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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2008 ARM Limited
* Copyright (C) 2014 Regents of the University of California
*/
#include <linux/export.h>
#include <linux/kallsyms.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/stacktrace.h>
#include <linux/ftrace.h>
#include <asm/stacktrace.h>
#ifdef CONFIG_FRAME_POINTER
extern asmlinkage void handle_exception(void);
static inline int fp_is_valid(unsigned long fp, unsigned long sp)
{
unsigned long low, high;
low = sp + sizeof(struct stackframe);
high = ALIGN(sp, THREAD_SIZE);
return !(fp < low || fp > high || fp & 0x07);
}
void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
bool (*fn)(void *, unsigned long), void *arg)
{
unsigned long fp, sp, pc;
int graph_idx = 0;
int level = 0;
if (regs) {
fp = frame_pointer(regs);
sp = user_stack_pointer(regs);
pc = instruction_pointer(regs);
} else if (task == NULL || task == current) {
fp = (unsigned long)__builtin_frame_address(0);
sp = current_stack_pointer;
pc = (unsigned long)walk_stackframe;
level = -1;
} else {
/* task blocked in __switch_to */
fp = task->thread.s[0];
sp = task->thread.sp;
pc = task->thread.ra;
}
for (;;) {
struct stackframe *frame;
if (unlikely(!__kernel_text_address(pc) || (level++ >= 0 && !fn(arg, pc))))
break;
if (unlikely(!fp_is_valid(fp, sp)))
break;
/* Unwind stack frame */
frame = (struct stackframe *)fp - 1;
sp = fp;
if (regs && (regs->epc == pc) && fp_is_valid(frame->ra, sp)) {
/* We hit function where ra is not saved on the stack */
fp = frame->ra;
pc = regs->ra;
} else {
fp = frame->fp;
pc = ftrace_graph_ret_addr(current, &graph_idx, frame->ra,
&frame->ra);
if (pc == (unsigned long)handle_exception) {
if (unlikely(!__kernel_text_address(pc) || !fn(arg, pc)))
break;
pc = ((struct pt_regs *)sp)->epc;
fp = ((struct pt_regs *)sp)->s0;
}
}
}
}
#else /* !CONFIG_FRAME_POINTER */
void notrace walk_stackframe(struct task_struct *task,
struct pt_regs *regs, bool (*fn)(void *, unsigned long), void *arg)
{
unsigned long sp, pc;
unsigned long *ksp;
if (regs) {
sp = user_stack_pointer(regs);
pc = instruction_pointer(regs);
} else if (task == NULL || task == current) {
sp = current_stack_pointer;
pc = (unsigned long)walk_stackframe;
} else {
/* task blocked in __switch_to */
sp = task->thread.sp;
pc = task->thread.ra;
}
if (unlikely(sp & 0x7))
return;
ksp = (unsigned long *)sp;
while (!kstack_end(ksp)) {
if (__kernel_text_address(pc) && unlikely(!fn(arg, pc)))
break;
pc = READ_ONCE_NOCHECK(*ksp++) - 0x4;
}
}
#endif /* CONFIG_FRAME_POINTER */
static bool print_trace_address(void *arg, unsigned long pc)
{
const char *loglvl = arg;
print_ip_sym(loglvl, pc);
return true;
}
noinline void dump_backtrace(struct pt_regs *regs, struct task_struct *task,
const char *loglvl)
{
walk_stackframe(task, regs, print_trace_address, (void *)loglvl);
}
void show_stack(struct task_struct *task, unsigned long *sp, const char *loglvl)
{
pr_cont("%sCall Trace:\n", loglvl);
dump_backtrace(NULL, task, loglvl);
}
static bool save_wchan(void *arg, unsigned long pc)
{
if (!in_sched_functions(pc)) {
unsigned long *p = arg;
*p = pc;
return false;
}
return true;
}
unsigned long __get_wchan(struct task_struct *task)
{
unsigned long pc = 0;
if (!try_get_task_stack(task))
return 0;
walk_stackframe(task, NULL, save_wchan, &pc);
put_task_stack(task);
return pc;
}
noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
struct task_struct *task, struct pt_regs *regs)
{
walk_stackframe(task, regs, consume_entry, cookie);
}
/*
* Get the return address for a single stackframe and return a pointer to the
* next frame tail.
*/
static unsigned long unwind_user_frame(stack_trace_consume_fn consume_entry,
void *cookie, unsigned long fp,
unsigned long reg_ra)
{
struct stackframe buftail;
unsigned long ra = 0;
unsigned long __user *user_frame_tail =
(unsigned long __user *)(fp - sizeof(struct stackframe));
/* Check accessibility of one struct frame_tail beyond */
if (!access_ok(user_frame_tail, sizeof(buftail)))
return 0;
if (__copy_from_user_inatomic(&buftail, user_frame_tail,
sizeof(buftail)))
return 0;
ra = reg_ra ? : buftail.ra;
fp = buftail.fp;
if (!ra || !consume_entry(cookie, ra))
return 0;
return fp;
}
void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
const struct pt_regs *regs)
{
unsigned long fp = 0;
fp = regs->s0;
if (!consume_entry(cookie, regs->epc))
return;
fp = unwind_user_frame(consume_entry, cookie, fp, regs->ra);
while (fp && !(fp & 0x7))
fp = unwind_user_frame(consume_entry, cookie, fp, 0);
}
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