[PATCH 1/3] stackleak: mark stackleak_track_stack() as notrace

[PATCH 1/3] stackleak: mark stackleak_track_stack() as notrace

[Anders Roxell]

Function graph tracing recurses into itself when stackleak is enabled,
causing the ftrace graph selftest to run for up to 90 seconds and
trigger the softlockup watchdog.

Breakpoint 2, ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:200
200             mcount_get_lr_addr        x0    //     pointer to function's saved lr
(gdb) bt
\#0  ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:200
\#1  0xffffff80081d5280 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:153
\#2  0xffffff8008555484 in stackleak_track_stack () at ../kernel/stackleak.c:106
\#3  0xffffff8008421ff8 in ftrace_ops_test (ops=0xffffff8009eaa840 <graph_ops>, ip=18446743524091297036, regs=<optimized out>) at ../kernel/trace/ftrace.c:1507
\#4  0xffffff8008428770 in __ftrace_ops_list_func (regs=<optimized out>, ignored=<optimized out>, parent_ip=<optimized out>, ip=<optimized out>) at ../kernel/trace/ftrace.c:6286
\#5  ftrace_ops_no_ops (ip=18446743524091297036, parent_ip=18446743524091242824) at ../kernel/trace/ftrace.c:6321
\#6  0xffffff80081d5280 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:153
\#7  0xffffff800832fd10 in irq_find_mapping (domain=0xffffffc03fc4bc80, hwirq=27) at ../kernel/irq/irqdomain.c:876
\#8  0xffffff800832294c in __handle_domain_irq (domain=0xffffffc03fc4bc80, hwirq=27, lookup=true, regs=0xffffff800814b840) at ../kernel/irq/irqdesc.c:650
\#9  0xffffff80081d52b4 in ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:205

Rework so we mark stackleak_track_stack as notrace

Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 kernel/stackleak.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/stackleak.c b/kernel/stackleak.c
index e42892926244..5de3bf596dd7 100644
--- a/kernel/stackleak.c
+++ b/kernel/stackleak.c
@@ -102,7 +102,7 @@ asmlinkage void stackleak_erase(void)
 	current->lowest_stack = current_top_of_stack() - THREAD_SIZE/64;
 }
 
-void __used stackleak_track_stack(void)
+void __used notrace stackleak_track_stack(void)
 {
 	/*
 	 * N.B. stackleak_erase() fills the kernel stack with the poison value,
-- 
2.19.2

Re: [PATCH 1/3] stackleak: mark stackleak_track_stack() as notrace

[Steven Rostedt]

On Fri, 30 Nov 2018 16:08:59 +0100
Anders Roxell <anders.roxell@linaro.org> wrote:

> Function graph tracing recurses into itself when stackleak is enabled,
> causing the ftrace graph selftest to run for up to 90 seconds and
> trigger the softlockup watchdog.
> 
> Breakpoint 2, ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:200
> 200             mcount_get_lr_addr        x0    //     pointer to function's saved lr
> (gdb) bt
> \#0  ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:200
> \#1  0xffffff80081d5280 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:153
> \#2  0xffffff8008555484 in stackleak_track_stack () at ../kernel/stackleak.c:106
> \#3  0xffffff8008421ff8 in ftrace_ops_test (ops=0xffffff8009eaa840 <graph_ops>, ip=18446743524091297036, regs=<optimized out>) at ../kernel/trace/ftrace.c:1507
> \#4  0xffffff8008428770 in __ftrace_ops_list_func (regs=<optimized out>, ignored=<optimized out>, parent_ip=<optimized out>, ip=<optimized out>) at ../kernel/trace/ftrace.c:6286
> \#5  ftrace_ops_no_ops (ip=18446743524091297036, parent_ip=18446743524091242824) at ../kernel/trace/ftrace.c:6321
> \#6  0xffffff80081d5280 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:153
> \#7  0xffffff800832fd10 in irq_find_mapping (domain=0xffffffc03fc4bc80, hwirq=27) at ../kernel/irq/irqdomain.c:876
> \#8  0xffffff800832294c in __handle_domain_irq (domain=0xffffffc03fc4bc80, hwirq=27, lookup=true, regs=0xffffff800814b840) at ../kernel/irq/irqdesc.c:650
> \#9  0xffffff80081d52b4 in ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:205
> 
> Rework so we mark stackleak_track_stack as notrace
> 
> Co-developed-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

-- Steve

> ---
>  kernel/stackleak.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/stackleak.c b/kernel/stackleak.c
> index e42892926244..5de3bf596dd7 100644
> --- a/kernel/stackleak.c
> +++ b/kernel/stackleak.c
> @@ -102,7 +102,7 @@ asmlinkage void stackleak_erase(void)
>  	current->lowest_stack = current_top_of_stack() - THREAD_SIZE/64;
>  }
>  
> -void __used stackleak_track_stack(void)
> +void __used notrace stackleak_track_stack(void)
>  {
>  	/*
>  	 * N.B. stackleak_erase() fills the kernel stack with the poison value,

Re: [PATCH 1/3] stackleak: mark stackleak_track_stack() as notrace

[Kees Cook]

On Fri, Nov 30, 2018 at 7:09 AM Anders Roxell <anders.roxell@linaro.org> wrote:
>
> Function graph tracing recurses into itself when stackleak is enabled,
> causing the ftrace graph selftest to run for up to 90 seconds and
> trigger the softlockup watchdog.
>
> Breakpoint 2, ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:200
> 200             mcount_get_lr_addr        x0    //     pointer to function's saved lr
> (gdb) bt
> \#0  ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:200
> \#1  0xffffff80081d5280 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:153
> \#2  0xffffff8008555484 in stackleak_track_stack () at ../kernel/stackleak.c:106
> \#3  0xffffff8008421ff8 in ftrace_ops_test (ops=0xffffff8009eaa840 <graph_ops>, ip=18446743524091297036, regs=<optimized out>) at ../kernel/trace/ftrace.c:1507
> \#4  0xffffff8008428770 in __ftrace_ops_list_func (regs=<optimized out>, ignored=<optimized out>, parent_ip=<optimized out>, ip=<optimized out>) at ../kernel/trace/ftrace.c:6286
> \#5  ftrace_ops_no_ops (ip=18446743524091297036, parent_ip=18446743524091242824) at ../kernel/trace/ftrace.c:6321
> \#6  0xffffff80081d5280 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:153
> \#7  0xffffff800832fd10 in irq_find_mapping (domain=0xffffffc03fc4bc80, hwirq=27) at ../kernel/irq/irqdomain.c:876
> \#8  0xffffff800832294c in __handle_domain_irq (domain=0xffffffc03fc4bc80, hwirq=27, lookup=true, regs=0xffffff800814b840) at ../kernel/irq/irqdesc.c:650
> \#9  0xffffff80081d52b4 in ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:205
>
> Rework so we mark stackleak_track_stack as notrace
>
> Co-developed-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
> ---
>  kernel/stackleak.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/stackleak.c b/kernel/stackleak.c
> index e42892926244..5de3bf596dd7 100644
> --- a/kernel/stackleak.c
> +++ b/kernel/stackleak.c
> @@ -102,7 +102,7 @@ asmlinkage void stackleak_erase(void)
>         current->lowest_stack = current_top_of_stack() - THREAD_SIZE/64;
>  }
>
> -void __used stackleak_track_stack(void)
> +void __used notrace stackleak_track_stack(void)
>  {
>         /*
>          * N.B. stackleak_erase() fills the kernel stack with the poison value,
> --
> 2.19.2
>

Acked-by: Kees Cook <keescook@chromium.org>

Steven, I assume this series going via your tree?

-- 
Kees Cook

Re: [PATCH 1/3] stackleak: mark stackleak_track_stack() as notrace

[Steven Rostedt]

On Wed, 5 Dec 2018 17:08:34 -0800
Kees Cook <keescook@chromium.org> wrote:

> > diff --git a/kernel/stackleak.c b/kernel/stackleak.c
> > index e42892926244..5de3bf596dd7 100644
> > --- a/kernel/stackleak.c
> > +++ b/kernel/stackleak.c
> > @@ -102,7 +102,7 @@ asmlinkage void stackleak_erase(void)
> >         current->lowest_stack = current_top_of_stack() - THREAD_SIZE/64;
> >  }
> >
> > -void __used stackleak_track_stack(void)
> > +void __used notrace stackleak_track_stack(void)
> >  {
> >         /*
> >          * N.B. stackleak_erase() fills the kernel stack with the poison value,
> > --
> > 2.19.2
> >  
> 
> Acked-by: Kees Cook <keescook@chromium.org>
> 
> Steven, I assume this series going via your tree?

??

A notrace addition doesn't make it mine.

I added changes for the cond_resched in a different patch series that
I'll pull in (they are independent from this). I'll Ack the Makefile
change in the tracing directory, but the rest belongs to others.

-- Steve

Re: [PATCH 1/3] stackleak: mark stackleak_track_stack() as notrace

[Steven Rostedt]

On Wed, 5 Dec 2018 21:26:51 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Wed, 5 Dec 2018 17:08:34 -0800
> Kees Cook <keescook@chromium.org> wrote:
> 

> I'll Ack the Makefile
> change in the tracing directory, but the rest belongs to others.
> 

I see I already acked that patch. BTW, when sending a patch series, you
really need a 0/3 patch as a header and the rest be threaded. I had a
hard time finding that patch in the sea of my INBOX.

If I was the one to pull it in, I wouldn't do it if the series was
unthreaded like this.

-- Steve

Re: [PATCH 1/3] stackleak: mark stackleak_track_stack() as notrace

[Kees Cook]

On Wed, Dec 5, 2018 at 6:29 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Wed, 5 Dec 2018 21:26:51 -0500
> Steven Rostedt <rostedt@goodmis.org> wrote:
>
> > On Wed, 5 Dec 2018 17:08:34 -0800
> > Kees Cook <keescook@chromium.org> wrote:
> >
>
> > I'll Ack the Makefile
> > change in the tracing directory, but the rest belongs to others.

Okay, I wasn't sure. Anders's patch was marked "1/3" so I thought it
was directed at you. :)

I'll grab this one in the gcc-plugins tree.

-Kees

-- 
Kees Cook

Re: [PATCH 1/3] stackleak: mark stackleak_track_stack() as notrace

[Steven Rostedt]

On Wed, 5 Dec 2018 19:29:11 -0800
Kees Cook <keescook@chromium.org> wrote:

> On Wed, Dec 5, 2018 at 6:29 PM Steven Rostedt <rostedt@goodmis.org> wrote:
> >
> > On Wed, 5 Dec 2018 21:26:51 -0500
> > Steven Rostedt <rostedt@goodmis.org> wrote:
> >  
> > > On Wed, 5 Dec 2018 17:08:34 -0800
> > > Kees Cook <keescook@chromium.org> wrote:
> > >  
> >  
> > > I'll Ack the Makefile
> > > change in the tracing directory, but the rest belongs to others.  
> 
> Okay, I wasn't sure. Anders's patch was marked "1/3" so I thought it
> was directed at you. :)
> 
> I'll grab this one in the gcc-plugins tree.

Should I just take patch 2 then? I'm thinking it's independent too.

I'm collecting patches for the next merge window right now so it wont
really be an issue if I do.

-- Steve

Re: [PATCH 1/3] stackleak: mark stackleak_track_stack() as notrace

[Kees Cook]

On Wed, Dec 5, 2018 at 7:43 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Wed, 5 Dec 2018 19:29:11 -0800
> Kees Cook <keescook@chromium.org> wrote:
>
> > On Wed, Dec 5, 2018 at 6:29 PM Steven Rostedt <rostedt@goodmis.org> wrote:
> > >
> > > On Wed, 5 Dec 2018 21:26:51 -0500
> > > Steven Rostedt <rostedt@goodmis.org> wrote:
> > >
> > > > On Wed, 5 Dec 2018 17:08:34 -0800
> > > > Kees Cook <keescook@chromium.org> wrote:
> > > >
> > >
> > > > I'll Ack the Makefile
> > > > change in the tracing directory, but the rest belongs to others.
> >
> > Okay, I wasn't sure. Anders's patch was marked "1/3" so I thought it
> > was directed at you. :)
> >
> > I'll grab this one in the gcc-plugins tree.
>
> Should I just take patch 2 then? I'm thinking it's independent too.
>
> I'm collecting patches for the next merge window right now so it wont
> really be an issue if I do.

Sure! I'm not sure what Anders's intention was, but yeah. :)

-- 
Kees Cook