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tracing/uprobes: Add @+file_offset fetch method

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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: Oleg Nesterov <oleg@redhat.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Oleg 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: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Namhyung Kim 2013-11-25 13:42:47 +09:00 committed by Steven Rostedt
parent 72fd293aa9
commit b7e0bf341f
5 changed files with 63 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
Documentation/trace/uprobetracer.txt
View File

@ -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.(*)

8
kernel/trace/trace_kprobe.c
View File

@ -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 */

13
kernel/trace/trace_probe.c
View File

@ -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)

2
kernel/trace/trace_probe.h
View File

@ -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), \
} \
}

40
kernel/trace/trace_uprobe.c
View File

@ -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);