lkml.org 
[lkml]   [2013]   [Dec]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 17/17] tracing/uprobes: Add @+file_offset fetch method
Date
From: Namhyung Kim <namhyung.kim@lge.com>

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>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: zhangwei(Jovi) <jovi.zhangwei@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
Documentation/trace/uprobetracer.txt | 1 +
kernel/trace/trace_kprobe.c | 8 ++++++++
kernel/trace/trace_probe.c | 13 +++++++++++-
kernel/trace/trace_probe.h | 2 ++
kernel/trace/trace_uprobe.c | 40 ++++++++++++++++++++++++++++++++++++
5 files changed, 63 insertions(+), 1 deletion(-)

diff --git a/Documentation/trace/uprobetracer.txt b/Documentation/trace/uprobetracer.txt
index 6e5cff263e2b..f1cf9a34ad9d 100644
--- a/Documentation/trace/uprobetracer.txt
+++ b/Documentation/trace/uprobetracer.txt
@@ -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.(*)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index d1d3d8982345..cc6bb8531f2f 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -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 */
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index a130d612e705..8364a421b4df 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -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)
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 2d5b8f5f5310..e29d743fef5d 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -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), \
} \
}

diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 6ed319be5a84..0f7681c7b757 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -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);

--
1.7.11.7


\
 
 \ /
  Last update: 2013-12-16 06:01    [W:0.212 / U:0.284 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site