tracing/uprobes: Add support for full argument access methods (b079d374) · Commits · 戴 / test

Documentation/trace/uprobetracer.txt

+25 −0

Original line number	Diff line number	Diff line
		@@ -31,6 +31,31 @@ Synopsis of uprobe_tracer

		FETCHARGS : Arguments. Each probe can have up to 128 args.
		%REG : Fetch register REG
		@ADDR : Fetch memory at ADDR (ADDR should be in userspace)
		$stackN : Fetch Nth entry of stack (N >= 0)
		$stack : Fetch stack address.
		$retval : Fetch return value.(*)
		+\|-offs(FETCHARG) : Fetch memory at FETCHARG +\|- offs address.(**)
		NAME=FETCHARG : Set NAME as the argument name of FETCHARG.
		FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types
		(u8/u16/u32/u64/s8/s16/s32/s64), "string" and bitfield
		are supported.

		(*) only for return probe.
		(**) this is useful for fetching a field of data structures.

		Types
		-----
		Several types are supported for fetch-args. Uprobe tracer will access memory
		by given type. Prefix 's' and 'u' means those types are signed and unsigned
		respectively. Traced arguments are shown in decimal (signed) or hex (unsigned).
		String type is a special type, which fetches a "null-terminated" string from
		user space.
		Bitfield is another special type, which takes 3 parameters, bit-width, bit-
		offset, and container-size (usually 32). The syntax is;

		b<bit-width>@<bit-offset>/<container-size>


		Event Profiling
		---------------

kernel/trace/trace_probe.c

+22 −12

Original line number	Diff line number	Diff line
		@@ -255,12 +255,18 @@ fail:
		}

		/* Special function : only accept unsigned long */
		static __kprobes void fetch_stack_address(struct pt_regs *regs,
		static __kprobes void fetch_kernel_stack_address(struct pt_regs *regs,
		void dummy, void dest)
		{
		(unsigned long )dest = kernel_stack_pointer(regs);
		}

		static __kprobes void fetch_user_stack_address(struct pt_regs *regs,
		void dummy, void dest)
		{
		(unsigned long )dest = user_stack_pointer(regs);
		}

		static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
		fetch_func_t orig_fn,
		const struct fetch_type *ftbl)
		@@ -305,7 +311,8 @@ int traceprobe_split_symbol_offset(char symbol, unsigned long offset)
		#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))

		static int parse_probe_vars(char arg, const struct fetch_type t,
		struct fetch_param *f, bool is_return)
		struct fetch_param *f, bool is_return,
		bool is_kprobe)
		{
		int ret = 0;
		unsigned long param;
		@@ -317,13 +324,16 @@ static int parse_probe_vars(char arg, const struct fetch_type t,
		ret = -EINVAL;
		} else if (strncmp(arg, "stack", 5) == 0) {
		if (arg[5] == '\0') {
		if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR) == 0)
		f->fn = fetch_stack_address;
		if (strcmp(t->name, DEFAULT_FETCH_TYPE_STR))
		return -EINVAL;

		if (is_kprobe)
		f->fn = fetch_kernel_stack_address;
		else
		ret = -EINVAL;
		f->fn = fetch_user_stack_address;
		} else if (isdigit(arg[5])) {
		ret = kstrtoul(arg + 5, 10, &param);
		if (ret \|\| param > PARAM_MAX_STACK)
		if (ret \|\| (is_kprobe && param > PARAM_MAX_STACK))
		ret = -EINVAL;
		else {
		f->fn = t->fetch[FETCH_MTD_stack];
		@@ -350,13 +360,9 @@ static int parse_probe_arg(char arg, const struct fetch_type t,
		ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
		BUG_ON(ftbl == NULL);

		/* Until uprobe_events supports only reg arguments */
		if (!is_kprobe && arg[0] != '%')
		return -EINVAL;

		switch (arg[0]) {
		case '$':
		ret = parse_probe_vars(arg + 1, t, f, is_return);
		ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
		break;

		case '%': /* named register */
		@@ -377,6 +383,10 @@ static int parse_probe_arg(char arg, const struct fetch_type t,
		f->fn = t->fetch[FETCH_MTD_memory];
		f->data = (void *)param;
		} else {
		/* uprobes don't support symbols */
		if (!is_kprobe)
		return -EINVAL;

		ret = traceprobe_split_symbol_offset(arg + 1, &offset);
		if (ret)
		break;

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