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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_S390_UNWIND_H
#define _ASM_S390_UNWIND_H
#include <linux/sched.h>
#include <linux/ftrace.h>
#include <asm/ptrace.h>
#include <asm/stacktrace.h>
/*
* To use the stack unwinder it has to be initialized with unwind_start.
* There four combinations for task and regs:
* 1) task==NULL, regs==NULL: the unwind starts for the task that is currently
* running, sp/ip picked up from the CPU registers
* 2) task==NULL, regs!=NULL: the unwind starts from the sp/ip found in
* the struct pt_regs of an interrupt frame for the current task
* 3) task!=NULL, regs==NULL: the unwind starts for an inactive task with
* the sp picked up from task->thread.ksp and the ip picked up from the
* return address stored by __switch_to
* 4) task!=NULL, regs!=NULL: the sp/ip are picked up from the interrupt
* frame 'regs' of a inactive task
* If 'first_frame' is not zero unwind_start skips unwind frames until it
* reaches the specified stack pointer.
* The end of the unwinding is indicated with unwind_done, this can be true
* right after unwind_start, e.g. with first_frame!=0 that can not be found.
* unwind_next_frame skips to the next frame.
* Once the unwind is completed unwind_error() can be used to check if there
* has been a situation where the unwinder could not correctly understand
* the tasks call chain.
*/
struct unwind_state {
struct stack_info stack_info;
unsigned long stack_mask;
struct task_struct *task;
struct pt_regs *regs;
unsigned long sp, ip;
int graph_idx;
bool reliable;
bool error;
};
void __unwind_start(struct unwind_state *state, struct task_struct *task,
struct pt_regs *regs, unsigned long first_frame);
bool unwind_next_frame(struct unwind_state *state);
unsigned long unwind_get_return_address(struct unwind_state *state);
static inline bool unwind_done(struct unwind_state *state)
{
return state->stack_info.type == STACK_TYPE_UNKNOWN;
}
static inline bool unwind_error(struct unwind_state *state)
{
return state->error;
}
static inline void unwind_start(struct unwind_state *state,
struct task_struct *task,
struct pt_regs *regs,
unsigned long sp)
{
sp = sp ? : get_stack_pointer(task, regs);
__unwind_start(state, task, regs, sp);
}
static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state)
{
return unwind_done(state) ? NULL : state->regs;
}
#define unwind_for_each_frame(state, task, regs, first_frame) \
for (unwind_start(state, task, regs, first_frame); \
!unwind_done(state); \
unwind_next_frame(state))
static inline void unwind_init(void) {}
static inline void unwind_module_init(struct module *mod, void *orc_ip,
size_t orc_ip_size, void *orc,
size_t orc_size) {}
#ifdef CONFIG_KASAN
/*
* This disables KASAN checking when reading a value from another task's stack,
* since the other task could be running on another CPU and could have poisoned
* the stack in the meantime.
*/
#define READ_ONCE_TASK_STACK(task, x) \
({ \
unsigned long val; \
if (task == current) \
val = READ_ONCE(x); \
else \
val = READ_ONCE_NOCHECK(x); \
val; \
})
#else
#define READ_ONCE_TASK_STACK(task, x) READ_ONCE(x)
#endif
#endif /* _ASM_S390_UNWIND_H */
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