[RFC/PATCH 1/3] scripts: Allow recordmcount to be used without tracing enabled

Stephen Boyd
2015-11-21T01:23:22Z

In the next patch we're going to modify recordmcount to also
record locations of calls to __aeabi_{u}idiv(). Lay the
groundwork for this by adding a flag to recordmcount that
indicates if we're expected to find calls to mcount or not.

Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Måns Rullgård <mans@mansr.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
---
kernel/trace/Kconfig | 4 ++++
scripts/Makefile.build | 15 +++++----------
scripts/recordmcount.c | 10 +++++++---
scripts/recordmcount.h | 2 +-
scripts/recordmcount.pl | 11 ++++++++---
5 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 8d6363f42169..578b666ed7d9 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -57,6 +57,10 @@ config HAVE_C_RECORDMCOUNT
help
C version of recordmcount available?

+config RUN_RECORDMCOUNT
+ def_bool y
+ depends on DYNAMIC_FTRACE && HAVE_FTRACE_MCOUNT_RECORD
+
config TRACER_MAX_TRACE
bool

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 01df30af4d4a..22f2eb10d434 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -210,7 +210,7 @@ cmd_modversions = \
fi;
endif

-ifdef CONFIG_FTRACE_MCOUNT_RECORD
+ifdef CONFIG_RUN_RECORDMCOUNT
ifdef BUILD_C_RECORDMCOUNT
ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
RECORDMCOUNT_FLAGS = -w
@@ -219,26 +219,21 @@ endif
# The empty.o file is created in the make process in order to determine
# the target endianness and word size. It is made before all other C
# files, including recordmcount.
-sub_cmd_record_mcount = \
+cmd_record_mcount = \
if [ $(@) != "scripts/mod/empty.o" ]; then \
- $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)"; \
+ $(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) $(if $(findstring $(CC_FLAGS_FTRACE),$(_c_flags)),-t,) "$(@)"; \
fi;
recordmcount_source := $(srctree)/scripts/recordmcount.c \
$(srctree)/scripts/recordmcount.h
else
-sub_cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
+cmd_record_mcount = set -e ; perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
"$(if $(CONFIG_64BIT),64,32)" \
"$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CFLAGS)" \
"$(LD)" "$(NM)" "$(RM)" "$(MV)" \
- "$(if $(part-of-module),1,0)" "$(@)";
+ "$(if $(part-of-module),1,0)" "$(if $(findstring $(CC_FLAGS_FTRACE),$(_c_flags)),1,0)" "$(@)";
recordmcount_source := $(srctree)/scripts/recordmcount.pl
endif
-cmd_record_mcount = \
- if [ "$(findstring $(CC_FLAGS_FTRACE),$(_c_flags))" = \
- "$(CC_FLAGS_FTRACE)" ]; then \
- $(sub_cmd_record_mcount) \
- fi;
endif

define rule_cc_o_c
diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index 698768bdc581..b6b4a5df647a 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -54,6 +54,7 @@ static struct stat sb; /* Remember .st_size, etc. */
static jmp_buf jmpenv; /* setjmp/longjmp per-file error escape */
static const char *altmcount; /* alternate mcount symbol name */
static int warn_on_notrace_sect; /* warn when section has mcount not being recorded */
+static int trace_mcount; /* Record mcount callers */

/* setjmp() return values */
enum {
@@ -453,19 +454,22 @@ main(int argc, char *argv[])
int c;
int i;

- while ((c = getopt(argc, argv, "w")) >= 0) {
+ while ((c = getopt(argc, argv, "wt")) >= 0) {
switch (c) {
case 'w':
warn_on_notrace_sect = 1;
break;
+ case 't':
+ trace_mcount = 1;
+ break;
default:
- fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
+ fprintf(stderr, "usage: recordmcount [-wt] file.o...\n");
return 0;
}
}

if ((argc - optind) < 1) {
- fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
+ fprintf(stderr, "usage: recordmcount [-wt] file.o...\n");
return 0;
}

diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index b9897e2be404..6e196dba748d 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -323,7 +323,7 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);

for (t = nrel; t; --t) {
- if (!mcountsym)
+ if (trace_mcount && !mcountsym)
mcountsym = get_mcountsym(sym0, relp, str0);

if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 826470d7f000..cff3040ddbdc 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -113,20 +113,25 @@ $P =~ s@.*/@@g;

my $V = '0.1';

-if ($#ARGV != 11) {
- print "usage: $P arch endian bits objdump objcopy cc ld nm rm mv is_module inputfile\n";
+if ($#ARGV != 12) {
+ print "usage: $P arch endian bits objdump objcopy cc ld nm rm mv is_module is_traced inputfile\n";
print "version: $V\n";
exit(1);
}

my ($arch, $endian, $bits, $objdump, $objcopy, $cc,
- $ld, $nm, $rm, $mv, $is_module, $inputfile) = @ARGV;
+ $ld, $nm, $rm, $mv, $is_module, $is_traced, $inputfile) = @ARGV;

# This file refers to mcount and shouldn't be ftraced, so lets' ignore it
if ($inputfile =~ m,kernel/trace/ftrace\.o$,) {
exit(0);
}

+# We only trace mcount calls
+if ($is_traced eq "0") {
+ exit(0);
+}
+
# Acceptable sections to record.
my %text_sections = (
".text" => 1,
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project