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: Steven J. Magnani <steve@digidescorp.com>
This commit is contained in:
parent
ba9c4f88d7
commit
ce3266c047
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@ -14,6 +14,11 @@
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#define _ASM_MICROBLAZE_EXCEPTIONS_H
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#ifdef __KERNEL__
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#ifndef CONFIG_MMU
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#define EX_HANDLER_STACK_SIZ (4*19)
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#endif
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#ifndef __ASSEMBLY__
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/* Macros to enable and disable HW exceptions in the MSR */
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@ -45,7 +45,6 @@ extern struct task_struct *_switch_to(struct thread_info *prev,
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#define smp_rmb() rmb()
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#define smp_wmb() wmb()
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void show_trace(struct task_struct *task, unsigned long *stack);
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void __bad_xchg(volatile void *ptr, int size);
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static inline unsigned long __xchg(unsigned long x, volatile void *ptr,
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@ -0,0 +1,29 @@
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/*
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* Backtrace support for Microblaze
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*
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* Copyright (C) 2010 Digital Design Corporation
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#ifndef __MICROBLAZE_UNWIND_H
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#define __MICROBLAZE_UNWIND_H
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struct stack_trace;
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struct trap_handler_info {
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unsigned long start_addr;
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unsigned long end_addr;
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const char *trap_name;
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};
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extern struct trap_handler_info microblaze_trap_handlers;
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extern const char _hw_exception_handler;
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extern const char ex_handler_unhandled;
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void microblaze_unwind(struct task_struct *task, struct stack_trace *trace);
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#endif /* __MICROBLAZE_UNWIND_H */
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@ -17,7 +17,7 @@ extra-y := head.o vmlinux.lds
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obj-y += dma.o exceptions.o \
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hw_exception_handler.o init_task.o intc.o irq.o of_device.o \
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of_platform.o process.o prom.o prom_parse.o ptrace.o \
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setup.o signal.o sys_microblaze.o timer.o traps.o reset.o
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reset.o setup.o signal.o sys_microblaze.o timer.o traps.o unwind.o
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obj-y += cpu/
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@ -588,3 +588,31 @@ sys_rt_sigsuspend_wrapper:
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#include "syscall_table.S"
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syscall_table_size=(.-sys_call_table)
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type_SYSCALL:
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.ascii "SYSCALL\0"
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type_IRQ:
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.ascii "IRQ\0"
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type_IRQ_PREEMPT:
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.ascii "IRQ (PREEMPTED)\0"
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type_SYSCALL_PREEMPT:
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.ascii " SYSCALL (PREEMPTED)\0"
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/*
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* Trap decoding for stack unwinder
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* Tuples are (start addr, end addr, string)
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* If return address lies on [start addr, end addr],
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* unwinder displays 'string'
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*/
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.align 4
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.global microblaze_trap_handlers
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microblaze_trap_handlers:
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/* Exact matches come first */
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.word ret_to_user ; .word ret_to_user ; .word type_SYSCALL
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.word ret_from_intr; .word ret_from_intr ; .word type_IRQ
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/* Fuzzy matches go here */
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.word ret_from_intr; .word no_intr_resched; .word type_IRQ_PREEMPT
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.word work_pending ; .word no_work_pending; .word type_SYSCALL_PREEMPT
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/* End of table */
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.word 0 ; .word 0 ; .word 0
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@ -1127,3 +1127,30 @@ ENTRY(_break)
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syscall_table_size=(.-sys_call_table)
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type_SYSCALL:
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.ascii "SYSCALL\0"
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type_IRQ:
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.ascii "IRQ\0"
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type_IRQ_PREEMPT:
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.ascii "IRQ (PREEMPTED)\0"
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type_SYSCALL_PREEMPT:
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.ascii " SYSCALL (PREEMPTED)\0"
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/*
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* Trap decoding for stack unwinder
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* Tuples are (start addr, end addr, string)
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* If return address lies on [start addr, end addr],
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* unwinder displays 'string'
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*/
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.align 4
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.global microblaze_trap_handlers
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microblaze_trap_handlers:
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/* Exact matches come first */
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.word ret_from_trap; .word ret_from_trap ; .word type_SYSCALL
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.word ret_from_irq ; .word ret_from_irq ; .word type_IRQ
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/* Fuzzy matches go here */
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.word ret_from_irq ; .word no_intr_resched ; .word type_IRQ_PREEMPT
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.word ret_from_trap; .word TRAP_return ; .word type_SYSCALL_PREEMPT
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/* End of table */
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.word 0 ; .word 0 ; .word 0
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@ -78,9 +78,6 @@
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#include <asm/asm-offsets.h>
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/* Helpful Macros */
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#ifndef CONFIG_MMU
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#define EX_HANDLER_STACK_SIZ (4*19)
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#endif
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#define NUM_TO_REG(num) r ## num
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#ifdef CONFIG_MMU
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@ -988,6 +985,7 @@ ex_unaligned_fixup:
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.end _unaligned_data_exception
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#endif /* CONFIG_MMU */
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.global ex_handler_unhandled
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ex_handler_unhandled:
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/* FIXME add handle function for unhandled exception - dump register */
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bri 0
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@ -14,52 +14,18 @@
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#include <linux/thread_info.h>
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#include <linux/ptrace.h>
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#include <linux/module.h>
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#include <asm/unwind.h>
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/* FIXME initial support */
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void save_stack_trace(struct stack_trace *trace)
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{
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unsigned long *sp;
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unsigned long addr;
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asm("addik %0, r1, 0" : "=r" (sp));
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while (!kstack_end(sp)) {
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addr = *sp++;
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if (__kernel_text_address(addr)) {
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if (trace->skip > 0)
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trace->skip--;
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else
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trace->entries[trace->nr_entries++] = addr;
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if (trace->nr_entries >= trace->max_entries)
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break;
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}
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}
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/* Exclude our helper functions from the trace*/
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trace->skip += 2;
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microblaze_unwind(NULL, trace);
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}
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EXPORT_SYMBOL_GPL(save_stack_trace);
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void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
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{
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unsigned int *sp;
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unsigned long addr;
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struct thread_info *ti = task_thread_info(tsk);
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if (tsk == current)
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asm("addik %0, r1, 0" : "=r" (sp));
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else
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sp = (unsigned int *)ti->cpu_context.r1;
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while (!kstack_end(sp)) {
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addr = *sp++;
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if (__kernel_text_address(addr)) {
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if (trace->skip > 0)
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trace->skip--;
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else
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trace->entries[trace->nr_entries++] = addr;
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if (trace->nr_entries >= trace->max_entries)
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break;
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}
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}
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microblaze_unwind(tsk, trace);
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}
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EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
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@ -16,13 +16,14 @@
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#include <asm/exceptions.h>
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#include <asm/system.h>
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#include <asm/unwind.h>
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void trap_init(void)
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{
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__enable_hw_exceptions();
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}
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static unsigned long kstack_depth_to_print = 24;
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static unsigned long kstack_depth_to_print; /* 0 == entire stack */
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static int __init kstack_setup(char *s)
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{
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}
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__setup("kstack=", kstack_setup);
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void show_trace(struct task_struct *task, unsigned long *stack)
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void show_stack(struct task_struct *task, unsigned long *sp)
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{
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unsigned long addr;
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unsigned long words_to_show;
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u32 fp = (u32) sp;
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if (!stack)
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stack = (unsigned long *)&stack;
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printk(KERN_NOTICE "Call Trace: ");
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#ifdef CONFIG_KALLSYMS
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printk(KERN_NOTICE "\n");
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#endif
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while (!kstack_end(stack)) {
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addr = *stack++;
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/*
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* If the address is either in the text segment of the
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* kernel, or in the region which contains vmalloc'ed
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* memory, it *may* be the address of a calling
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* routine; if so, print it so that someone tracing
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* down the cause of the crash will be able to figure
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* out the call path that was taken.
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*/
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if (kernel_text_address(addr))
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print_ip_sym(addr);
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if (fp == 0) {
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if (task) {
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fp = ((struct thread_info *)
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(task->stack))->cpu_context.r1;
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} else {
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/* Pick up caller of dump_stack() */
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fp = (u32)&sp - 8;
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}
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printk(KERN_NOTICE "\n");
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}
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words_to_show = (THREAD_SIZE - (fp & (THREAD_SIZE - 1))) >> 2;
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if (kstack_depth_to_print && (words_to_show > kstack_depth_to_print))
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words_to_show = kstack_depth_to_print;
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pr_info("Kernel Stack:\n");
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/*
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* Make the first line an 'odd' size if necessary to get
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* remaining lines to start at an address multiple of 0x10
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*/
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if (fp & 0xF) {
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unsigned long line1_words = (0x10 - (fp & 0xF)) >> 2;
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if (line1_words < words_to_show) {
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print_hex_dump(KERN_INFO, "", DUMP_PREFIX_ADDRESS, 32,
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4, (void *)fp, line1_words << 2, 0);
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fp += line1_words << 2;
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words_to_show -= line1_words;
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}
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}
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print_hex_dump(KERN_INFO, "", DUMP_PREFIX_ADDRESS, 32, 4, (void *)fp,
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words_to_show << 2, 0);
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printk(KERN_INFO "\n\n");
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pr_info("Call Trace:\n");
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microblaze_unwind(task, NULL);
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pr_info("\n");
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if (!task)
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task = current;
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debug_show_held_locks(task);
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}
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void show_stack(struct task_struct *task, unsigned long *sp)
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{
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unsigned long *stack;
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int i;
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if (sp == NULL) {
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if (task)
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sp = (unsigned long *) ((struct thread_info *)
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(task->stack))->cpu_context.r1;
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else
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sp = (unsigned long *)&sp;
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}
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stack = sp;
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printk(KERN_INFO "\nStack:\n ");
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for (i = 0; i < kstack_depth_to_print; i++) {
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if (kstack_end(sp))
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break;
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if (i && ((i % 8) == 0))
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printk("\n ");
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printk("%08lx ", *sp++);
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}
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printk("\n");
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show_trace(task, stack);
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}
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void dump_stack(void)
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{
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show_stack(NULL, NULL);
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@ -0,0 +1,318 @@
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/*
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* Backtrace support for Microblaze
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*
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* Copyright (C) 2010 Digital Design Corporation
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*
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* Based on arch/sh/kernel/cpu/sh5/unwind.c code which is:
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* Copyright (C) 2004 Paul Mundt
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* Copyright (C) 2004 Richard Curnow
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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/* #define DEBUG 1 */
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#include <linux/kallsyms.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/stacktrace.h>
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/module.h>
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#include <linux/io.h>
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#include <asm/sections.h>
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#include <asm/exceptions.h>
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#include <asm/unwind.h>
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struct stack_trace;
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/*
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* On Microblaze, finding the previous stack frame is a little tricky.
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* At this writing (3/2010), Microblaze does not support CONFIG_FRAME_POINTERS,
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* and even if it did, gcc (4.1.2) does not store the frame pointer at
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* a consistent offset within each frame. To determine frame size, it is
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* necessary to search for the assembly instruction that creates or reclaims
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* the frame and extract the size from it.
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*
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* Microblaze stores the stack pointer in r1, and creates a frame via
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*
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* addik r1, r1, -FRAME_SIZE
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*
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* The frame is reclaimed via
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*
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* addik r1, r1, FRAME_SIZE
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*
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* Frame creation occurs at or near the top of a function.
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* Depending on the compiler, reclaim may occur at the end, or before
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* a mid-function return.
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*
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* A stack frame is usually not created in a leaf function.
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*
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*/
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/**
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* get_frame_size - Extract the stack adjustment from an
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* "addik r1, r1, adjust" instruction
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* @instr : Microblaze instruction
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*
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* Return - Number of stack bytes the instruction reserves or reclaims
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*/
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inline long get_frame_size(unsigned long instr)
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{
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return abs((s16)(instr & 0xFFFF));
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}
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/**
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* find_frame_creation - Search backward to find the instruction that creates
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* the stack frame (hopefully, for the same function the
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* initial PC is in).
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* @pc : Program counter at which to begin the search
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*
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* Return - PC at which stack frame creation occurs
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* NULL if this cannot be found, i.e. a leaf function
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*/
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static unsigned long *find_frame_creation(unsigned long *pc)
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{
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int i;
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/* NOTE: Distance to search is arbitrary
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* 250 works well for most things,
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* 750 picks up things like tcp_recvmsg(),
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* 1000 needed for fat_fill_super()
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*/
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for (i = 0; i < 1000; i++, pc--) {
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unsigned long instr;
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s16 frame_size;
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if (!kernel_text_address((unsigned long) pc))
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return NULL;
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instr = *pc;
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/* addik r1, r1, foo ? */
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if ((instr & 0xFFFF0000) != 0x30210000)
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continue; /* No */
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frame_size = get_frame_size(instr);
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if ((frame_size < 8) || (frame_size & 3)) {
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pr_debug(" Invalid frame size %d at 0x%p\n",
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frame_size, pc);
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return NULL;
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}
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pr_debug(" Found frame creation at 0x%p, size %d\n", pc,
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frame_size);
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return pc;
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}
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return NULL;
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}
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/**
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* lookup_prev_stack_frame - Find the stack frame of the previous function.
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* @fp : Frame (stack) pointer for current function
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* @pc : Program counter within current function
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* @leaf_return : r15 value within current function. If the current function
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* is a leaf, this is the caller's return address.
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* @pprev_fp : On exit, set to frame (stack) pointer for previous function
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* @pprev_pc : On exit, set to current function caller's return address
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*
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* Return - 0 on success, -EINVAL if the previous frame cannot be found
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*/
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static int lookup_prev_stack_frame(unsigned long fp, unsigned long pc,
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unsigned long leaf_return,
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unsigned long *pprev_fp,
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unsigned long *pprev_pc)
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{
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unsigned long *prologue = NULL;
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/* _switch_to is a special leaf function */
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if (pc != (unsigned long) &_switch_to)
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prologue = find_frame_creation((unsigned long *)pc);
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if (prologue) {
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long frame_size = get_frame_size(*prologue);
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*pprev_fp = fp + frame_size;
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*pprev_pc = *(unsigned long *)fp;
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} else {
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if (!leaf_return)
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return -EINVAL;
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*pprev_pc = leaf_return;
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*pprev_fp = fp;
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}
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/* NOTE: don't check kernel_text_address here, to allow display
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* of userland return address
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*/
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return (!*pprev_pc || (*pprev_pc & 3)) ? -EINVAL : 0;
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}
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static void microblaze_unwind_inner(struct task_struct *task,
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unsigned long pc, unsigned long fp,
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unsigned long leaf_return,
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struct stack_trace *trace);
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/**
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* unwind_trap - Unwind through a system trap, that stored previous state
|
||||
* on the stack.
|
||||
*/
|
||||
#ifdef CONFIG_MMU
|
||||
static inline void unwind_trap(struct task_struct *task, unsigned long pc,
|
||||
unsigned long fp, struct stack_trace *trace)
|
||||
{
|
||||
/* To be implemented */
|
||||
}
|
||||
#else
|
||||
static inline void unwind_trap(struct task_struct *task, unsigned long pc,
|
||||
unsigned long fp, struct stack_trace *trace)
|
||||
{
|
||||
const struct pt_regs *regs = (const struct pt_regs *) fp;
|
||||
microblaze_unwind_inner(task, regs->pc, regs->r1, regs->r15, trace);
|
||||
}
|
||||
#endif
|
||||
|
||||
/**
|
||||
* microblaze_unwind_inner - Unwind the stack from the specified point
|
||||
* @task : Task whose stack we are to unwind (may be NULL)
|
||||
* @pc : Program counter from which we start unwinding
|
||||
* @fp : Frame (stack) pointer from which we start unwinding
|
||||
* @leaf_return : Value of r15 at pc. If the function is a leaf, this is
|
||||
* the caller's return address.
|
||||
* @trace : Where to store stack backtrace (PC values).
|
||||
* NULL == print backtrace to kernel log
|
||||
*/
|
||||
void microblaze_unwind_inner(struct task_struct *task,
|
||||
unsigned long pc, unsigned long fp,
|
||||
unsigned long leaf_return,
|
||||
struct stack_trace *trace)
|
||||
{
|
||||
int ofs = 0;
|
||||
|
||||
pr_debug(" Unwinding with PC=%p, FP=%p\n", (void *)pc, (void *)fp);
|
||||
if (!pc || !fp || (pc & 3) || (fp & 3)) {
|
||||
pr_debug(" Invalid state for unwind, aborting\n");
|
||||
return;
|
||||
}
|
||||
for (; pc != 0;) {
|
||||
unsigned long next_fp, next_pc = 0;
|
||||
unsigned long return_to = pc + 2 * sizeof(unsigned long);
|
||||
const struct trap_handler_info *handler =
|
||||
µblaze_trap_handlers;
|
||||
|
||||
/* Is previous function the HW exception handler? */
|
||||
if ((return_to >= (unsigned long)&_hw_exception_handler)
|
||||
&&(return_to < (unsigned long)&ex_handler_unhandled)) {
|
||||
/*
|
||||
* HW exception handler doesn't save all registers,
|
||||
* so we open-code a special case of unwind_trap()
|
||||
*/
|
||||
#ifndef CONFIG_MMU
|
||||
const struct pt_regs *regs =
|
||||
(const struct pt_regs *) fp;
|
||||
#endif
|
||||
pr_info("HW EXCEPTION\n");
|
||||
#ifndef CONFIG_MMU
|
||||
microblaze_unwind_inner(task, regs->r17 - 4,
|
||||
fp + EX_HANDLER_STACK_SIZ,
|
||||
regs->r15, trace);
|
||||
#endif
|
||||
return;
|
||||
}
|
||||
|
||||
/* Is previous function a trap handler? */
|
||||
for (; handler->start_addr; ++handler) {
|
||||
if ((return_to >= handler->start_addr)
|
||||
&& (return_to <= handler->end_addr)) {
|
||||
if (!trace)
|
||||
pr_info("%s\n", handler->trap_name);
|
||||
unwind_trap(task, pc, fp, trace);
|
||||
return;
|
||||
}
|
||||
}
|
||||
pc -= ofs;
|
||||
|
||||
if (trace) {
|
||||
#ifdef CONFIG_STACKTRACE
|
||||
if (trace->skip > 0)
|
||||
trace->skip--;
|
||||
else
|
||||
trace->entries[trace->nr_entries++] = pc;
|
||||
|
||||
if (trace->nr_entries >= trace->max_entries)
|
||||
break;
|
||||
#endif
|
||||
} else {
|
||||
/* Have we reached userland? */
|
||||
if (unlikely(pc == task_pt_regs(task)->pc)) {
|
||||
pr_info("[<%p>] PID %lu [%s]\n",
|
||||
(void *) pc,
|
||||
(unsigned long) task->pid,
|
||||
task->comm);
|
||||
break;
|
||||
} else
|
||||
print_ip_sym(pc);
|
||||
}
|
||||
|
||||
/* Stop when we reach anything not part of the kernel */
|
||||
if (!kernel_text_address(pc))
|
||||
break;
|
||||
|
||||
if (lookup_prev_stack_frame(fp, pc, leaf_return, &next_fp,
|
||||
&next_pc) == 0) {
|
||||
ofs = sizeof(unsigned long);
|
||||
pc = next_pc & ~3;
|
||||
fp = next_fp;
|
||||
leaf_return = 0;
|
||||
} else {
|
||||
pr_debug(" Failed to find previous stack frame\n");
|
||||
break;
|
||||
}
|
||||
|
||||
pr_debug(" Next PC=%p, next FP=%p\n",
|
||||
(void *)next_pc, (void *)next_fp);
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* microblaze_unwind - Stack unwinder for Microblaze (external entry point)
|
||||
* @task : Task whose stack we are to unwind (NULL == current)
|
||||
* @trace : Where to store stack backtrace (PC values).
|
||||
* NULL == print backtrace to kernel log
|
||||
*/
|
||||
void microblaze_unwind(struct task_struct *task, struct stack_trace *trace)
|
||||
{
|
||||
if (task) {
|
||||
if (task == current) {
|
||||
const struct pt_regs *regs = task_pt_regs(task);
|
||||
microblaze_unwind_inner(task, regs->pc, regs->r1,
|
||||
regs->r15, trace);
|
||||
} else {
|
||||
struct thread_info *thread_info =
|
||||
(struct thread_info *)(task->stack);
|
||||
const struct cpu_context *cpu_context =
|
||||
&thread_info->cpu_context;
|
||||
|
||||
microblaze_unwind_inner(task,
|
||||
(unsigned long) &_switch_to,
|
||||
cpu_context->r1,
|
||||
cpu_context->r15, trace);
|
||||
}
|
||||
} else {
|
||||
unsigned long pc, fp;
|
||||
|
||||
__asm__ __volatile__ ("or %0, r1, r0" : "=r" (fp));
|
||||
|
||||
__asm__ __volatile__ (
|
||||
"brlid %0, 0f;"
|
||||
"nop;"
|
||||
"0:"
|
||||
: "=r" (pc)
|
||||
);
|
||||
|
||||
/* Since we are not a leaf function, use leaf_return = 0 */
|
||||
microblaze_unwind_inner(current, pc, fp, 0, trace);
|
||||
}
|
||||
}
|
||||
|
Loading…
Reference in New Issue