![Masami Hiramatsu](/assets/img/avatar_default.png)
Prohibit probing on return_address() and subroutines which is called from return_address(), since the it is invoked from trace_hardirqs_off() which is also kprobe blacklisted. Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Will Deacon <will@kernel.org>
213 lines
5.1 KiB
C
213 lines
5.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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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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#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/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/sched/task_stack.h>
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#include <linux/stacktrace.h>
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#include <asm/irq.h>
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#include <asm/stack_pointer.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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/*
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* Unwind from one frame record (A) to the next frame record (B).
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*
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* We terminate early if the location of B indicates a malformed chain of frame
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* records (e.g. a cycle), determined based on the location and fp value of A
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* and the location (but not the fp value) of B.
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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 fp = frame->fp;
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struct stack_info info;
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if (fp & 0xf)
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return -EINVAL;
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if (!tsk)
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tsk = current;
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if (!on_accessible_stack(tsk, fp, &info))
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return -EINVAL;
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if (test_bit(info.type, frame->stacks_done))
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return -EINVAL;
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/*
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* As stacks grow downward, any valid record on the same stack must be
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* at a strictly higher address than the prior record.
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*
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* Stacks can nest in several valid orders, e.g.
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*
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* TASK -> IRQ -> OVERFLOW -> SDEI_NORMAL
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* TASK -> SDEI_NORMAL -> SDEI_CRITICAL -> OVERFLOW
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*
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* ... but the nesting itself is strict. Once we transition from one
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* stack to another, it's never valid to unwind back to that first
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* stack.
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*/
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if (info.type == frame->prev_type) {
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if (fp <= frame->prev_fp)
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return -EINVAL;
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} else {
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set_bit(frame->prev_type, frame->stacks_done);
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}
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/*
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* Record this frame record's values and location. The prev_fp and
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* prev_type are only meaningful to the next unwind_frame() invocation.
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*/
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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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frame->prev_fp = fp;
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frame->prev_type = info.type;
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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if (tsk->ret_stack &&
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(frame->pc == (unsigned long)return_to_handler)) {
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struct ftrace_ret_stack *ret_stack;
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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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ret_stack = ftrace_graph_get_ret_stack(tsk, frame->graph++);
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if (WARN_ON_ONCE(!ret_stack))
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return -EINVAL;
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frame->pc = ret_stack->ret;
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}
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#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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/*
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* Frames created upon entry from EL0 have NULL FP and PC values, so
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* don't bother reporting these. Frames created by __noreturn functions
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* might have a valid FP even if PC is bogus, so only terminate where
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* both are NULL.
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*/
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if (!frame->fp && !frame->pc)
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return -EINVAL;
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return 0;
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}
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NOKPROBE_SYMBOL(unwind_frame);
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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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NOKPROBE_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_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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start_backtrace(&frame, regs->regs[29], regs->pc);
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walk_stackframe(current, &frame, save_trace, &data);
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}
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EXPORT_SYMBOL_GPL(save_stack_trace_regs);
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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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if (!try_get_task_stack(tsk))
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return;
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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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start_backtrace(&frame, thread_saved_fp(tsk),
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thread_saved_pc(tsk));
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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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start_backtrace(&frame,
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(unsigned long)__builtin_frame_address(0),
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(unsigned long)__save_stack_trace);
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}
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walk_stackframe(tsk, &frame, save_trace, &data);
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put_task_stack(tsk);
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}
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EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
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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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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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