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Date: Tue, 13 Jun 2017 16:21:48 -0500
From: Jeremy Linton <jeremy.linton@....com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
mingo@...hat.com, rusty@...tcorp.com.au, jeyu@...hat.com,
kirill.shutemov@...ux.intel.com, christoffer.dall@...aro.org,
marc.zyngier@....com, jcm@...masters.org
Subject: Re: [PATCH 12/12] tracing: Rename update the enum_map file
Hi,
On 06/13/2017 04:12 PM, Steven Rostedt wrote:
> On Wed, 31 May 2017 16:56:53 -0500
> Jeremy Linton <jeremy.linton@....com> wrote:
>
>> The enum_map file is used to display a list of symbol
>> to name conversions. As its now used to resolve sizeof
>> lets update the name and description.
>>
>> Signed-off-by: Jeremy Linton <jeremy.linton@....com>
>> ---
>> kernel/trace/Kconfig | 22 +++++++++++-----------
>> kernel/trace/trace.c | 20 ++++++++++----------
>> 2 files changed, 21 insertions(+), 21 deletions(-)
>>
>> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
>> index 7e06f04..434c840 100644
>> --- a/kernel/trace/Kconfig
>> +++ b/kernel/trace/Kconfig
>> @@ -667,30 +667,30 @@ config RING_BUFFER_STARTUP_TEST
>>
>> If unsure, say N
>>
>> -config TRACE_ENUM_MAP_FILE
>> - bool "Show enum mappings for trace events"
>> +config TRACE_EVAL_MAP_FILE
>> + bool "Show eval mappings for trace events"
>> depends on TRACING
>> help
>> - The "print fmt" of the trace events will show the enum names instead
>> - of their values. This can cause problems for user space tools that
>> - use this string to parse the raw data as user space does not know
>> + The "print fmt" of the trace events will show the enum/sizeof names
>> + instead of their values. This can cause problems for user space tools
>> + that use this string to parse the raw data as user space does not know
>> how to convert the string to its value.
>>
>> To fix this, there's a special macro in the kernel that can be used
>> - to convert the enum into its value. If this macro is used, then the
>> - print fmt strings will have the enums converted to their values.
>> + to convert an enum/sizeof into its value. If this macro is used, then
>> + the print fmt strings will be converted to their values.
>>
>> If something does not get converted properly, this option can be
>> - used to show what enums the kernel tried to convert.
>> + used to show what enums/sizeof the kernel tried to convert.
>>
>> - This option is for debugging the enum conversions. A file is created
>> - in the tracing directory called "enum_map" that will show the enum
>> + This option is for debugging the conversions. A file is created
>> + in the tracing directory called "eval_map" that will show the
>> names matched with their values and what trace event system they
>> belong too.
>>
>> Normally, the mapping of the strings to values will be freed after
>> boot up or module load. With this option, they will not be freed, as
>> - they are needed for the "enum_map" file. Enabling this option will
>> + they are needed for the "eval_map" file. Enabling this option will
>> increase the memory footprint of the running kernel.
>>
>> If unsure, say N
>> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
>> index 676c808..7297e9d 100644
>> --- a/kernel/trace/trace.c
>> +++ b/kernel/trace/trace.c
>> @@ -120,8 +120,8 @@ enum ftrace_dump_mode ftrace_dump_on_oops;
>> /* When set, tracing will stop when a WARN*() is hit */
>> int __disable_trace_on_warning;
>>
>> -#ifdef CONFIG_TRACE_ENUM_MAP_FILE
>> -/* Map of enums to their values, for "enum_map" file */
>> +#ifdef CONFIG_TRACE_EVAL_MAP_FILE
>> +/* Map of enums to their values, for "eval_map" file */
>> struct trace_eval_map_head {
>> struct module *mod;
>> unsigned long length;
>> @@ -145,7 +145,7 @@ static DEFINE_MUTEX(trace_eval_mutex);
>> * one at the beginning, and one at the end. The beginning item contains
>> * the count of the saved maps (head.length), and the module they
>> * belong to if not built in (head.mod). The ending item contains a
>> - * pointer to the next array of saved enum_eval/enum_map items.
>> + * pointer to the next array of saved eval_map items.
>> */
>> union trace_eval_map_item {
>> struct trace_eval_map map;
>> @@ -154,7 +154,7 @@ union trace_eval_map_item {
>> };
>>
>> static union trace_eval_map_item *trace_eval_maps;
>> -#endif /* CONFIG_TRACE_ENUM_MAP_FILE */
>> +#endif /* CONFIG_TRACE_EVAL_MAP_FILE */
>>
>> static int tracing_set_tracer(struct trace_array *tr, const char *buf);
>>
>> @@ -4717,7 +4717,7 @@ static const struct file_operations tracing_saved_cmdlines_size_fops = {
>> .write = tracing_saved_cmdlines_size_write,
>> };
>>
>> -#ifdef CONFIG_TRACE_ENUM_MAP_FILE
>> +#ifdef CONFIG_TRACE_EVAL_MAP_FILE
>> static union trace_eval_map_item *
>> update_eval_map(union trace_eval_map_item *ptr)
>> {
>> @@ -4868,15 +4868,15 @@ trace_insert_eval_map_file(struct module *mod, struct trace_eval_map **start,
>>
>> static void trace_create_eval_file(struct dentry *d_tracer)
>> {
>> - trace_create_file("enum_map", 0444, d_tracer,
>> + trace_create_file("eval_map", 0444, d_tracer,
>> NULL, &tracing_eval_map_fops);
>
> Hmm, I have to audit some userspace code to see if this is used. The
> enum_map was a debug feature, but it could have been used by some tools.
I thought perf was using it, but I was mistaken. I didn't find anything
using it, but to be on the safe side I placed this patch last so it
could be dropped if a user was found. The CONFIG option seems to be
disabled in the couple distro's I checked, further indicating that if
someone is using it, they are seemingly obscure.
>> }
>>
>> -#else /* CONFIG_TRACE_ENUM_MAP_FILE */
>> +#else /* CONFIG_TRACE_EVAL_MAP_FILE */
>> static inline void trace_create_eval_file(struct dentry *d_tracer) { }
>> static inline void trace_insert_eval_map_file(struct module *mod,
>> struct trace_eval_map **start, int len) { }
>> -#endif /* !CONFIG_TRACE_ENUM_MAP_FILE */
>> +#endif /* !CONFIG_TRACE_EVAL_MAP_FILE */
>>
>> static void trace_insert_eval_map(struct module *mod,
>> struct trace_eval_map **start, int len)
>> @@ -7731,7 +7731,7 @@ static void trace_module_add_evals(struct module *mod)
>> trace_insert_eval_map(mod, mod->trace_evals, mod->num_trace_evals);
>> }
>>
>> -#ifdef CONFIG_TRACE_ENUM_MAP_FILE
>> +#ifdef CONFIG_TRACE_EVAL_MAP_FILE
>> static void trace_module_remove_evals(struct module *mod)
>> {
>> union trace_eval_map_item *map;
>> @@ -7761,7 +7761,7 @@ static void trace_module_remove_evals(struct module *mod)
>> }
>> #else
>> static inline void trace_module_remove_evals(struct module *mod) { }
>> -#endif /* CONFIG_TRACE_ENUM_MAP_FILE */
>> +#endif /* CONFIG_TRACE_EVAL_MAP_FILE */
>>
>> static int trace_module_notify(struct notifier_block *self,
>> unsigned long val, void *data)
>
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