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Message-ID: <87k3fmoenh.fsf@sejong.aot.lge.com>
Date: Tue, 03 Dec 2013 11:24:18 +0900
From: Namhyung Kim <namhyung@...nel.org>
To: Oleg Nesterov <oleg@...hat.com>
Cc: Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
Hyeoncheol Lee <cheol.lee@....com>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
"zhangwei\(Jovi\)" <jovi.zhangwei@...wei.com>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
Hemant Kumar <hkshaw@...ux.vnet.ibm.com>,
LKML <linux-kernel@...r.kernel.org>,
Namhyung Kim <namhyung.kim@....com>
Subject: Re: [PATCH 08/17] tracing/probes: Split [ku]probes_fetch_type_table
Hi Oleg,
On Mon, 2 Dec 2013 18:09:52 +0100, Oleg Nesterov wrote:
> On 12/02, Oleg Nesterov wrote:
>>
>> On 11/27, Namhyung Kim wrote:
>> >
>> > Use separate fetch_type_table for kprobes and uprobes. It currently
>> > shares all fetch methods but some of them will be implemented
>> > differently later.
>>
>> Hmm. This looks wrong, afaics...
>>
>> > static int parse_probe_arg(char *arg, const struct fetch_type *t,
>> > struct fetch_param *f, bool is_return, bool is_kprobe)
>> > {
>> > + const struct fetch_type *ftbl;
>> > unsigned long param;
>> > long offset;
>> > char *tmp;
>> > - int ret;
>> > + int ret = 0;
>> >
>> > - ret = 0;
>> > + ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
>>
>> OK, but what if, say, CONFIG_KPROBE_EVENT && !CONFIG_UPROBE_EVENT ?
>> The kernel won't compile in this case?
>
> Ah, wait, probably I was wrong. I didn't noticee that this patch
> does
>
> extern __weak const struct fetch_type kprobes_fetch_type_table[];
> extern __weak const struct fetch_type uprobes_fetch_type_table[];
>
> Is it the reason for "weak" ?
Exactly!
>
> If yes, perhaps this deserves a comment or at least a note in the changelog.
> Or is there another reason?
Nope. I'll add a comment and a note in the changelog too. Please see the
new version below.
>
> I am wondering if this should always work, with any toolchain. I simply
> do not know what is the documented behaviour if a "weak" symbol is never
> defined.
It's something like a weak reference - if it couldn't find a definition
the ref would have value of 0 instead of error. I'm not sure this is a
standard or documented behavior but it worked for a long time AFAIK so I
guess it's pretty compatible.
Btw I found this:
http://gcc.gnu.org/ml/gcc/1999-02n/msg01219.html
Thanks,
Namhyung
>From 510612b00f3e8c7c1322b3ce10be87296d9bce28 Mon Sep 17 00:00:00 2001
From: Namhyung Kim <namhyung.kim@....com>
Date: Tue, 26 Nov 2013 14:56:28 +0900
Subject: [PATCH v8 08/17] tracing/probes: Split [ku]probes_fetch_type_table
Use separate fetch_type_table for kprobes and uprobes. It currently
shares all fetch methods but some of them will be implemented
differently later.
This is not to break build if [ku]probes is configured alone (like
!CONFIG_KPROBE_EVENT and CONFIG_UPROBE_EVENT). So I added '__weak'
to the table declaration so that it can be safely omitted when it
configured out.
Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: zhangwei(Jovi) <jovi.zhangwei@...wei.com>
Cc: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
kernel/trace/trace_kprobe.c | 18 +++++++++++
kernel/trace/trace_probe.c | 64 +++++++++++++++-----------------------
kernel/trace/trace_probe.h | 76 ++++++++++++++++++++++++++++++++++++++-------
kernel/trace/trace_uprobe.c | 18 +++++++++++
4 files changed, 126 insertions(+), 50 deletions(-)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 62d6c961bbce..d00ee5ce6ccc 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -88,6 +88,24 @@ static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
static int kretprobe_dispatcher(struct kretprobe_instance *ri,
struct pt_regs *regs);
+/* Fetch type information table */
+const struct fetch_type kprobes_fetch_type_table[] = {
+ /* Special types */
+ [FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
+ sizeof(u32), 1, "__data_loc char[]"),
+ [FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
+ string_size, sizeof(u32), 0, "u32"),
+ /* Basic types */
+ ASSIGN_FETCH_TYPE(u8, u8, 0),
+ ASSIGN_FETCH_TYPE(u16, u16, 0),
+ ASSIGN_FETCH_TYPE(u32, u32, 0),
+ ASSIGN_FETCH_TYPE(u64, u64, 0),
+ ASSIGN_FETCH_TYPE(s8, u8, 1),
+ ASSIGN_FETCH_TYPE(s16, u16, 1),
+ ASSIGN_FETCH_TYPE(s32, u32, 1),
+ ASSIGN_FETCH_TYPE(s64, u64, 1),
+};
+
/*
* Allocate new trace_probe and initialize it (including kprobes).
*/
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index c26bc9eaa2ac..68b00a214fcc 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -54,10 +54,6 @@ DEFINE_BASIC_PRINT_TYPE_FUNC(s16, "%d")
DEFINE_BASIC_PRINT_TYPE_FUNC(s32, "%d")
DEFINE_BASIC_PRINT_TYPE_FUNC(s64, "%Ld")
-/* For defining macros, define string/string_size types */
-typedef u32 string;
-typedef u32 string_size;
-
/* Print type function for string type */
__kprobes int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s,
const char *name,
@@ -74,7 +70,6 @@ __kprobes int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s,
const char PRINT_TYPE_FMT_NAME(string)[] = "\\\"%s\\\"";
-#define FETCH_FUNC_NAME(method, type) fetch_##method##_##type
/*
* Define macro for basic types - we don't need to define s* types, because
* we have to care only about bitwidth at recording time.
@@ -359,25 +354,8 @@ free_bitfield_fetch_param(struct bitfield_fetch_param *data)
kfree(data);
}
-/* Fetch type information table */
-static const struct fetch_type fetch_type_table[] = {
- /* Special types */
- [FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
- sizeof(u32), 1, "__data_loc char[]"),
- [FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
- string_size, sizeof(u32), 0, "u32"),
- /* Basic types */
- ASSIGN_FETCH_TYPE(u8, u8, 0),
- ASSIGN_FETCH_TYPE(u16, u16, 0),
- ASSIGN_FETCH_TYPE(u32, u32, 0),
- ASSIGN_FETCH_TYPE(u64, u64, 0),
- ASSIGN_FETCH_TYPE(s8, u8, 1),
- ASSIGN_FETCH_TYPE(s16, u16, 1),
- ASSIGN_FETCH_TYPE(s32, u32, 1),
- ASSIGN_FETCH_TYPE(s64, u64, 1),
-};
-
-static const struct fetch_type *find_fetch_type(const char *type)
+static const struct fetch_type *find_fetch_type(const char *type,
+ const struct fetch_type *ftbl)
{
int i;
@@ -398,21 +376,21 @@ static const struct fetch_type *find_fetch_type(const char *type)
switch (bs) {
case 8:
- return find_fetch_type("u8");
+ return find_fetch_type("u8", ftbl);
case 16:
- return find_fetch_type("u16");
+ return find_fetch_type("u16", ftbl);
case 32:
- return find_fetch_type("u32");
+ return find_fetch_type("u32", ftbl);
case 64:
- return find_fetch_type("u64");
+ return find_fetch_type("u64", ftbl);
default:
goto fail;
}
}
- for (i = 0; i < ARRAY_SIZE(fetch_type_table); i++)
- if (strcmp(type, fetch_type_table[i].name) == 0)
- return &fetch_type_table[i];
+ for (i = 0; i < NR_FETCH_TYPES; i++)
+ if (strcmp(type, ftbl[i].name) == 0)
+ return &ftbl[i];
fail:
return NULL;
@@ -426,16 +404,17 @@ static __kprobes void fetch_stack_address(struct pt_regs *regs,
}
static fetch_func_t get_fetch_size_function(const struct fetch_type *type,
- fetch_func_t orig_fn)
+ fetch_func_t orig_fn,
+ const struct fetch_type *ftbl)
{
int i;
- if (type != &fetch_type_table[FETCH_TYPE_STRING])
+ if (type != &ftbl[FETCH_TYPE_STRING])
return NULL; /* Only string type needs size function */
for (i = 0; i < FETCH_MTD_END; i++)
if (type->fetch[i] == orig_fn)
- return fetch_type_table[FETCH_TYPE_STRSIZE].fetch[i];
+ return ftbl[FETCH_TYPE_STRSIZE].fetch[i];
WARN_ON(1); /* This should not happen */
@@ -504,12 +483,14 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,
static int parse_probe_arg(char *arg, const struct fetch_type *t,
struct fetch_param *f, bool is_return, bool is_kprobe)
{
+ const struct fetch_type *ftbl;
unsigned long param;
long offset;
char *tmp;
- int ret;
+ int ret = 0;
- ret = 0;
+ 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] != '%')
@@ -568,7 +549,7 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
struct deref_fetch_param *dprm;
const struct fetch_type *t2;
- t2 = find_fetch_type(NULL);
+ t2 = find_fetch_type(NULL, ftbl);
*tmp = '\0';
dprm = kzalloc(sizeof(struct deref_fetch_param), GFP_KERNEL);
@@ -637,9 +618,13 @@ static int __parse_bitfield_probe_arg(const char *bf,
int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
struct probe_arg *parg, bool is_return, bool is_kprobe)
{
+ const struct fetch_type *ftbl;
const char *t;
int ret;
+ ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
+ BUG_ON(ftbl == NULL);
+
if (strlen(arg) > MAX_ARGSTR_LEN) {
pr_info("Argument is too long.: %s\n", arg);
return -ENOSPC;
@@ -654,7 +639,7 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
arg[t - parg->comm] = '\0';
t++;
}
- parg->type = find_fetch_type(t);
+ parg->type = find_fetch_type(t, ftbl);
if (!parg->type) {
pr_info("Unsupported type: %s\n", t);
return -EINVAL;
@@ -668,7 +653,8 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
if (ret >= 0) {
parg->fetch_size.fn = get_fetch_size_function(parg->type,
- parg->fetch.fn);
+ parg->fetch.fn,
+ ftbl);
parg->fetch_size.data = parg->fetch.data;
}
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 7c6be146f444..99d3aa1f2d8a 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -126,24 +126,70 @@ struct fetch_param {
void *data;
};
+/* For defining macros, define string/string_size types */
+typedef u32 string;
+typedef u32 string_size;
+
#define PRINT_TYPE_FUNC_NAME(type) print_type_##type
#define PRINT_TYPE_FMT_NAME(type) print_type_format_##type
/* Printing in basic type function template */
-#define DECLARE_BASIC_PRINT_TYPE_FUNC(type, fmt) \
+#define DECLARE_BASIC_PRINT_TYPE_FUNC(type) \
__kprobes int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s, \
const char *name, \
void *data, void *ent); \
-extern const char PRINT_TYPE_FMT_NAME(type)[];
-
-DECLARE_BASIC_PRINT_TYPE_FUNC(u8 , "%x")
-DECLARE_BASIC_PRINT_TYPE_FUNC(u16, "%x")
-DECLARE_BASIC_PRINT_TYPE_FUNC(u32, "%x")
-DECLARE_BASIC_PRINT_TYPE_FUNC(u64, "%Lx")
-DECLARE_BASIC_PRINT_TYPE_FUNC(s8, "%d")
-DECLARE_BASIC_PRINT_TYPE_FUNC(s16, "%d")
-DECLARE_BASIC_PRINT_TYPE_FUNC(s32, "%d")
-DECLARE_BASIC_PRINT_TYPE_FUNC(s64, "%Ld")
+extern const char PRINT_TYPE_FMT_NAME(type)[]
+
+DECLARE_BASIC_PRINT_TYPE_FUNC(u8);
+DECLARE_BASIC_PRINT_TYPE_FUNC(u16);
+DECLARE_BASIC_PRINT_TYPE_FUNC(u32);
+DECLARE_BASIC_PRINT_TYPE_FUNC(u64);
+DECLARE_BASIC_PRINT_TYPE_FUNC(s8);
+DECLARE_BASIC_PRINT_TYPE_FUNC(s16);
+DECLARE_BASIC_PRINT_TYPE_FUNC(s32);
+DECLARE_BASIC_PRINT_TYPE_FUNC(s64);
+DECLARE_BASIC_PRINT_TYPE_FUNC(string);
+
+#define FETCH_FUNC_NAME(method, type) fetch_##method##_##type
+
+/* Declare macro for basic types */
+#define DECLARE_FETCH_FUNC(method, type) \
+extern void FETCH_FUNC_NAME(method, type)(struct pt_regs *regs, \
+ void *data, void *dest)
+
+#define DECLARE_BASIC_FETCH_FUNCS(method) \
+DECLARE_FETCH_FUNC(method, u8); \
+DECLARE_FETCH_FUNC(method, u16); \
+DECLARE_FETCH_FUNC(method, u32); \
+DECLARE_FETCH_FUNC(method, u64)
+
+DECLARE_BASIC_FETCH_FUNCS(reg);
+#define fetch_reg_string NULL
+#define fetch_reg_string_size NULL
+
+DECLARE_BASIC_FETCH_FUNCS(stack);
+#define fetch_stack_string NULL
+#define fetch_stack_string_size NULL
+
+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);
+
+DECLARE_BASIC_FETCH_FUNCS(deref);
+DECLARE_FETCH_FUNC(deref, string);
+DECLARE_FETCH_FUNC(deref, string_size);
+
+DECLARE_BASIC_FETCH_FUNCS(bitfield);
+#define fetch_bitfield_string NULL
+#define fetch_bitfield_string_size NULL
/* Default (unsigned long) fetch type */
#define __DEFAULT_FETCH_TYPE(t) u##t
@@ -178,6 +224,14 @@ ASSIGN_FETCH_FUNC(bitfield, ftype), \
#define FETCH_TYPE_STRING 0
#define FETCH_TYPE_STRSIZE 1
+#define NR_FETCH_TYPES 10
+
+/*
+ * Fetch type information table.
+ * It's declared as a weak symbol due to conditional compilation.
+ */
+extern __weak const struct fetch_type kprobes_fetch_type_table[];
+extern __weak const struct fetch_type uprobes_fetch_type_table[];
struct probe_arg {
struct fetch_param fetch;
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index b233d9cb1216..c66ddc744f12 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -74,6 +74,24 @@ 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);
+/* Fetch type information table */
+const struct fetch_type uprobes_fetch_type_table[] = {
+ /* Special types */
+ [FETCH_TYPE_STRING] = __ASSIGN_FETCH_TYPE("string", string, string,
+ sizeof(u32), 1, "__data_loc char[]"),
+ [FETCH_TYPE_STRSIZE] = __ASSIGN_FETCH_TYPE("string_size", u32,
+ string_size, sizeof(u32), 0, "u32"),
+ /* Basic types */
+ ASSIGN_FETCH_TYPE(u8, u8, 0),
+ ASSIGN_FETCH_TYPE(u16, u16, 0),
+ ASSIGN_FETCH_TYPE(u32, u32, 0),
+ ASSIGN_FETCH_TYPE(u64, u64, 0),
+ ASSIGN_FETCH_TYPE(s8, u8, 1),
+ ASSIGN_FETCH_TYPE(s16, u16, 1),
+ ASSIGN_FETCH_TYPE(s32, u32, 1),
+ ASSIGN_FETCH_TYPE(s64, u64, 1),
+};
+
static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
{
rwlock_init(&filter->rwlock);
--
1.7.11.7
--
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