From: nikolay.borisov@arm•com (Nikolay Borisov)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH RESEND 1/7] ARM: Make thread_save_fp macro aware of THUMB2 mode
Date: Fri, 23 May 2014 12:53:43 +0100 [thread overview]
Message-ID: <000001cf767d$a5dd3140$f19793c0$@borisov@arm.com> (raw)
In-Reply-To: <20140523095356.GH20155@pengutronix.de>
> -----Original Message-----
> From: linux-arm-kernel [mailto:linux-arm-kernel-
> bounces at lists.infradead.org] On Behalf Of Uwe Kleine-K?nig
> Sent: 23 May 2014 10:54
> To: Nikolay Borisov
> Cc: rric at kernel.org; a.p.zijlstra at chello.nl; jld at mozilla.com;
> sboyd at codeaurora.org; Will Deacon; dave.long at linaro.org; Dave P Martin;
> linux-arm-kernel at lists.infradead.org
> Subject: Re: [PATCH RESEND 1/7] ARM: Make thread_save_fp macro aware of
> THUMB2 mode
>
> Hello,
>
> On Fri, May 23, 2014 at 10:26:30AM +0100, Nikolay Borisov wrote:
> > The thread_save_fp macro has been defined so that it always reads the
> fp member
> > of the cpu_context_save struct. However, in the case of THUMB2 the fp
> is saved
> > not in the fp (r11) member but rather in r7.
> >
> > This patch changes the way the macro is defined such that FP is read
> from the
> > correct place depending on whether we are a THUMB2 kernel or not.
> This enables
> > the backtrace in sitaution such as "echo t > /proc/sysrq-trigger" or
> the
> > function in which a process sleeping when "ps -Al" is invoked.
> >
> > Signed-off-by: Nikolay Borisov <Nikolay.Borisov@arm•com>
> > Reviewed-by: Anurag Aggarwal <anurag19aggarwal@gmail•com>
> > ---
> > arch/arm/include/asm/thread_info.h | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/arch/arm/include/asm/thread_info.h
> b/arch/arm/include/asm/thread_info.h
> > index f989d7c..e4e4208 100644
> > --- a/arch/arm/include/asm/thread_info.h
> > +++ b/arch/arm/include/asm/thread_info.h
> > @@ -114,8 +114,14 @@ static inline struct thread_info
> *current_thread_info(void)
> > ((unsigned long)(task_thread_info(tsk)->cpu_context.pc))
> > #define thread_saved_sp(tsk) \
> > ((unsigned long)(task_thread_info(tsk)->cpu_context.sp))
> > +
> > +#ifndef CONFIG_THUMB2_KERNEL
> > #define thread_saved_fp(tsk) \
> > ((unsigned long)(task_thread_info(tsk)->cpu_context.fp))
> > +#else
> > +#define thread_saved_fp(tsk) \
> > + ((unsigned long)(task_thread_info(tsk)->cpu_context.r7))
> > +#endif
> A comment would be nice here describing that it's gcc who forces this
> on
> us. Did you test if the same happens with clang?
>
Just checked with one of the LLVM compiler engineers and he said that
LLVM also conforms to this behaviour e.g. R7 is used as a frame pointer
in THUMB2 mode. In addition to that, mainline doesn't compile with LLVM
(yet).
> Uwe
>
Regards,
Nikolay
> --
> Pengutronix e.K. | Uwe Kleine-K?nig
> |
> Industrial Linux Solutions | http://www.pengutronix.de/
> |
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2014-05-23 11:53 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-23 9:26 [PATCH RESEND 0/7] Fix backtrace support in THUMB2 mode Nikolay Borisov
2014-05-23 9:26 ` [PATCH RESEND 1/7] ARM: Make thread_save_fp macro aware of " Nikolay Borisov
2014-05-23 9:53 ` Uwe Kleine-König
2014-05-23 11:53 ` Nikolay Borisov [this message]
2014-05-23 9:26 ` [PATCH RESEND 2/7] ARM: Introduce arm_get_current_stack_frame() Nikolay Borisov
2014-05-23 12:11 ` Robert Richter
2014-05-23 9:26 ` [PATCH RESEND 3/7] ARM: perf: Make perf use arm_get_current_stackframe Nikolay Borisov
2014-05-23 9:26 ` [PATCH RESEND 4/7] ARM: time: Make use of arm_get_current_stackframe Nikolay Borisov
2014-05-23 9:26 ` [PATCH RESEND 5/7] ARM: unwind: Use arm_get_current_stackframe Nikolay Borisov
2014-05-23 9:26 ` [PATCH RESEND 6/7] ARM: traps: Make use of the frame_pointer macro Nikolay Borisov
2014-05-23 9:26 ` [PATCH RESEND 7/7] ARM: oprofile: Use of arm_get_current_stackframe Nikolay Borisov
2014-05-23 16:55 ` [PATCH RESEND 0/7] Fix backtrace support in THUMB2 mode Will Deacon
2014-06-17 14:49 ` Russell King - ARM Linux
2014-06-17 15:12 ` Nikolay Borisov
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