* Re: [PATCH 3/5]explictly ignore a file in recordmcount.pl
2008-12-23 6:08 [PATCH 3/5]explictly ignore a file in recordmcount.pl Shaohua Li
@ 2008-12-23 14:22 ` Steven Rostedt
2008-12-24 0:43 ` Shaohua Li
2008-12-24 0:48 ` Steven Rostedt
2 siblings, 0 replies; 4+ messages in thread
From: Steven Rostedt @ 2008-12-23 14:22 UTC (permalink / raw)
To: linux-ia64
On Tue, 2008-12-23 at 14:08 +0800, Shaohua Li wrote:
> In IA64, a function pointer isn't a 'unsigned long' but a
> 'struct {unsigned long ip, unsigned long gp}'. MCOUNT_ADDR is determined
> at link time not compile time, so explictly ignore kernel/trace/ftrace.o
> in recordmcount.pl.
>
> Signed-off-by: Shaohua Li <shaohua.li@intel.com>
> ---
> kernel/trace/ftrace.c | 10 +---------
> scripts/recordmcount.pl | 5 +++++
> 2 files changed, 6 insertions(+), 9 deletions(-)
>
> Index: linux/kernel/trace/ftrace.c
> =================================> --- linux.orig/kernel/trace/ftrace.c 2008-12-23 13:11:28.000000000 +0800
> +++ linux/kernel/trace/ftrace.c 2008-12-23 13:24:59.000000000 +0800
> @@ -263,14 +263,6 @@ static void ftrace_update_pid_func(void)
> # error Dynamic ftrace depends on MCOUNT_RECORD
> #endif
>
> -/*
> - * Since MCOUNT_ADDR may point to mcount itself, we do not want
> - * to get it confused by reading a reference in the code as we
> - * are parsing on objcopy output of text. Use a variable for
> - * it instead.
> - */
> -static unsigned long mcount_addr = MCOUNT_ADDR;
> -
> enum {
> FTRACE_ENABLE_CALLS = (1 << 0),
> FTRACE_DISABLE_CALLS = (1 << 1),
> @@ -575,7 +567,7 @@ ftrace_code_disable(struct module *mod,
>
> ip = rec->ip;
>
> - ret = ftrace_make_nop(mod, rec, mcount_addr);
> + ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
This change will make dynamic ftrace fail on other archs (ppc and x86).
Please read the comment you deleted. By using MCOUNT_ADDR directly in
the code, you will create a reference to mcount in a text section that
will confuse recordmcount.pl. It will think this reference is a call to
mcount and when it tries to modify it, it will fail because the code is
not a call.
-- Steve
> if (ret) {
> ftrace_bug(ret, ip);
> rec->flags |= FTRACE_FL_FAILED;
> Index: linux/scripts/recordmcount.pl
> =================================> --- linux.orig/scripts/recordmcount.pl 2008-12-23 13:24:38.000000000 +0800
> +++ linux/scripts/recordmcount.pl 2008-12-23 13:24:59.000000000 +0800
> @@ -109,6 +109,11 @@ if ($#ARGV < 7) {
> my ($arch, $bits, $objdump, $objcopy, $cc,
> $ld, $nm, $rm, $mv, $is_module, $inputfile) = @ARGV;
>
> +# This file refers to mcount and shouldn't be ftraced, so lets' ignore it
> +if ($inputfile eq "kernel/trace/ftrace.o") {
> + exit(0);
> +}
> +
> # Acceptable sections to record.
> my %text_sections = (
> ".text" => 1,
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH 3/5]explictly ignore a file in recordmcount.pl
2008-12-23 6:08 [PATCH 3/5]explictly ignore a file in recordmcount.pl Shaohua Li
2008-12-23 14:22 ` Steven Rostedt
@ 2008-12-24 0:43 ` Shaohua Li
2008-12-24 0:48 ` Steven Rostedt
2 siblings, 0 replies; 4+ messages in thread
From: Shaohua Li @ 2008-12-24 0:43 UTC (permalink / raw)
To: linux-ia64
On Tue, Dec 23, 2008 at 10:22:04PM +0800, Steven Rostedt wrote:
>
> On Tue, 2008-12-23 at 14:08 +0800, Shaohua Li wrote:
> > In IA64, a function pointer isn't a 'unsigned long' but a
> > 'struct {unsigned long ip, unsigned long gp}'. MCOUNT_ADDR is determined
> > at link time not compile time, so explictly ignore kernel/trace/ftrace.o
> > in recordmcount.pl.
> >
> > Signed-off-by: Shaohua Li <shaohua.li@intel.com>
> > ---
> > kernel/trace/ftrace.c | 10 +---------
> > scripts/recordmcount.pl | 5 +++++
> > 2 files changed, 6 insertions(+), 9 deletions(-)
> >
> > Index: linux/kernel/trace/ftrace.c
> > =================================> > --- linux.orig/kernel/trace/ftrace.c 2008-12-23 13:11:28.000000000 +0800
> > +++ linux/kernel/trace/ftrace.c 2008-12-23 13:24:59.000000000 +0800
> > @@ -263,14 +263,6 @@ static void ftrace_update_pid_func(void)
> > # error Dynamic ftrace depends on MCOUNT_RECORD
> > #endif
> >
> > -/*
> > - * Since MCOUNT_ADDR may point to mcount itself, we do not want
> > - * to get it confused by reading a reference in the code as we
> > - * are parsing on objcopy output of text. Use a variable for
> > - * it instead.
> > - */
> > -static unsigned long mcount_addr = MCOUNT_ADDR;
> > -
> > enum {
> > FTRACE_ENABLE_CALLS = (1 << 0),
> > FTRACE_DISABLE_CALLS = (1 << 1),
> > @@ -575,7 +567,7 @@ ftrace_code_disable(struct module *mod,
> >
> > ip = rec->ip;
> >
> > - ret = ftrace_make_nop(mod, rec, mcount_addr);
> > + ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
>
> This change will make dynamic ftrace fail on other archs (ppc and x86).
> Please read the comment you deleted. By using MCOUNT_ADDR directly in
> the code, you will create a reference to mcount in a text section that
> will confuse recordmcount.pl. It will think this reference is a call to
> mcount and when it tries to modify it, it will fail because the code is
> not a call.
Did you read the changes just at the bottom? I explictly ignored
kernel/trace/ftrace.o in recordmcount.pl.
Thanks,
Shaohua
>
> > if (ret) {
> > ftrace_bug(ret, ip);
> > rec->flags |= FTRACE_FL_FAILED;
> > Index: linux/scripts/recordmcount.pl
> > =================================> > --- linux.orig/scripts/recordmcount.pl 2008-12-23 13:24:38.000000000 +0800
> > +++ linux/scripts/recordmcount.pl 2008-12-23 13:24:59.000000000 +0800
> > @@ -109,6 +109,11 @@ if ($#ARGV < 7) {
> > my ($arch, $bits, $objdump, $objcopy, $cc,
> > $ld, $nm, $rm, $mv, $is_module, $inputfile) = @ARGV;
> >
> > +# This file refers to mcount and shouldn't be ftraced, so lets' ignore it
> > +if ($inputfile eq "kernel/trace/ftrace.o") {
> > + exit(0);
> > +}
> > +
> > # Acceptable sections to record.
> > my %text_sections = (
> > ".text" => 1,
> >
> >
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH 3/5]explictly ignore a file in recordmcount.pl
2008-12-23 6:08 [PATCH 3/5]explictly ignore a file in recordmcount.pl Shaohua Li
2008-12-23 14:22 ` Steven Rostedt
2008-12-24 0:43 ` Shaohua Li
@ 2008-12-24 0:48 ` Steven Rostedt
2 siblings, 0 replies; 4+ messages in thread
From: Steven Rostedt @ 2008-12-24 0:48 UTC (permalink / raw)
To: linux-ia64
On Wed, 2008-12-24 at 08:43 +0800, Shaohua Li wrote:
> On Tue, Dec 23, 2008 at 10:22:04PM +0800, Steven Rostedt wrote:
> >
> > On Tue, 2008-12-23 at 14:08 +0800, Shaohua Li wrote:
> > > In IA64, a function pointer isn't a 'unsigned long' but a
> > > 'struct {unsigned long ip, unsigned long gp}'. MCOUNT_ADDR is determined
> > > at link time not compile time, so explictly ignore kernel/trace/ftrace.o
> > > in recordmcount.pl.
> > >
> > > Signed-off-by: Shaohua Li <shaohua.li@intel.com>
> > > ---
> > > kernel/trace/ftrace.c | 10 +---------
> > > scripts/recordmcount.pl | 5 +++++
> > > 2 files changed, 6 insertions(+), 9 deletions(-)
> > >
> > > Index: linux/kernel/trace/ftrace.c
> > > =================================> > > --- linux.orig/kernel/trace/ftrace.c 2008-12-23 13:11:28.000000000 +0800
> > > +++ linux/kernel/trace/ftrace.c 2008-12-23 13:24:59.000000000 +0800
> > > @@ -263,14 +263,6 @@ static void ftrace_update_pid_func(void)
> > > # error Dynamic ftrace depends on MCOUNT_RECORD
> > > #endif
> > >
> > > -/*
> > > - * Since MCOUNT_ADDR may point to mcount itself, we do not want
> > > - * to get it confused by reading a reference in the code as we
> > > - * are parsing on objcopy output of text. Use a variable for
> > > - * it instead.
> > > - */
> > > -static unsigned long mcount_addr = MCOUNT_ADDR;
> > > -
> > > enum {
> > > FTRACE_ENABLE_CALLS = (1 << 0),
> > > FTRACE_DISABLE_CALLS = (1 << 1),
> > > @@ -575,7 +567,7 @@ ftrace_code_disable(struct module *mod,
> > >
> > > ip = rec->ip;
> > >
> > > - ret = ftrace_make_nop(mod, rec, mcount_addr);
> > > + ret = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
> >
> > This change will make dynamic ftrace fail on other archs (ppc and x86).
> > Please read the comment you deleted. By using MCOUNT_ADDR directly in
> > the code, you will create a reference to mcount in a text section that
> > will confuse recordmcount.pl. It will think this reference is a call to
> > mcount and when it tries to modify it, it will fail because the code is
> > not a call.
> Did you read the changes just at the bottom? I explictly ignored
> kernel/trace/ftrace.o in recordmcount.pl.
>
> Thanks,
> Shaohua
>
> >
> > > if (ret) {
> > > ftrace_bug(ret, ip);
> > > rec->flags |= FTRACE_FL_FAILED;
> > > Index: linux/scripts/recordmcount.pl
> > > =================================> > > --- linux.orig/scripts/recordmcount.pl 2008-12-23 13:24:38.000000000 +0800
> > > +++ linux/scripts/recordmcount.pl 2008-12-23 13:24:59.000000000 +0800
> > > @@ -109,6 +109,11 @@ if ($#ARGV < 7) {
> > > my ($arch, $bits, $objdump, $objcopy, $cc,
> > > $ld, $nm, $rm, $mv, $is_module, $inputfile) = @ARGV;
> > >
> > > +# This file refers to mcount and shouldn't be ftraced, so lets' ignore it
> > > +if ($inputfile eq "kernel/trace/ftrace.o") {
> > > + exit(0);
> > > +}
> > > +
I did see this before, just forgot about it ;-)
Well, fine then, but it is getting a bit more fragile than I would like.
-- Steve
> > > # Acceptable sections to record.
> > > my %text_sections = (
> > > ".text" => 1,
> > >
> > >
> >
^ permalink raw reply [flat|nested] 4+ messages in thread