ftrace/x86: Add support for C version of recordmcount

This patch adds the support for the C version of recordmcount and
compile times show ~ 12% improvement.

After verifying this works, other archs can add:

 HAVE_C_MCOUNT_RECORD

in its Kconfig and it will use the C version of recordmcount
instead of the perl version.

Cc: <linux-arch@vger.kernel.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: linux-kbuild@vger.kernel.org
Cc: John Reiser <jreiser@bitwagon.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

5 files changed, 17 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index 534c09c255de..0dd3a8d93132 100644
--- a/Makefile
+++ b/Makefile
@@ -568,6 +568,12 @@ endif
 
 ifdef CONFIG_FUNCTION_TRACER
 KBUILD_CFLAGS   += -pg
+ifdef CONFIG_DYNAMIC_FTRACE
+        ifdef CONFIG_HAVE_C_MCOUNT_RECORD
+                BUILD_C_RECORDMCOUNT := y
+                export BUILD_C_RECORDMCOUNT
+        endif
+endif
 endif
 
 # We trigger additional mismatches with less inlining
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c14d8b4d2f71..788b50ef5fc4 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -33,6 +33,7 @@ config X86
         select HAVE_KRETPROBES
         select HAVE_OPTPROBES
         select HAVE_FTRACE_MCOUNT_RECORD
+        select HAVE_C_MCOUNT_RECORD
         select HAVE_DYNAMIC_FTRACE
         select HAVE_FUNCTION_TRACER
         select HAVE_FUNCTION_GRAPH_TRACER
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 538501c6ea50..df00fbbaf609 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -49,6 +49,11 @@ config HAVE_SYSCALL_TRACEPOINTS
         help
           See Documentation/trace/ftrace-design.txt
 
+config HAVE_C_MCOUNT_RECORD
+        bool
+        help
+          C version of recordmcount available?
+
 config TRACER_MAX_TRACE
         bool
 
diff --git a/scripts/Makefile b/scripts/Makefile
index 842dbc2d5aed..2e088109fbd5 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -11,6 +11,7 @@ hostprogs-$(CONFIG_KALLSYMS)     += kallsyms
 hostprogs-$(CONFIG_LOGO)         += pnmtologo
 hostprogs-$(CONFIG_VT)           += conmakehash
 hostprogs-$(CONFIG_IKCONFIG)     += bin2c
+hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
 
 always          := $(hostprogs-y) $(hostprogs-m)
 
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index a1a5cf95a68d..4d03a7efc689 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -209,12 +209,16 @@ cmd_modversions =								\
 endif
 
 ifdef CONFIG_FTRACE_MCOUNT_RECORD
+ifdef BUILD_C_RECORDMCOUNT
+cmd_record_mcount = $(srctree)/scripts/recordmcount "$(@)";
+else
 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)" "$(LD)" "$(NM)" "$(RM)" "$(MV)" \
         "$(if $(part-of-module),1,0)" "$(@)";
 endif
+endif
 
 define rule_cc_o_c
         $(call echo-cmd,checksrc) $(cmd_checksrc)                         \