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mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-15 16:53:54 +08:00

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:
Steven J. Magnani 2010-04-27 12:37:54 -05:00 committed by Michal Simek
parent ba9c4f88d7
commit ce3266c047
10 changed files with 454 additions and 95 deletions

View File

@ -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 */

View File

@ -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,

View File

@ -0,0 +1,29 @@
/*
* 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 */

View File

@ -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/

View File

@ -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

View File

@ -1127,3 +1127,30 @@ ENTRY(_break)
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_from_trap; .word ret_from_trap ; .word type_SYSCALL
.word ret_from_irq ; .word ret_from_irq ; .word type_IRQ
/* Fuzzy matches go here */
.word ret_from_irq ; .word no_intr_resched ; .word type_IRQ_PREEMPT
.word ret_from_trap; .word TRAP_return ; .word type_SYSCALL_PREEMPT
/* End of table */
.word 0 ; .word 0 ; .word 0

View File

@ -78,9 +78,6 @@
#include <asm/asm-offsets.h>
/* Helpful Macros */
#ifndef CONFIG_MMU
#define EX_HANDLER_STACK_SIZ (4*19)
#endif
#define NUM_TO_REG(num) r ## num
#ifdef CONFIG_MMU
@ -988,6 +985,7 @@ ex_unaligned_fixup:
.end _unaligned_data_exception
#endif /* CONFIG_MMU */
.global ex_handler_unhandled
ex_handler_unhandled:
/* FIXME add handle function for unhandled exception - dump register */
bri 0

View File

@ -14,52 +14,18 @@
#include <linux/thread_info.h>
#include <linux/ptrace.h>
#include <linux/module.h>
#include <asm/unwind.h>
/* FIXME initial support */
void save_stack_trace(struct stack_trace *trace)
{
unsigned long *sp;
unsigned long addr;
asm("addik %0, r1, 0" : "=r" (sp));
while (!kstack_end(sp)) {
addr = *sp++;
if (__kernel_text_address(addr)) {
if (trace->skip > 0)
trace->skip--;
else
trace->entries[trace->nr_entries++] = addr;
if (trace->nr_entries >= trace->max_entries)
break;
}
}
/* Exclude our helper functions from the trace*/
trace->skip += 2;
microblaze_unwind(NULL, trace);
}
EXPORT_SYMBOL_GPL(save_stack_trace);
void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
{
unsigned int *sp;
unsigned long addr;
struct thread_info *ti = task_thread_info(tsk);
if (tsk == current)
asm("addik %0, r1, 0" : "=r" (sp));
else
sp = (unsigned int *)ti->cpu_context.r1;
while (!kstack_end(sp)) {
addr = *sp++;
if (__kernel_text_address(addr)) {
if (trace->skip > 0)
trace->skip--;
else
trace->entries[trace->nr_entries++] = addr;
if (trace->nr_entries >= trace->max_entries)
break;
}
}
microblaze_unwind(tsk, trace);
}
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);

View File

@ -16,13 +16,14 @@
#include <asm/exceptions.h>
#include <asm/system.h>
#include <asm/unwind.h>
void trap_init(void)
{
__enable_hw_exceptions();
}
static unsigned long kstack_depth_to_print = 24;
static unsigned long kstack_depth_to_print; /* 0 == entire stack */
static int __init kstack_setup(char *s)
{
@ -30,31 +31,47 @@ static int __init kstack_setup(char *s)
}
__setup("kstack=", kstack_setup);
void show_trace(struct task_struct *task, unsigned long *stack)
void show_stack(struct task_struct *task, unsigned long *sp)
{
unsigned long addr;
unsigned long words_to_show;
u32 fp = (u32) sp;
if (!stack)
stack = (unsigned long *)&stack;
printk(KERN_NOTICE "Call Trace: ");
#ifdef CONFIG_KALLSYMS
printk(KERN_NOTICE "\n");
#endif
while (!kstack_end(stack)) {
addr = *stack++;
/*
* If the address is either in the text segment of the
* kernel, or in the region which contains vmalloc'ed
* memory, it *may* be the address of a calling
* routine; if so, print it so that someone tracing
* down the cause of the crash will be able to figure
* out the call path that was taken.
*/
if (kernel_text_address(addr))
print_ip_sym(addr);
if (fp == 0) {
if (task) {
fp = ((struct thread_info *)
(task->stack))->cpu_context.r1;
} else {
/* Pick up caller of dump_stack() */
fp = (u32)&sp - 8;
}
}
printk(KERN_NOTICE "\n");
words_to_show = (THREAD_SIZE - (fp & (THREAD_SIZE - 1))) >> 2;
if (kstack_depth_to_print && (words_to_show > kstack_depth_to_print))
words_to_show = kstack_depth_to_print;
pr_info("Kernel Stack:\n");
/*
* Make the first line an 'odd' size if necessary to get
* remaining lines to start at an address multiple of 0x10
*/
if (fp & 0xF) {
unsigned long line1_words = (0x10 - (fp & 0xF)) >> 2;
if (line1_words < words_to_show) {
print_hex_dump(KERN_INFO, "", DUMP_PREFIX_ADDRESS, 32,
4, (void *)fp, line1_words << 2, 0);
fp += line1_words << 2;
words_to_show -= line1_words;
}
}
print_hex_dump(KERN_INFO, "", DUMP_PREFIX_ADDRESS, 32, 4, (void *)fp,
words_to_show << 2, 0);
printk(KERN_INFO "\n\n");
pr_info("Call Trace:\n");
microblaze_unwind(task, NULL);
pr_info("\n");
if (!task)
task = current;
@ -62,34 +79,6 @@ void show_trace(struct task_struct *task, unsigned long *stack)
debug_show_held_locks(task);
}
void show_stack(struct task_struct *task, unsigned long *sp)
{
unsigned long *stack;
int i;
if (sp == NULL) {
if (task)
sp = (unsigned long *) ((struct thread_info *)
(task->stack))->cpu_context.r1;
else
sp = (unsigned long *)&sp;
}
stack = sp;
printk(KERN_INFO "\nStack:\n ");
for (i = 0; i < kstack_depth_to_print; i++) {
if (kstack_end(sp))
break;
if (i && ((i % 8) == 0))
printk("\n ");
printk("%08lx ", *sp++);
}
printk("\n");
show_trace(task, stack);
}
void dump_stack(void)
{
show_stack(NULL, NULL);

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@ -0,0 +1,318 @@
/*
* Backtrace support for Microblaze
*
* Copyright (C) 2010 Digital Design Corporation
*
* Based on arch/sh/kernel/cpu/sh5/unwind.c code which is:
* Copyright (C) 2004 Paul Mundt
* Copyright (C) 2004 Richard Curnow
*
* 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.
*/
/* #define DEBUG 1 */
#include <linux/kallsyms.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/stacktrace.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/io.h>
#include <asm/sections.h>
#include <asm/exceptions.h>
#include <asm/unwind.h>
struct stack_trace;
/*
* On Microblaze, finding the previous stack frame is a little tricky.
* At this writing (3/2010), Microblaze does not support CONFIG_FRAME_POINTERS,
* and even if it did, gcc (4.1.2) does not store the frame pointer at
* a consistent offset within each frame. To determine frame size, it is
* necessary to search for the assembly instruction that creates or reclaims
* the frame and extract the size from it.
*
* Microblaze stores the stack pointer in r1, and creates a frame via
*
* addik r1, r1, -FRAME_SIZE
*
* The frame is reclaimed via
*
* addik r1, r1, FRAME_SIZE
*
* Frame creation occurs at or near the top of a function.
* Depending on the compiler, reclaim may occur at the end, or before
* a mid-function return.
*
* A stack frame is usually not created in a leaf function.
*
*/
/**
* get_frame_size - Extract the stack adjustment from an
* "addik r1, r1, adjust" instruction
* @instr : Microblaze instruction
*
* Return - Number of stack bytes the instruction reserves or reclaims
*/
inline long get_frame_size(unsigned long instr)
{
return abs((s16)(instr & 0xFFFF));
}
/**
* find_frame_creation - Search backward to find the instruction that creates
* the stack frame (hopefully, for the same function the
* initial PC is in).
* @pc : Program counter at which to begin the search
*
* Return - PC at which stack frame creation occurs
* NULL if this cannot be found, i.e. a leaf function
*/
static unsigned long *find_frame_creation(unsigned long *pc)
{
int i;
/* NOTE: Distance to search is arbitrary
* 250 works well for most things,
* 750 picks up things like tcp_recvmsg(),
* 1000 needed for fat_fill_super()
*/
for (i = 0; i < 1000; i++, pc--) {
unsigned long instr;
s16 frame_size;
if (!kernel_text_address((unsigned long) pc))
return NULL;
instr = *pc;
/* addik r1, r1, foo ? */
if ((instr & 0xFFFF0000) != 0x30210000)
continue; /* No */
frame_size = get_frame_size(instr);
if ((frame_size < 8) || (frame_size & 3)) {
pr_debug(" Invalid frame size %d at 0x%p\n",
frame_size, pc);
return NULL;
}
pr_debug(" Found frame creation at 0x%p, size %d\n", pc,
frame_size);
return pc;
}
return NULL;
}
/**
* lookup_prev_stack_frame - Find the stack frame of the previous function.
* @fp : Frame (stack) pointer for current function
* @pc : Program counter within current function
* @leaf_return : r15 value within current function. If the current function
* is a leaf, this is the caller's return address.
* @pprev_fp : On exit, set to frame (stack) pointer for previous function
* @pprev_pc : On exit, set to current function caller's return address
*
* Return - 0 on success, -EINVAL if the previous frame cannot be found
*/
static int lookup_prev_stack_frame(unsigned long fp, unsigned long pc,
unsigned long leaf_return,
unsigned long *pprev_fp,
unsigned long *pprev_pc)
{
unsigned long *prologue = NULL;
/* _switch_to is a special leaf function */
if (pc != (unsigned long) &_switch_to)
prologue = find_frame_creation((unsigned long *)pc);
if (prologue) {
long frame_size = get_frame_size(*prologue);
*pprev_fp = fp + frame_size;
*pprev_pc = *(unsigned long *)fp;
} else {
if (!leaf_return)
return -EINVAL;
*pprev_pc = leaf_return;
*pprev_fp = fp;
}
/* NOTE: don't check kernel_text_address here, to allow display
* of userland return address
*/
return (!*pprev_pc || (*pprev_pc & 3)) ? -EINVAL : 0;
}
static void microblaze_unwind_inner(struct task_struct *task,
unsigned long pc, unsigned long fp,
unsigned long leaf_return,
struct stack_trace *trace);
/**
* 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 =
&microblaze_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);
}
}