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/* SPDX-License-Identifier: GPL-2.0 */
#include <linux/sched.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
#include <linux/interrupt.h>
#include <asm/sections.h>
#include <asm/ptrace.h>
#include <asm/bitops.h>
#include <asm/stacktrace.h>
#include <asm/unwind.h>
unsigned long unwind_get_return_address(struct unwind_state *state)
{
if (unwind_done(state))
return 0;
return __kernel_text_address(state->ip) ? state->ip : 0;
}
EXPORT_SYMBOL_GPL(unwind_get_return_address);
static bool outside_of_stack(struct unwind_state *state, unsigned long sp)
{
return (sp <= state->sp) ||
(sp > state->stack_info.end - sizeof(struct stack_frame));
}
static bool update_stack_info(struct unwind_state *state, unsigned long sp)
{
struct stack_info *info = &state->stack_info;
unsigned long *mask = &state->stack_mask;
/* New stack pointer leaves the current stack */
if (get_stack_info(sp, state->task, info, mask) != 0 ||
!on_stack(info, sp, sizeof(struct stack_frame)))
/* 'sp' does not point to a valid stack */
return false;
return true;
}
bool unwind_next_frame(struct unwind_state *state)
{
struct stack_info *info = &state->stack_info;
struct stack_frame *sf;
struct pt_regs *regs;
unsigned long sp, ip;
bool reliable;
regs = state->regs;
if (unlikely(regs)) {
if (state->reuse_sp) {
sp = state->sp;
state->reuse_sp = false;
} else {
sp = READ_ONCE_NOCHECK(regs->gprs[15]);
if (unlikely(outside_of_stack(state, sp))) {
if (!update_stack_info(state, sp))
goto out_err;
}
}
sf = (struct stack_frame *) sp;
ip = READ_ONCE_NOCHECK(sf->gprs[8]);
reliable = false;
regs = NULL;
} else {
sf = (struct stack_frame *) state->sp;
sp = READ_ONCE_NOCHECK(sf->back_chain);
if (likely(sp)) {
/* Non-zero back-chain points to the previous frame */
if (unlikely(outside_of_stack(state, sp))) {
if (!update_stack_info(state, sp))
goto out_err;
}
sf = (struct stack_frame *) sp;
ip = READ_ONCE_NOCHECK(sf->gprs[8]);
reliable = true;
} else {
/* No back-chain, look for a pt_regs structure */
sp = state->sp + STACK_FRAME_OVERHEAD;
if (!on_stack(info, sp, sizeof(struct pt_regs)))
goto out_stop;
regs = (struct pt_regs *) sp;
if (READ_ONCE_NOCHECK(regs->psw.mask) & PSW_MASK_PSTATE)
goto out_stop;
ip = READ_ONCE_NOCHECK(regs->psw.addr);
reliable = true;
}
}
ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, (void *) sp);
/* Update unwind state */
state->sp = sp;
state->ip = ip;
state->regs = regs;
state->reliable = reliable;
return true;
out_err:
state->error = true;
out_stop:
state->stack_info.type = STACK_TYPE_UNKNOWN;
return false;
}
EXPORT_SYMBOL_GPL(unwind_next_frame);
void __unwind_start(struct unwind_state *state, struct task_struct *task,
struct pt_regs *regs, unsigned long sp)
{
struct stack_info *info = &state->stack_info;
unsigned long *mask = &state->stack_mask;
bool reliable, reuse_sp;
struct stack_frame *sf;
unsigned long ip;
memset(state, 0, sizeof(*state));
state->task = task;
state->regs = regs;
/* Don't even attempt to start from user mode regs: */
if (regs && user_mode(regs)) {
info->type = STACK_TYPE_UNKNOWN;
return;
}
/* Get current stack pointer and initialize stack info */
if (get_stack_info(sp, task, info, mask) != 0 ||
!on_stack(info, sp, sizeof(struct stack_frame))) {
/* Something is wrong with the stack pointer */
info->type = STACK_TYPE_UNKNOWN;
state->error = true;
return;
}
/* Get the instruction pointer from pt_regs or the stack frame */
if (regs) {
ip = READ_ONCE_NOCHECK(regs->psw.addr);
reliable = true;
reuse_sp = true;
} else {
sf = (struct stack_frame *) sp;
ip = READ_ONCE_NOCHECK(sf->gprs[8]);
reliable = false;
reuse_sp = false;
}
ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, NULL);
/* Update unwind state */
state->sp = sp;
state->ip = ip;
state->reliable = reliable;
state->reuse_sp = reuse_sp;
}
EXPORT_SYMBOL_GPL(__unwind_start);
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