[PATCH] trace: don't use __weak in header files

From: Stephen Rothwell
Date: Thu Mar 12 2015 - 01:58:46 EST


The commit that added a check for this to checkpatch says:

"Using weak declarations can have unintended link defects. The __weak on
the declaration causes non-weak definitions to become weak."

In this case, when a PowerPC kernel is built with CONFIG_KPROBE_EVENT
but not CONFIG_UPROBE_EVENT, it generates the following warning:

WARNING: 1 bad relocations
c0000000014f2190 R_PPC64_ADDR64 uprobes_fetch_type_table

This is fixed by passing the fetch_table arrays to
traceprobe_parse_probe_arg() which also means that they can never be NULL.

Signed-off-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
---
kernel/trace/trace_kprobe.c | 5 +++--
kernel/trace/trace_probe.c | 19 +++++++------------
kernel/trace/trace_probe.h | 10 ++--------
kernel/trace/trace_uprobe.c | 5 +++--
4 files changed, 15 insertions(+), 24 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 5edb518be345..e6f9cbf4388d 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -250,7 +250,7 @@ DEFINE_FETCH_symbol(string_size)
#define fetch_file_offset_string_size NULL

/* Fetch type information table */
-const struct fetch_type kprobes_fetch_type_table[] = {
+static 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[]"),
@@ -760,7 +760,8 @@ static int create_trace_kprobe(int argc, char **argv)

/* Parse fetch argument */
ret = traceprobe_parse_probe_arg(arg, &tk->tp.size, parg,
- is_return, true);
+ is_return, true,
+ kprobes_fetch_type_table);
if (ret) {
pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
goto error;
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index b983b2fd2ca1..1769a81da8a7 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -356,17 +356,14 @@ static int parse_probe_vars(char *arg, const struct fetch_type *t,

/* Recursive argument parser */
static int parse_probe_arg(char *arg, const struct fetch_type *t,
- struct fetch_param *f, bool is_return, bool is_kprobe)
+ struct fetch_param *f, bool is_return, bool is_kprobe,
+ const struct fetch_type *ftbl)
{
- const struct fetch_type *ftbl;
unsigned long param;
long offset;
char *tmp;
int ret = 0;

- ftbl = is_kprobe ? kprobes_fetch_type_table : uprobes_fetch_type_table;
- BUG_ON(ftbl == NULL);
-
switch (arg[0]) {
case '$':
ret = parse_probe_vars(arg + 1, t, f, is_return, is_kprobe);
@@ -447,7 +444,7 @@ static int parse_probe_arg(char *arg, const struct fetch_type *t,
dprm->fetch_size = get_fetch_size_function(t,
dprm->fetch, ftbl);
ret = parse_probe_arg(arg, t2, &dprm->orig, is_return,
- is_kprobe);
+ is_kprobe, ftbl);
if (ret)
kfree(dprm);
else {
@@ -505,15 +502,12 @@ static int __parse_bitfield_probe_arg(const char *bf,

/* String length checking wrapper */
int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
- struct probe_arg *parg, bool is_return, bool is_kprobe)
+ struct probe_arg *parg, bool is_return, bool is_kprobe,
+ const struct fetch_type *ftbl)
{
- 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;
@@ -535,7 +529,8 @@ int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
}
parg->offset = *size;
*size += parg->type->size;
- ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return, is_kprobe);
+ ret = parse_probe_arg(arg, parg->type, &parg->fetch, is_return,
+ is_kprobe, ftbl);

if (ret >= 0 && t != NULL)
ret = __parse_bitfield_probe_arg(t, parg->type, &parg->fetch);
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 4f815fbce16d..e30f6cce4af6 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -229,13 +229,6 @@ ASSIGN_FETCH_FUNC(file_offset, ftype), \
#define FETCH_TYPE_STRING 0
#define FETCH_TYPE_STRSIZE 1

-/*
- * 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[];
-
#ifdef CONFIG_KPROBE_EVENT
struct symbol_cache;
unsigned long update_symbol_cache(struct symbol_cache *sc);
@@ -333,7 +326,8 @@ find_event_file_link(struct trace_probe *tp, struct ftrace_event_file *file)
}

extern int traceprobe_parse_probe_arg(char *arg, ssize_t *size,
- struct probe_arg *parg, bool is_return, bool is_kprobe);
+ struct probe_arg *parg, bool is_return, bool is_kprobe,
+ const struct fetch_type *ftbl);

extern int traceprobe_conflict_field_name(const char *name,
struct probe_arg *args, int narg);
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 8520acc34b18..be8a7b1947d8 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -196,7 +196,7 @@ DEFINE_FETCH_file_offset(string)
DEFINE_FETCH_file_offset(string_size)

/* Fetch type information table */
-const struct fetch_type uprobes_fetch_type_table[] = {
+static 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[]"),
@@ -535,7 +535,8 @@ static int create_trace_uprobe(int argc, char **argv)

/* Parse fetch argument */
ret = traceprobe_parse_probe_arg(arg, &tu->tp.size, parg,
- is_return, false);
+ is_return, false,
+ uprobes_fetch_type_table);
if (ret) {
pr_info("Parse error at argument[%d]. (%d)\n", i, ret);
goto error;
--
2.1.4

--
Cheers,
Stephen Rothwell sfr@xxxxxxxxxxxxxxxx

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