189 lines
4.8 KiB
C
189 lines
4.8 KiB
C
/*
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* Stack tracing support
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*
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/ftrace.h>
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#include <linux/sched.h>
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#include <linux/stacktrace.h>
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#include <asm/irq.h>
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#include <asm/stacktrace.h>
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/*
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* AArch64 PCS assigns the frame pointer to x29.
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*
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* A simple function prologue looks like this:
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* sub sp, sp, #0x10
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* stp x29, x30, [sp]
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* mov x29, sp
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*
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* A simple function epilogue looks like this:
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* mov sp, x29
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* ldp x29, x30, [sp]
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* add sp, sp, #0x10
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*/
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int notrace unwind_frame(struct task_struct *tsk, 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 irq_stack_ptr;
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/*
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* Switching between stacks is valid when tracing current and in
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* non-preemptible context.
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*/
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if (tsk == current && !preemptible())
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irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
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else
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irq_stack_ptr = 0;
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low = frame->sp;
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/* irq stacks are not THREAD_SIZE aligned */
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if (on_irq_stack(frame->sp, raw_smp_processor_id()))
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high = irq_stack_ptr;
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else
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high = ALIGN(low, THREAD_SIZE) - 0x20;
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if (fp < low || fp > high || fp & 0xf)
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return -EINVAL;
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frame->sp = fp + 0x10;
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frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));
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frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8));
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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if (tsk && tsk->ret_stack &&
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(frame->pc == (unsigned long)return_to_handler)) {
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/*
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* This is a case where function graph tracer has
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* modified a return address (LR) in a stack frame
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* to hook a function return.
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* So replace it to an original value.
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*/
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frame->pc = tsk->ret_stack[frame->graph--].ret;
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}
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#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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/*
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* Check whether we are going to walk through from interrupt stack
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* to task stack.
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* If we reach the end of the stack - and its an interrupt stack,
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* unpack the dummy frame to find the original elr.
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*
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* Check the frame->fp we read from the bottom of the irq_stack,
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* and the original task stack pointer are both in current->stack.
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*/
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if (frame->sp == irq_stack_ptr) {
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struct pt_regs *irq_args;
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unsigned long orig_sp = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
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if (object_is_on_stack((void *)orig_sp) &&
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object_is_on_stack((void *)frame->fp)) {
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frame->sp = orig_sp;
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/* orig_sp is the saved pt_regs, find the elr */
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irq_args = (struct pt_regs *)orig_sp;
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frame->pc = irq_args->pc;
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} else {
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/*
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* This frame has a non-standard format, and we
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* didn't fix it, because the data looked wrong.
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* Refuse to output this frame.
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*/
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return -EINVAL;
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}
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}
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return 0;
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}
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void notrace walk_stackframe(struct task_struct *tsk, 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(tsk, 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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void save_stack_trace_tsk(struct task_struct *tsk, 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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if (tsk != current) {
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data.no_sched_functions = 1;
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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.pc = thread_saved_pc(tsk);
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} else {
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data.no_sched_functions = 0;
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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.pc = (unsigned long)save_stack_trace_tsk;
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}
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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frame.graph = tsk->curr_ret_stack;
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#endif
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walk_stackframe(tsk, &frame, save_trace, &data);
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if (trace->nr_entries < trace->max_entries)
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trace->entries[trace->nr_entries++] = ULONG_MAX;
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}
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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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