Patch "perf trace: Allow associating scnprintf routines with well known arg names" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    perf trace: Allow associating scnprintf routines with well known arg names

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     perf-trace-allow-associating-scnprintf-routines-with.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 4633c53bb25998d8a4824c9249b4a63fc817076a
Author: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Date:   Mon Oct 7 15:50:15 2019 -0300

    perf trace: Allow associating scnprintf routines with well known arg names
    
    [ Upstream commit 5d88099bc00dccddf5da18e25e1223f01644f7a2 ]
    
    For instance 'msr' appears in several tracepoints, so we can associate
    it with a single scnprintf() routine auto-generated from kernel headers,
    as will be done in followup patches.
    
    Start with an empty array of associations.
    
    Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
    Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
    Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
    Link: https://lkml.kernel.org/n/tip-89ptht6s5fez82lykuwq1eyb@xxxxxxxxxxxxxx
    Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
    Stable-dep-of: 03e9a5d8eb55 ("perf trace: Handle failure when trace point folder is missed")
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index e01952883cbc..02cf39970ed0 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1455,6 +1455,27 @@ static int syscall__alloc_arg_fmts(struct syscall *sc, int nr_args)
 	return 0;
 }
 
+static struct syscall_arg_fmt syscall_arg_fmts__by_name[] = {
+};
+
+static int syscall_arg_fmt__cmp(const void *name, const void *fmtp)
+{
+       const struct syscall_arg_fmt *fmt = fmtp;
+       return strcmp(name, fmt->name);
+}
+
+static struct syscall_arg_fmt *
+__syscall_arg_fmt__find_by_name(struct syscall_arg_fmt *fmts, const int nmemb, const char *name)
+{
+       return bsearch(name, fmts, nmemb, sizeof(struct syscall_arg_fmt), syscall_arg_fmt__cmp);
+}
+
+static struct syscall_arg_fmt *syscall_arg_fmt__find_by_name(const char *name)
+{
+       const int nmemb = ARRAY_SIZE(syscall_arg_fmts__by_name);
+       return __syscall_arg_fmt__find_by_name(syscall_arg_fmts__by_name, nmemb, name);
+}
+
 static struct tep_format_field *
 syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format_field *field)
 {
@@ -1491,6 +1512,11 @@ syscall_arg_fmt__init_array(struct syscall_arg_fmt *arg, struct tep_format_field
 			 * 7 unsigned long
 			 */
 			arg->scnprintf = SCA_FD;
+               } else {
+			struct syscall_arg_fmt *fmt = syscall_arg_fmt__find_by_name(field->name);
+
+			if (fmt)
+				arg->scnprintf = fmt->scnprintf;
 		}
 	}