2013-04-14 23:20:48 -06:00
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/*
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2015-06-24 22:27:16 -06:00
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* Kernel and userspace stack tracing.
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2013-04-14 23:20:48 -06:00
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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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* Copyright (C) 2001 - 2013 Tensilica Inc.
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2015-06-24 22:27:16 -06:00
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* Copyright (C) 2015 Cadence Design Systems Inc.
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2013-04-14 23:20:48 -06:00
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*/
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#include <linux/export.h>
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#include <linux/sched.h>
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#include <linux/stacktrace.h>
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#include <asm/stacktrace.h>
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#include <asm/traps.h>
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2015-06-24 22:27:16 -06:00
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#include <asm/uaccess.h>
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#if IS_ENABLED(CONFIG_OPROFILE) || IS_ENABLED(CONFIG_PERF_EVENTS)
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/* Address of common_exception_return, used to check the
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* transition from kernel to user space.
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*/
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extern int common_exception_return;
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/* A struct that maps to the part of the frame containing the a0 and
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* a1 registers.
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*/
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struct frame_start {
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unsigned long a0;
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unsigned long a1;
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};
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void xtensa_backtrace_user(struct pt_regs *regs, unsigned int depth,
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int (*ufn)(struct stackframe *frame, void *data),
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void *data)
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{
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unsigned long windowstart = regs->windowstart;
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unsigned long windowbase = regs->windowbase;
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unsigned long a0 = regs->areg[0];
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unsigned long a1 = regs->areg[1];
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unsigned long pc = regs->pc;
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struct stackframe frame;
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int index;
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if (!depth--)
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return;
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frame.pc = pc;
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frame.sp = a1;
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if (pc == 0 || pc >= TASK_SIZE || ufn(&frame, data))
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return;
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/* Two steps:
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*
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* 1. Look through the register window for the
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* previous PCs in the call trace.
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*
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* 2. Look on the stack.
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*/
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/* Step 1. */
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/* Rotate WINDOWSTART to move the bit corresponding to
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* the current window to the bit #0.
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*/
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windowstart = (windowstart << WSBITS | windowstart) >> windowbase;
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/* Look for bits that are set, they correspond to
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* valid windows.
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*/
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for (index = WSBITS - 1; (index > 0) && depth; depth--, index--)
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if (windowstart & (1 << index)) {
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/* Get the PC from a0 and a1. */
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pc = MAKE_PC_FROM_RA(a0, pc);
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/* Read a0 and a1 from the
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* corresponding position in AREGs.
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*/
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a0 = regs->areg[index * 4];
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a1 = regs->areg[index * 4 + 1];
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frame.pc = pc;
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frame.sp = a1;
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if (pc == 0 || pc >= TASK_SIZE || ufn(&frame, data))
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return;
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}
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/* Step 2. */
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/* We are done with the register window, we need to
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* look through the stack.
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*/
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if (!depth)
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return;
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/* Start from the a1 register. */
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/* a1 = regs->areg[1]; */
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while (a0 != 0 && depth--) {
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struct frame_start frame_start;
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/* Get the location for a1, a0 for the
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* previous frame from the current a1.
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*/
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unsigned long *psp = (unsigned long *)a1;
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psp -= 4;
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/* Check if the region is OK to access. */
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if (!access_ok(VERIFY_READ, psp, sizeof(frame_start)))
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return;
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/* Copy a1, a0 from user space stack frame. */
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if (__copy_from_user_inatomic(&frame_start, psp,
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sizeof(frame_start)))
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return;
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pc = MAKE_PC_FROM_RA(a0, pc);
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a0 = frame_start.a0;
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a1 = frame_start.a1;
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frame.pc = pc;
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frame.sp = a1;
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if (pc == 0 || pc >= TASK_SIZE || ufn(&frame, data))
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return;
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}
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}
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EXPORT_SYMBOL(xtensa_backtrace_user);
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void xtensa_backtrace_kernel(struct pt_regs *regs, unsigned int depth,
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int (*kfn)(struct stackframe *frame, void *data),
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int (*ufn)(struct stackframe *frame, void *data),
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void *data)
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{
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unsigned long pc = regs->depc > VALID_DOUBLE_EXCEPTION_ADDRESS ?
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regs->depc : regs->pc;
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unsigned long sp_start, sp_end;
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unsigned long a0 = regs->areg[0];
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unsigned long a1 = regs->areg[1];
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sp_start = a1 & ~(THREAD_SIZE - 1);
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sp_end = sp_start + THREAD_SIZE;
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/* Spill the register window to the stack first. */
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spill_registers();
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/* Read the stack frames one by one and create the PC
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* from the a0 and a1 registers saved there.
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*/
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while (a1 > sp_start && a1 < sp_end && depth--) {
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struct stackframe frame;
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unsigned long *psp = (unsigned long *)a1;
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frame.pc = pc;
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frame.sp = a1;
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if (kernel_text_address(pc) && kfn(&frame, data))
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return;
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if (pc == (unsigned long)&common_exception_return) {
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regs = (struct pt_regs *)a1;
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if (user_mode(regs)) {
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if (ufn == NULL)
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return;
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xtensa_backtrace_user(regs, depth, ufn, data);
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return;
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}
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a0 = regs->areg[0];
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a1 = regs->areg[1];
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continue;
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}
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sp_start = a1;
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pc = MAKE_PC_FROM_RA(a0, pc);
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a0 = *(psp - 4);
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a1 = *(psp - 3);
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}
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}
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EXPORT_SYMBOL(xtensa_backtrace_kernel);
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#endif
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2013-04-14 23:20:48 -06:00
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void walk_stackframe(unsigned long *sp,
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int (*fn)(struct stackframe *frame, void *data),
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void *data)
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{
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unsigned long a0, a1;
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unsigned long sp_end;
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a1 = (unsigned long)sp;
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sp_end = ALIGN(a1, THREAD_SIZE);
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spill_registers();
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while (a1 < sp_end) {
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struct stackframe frame;
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sp = (unsigned long *)a1;
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a0 = *(sp - 4);
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a1 = *(sp - 3);
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if (a1 <= (unsigned long)sp)
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break;
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frame.pc = MAKE_PC_FROM_RA(a0, a1);
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frame.sp = a1;
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if (fn(&frame, data))
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return;
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}
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}
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#ifdef CONFIG_STACKTRACE
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struct stack_trace_data {
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struct stack_trace *trace;
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unsigned skip;
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};
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static int stack_trace_cb(struct stackframe *frame, void *data)
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{
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struct stack_trace_data *trace_data = data;
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struct stack_trace *trace = trace_data->trace;
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if (trace_data->skip) {
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--trace_data->skip;
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return 0;
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}
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if (!kernel_text_address(frame->pc))
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return 0;
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trace->entries[trace->nr_entries++] = frame->pc;
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return trace->nr_entries >= trace->max_entries;
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}
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void save_stack_trace_tsk(struct task_struct *task, struct stack_trace *trace)
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{
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struct stack_trace_data trace_data = {
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.trace = trace,
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.skip = trace->skip,
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};
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walk_stackframe(stack_pointer(task), stack_trace_cb, &trace_data);
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}
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EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
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void save_stack_trace(struct stack_trace *trace)
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{
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save_stack_trace_tsk(current, trace);
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}
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EXPORT_SYMBOL_GPL(save_stack_trace);
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#endif
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2013-04-07 15:29:19 -06:00
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#ifdef CONFIG_FRAME_POINTER
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struct return_addr_data {
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unsigned long addr;
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unsigned skip;
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};
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static int return_address_cb(struct stackframe *frame, void *data)
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{
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struct return_addr_data *r = data;
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if (r->skip) {
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--r->skip;
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return 0;
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}
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if (!kernel_text_address(frame->pc))
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return 0;
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r->addr = frame->pc;
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return 1;
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}
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unsigned long return_address(unsigned level)
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{
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struct return_addr_data r = {
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.skip = level + 1,
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};
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walk_stackframe(stack_pointer(NULL), return_address_cb, &r);
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return r.addr;
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}
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EXPORT_SYMBOL(return_address);
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#endif
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