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

[Alan Kao]

On Wed, Jan 10, 2018 at 08:43:54AM +0100, Christoph Hellwig wrote:
> On Wed, Jan 10, 2018 at 03:38:09PM +0800, Alan Kao wrote:
> > -LDFLAGS_vmlinux :=
> > +ifeq ($(CONFIG_DYNAMIC_FTRACE),y)
> > +   LDFLAGS_vmlinux := --no-relax
> > +else
> > +   LDFLAGS_vmlinux :=
> > +endif
> 
> Why not:
> 
> LDFLAGS_vmlinux :=
> ifeq ($(CONFIG_DYNAMIC_FTRACE),y)
> LDFLAGS_vmlinux += --no-relax
> endif
> 
Thanks for the comment! This will be enhanced in the next try.

Alan

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

[Alan Kao]

On Wed, Jan 10, 2018 at 08:43:54AM +0100, Christoph Hellwig wrote:
> On Wed, Jan 10, 2018 at 03:38:09PM +0800, Alan Kao wrote:
> > -LDFLAGS_vmlinux :=
> > +ifeq ($(CONFIG_DYNAMIC_FTRACE),y)
> > +   LDFLAGS_vmlinux := --no-relax
> > +else
> > +   LDFLAGS_vmlinux :=
> > +endif
> 
> Why not:
> 
> LDFLAGS_vmlinux :=
> ifeq ($(CONFIG_DYNAMIC_FTRACE),y)
> LDFLAGS_vmlinux += --no-relax
> endif
> 
Thanks for the comment! This will be enhanced in the next try.

Alan

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

[Christoph Hellwig]

On Wed, Jan 10, 2018 at 03:38:09PM +0800, Alan Kao wrote:
> -LDFLAGS_vmlinux :=
> +ifeq ($(CONFIG_DYNAMIC_FTRACE),y)
> + LDFLAGS_vmlinux := --no-relax
> +else
> + LDFLAGS_vmlinux :=
> +endif

Why not:

LDFLAGS_vmlinux :=
ifeq ($(CONFIG_DYNAMIC_FTRACE),y)
LDFLAGS_vmlinux += --no-relax
endif

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

[Christoph Hellwig]

On Wed, Jan 10, 2018 at 03:38:09PM +0800, Alan Kao wrote:
> -LDFLAGS_vmlinux :=
> +ifeq ($(CONFIG_DYNAMIC_FTRACE),y)
> + LDFLAGS_vmlinux := --no-relax
> +else
> + LDFLAGS_vmlinux :=
> +endif

Why not:

LDFLAGS_vmlinux :=
ifeq ($(CONFIG_DYNAMIC_FTRACE),y)
LDFLAGS_vmlinux += --no-relax
endif

[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 
Signed-off-by: Alan Kao 
---
 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

[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 
Signed-off-by: Alan Kao 
---
 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