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// SPDX-License-Identifier: GPL-2.0
/*
* Stack trace management functions
*
* Copyright (C) 2022 Loongson Technology Corporation Limited
*/
#include <linux/sched.h>
#include <linux/stacktrace.h>
#include <linux/uaccess.h>
#include <asm/stacktrace.h>
#include <asm/unwind.h>
void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
struct task_struct *task, struct pt_regs *regs)
{
unsigned long addr;
struct pt_regs dummyregs;
struct unwind_state state;
if (!regs) {
regs = &dummyregs;
if (task == current) {
regs->regs[3] = (unsigned long)__builtin_frame_address(0);
regs->csr_era = (unsigned long)__builtin_return_address(0);
} else {
regs->regs[3] = thread_saved_fp(task);
regs->csr_era = thread_saved_ra(task);
}
regs->regs[1] = 0;
regs->regs[22] = 0;
}
for (unwind_start(&state, task, regs);
!unwind_done(&state); unwind_next_frame(&state)) {
addr = unwind_get_return_address(&state);
if (!addr || !consume_entry(cookie, addr))
break;
}
}
int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry,
void *cookie, struct task_struct *task)
{
unsigned long addr;
struct pt_regs dummyregs;
struct pt_regs *regs = &dummyregs;
struct unwind_state state;
if (task == current) {
regs->regs[3] = (unsigned long)__builtin_frame_address(0);
regs->csr_era = (unsigned long)__builtin_return_address(0);
} else {
regs->regs[3] = thread_saved_fp(task);
regs->csr_era = thread_saved_ra(task);
}
regs->regs[1] = 0;
regs->regs[22] = 0;
for (unwind_start(&state, task, regs);
!unwind_done(&state) && !unwind_error(&state); unwind_next_frame(&state)) {
addr = unwind_get_return_address(&state);
/*
* A NULL or invalid return address probably means there's some
* generated code which __kernel_text_address() doesn't know about.
*/
if (!addr)
return -EINVAL;
if (!consume_entry(cookie, addr))
return -EINVAL;
}
/* Check for stack corruption */
if (unwind_error(&state))
return -EINVAL;
return 0;
}
static int
copy_stack_frame(unsigned long fp, struct stack_frame *frame)
{
int ret = 1;
unsigned long err;
unsigned long __user *user_frame_tail;
user_frame_tail = (unsigned long *)(fp - sizeof(struct stack_frame));
if (!access_ok(user_frame_tail, sizeof(*frame)))
return 0;
pagefault_disable();
err = (__copy_from_user_inatomic(frame, user_frame_tail, sizeof(*frame)));
if (err || (unsigned long)user_frame_tail >= frame->fp)
ret = 0;
pagefault_enable();
return ret;
}
void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
const struct pt_regs *regs)
{
unsigned long fp = regs->regs[22];
while (fp && !((unsigned long)fp & 0xf)) {
struct stack_frame frame;
frame.fp = 0;
frame.ra = 0;
if (!copy_stack_frame(fp, &frame))
break;
if (!frame.ra)
break;
if (!consume_entry(cookie, frame.ra))
break;
fp = frame.fp;
}
}
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