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Commit 9c0729dc authored by Soeren Sandmann Pedersen's avatar Soeren Sandmann Pedersen Committed by Frederic Weisbecker
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x86: Eliminate bp argument from the stack tracing routines 



The various stack tracing routines take a 'bp' argument in which the
caller is supposed to provide the base pointer to use, or 0 if doesn't
have one. Since bp is garbage whenever CONFIG_FRAME_POINTER is not
defined, this means all callers in principle should either always pass
0, or be conditional on CONFIG_FRAME_POINTER.

However, there are only really three use cases for stack tracing:

(a) Trace the current task, including IRQ stack if any
(b) Trace the current task, but skip IRQ stack
(c) Trace some other task

In all cases, if CONFIG_FRAME_POINTER is not defined, bp should just
be 0.  If it _is_ defined, then

- in case (a) bp should be gotten directly from the CPU's register, so
  the caller should pass NULL for regs,

- in case (b) the caller should should pass the IRQ registers to
  dump_trace(),

- in case (c) bp should be gotten from the top of the task's stack, so
  the caller should pass NULL for regs.

Hence, the bp argument is not necessary because the combination of
task and regs is sufficient to determine an appropriate value for bp.

This patch introduces a new inline function stack_frame(task, regs)
that computes the desired bp. This function is then called from the
two versions of dump_stack().

Signed-off-by: default avatarSoren Sandmann <ssp@redhat.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arjan van de Ven <arjan@infradead.org>,
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>,
LKML-Reference: <m3oc9rop28.fsf@dhcp-100-3-82.bos.redhat.com>>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent 3985c7ce

arch/x86/include/asm/kdebug.h

+1 −1
Original line number Diff line number Diff line
@@ -28,7 +28,7 @@ extern void die(const char *, struct pt_regs *,long); 
extern int __must_check __die(const char *, struct pt_regs *, long);

extern void show_registers(struct pt_regs *regs);

extern void show_trace(struct task_struct *t, struct pt_regs *regs,

		       unsigned long *sp, unsigned long bp);

		       unsigned long *sp);

extern void __show_regs(struct pt_regs *regs, int all);

extern void show_regs(struct pt_regs *regs);

extern unsigned long oops_begin(void);

arch/x86/include/asm/stacktrace.h

+30 −3
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#define _ASM_X86_STACKTRACE_H



#include <linux/uaccess.h>

#include <linux/ptrace.h>



extern int kstack_depth_to_print;
@@ -46,7 +47,7 @@ struct stacktrace_ops { 
};



void dump_trace(struct task_struct *tsk, struct pt_regs *regs,

		unsigned long *stack, unsigned long bp,

		unsigned long *stack,

		const struct stacktrace_ops *ops, void *data);



#ifdef CONFIG_X86_32
@@ -57,13 +58,39 @@ void dump_trace(struct task_struct *tsk, struct pt_regs *regs, 
#define get_bp(bp) asm("movq %%rbp, %0" : "=r" (bp) :)

#endif



#ifdef CONFIG_FRAME_POINTER

static inline unsigned long

stack_frame(struct task_struct *task, struct pt_regs *regs)

{

	unsigned long bp;



	if (regs)

		return regs->bp;



	if (task == current) {

		/* Grab bp right from our regs */

		get_bp(bp);

		return bp;

	}



	/* bp is the last reg pushed by switch_to */

	return *(unsigned long *)task->thread.sp;

}

#else

static inline unsigned long

stack_frame(struct task_struct *task, struct pt_regs *regs)

{

	return 0;

}

#endif



extern void

show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,

		unsigned long *stack, unsigned long bp, char *log_lvl);

		   unsigned long *stack, char *log_lvl);



extern void

show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,

		unsigned long *sp, unsigned long bp, char *log_lvl);

		   unsigned long *sp, char *log_lvl);



extern unsigned int code_bytes;

arch/x86/kernel/cpu/perf_event.c

+1 −1
Original line number Diff line number Diff line
@@ -1666,7 +1666,7 @@ perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs) 


	perf_callchain_store(entry, regs->ip);



	dump_trace(NULL, regs, NULL, regs->bp, &backtrace_ops, entry);

	dump_trace(NULL, regs, NULL, &backtrace_ops, entry);

}



#ifdef CONFIG_COMPAT

arch/x86/kernel/dumpstack.c

+6 −6
Original line number Diff line number Diff line
@@ -175,21 +175,21 @@ static const struct stacktrace_ops print_trace_ops = { 


void

show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,

		unsigned long *stack, unsigned long bp, char *log_lvl)

		unsigned long *stack, char *log_lvl)

{

	printk("%sCall Trace:\n", log_lvl);

	dump_trace(task, regs, stack, bp, &print_trace_ops, log_lvl);

	dump_trace(task, regs, stack, &print_trace_ops, log_lvl);

}



void show_trace(struct task_struct *task, struct pt_regs *regs,

		unsigned long *stack, unsigned long bp)

		unsigned long *stack)

{

	show_trace_log_lvl(task, regs, stack, bp, "");

	show_trace_log_lvl(task, regs, stack, "");

}



void show_stack(struct task_struct *task, unsigned long *sp)

{

	show_stack_log_lvl(task, NULL, sp, 0, "");

	show_stack_log_lvl(task, NULL, sp, "");

}



/*
@@ -210,7 +210,7 @@ void dump_stack(void) 
		init_utsname()->release,

		(int)strcspn(init_utsname()->version, " "),

		init_utsname()->version);

	show_trace(NULL, NULL, &stack, bp);

	show_trace(NULL, NULL, &stack);

}

EXPORT_SYMBOL(dump_stack);

arch/x86/kernel/dumpstack_32.c

+7 −18
Original line number Diff line number Diff line
@@ -17,11 +17,12 @@ 
#include <asm/stacktrace.h>





void dump_trace(struct task_struct *task, struct pt_regs *regs,

		unsigned long *stack, unsigned long bp,

void dump_trace(struct task_struct *task,

		struct pt_regs *regs, unsigned long *stack,

		const struct stacktrace_ops *ops, void *data)

{

	int graph = 0;

	unsigned long bp;



	if (!task)

		task = current;
@@ -34,18 +35,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs, 
			stack = (unsigned long *)task->thread.sp;

	}



#ifdef CONFIG_FRAME_POINTER

	if (!bp) {

		if (task == current) {

			/* Grab bp right from our regs */

			get_bp(bp);

		} else {

			/* bp is the last reg pushed by switch_to */

			bp = *(unsigned long *) task->thread.sp;

		}

	}

#endif



	bp = stack_frame(task, regs);

	for (;;) {

		struct thread_info *context;
@@ -65,7 +55,7 @@ EXPORT_SYMBOL(dump_trace); 


void

show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,

		   unsigned long *sp, unsigned long bp, char *log_lvl)

		   unsigned long *sp, char *log_lvl)

{

	unsigned long *stack;

	int i;
@@ -87,7 +77,7 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs, 
		touch_nmi_watchdog();

	}

	printk(KERN_CONT "\n");

	show_trace_log_lvl(task, regs, sp, bp, log_lvl);

	show_trace_log_lvl(task, regs, sp, log_lvl);

}
@@ -112,8 +102,7 @@ void show_registers(struct pt_regs *regs) 
		u8 *ip;



		printk(KERN_EMERG "Stack:\n");

		show_stack_log_lvl(NULL, regs, &regs->sp,

				0, KERN_EMERG);

		show_stack_log_lvl(NULL, regs, &regs->sp, KERN_EMERG);



		printk(KERN_EMERG "Code: ");