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/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef _SETJMP_H_
#define _SETJMP_H_ 1
/**
* DOC: Overview
*
* The long jump API allows to perform nonlocal gotos, that is jump from one
* function to another typically further down in the stack, while properly
* restoring the stack's state (unwinding). The two functions needed to do this
* are setjmp() and longjmp().
*
* In addition to these two standard POSIX.1-2001/C89 functions, a third one is
* present in U-Boot: initjmp(). It is an extension which allows to implement
* user-mode threads.
*/
#ifdef CONFIG_HAVE_SETJMP
#include <asm/setjmp.h>
#else
struct jmp_buf_data {
};
#endif
#include <linux/compiler_attributes.h>
#include <stddef.h>
/**
* typedef jmp_buf - information needed to restore a calling environment
*/
typedef struct jmp_buf_data jmp_buf[1];
/**
* setjmp() - prepare for a long jump
*
* Registers, the stack pointer, and the return address are saved in the
* jump bufffer. The function returns zero afterwards. When longjmp() is
* executed the function returns a second time with a non-zero value.
*
* @env: jump buffer used to store register values
* Return: 0 after setting up jump buffer, non-zero after longjmp()
*/
int setjmp(jmp_buf env);
/**
* longjmp() - long jump
*
* Jump back to the address and the register state saved by setjmp().
*
* @env: jump buffer
* @val: value to be returned by setjmp(), 0 is replaced by 1
*/
void longjmp(jmp_buf env, int val);
/**
* initjmp() - prepare for a long jump to a given function with a given stack
*
* This function sets up a jump buffer for later use with longjmp(). It allows
* to branch to a specific function with a specific stack. Please note that
* @func MUST NOT return. It shall typically restore the main stack and resume
* execution by doing a long jump to a jump buffer initialized by setjmp()
* before the long jump. initjmp() allows to implement multithreading.
*
* @env: jump buffer
* @func: function to be called on longjmp(), MUST NOT RETURN
* @stack_base: the stack to be used by @func (lower address)
* @stack_sz: the stack size in bytes
*/
int initjmp(jmp_buf env, void __noreturn (*func)(void), void *stack_base,
size_t stack_sz);
#endif /* _SETJMP_H_ */
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