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Commit b7e0bf34 authored by Namhyung Kim's avatar Namhyung Kim Committed by Steven Rostedt
Browse files

tracing/uprobes: Add @+file_offset fetch method 



Enable to fetch data from a file offset.  Currently it only supports
fetching from same binary uprobe set.  It'll translate the file offset
to a proper virtual address in the process.

The syntax is "@+OFFSET" as it does similar to normal memory fetching
(@ADDR) which does no address translation.

Suggested-by: default avatarOleg Nesterov <oleg@redhat.com>
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 72fd293a

Documentation/trace/uprobetracer.txt

+1 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ 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)

   @+OFFSET	: Fetch memory at OFFSET (OFFSET from same file as PATH)

   $stackN	: Fetch Nth entry of stack (N >= 0)

   $stack	: Fetch stack address.

   $retval	: Fetch return value.(*)

kernel/trace/trace_kprobe.c

+8 −0
Original line number Diff line number Diff line
@@ -239,6 +239,14 @@ DEFINE_BASIC_FETCH_FUNCS(symbol) 
DEFINE_FETCH_symbol(string)

DEFINE_FETCH_symbol(string_size)



/* kprobes don't support file_offset fetch methods */

#define fetch_file_offset_u8		NULL

#define fetch_file_offset_u16		NULL

#define fetch_file_offset_u32		NULL

#define fetch_file_offset_u64		NULL

#define fetch_file_offset_string	NULL

#define fetch_file_offset_string_size	NULL



/* Fetch type information table */

const struct fetch_type kprobes_fetch_type_table[] = {

	/* Special types */

kernel/trace/trace_probe.c

+12 −1
Original line number Diff line number Diff line
@@ -374,7 +374,7 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t, 
		}

		break;



	case '@':	/* memory or symbol */

	case '@':	/* memory, file-offset or symbol */

		if (isdigit(arg[1])) {

			ret = kstrtoul(arg + 1, 0, &param);

			if (ret)
@@ -382,6 +382,17 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t, 


			f->fn = t->fetch[FETCH_MTD_memory];

			f->data = (void *)param;

		} else if (arg[1] == '+') {

			/* kprobes don't support file offsets */

			if (is_kprobe)

				return -EINVAL;



			ret = kstrtol(arg + 2, 0, &offset);

			if (ret)

				break;



			f->fn = t->fetch[FETCH_MTD_file_offset];

			f->data = (void *)offset;

		} else {

			/* uprobes don't support symbols */

			if (!is_kprobe)

kernel/trace/trace_probe.h

+2 −0
Original line number Diff line number Diff line
@@ -106,6 +106,7 @@ enum { 
	FETCH_MTD_symbol,

	FETCH_MTD_deref,

	FETCH_MTD_bitfield,

	FETCH_MTD_file_offset,

	FETCH_MTD_END,

};
@@ -217,6 +218,7 @@ ASSIGN_FETCH_FUNC(memory, ftype), \ 
ASSIGN_FETCH_FUNC(symbol, ftype),			\

ASSIGN_FETCH_FUNC(deref, ftype),			\

ASSIGN_FETCH_FUNC(bitfield, ftype),			\

ASSIGN_FETCH_FUNC(file_offset, ftype),			\

	  }						\

	}

kernel/trace/trace_uprobe.c

+40 −0
Original line number Diff line number Diff line
@@ -70,6 +70,11 @@ static int unregister_uprobe_event(struct trace_uprobe *tu); 
static DEFINE_MUTEX(uprobe_lock);

static LIST_HEAD(uprobe_list);



struct uprobe_dispatch_data {

	struct trace_uprobe	*tu;

	unsigned long		bp_addr;

};



static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);

static int uretprobe_dispatcher(struct uprobe_consumer *con,

				unsigned long func, struct pt_regs *regs);
@@ -175,6 +180,29 @@ static __kprobes void FETCH_FUNC_NAME(memory, string_size)(struct pt_regs *regs, 
#define fetch_symbol_string		NULL

#define fetch_symbol_string_size	NULL



static unsigned long translate_user_vaddr(void *file_offset)

{

	unsigned long base_addr;

	struct uprobe_dispatch_data *udd;



	udd = (void *) current->utask->vaddr;



	base_addr = udd->bp_addr - udd->tu->offset;

	return base_addr + (unsigned long)file_offset;

}



#define DEFINE_FETCH_file_offset(type)					\

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

					void *offset, void *dest) 	\

{									\

	void *vaddr = (void *)translate_user_vaddr(offset);		\

									\

	FETCH_FUNC_NAME(memory, type)(regs, vaddr, dest);		\

}

DEFINE_BASIC_FETCH_FUNCS(file_offset)

DEFINE_FETCH_file_offset(string)

DEFINE_FETCH_file_offset(string_size)



/* Fetch type information table */

const struct fetch_type uprobes_fetch_type_table[] = {

	/* Special types */
@@ -1106,11 +1134,17 @@ int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type, 
static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)

{

	struct trace_uprobe *tu;

	struct uprobe_dispatch_data udd;

	int ret = 0;



	tu = container_of(con, struct trace_uprobe, consumer);

	tu->nhit++;



	udd.tu = tu;

	udd.bp_addr = instruction_pointer(regs);



	current->utask->vaddr = (unsigned long) &udd;



	if (tu->tp.flags & TP_FLAG_TRACE)

		ret |= uprobe_trace_func(tu, regs);
@@ -1125,9 +1159,15 @@ static int uretprobe_dispatcher(struct uprobe_consumer *con, 
				unsigned long func, struct pt_regs *regs)

{

	struct trace_uprobe *tu;

	struct uprobe_dispatch_data udd;



	tu = container_of(con, struct trace_uprobe, consumer);



	udd.tu = tu;

	udd.bp_addr = func;



	current->utask->vaddr = (unsigned long) &udd;



	if (tu->tp.flags & TP_FLAG_TRACE)

		uretprobe_trace_func(tu, func, regs);