dump_stack调用过程【原创】
dump_stack调用:
void dump_stack(void)
{
dump_backtrace(NULL, NULL);
}
继续看:
static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
{
unsigned int fp, mode;
int ok = 1;
printk("Backtrace: ");
if (!tsk)
tsk = current;
if (regs) {
fp = regs->ARM_fp;
mode = processor_mode(regs);
} else if (tsk != current) {
fp = thread_saved_fp(tsk);
mode = 0x10;
} else {
asm("mov %0, fp" : "=r" (fp) : : "cc");
mode = 0x10;
}
if (!fp) {
printk("no frame pointer");
ok = 0;
} else if (verify_stack(fp)) {
printk("invalid frame pointer 0x%08x", fp);
ok = 0;
} else if (fp < (unsigned long)end_of_stack(tsk))
printk("frame pointer underflow");
printk("\n");
if (ok)
c_backtrace(fp, mode);
}
#endif
我们搜索这个 c_backtrace 函数
在arch\arm\lib中 backtrace.S中
#include <linux/linkage.h>
#include <asm/assembler.h>
.text
@ fp is 0 or stack frame
#define frame r4
#define sv_fp r5
#define sv_pc r6
#define mask r7
#define offset r8
ENTRY(c_backtrace)
。。。。
1003: ldr r2, [sv_pc, #-4] @ if stmfd sp!, {args} exists,
ldr r3, .Ldsi+4 @ adjust saved 'pc' back one
teq r3, r2, lsr #10 @ instruction
subne r0, sv_pc, #4 @ allow for mov
subeq r0, sv_pc, #8 @ allow for mov + stmia
ldr r1, [frame, #-4] @ get saved lr
mov r2, frame
bic r1, r1, mask @ mask PC/LR for the mode
bl dump_backtrace_entry
ldr r1, [sv_pc, #-4] @ if stmfd sp!, {args} exists,
ldr r3, .Ldsi+4
teq r3, r1, lsr #10
ldreq r0, [frame, #-8] @ get sp
subeq r0, r0, #4 @ point at the last arg
bleq .Ldumpstm @ dump saved registers
1004: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, ip, lr, pc}
再看这个函数 dump_backtrace_entry
void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
{
#ifdef CONFIG_KALLSYMS
printk("[<%08lx>] (%pS) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
#else
printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
#endif
if (in_exception_text(where))
dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
}
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