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Message-ID: <20150312111419.7315150f@gandalf.local.home>
Date: Thu, 12 Mar 2015 11:14:19 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Stephen Rothwell <sfr@...b.auug.org.au>
Cc: Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Subject: Re: [PATCH] trace: don't use __weak in header files
Masami and Srikar,
Can I get your ACKs for this?
Thanks,
-- Steve
On Thu, 12 Mar 2015 16:58:34 +1100
Stephen Rothwell <sfr@...b.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@...b.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;
--
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