249 lines
6.1 KiB
C
249 lines
6.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/export.h>
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#include <linux/kprobes.h>
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#include <linux/sched.h>
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#include <linux/sched/debug.h>
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#include <linux/stacktrace.h>
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#include <asm/sections.h>
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#include <asm/stacktrace.h>
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#include <asm/traps.h>
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#include "reboot.h"
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#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND)
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/*
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* Unwind the current stack frame and store the new register values in the
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* structure passed as argument. Unwinding is equivalent to a function return,
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* hence the new PC value rather than LR should be used for backtrace.
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*
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* With framepointer enabled, a simple function prologue looks like this:
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* mov ip, sp
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* stmdb sp!, {fp, ip, lr, pc}
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* sub fp, ip, #4
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*
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* A simple function epilogue looks like this:
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* ldm sp, {fp, sp, pc}
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*
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* When compiled with clang, pc and sp are not pushed. A simple function
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* prologue looks like this when built with clang:
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*
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* stmdb {..., fp, lr}
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* add fp, sp, #x
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* sub sp, sp, #y
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*
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* A simple function epilogue looks like this when built with clang:
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*
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* sub sp, fp, #x
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* ldm {..., fp, pc}
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*
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*
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* Note that with framepointer enabled, even the leaf functions have the same
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* prologue and epilogue, therefore we can ignore the LR value in this case.
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*/
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extern unsigned long call_with_stack_end;
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static int frame_pointer_check(struct stackframe *frame)
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{
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unsigned long high, low;
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unsigned long fp = frame->fp;
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unsigned long pc = frame->pc;
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/*
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* call_with_stack() is the only place we allow SP to jump from one
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* stack to another, with FP and SP pointing to different stacks,
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* skipping the FP boundary check at this point.
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*/
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if (pc >= (unsigned long)&call_with_stack &&
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pc < (unsigned long)&call_with_stack_end)
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return 0;
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/* only go to a higher address on the stack */
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low = frame->sp;
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high = ALIGN(low, THREAD_SIZE);
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/* check current frame pointer is within bounds */
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#ifdef CONFIG_CC_IS_CLANG
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if (fp < low + 4 || fp > high - 4)
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return -EINVAL;
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#else
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if (fp < low + 12 || fp > high - 4)
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return -EINVAL;
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#endif
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return 0;
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}
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int notrace unwind_frame(struct stackframe *frame)
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{
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unsigned long fp = frame->fp;
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if (frame_pointer_check(frame))
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return -EINVAL;
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/*
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* When we unwind through an exception stack, include the saved PC
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* value into the stack trace.
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*/
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if (frame->ex_frame) {
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struct pt_regs *regs = (struct pt_regs *)frame->sp;
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/*
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* We check that 'regs + sizeof(struct pt_regs)' (that is,
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* ®s[1]) does not exceed the bottom of the stack to avoid
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* accessing data outside the task's stack. This may happen
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* when frame->ex_frame is a false positive.
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*/
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if ((unsigned long)®s[1] > ALIGN(frame->sp, THREAD_SIZE))
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return -EINVAL;
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frame->pc = regs->ARM_pc;
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frame->ex_frame = false;
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return 0;
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}
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/* restore the registers from the stack frame */
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#ifdef CONFIG_CC_IS_CLANG
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frame->sp = frame->fp;
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frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));
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frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 4));
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#else
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frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp - 12));
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frame->sp = READ_ONCE_NOCHECK(*(unsigned long *)(fp - 8));
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frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp - 4));
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#endif
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#ifdef CONFIG_KRETPROBES
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if (is_kretprobe_trampoline(frame->pc))
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frame->pc = kretprobe_find_ret_addr(frame->tsk,
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(void *)frame->fp, &frame->kr_cur);
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#endif
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if (in_entry_text(frame->pc))
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frame->ex_frame = true;
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return 0;
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}
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#endif
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void notrace walk_stackframe(struct stackframe *frame,
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int (*fn)(struct stackframe *, void *), void *data)
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{
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while (1) {
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int ret;
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if (fn(frame, data))
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break;
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ret = unwind_frame(frame);
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if (ret < 0)
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break;
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}
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}
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EXPORT_SYMBOL(walk_stackframe);
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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 int no_sched_functions;
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unsigned int skip;
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};
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static int save_trace(struct stackframe *frame, void *d)
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{
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struct stack_trace_data *data = d;
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struct stack_trace *trace = data->trace;
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unsigned long addr = frame->pc;
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if (data->no_sched_functions && in_sched_functions(addr))
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return 0;
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if (data->skip) {
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data->skip--;
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return 0;
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}
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trace->entries[trace->nr_entries++] = addr;
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return trace->nr_entries >= trace->max_entries;
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}
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/* This must be noinline to so that our skip calculation works correctly */
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static noinline void __save_stack_trace(struct task_struct *tsk,
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struct stack_trace *trace, unsigned int nosched)
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{
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struct stack_trace_data data;
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struct stackframe frame;
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data.trace = trace;
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data.skip = trace->skip;
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data.no_sched_functions = nosched;
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if (tsk != current) {
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#ifdef CONFIG_SMP
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/*
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* What guarantees do we have here that 'tsk' is not
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* running on another CPU? For now, ignore it as we
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* can't guarantee we won't explode.
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*/
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return;
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#else
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frame.fp = thread_saved_fp(tsk);
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frame.sp = thread_saved_sp(tsk);
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frame.lr = 0; /* recovered from the stack */
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frame.pc = thread_saved_pc(tsk);
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#endif
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} else {
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/* We don't want this function nor the caller */
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data.skip += 2;
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frame.fp = (unsigned long)__builtin_frame_address(0);
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frame.sp = current_stack_pointer;
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frame.lr = (unsigned long)__builtin_return_address(0);
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here:
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frame.pc = (unsigned long)&&here;
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}
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#ifdef CONFIG_KRETPROBES
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frame.kr_cur = NULL;
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frame.tsk = tsk;
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#endif
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#ifdef CONFIG_UNWINDER_FRAME_POINTER
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frame.ex_frame = false;
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#endif
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walk_stackframe(&frame, save_trace, &data);
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}
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void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
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{
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struct stack_trace_data data;
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struct stackframe frame;
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data.trace = trace;
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data.skip = trace->skip;
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data.no_sched_functions = 0;
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frame.fp = regs->ARM_fp;
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frame.sp = regs->ARM_sp;
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frame.lr = regs->ARM_lr;
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frame.pc = regs->ARM_pc;
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#ifdef CONFIG_KRETPROBES
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frame.kr_cur = NULL;
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frame.tsk = current;
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#endif
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#ifdef CONFIG_UNWINDER_FRAME_POINTER
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frame.ex_frame = in_entry_text(frame.pc);
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#endif
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walk_stackframe(&frame, save_trace, &data);
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}
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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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__save_stack_trace(tsk, trace, 1);
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}
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EXPORT_SYMBOL(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(current, trace, 0);
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}
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EXPORT_SYMBOL_GPL(save_stack_trace);
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#endif
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