	/* Nmi's are currently unsupported */
9a5fd902	418	if (unlikely(in_nmi()))
380c4b14 FW	419	return;
	420
	421	if (unlikely(atomic_read(&current->tracing_graph_pause)))
e7d3737e FW	422	return;
	423
	424	/*
	425	* Protect against fault, even if it shouldn't
	426	* happen. This tool is too much intrusive to
	427	* ignore such a protection.
	428	*/
	429	asm volatile(
96665788 SR	430	"1: " _ASM_MOV " (%[parent]), %[old]\n"
96665788 SR	431	"2: " _ASM_MOV " %[return_hooker], (%[parent])\n"
e7d3737e	432	" movl $0, %[faulted]\n"
e3944bfa	433	"3:\n"
e7d3737e FW	434
e7d3737e FW	435	".section .fixup, \"ax\"\n"
e3944bfa SR	436	"4: movl $1, %[faulted]\n"
e3944bfa SR	437	" jmp 3b\n"
e7d3737e FW	438	".previous\n"
e7d3737e FW	439
e3944bfa SR	440	_ASM_EXTABLE(1b, 4b)
e3944bfa SR	441	_ASM_EXTABLE(2b, 4b)
e7d3737e	442
96665788 SR	443	: [old] "=r" (old), [faulted] "=r" (faulted)
96665788 SR	444	: [parent] "r" (parent), [return_hooker] "r" (return_hooker)
e7d3737e FW	445	: "memory"
	446	);
	447
14a866c5 SR	448	if (unlikely(faulted)) {
	449	ftrace_graph_stop();
	450	WARN_ON(1);
e7d3737e FW	451	return;
	452	}
	453
5d1a03dc	454	if (ftrace_push_return_trace(old, self_addr, &trace.depth) == -EBUSY) {
e7d3737e	455	*parent = old;
287b6e68 FW	456	return;
	457	}
	458
	459	trace.func = self_addr;
287b6e68	460
e49dc19c SR	461	/* Only trace if the calling function expects to */
	462	if (!ftrace_graph_entry(&trace)) {
	463	current->curr_ret_stack--;
	464	*parent = old;
	465	}
e7d3737e	466	}
fb52607a	467	#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
f58ba100 FW	468
	469	#ifdef CONFIG_FTRACE_SYSCALLS
	470
	471	extern unsigned long __start_syscalls_metadata[];
	472	extern unsigned long __stop_syscalls_metadata[];
	473	extern unsigned long *sys_call_table;
	474
	475	static struct syscall_metadata **syscalls_metadata;
	476
	477	static struct syscall_metadata find_syscall_meta(unsigned long syscall)
	478	{
	479	struct syscall_metadata *start;
	480	struct syscall_metadata *stop;
	481	char str[KSYM_SYMBOL_LEN];
	482
	483
	484	start = (struct syscall_metadata *)__start_syscalls_metadata;
	485	stop = (struct syscall_metadata *)__stop_syscalls_metadata;
	486	kallsyms_lookup((unsigned long) syscall, NULL, NULL, NULL, str);
	487
	488	for ( ; start < stop; start++) {
	489	if (start->name && !strcmp(start->name, str))
	490	return start;
	491	}
	492	return NULL;
	493	}
	494
	495	struct syscall_metadata *syscall_nr_to_meta(int nr)
	496	{
	497	if (!syscalls_metadata \|\| nr >= FTRACE_SYSCALL_MAX \|\| nr < 0)
	498	return NULL;
	499
	500	return syscalls_metadata[nr];
	501	}
	502
	503	void arch_init_ftrace_syscalls(void)
	504	{
	505	int i;
	506	struct syscall_metadata *meta;
	507	unsigned long **psys_syscall_table = &sys_call_table;
	508	static atomic_t refs;
	509
	510	if (atomic_inc_return(&refs) != 1)
	511	goto end;
	512
	513	syscalls_metadata = kzalloc(sizeof(syscalls_metadata)
	514	FTRACE_SYSCALL_MAX, GFP_KERNEL);
	515	if (!syscalls_metadata) {
	516	WARN_ON(1);
	517	return;
	518	}
	519
	520	for (i = 0; i < FTRACE_SYSCALL_MAX; i++) {
	521	meta = find_syscall_meta(psys_syscall_table[i]);
	522	syscalls_metadata[i] = meta;
	523	}
	524	return;
	525
	526	/* Paranoid: avoid overflow */
	527	end:
	528	atomic_dec(&refs);
	529	}
	530	#endif