diff options
| -rw-r--r-- | arch/Kconfig | 7 | ||||
| -rw-r--r-- | doc/api/index.rst | 1 | ||||
| -rw-r--r-- | doc/api/setjmp.rst | 10 | ||||
| -rw-r--r-- | include/setjmp.h | 32 |
4 files changed, 50 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index 35b19f9bfdc..14111ca14fb 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -13,6 +13,13 @@ config HAVE_SETJMP help The architecture supports setjmp() and longjmp(). +config HAVE_INITJMP + bool + depends on HAVE_SETJMP + help + The architecture supports initjmp(), a non-standard companion to + setjmp() and longjmp(). + config SUPPORT_BIG_ENDIAN bool diff --git a/doc/api/index.rst b/doc/api/index.rst index a108718ea99..0dc9ad45d41 100644 --- a/doc/api/index.rst +++ b/doc/api/index.rst @@ -25,6 +25,7 @@ U-Boot API documentation rng sandbox serial + setjmp sysreset timer unicode diff --git a/doc/api/setjmp.rst b/doc/api/setjmp.rst new file mode 100644 index 00000000000..7718047085c --- /dev/null +++ b/doc/api/setjmp.rst @@ -0,0 +1,10 @@ +.. SPDX-License-Identifier: GPL-2.0-or-later + +Long jump API +============= + +.. kernel-doc:: include/setjmp.h + :doc: Overview + +.. kernel-doc:: include/setjmp.h + :internal: diff --git a/include/setjmp.h b/include/setjmp.h index 37d3a8af85d..32dd48803e9 100644 --- a/include/setjmp.h +++ b/include/setjmp.h @@ -3,12 +3,27 @@ #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 @@ -37,4 +52,21 @@ int setjmp(jmp_buf env); */ 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_ */ |