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

[Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>]

(2015/03/13 0:14), Steven Rostedt wrote:
> 
> Masami and Srikar,
> 
> Can I get your ACKs for this?

Yes, looks good and clean to me :)

Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Thanks!

> 
> Thanks,
> 
> -- Steve
> 
> 
> On Thu, 12 Mar 2015 16:58:34 +1100
> Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> 
>> 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@canb.auug.org.au>
>> ---
>>  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;
> 
> 


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com