Commit 5baaa59e authored by Namhyung Kim's avatar Namhyung Kim Committed by Steven Rostedt
Browse files

tracing/probes: Implement 'memory' fetch method for uprobes 



Use separate method to fetch from memory.  Move existing functions to
trace_kprobe.c and make them static.  Also add new memory fetch
implementation for uprobes.

Acked-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
parent 3925f4a5

kernel/trace/trace_kprobe.c

+77 −0
Original line number Diff line number Diff line
@@ -148,6 +148,83 @@ DEFINE_BASIC_FETCH_FUNCS(stack) 
#define fetch_stack_string	NULL

#define fetch_stack_string_size	NULL



#define DEFINE_FETCH_memory(type)					\

static __kprobes void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,\

					  void *addr, void *dest)	\

{									\

	type retval;							\

	if (probe_kernel_address(addr, retval))				\

		*(type *)dest = 0;					\

	else								\

		*(type *)dest = retval;					\

}

DEFINE_BASIC_FETCH_FUNCS(memory)

/*

 * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max

 * length and relative data location.

 */

static __kprobes void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,

						      void *addr, void *dest)

{

	long ret;

	int maxlen = get_rloc_len(*(u32 *)dest);

	u8 *dst = get_rloc_data(dest);

	u8 *src = addr;

	mm_segment_t old_fs = get_fs();



	if (!maxlen)

		return;



	/*

	 * Try to get string again, since the string can be changed while

	 * probing.

	 */

	set_fs(KERNEL_DS);

	pagefault_disable();



	do

		ret = __copy_from_user_inatomic(dst++, src++, 1);

	while (dst[-1] && ret == 0 && src - (u8 *)addr < maxlen);



	dst[-1] = '\0';

	pagefault_enable();

	set_fs(old_fs);



	if (ret < 0) {	/* Failed to fetch string */

		((u8 *)get_rloc_data(dest))[0] = '\0';

		*(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));

	} else {

		*(u32 *)dest = make_data_rloc(src - (u8 *)addr,

					      get_rloc_offs(*(u32 *)dest));

	}

}



/* Return the length of string -- including null terminal byte */

static __kprobes void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,

							void *addr, void *dest)

{

	mm_segment_t old_fs;

	int ret, len = 0;

	u8 c;



	old_fs = get_fs();

	set_fs(KERNEL_DS);

	pagefault_disable();



	do {

		ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);

		len++;

	} while (c && ret == 0 && len < MAX_STRING_SIZE);



	pagefault_enable();

	set_fs(old_fs);



	if (ret < 0)	/* Failed to check the length */

		*(u32 *)dest = 0;

	else

		*(u32 *)dest = len;

}



#define DEFINE_FETCH_symbol(type)					\

__kprobes void FETCH_FUNC_NAME(symbol, type)(struct pt_regs *regs,	\

					  void *data, void *dest)	\

kernel/trace/trace_probe.c

+0 −77
Original line number Diff line number Diff line
@@ -103,83 +103,6 @@ DEFINE_BASIC_FETCH_FUNCS(retval) 
#define fetch_retval_string		NULL

#define fetch_retval_string_size	NULL



#define DEFINE_FETCH_memory(type)					\

__kprobes void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,	\

					  void *addr, void *dest)	\

{									\

	type retval;							\

	if (probe_kernel_address(addr, retval))				\

		*(type *)dest = 0;					\

	else								\

		*(type *)dest = retval;					\

}

DEFINE_BASIC_FETCH_FUNCS(memory)

/*

 * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max

 * length and relative data location.

 */

__kprobes void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,

						      void *addr, void *dest)

{

	long ret;

	int maxlen = get_rloc_len(*(u32 *)dest);

	u8 *dst = get_rloc_data(dest);

	u8 *src = addr;

	mm_segment_t old_fs = get_fs();



	if (!maxlen)

		return;



	/*

	 * Try to get string again, since the string can be changed while

	 * probing.

	 */

	set_fs(KERNEL_DS);

	pagefault_disable();



	do

		ret = __copy_from_user_inatomic(dst++, src++, 1);

	while (dst[-1] && ret == 0 && src - (u8 *)addr < maxlen);



	dst[-1] = '\0';

	pagefault_enable();

	set_fs(old_fs);



	if (ret < 0) {	/* Failed to fetch string */

		((u8 *)get_rloc_data(dest))[0] = '\0';

		*(u32 *)dest = make_data_rloc(0, get_rloc_offs(*(u32 *)dest));

	} else {

		*(u32 *)dest = make_data_rloc(src - (u8 *)addr,

					      get_rloc_offs(*(u32 *)dest));

	}

}



/* Return the length of string -- including null terminal byte */

__kprobes void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,

							void *addr, void *dest)

{

	mm_segment_t old_fs;

	int ret, len = 0;

	u8 c;



	old_fs = get_fs();

	set_fs(KERNEL_DS);

	pagefault_disable();



	do {

		ret = __copy_from_user_inatomic(&c, (u8 *)addr + len, 1);

		len++;

	} while (c && ret == 0 && len < MAX_STRING_SIZE);



	pagefault_enable();

	set_fs(old_fs);



	if (ret < 0)	/* Failed to check the length */

		*(u32 *)dest = 0;

	else

		*(u32 *)dest = len;

}



/* Dereference memory access function */

struct deref_fetch_param {

	struct fetch_param	orig;

kernel/trace/trace_probe.h

+0 −4
Original line number Diff line number Diff line
@@ -171,10 +171,6 @@ DECLARE_BASIC_FETCH_FUNCS(retval); 
#define fetch_retval_string			NULL

#define fetch_retval_string_size		NULL



DECLARE_BASIC_FETCH_FUNCS(memory);

DECLARE_FETCH_FUNC(memory, string);

DECLARE_FETCH_FUNC(memory, string_size);



DECLARE_BASIC_FETCH_FUNCS(symbol);

DECLARE_FETCH_FUNC(symbol, string);

DECLARE_FETCH_FUNC(symbol, string_size);

kernel/trace/trace_uprobe.c

+52 −0
Original line number Diff line number Diff line
@@ -114,6 +114,58 @@ DEFINE_BASIC_FETCH_FUNCS(stack) 
#define fetch_stack_string	NULL

#define fetch_stack_string_size	NULL



#define DEFINE_FETCH_memory(type)					\

static __kprobes void FETCH_FUNC_NAME(memory, type)(struct pt_regs *regs,\

						void *addr, void *dest) \

{									\

	type retval;							\

	void __user *vaddr = (void __force __user *) addr;		\

									\

	if (copy_from_user(&retval, vaddr, sizeof(type)))		\

		*(type *)dest = 0;					\

	else								\

		*(type *) dest = retval;				\

}

DEFINE_BASIC_FETCH_FUNCS(memory)

/*

 * Fetch a null-terminated string. Caller MUST set *(u32 *)dest with max

 * length and relative data location.

 */

static __kprobes void FETCH_FUNC_NAME(memory, string)(struct pt_regs *regs,

						      void *addr, void *dest)

{

	long ret;

	u32 rloc = *(u32 *)dest;

	int maxlen  = get_rloc_len(rloc);

	u8 *dst = get_rloc_data(dest);

	void __user *src = (void __force __user *) addr;



	if (!maxlen)

		return;



	ret = strncpy_from_user(dst, src, maxlen);



	if (ret < 0) {	/* Failed to fetch string */

		((u8 *)get_rloc_data(dest))[0] = '\0';

		*(u32 *)dest = make_data_rloc(0, get_rloc_offs(rloc));

	} else {

		*(u32 *)dest = make_data_rloc(ret, get_rloc_offs(rloc));

	}

}



static __kprobes void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs,

						      void *addr, void *dest)

{

	int len;

	void __user *vaddr = (void __force __user *) addr;



	len = strnlen_user(vaddr, MAX_STRING_SIZE);



	if (len == 0 || len > MAX_STRING_SIZE)  /* Failed to check length */

		*(u32 *)dest = 0;

	else

		*(u32 *)dest = len;

}



/* uprobes do not support symbol fetch methods */

#define fetch_symbol_u8			NULL

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