From mboxrd@z Thu Jan 1 00:00:00 1970 From: nikolay.borisov@arm.com (Nikolay Borisov) Date: Tue, 6 May 2014 10:02:02 +0100 Subject: [PATCH v2] ARM: unwinder: Fix handling of 'fp' in thumb2 mode In-Reply-To: References: <1399045056-26751-1-git-send-email-Nikolay.Borisov@arm.com> Message-ID: <000101cf6909$d8bf46b0$8a3dd410$@borisov@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, > -----Original Message----- > From: Anurag Aggarwal [mailto:anurag19aggarwal at gmail.com] > Sent: 03 May 2014 07:57 > To: Nikolay Borisov > Cc: linux-arm-kernel at lists.infradead.org; Dave P Martin; Catalin > Marinas > Subject: Re: [PATCH v2] ARM: unwinder: Fix handling of 'fp' in thumb2 > mode > > Seems good. > > I would like to know what kind of testing you have done that for this, > Other than that you can add my review statement > Without this patch if you use the magic sysrq to print backtrace of all the running tasks in the system those that are sleeping would not print a backtrace. With the patch this works correctly. Another case where you can observe the change is in the invocation of the "ps -Al" which shows (among other things) which function the sleeping task is blocked in. > On Fri, May 2, 2014 at 9:07 PM, 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. > > > > Another place where similar change is requried is when working with > pt_reg. > > regs->ARM_fp is defined such that r11 is always referenced as the > frame pointer, > > so the definition of ARM_fp needs to change depending on the type of > kernel we > > are running. > > > > Changes since v1: > > * Added changes for the pt_reg structure. > > > > Signed-off-by: Nikolay Borisov > > Reviewed-by: Anurag Aggarwal > > > > > handle the case when we've got regs present > > --- > > arch/arm/include/asm/thread_info.h | 6 ++++++ > > arch/arm/include/uapi/asm/ptrace.h | 4 ++++ > > 2 files changed, 10 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 > > > > extern void crunch_task_disable(struct thread_info *); > > extern void crunch_task_copy(struct thread_info *, void *); > > diff --git a/arch/arm/include/uapi/asm/ptrace.h > b/arch/arm/include/uapi/asm/ptrace.h > > index 5af0ed1..92e1bae 100644 > > --- a/arch/arm/include/uapi/asm/ptrace.h > > +++ b/arch/arm/include/uapi/asm/ptrace.h > > @@ -131,7 +131,11 @@ struct pt_regs { > > #define ARM_lr uregs[14] > > #define ARM_sp uregs[13] > > #define ARM_ip uregs[12] > > +#ifndef CONFIG_THUMB2_KERNEL > > #define ARM_fp uregs[11] > > +#else > > +#define ARM_fp uregs[7] > > +#endif > > #define ARM_r10 uregs[10] > > #define ARM_r9 uregs[9] > > #define ARM_r8 uregs[8] > > -- > > 1.8.1.5 > > > >