[PATCH 1/6] riscv/ftrace: Add RECORD_MCOUNT support

[Alan Kao]

Now recordmcount.pl recognizes RISC-V object files. For the mechanism to
work, we have to disable the linker relaxation. This is because
relaxation happens after the script records offsets of _mcount call
sites, resulting in a unreliable record. 

Cc: Greentime Hu <greentime@xxxxxxxxxxxxx>
Signed-off-by: Alan Kao <alankao@xxxxxxxxxxxxx>
---
 arch/riscv/Kconfig      | 1 +
 arch/riscv/Makefile     | 6 +++++-
 scripts/recordmcount.pl | 5 +++++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 504ba386b22e..346dd1b0fb05 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -112,6 +112,7 @@ config ARCH_RV64I
 	select 64BIT
 	select HAVE_FUNCTION_TRACER
 	select HAVE_FUNCTION_GRAPH_TRACER
+	select HAVE_FTRACE_MCOUNT_RECORD
 
 endchoice
 
diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 6719dd30ec5b..2bc39c6d9662 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -10,7 +10,11 @@
 
 LDFLAGS         :=
 OBJCOPYFLAGS    := -O binary
-LDFLAGS_vmlinux :=
+ifeq ($(CONFIG_DYNAMIC_FTRACE),y)
+	LDFLAGS_vmlinux := --no-relax
+else
+	LDFLAGS_vmlinux :=
+endif
 KBUILD_AFLAGS_MODULE += -fPIC
 KBUILD_CFLAGS_MODULE += -fPIC
 
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 2033af758173..d44d55db7c06 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -376,6 +376,11 @@ if ($arch eq "x86_64") {
     $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s__mcount\$";
     $type = ".quad";
     $alignment = 8;
+} elsif ($arch eq "riscv") {
+    $function_regex = "^([0-9a-fA-F]+)\\s+<([^.0-9][0-9a-zA-Z_\\.]+)>:";
+    $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL\\s_mcount\$";
+    $type = ".quad";
+    $alignment = 2;
 } else {
     die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
 }
-- 
2.15.1