Commit ce3266c0 authored by Steven J. Magnani's avatar Steven J. Magnani Committed by Michal Simek
Browse files

microblaze: Add stack unwinder 



Implement intelligent backtracing by searching for stack frame creation,
and emitting only return addresses. Use print_hex_dump() to display the
entire binary kernel stack.

Limitation: MMU kernels are not currently able to trace beyond a system trap
(interrupt, syscall, etc.). It is the intent of this patch to provide
infrastructure that can be extended to add this capability later.

Changes from V1:
* Removed checks in find_frame_creation() that prevented location of the frame
  creation instruction in heavily optimized code
* Various formatting/commenting/file location tweaks per review comments
* Dropped Kconfig option to enable STACKTRACE as something logically separate

Signed-off-by: default avatarSteven J. Magnani <steve@digidescorp.com>
parent ba9c4f88

arch/microblaze/include/asm/exceptions.h

+5 −0
Original line number Diff line number Diff line
@@ -14,6 +14,11 @@ 
#define _ASM_MICROBLAZE_EXCEPTIONS_H



#ifdef __KERNEL__



#ifndef CONFIG_MMU

#define EX_HANDLER_STACK_SIZ	(4*19)

#endif



#ifndef __ASSEMBLY__



/* Macros to enable and disable HW exceptions in the MSR */

arch/microblaze/include/asm/system.h

+0 −1
Original line number Diff line number Diff line
@@ -45,7 +45,6 @@ extern struct task_struct *_switch_to(struct thread_info *prev, 
#define smp_rmb()		rmb()

#define smp_wmb()		wmb()



void show_trace(struct task_struct *task, unsigned long *stack);

void __bad_xchg(volatile void *ptr, int size);



static inline unsigned long __xchg(unsigned long x, volatile void *ptr,

arch/microblaze/include/asm/unwind.h

0 → 100644
+29 −0
Original line number Diff line number Diff line 
/*

 * Backtrace support for Microblaze

 *

 * Copyright (C) 2010  Digital Design Corporation

 *

 * This file is subject to the terms and conditions of the GNU General Public

 * License.  See the file "COPYING" in the main directory of this archive

 * for more details.

 */



#ifndef __MICROBLAZE_UNWIND_H

#define __MICROBLAZE_UNWIND_H



struct stack_trace;



struct trap_handler_info {

	unsigned long start_addr;

	unsigned long end_addr;

	const char    *trap_name;

};

extern struct trap_handler_info microblaze_trap_handlers;



extern const char _hw_exception_handler;

extern const char ex_handler_unhandled;



void microblaze_unwind(struct task_struct *task, struct stack_trace *trace);



#endif	/* __MICROBLAZE_UNWIND_H */

arch/microblaze/kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -17,7 +17,7 @@ extra-y := head.o vmlinux.lds 
obj-y += dma.o exceptions.o \

	hw_exception_handler.o init_task.o intc.o irq.o of_device.o \

	of_platform.o process.o prom.o prom_parse.o ptrace.o \

	setup.o signal.o sys_microblaze.o timer.o traps.o reset.o

	reset.o setup.o signal.o sys_microblaze.o timer.o traps.o unwind.o



obj-y += cpu/

arch/microblaze/kernel/entry-nommu.S

+28 −0
Original line number Diff line number Diff line
@@ -588,3 +588,31 @@ sys_rt_sigsuspend_wrapper: 
#include "syscall_table.S"



syscall_table_size=(.-sys_call_table)



type_SYSCALL:

	.ascii "SYSCALL\0"

type_IRQ:

	.ascii "IRQ\0"

type_IRQ_PREEMPT:

	.ascii "IRQ (PREEMPTED)\0"

type_SYSCALL_PREEMPT:

	.ascii " SYSCALL (PREEMPTED)\0"



	/*

	 * Trap decoding for stack unwinder

	 * Tuples are (start addr, end addr, string)

	 * If return address lies on [start addr, end addr],

	 * unwinder displays 'string'

	 */



	.align 4

.global microblaze_trap_handlers

microblaze_trap_handlers:

	/* Exact matches come first */

	.word ret_to_user  ; .word ret_to_user    ; .word type_SYSCALL

	.word ret_from_intr; .word ret_from_intr  ; .word type_IRQ

	/* Fuzzy matches go here */

	.word ret_from_intr; .word no_intr_resched; .word type_IRQ_PREEMPT

	.word work_pending ; .word no_work_pending; .word type_SYSCALL_PREEMPT

	/* End of table */

	.word 0             ; .word 0               ; .word 0

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