| /* Assembly code template for system call stubs. |
| Copyright (C) 2009-2018 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| /* The real guts of this work are in the macros defined in the |
| machine- and kernel-specific sysdep.h header file. Cancellable syscalls |
| should be implemented using C implementation with SYSCALL_CANCEL macro. |
| |
| Each system call's object is built by a rule in sysd-syscalls |
| generated by make-syscalls.sh that #include's this file after |
| defining a few macros: |
| SYSCALL_NAME syscall name |
| SYSCALL_NARGS number of arguments this call takes |
| SYSCALL_SYMBOL primary symbol name |
| SYSCALL_NOERRNO 1 to define a no-errno version (see below) |
| SYSCALL_ERRVAL 1 to define an error-value version (see below) |
| |
| We used to simply pipe the correct three lines below through cpp into |
| the assembler. The main reason to have this file instead is so that |
| stub objects can be assembled with -g and get source line information |
| that leads a user back to a source file and these fine comments. The |
| average user otherwise has a hard time knowing which "syscall-like" |
| functions in libc are plain stubs and which have nontrivial C wrappers. |
| Some versions of the "plain" stub generation macros are more than a few |
| instructions long and the untrained eye might not distinguish them from |
| some compiled code that inexplicably lacks source line information. */ |
| |
| #include <sysdep.h> |
| |
| /* This indirection is needed so that SYMBOL gets macro-expanded. */ |
| #define syscall_hidden_def(SYMBOL) hidden_def (SYMBOL) |
| |
| #define T_PSEUDO(SYMBOL, NAME, N) PSEUDO (SYMBOL, NAME, N) |
| #define T_PSEUDO_NOERRNO(SYMBOL, NAME, N) PSEUDO_NOERRNO (SYMBOL, NAME, N) |
| #define T_PSEUDO_ERRVAL(SYMBOL, NAME, N) PSEUDO_ERRVAL (SYMBOL, NAME, N) |
| #define T_PSEUDO_END(SYMBOL) PSEUDO_END (SYMBOL) |
| #define T_PSEUDO_END_NOERRNO(SYMBOL) PSEUDO_END_NOERRNO (SYMBOL) |
| #define T_PSEUDO_END_ERRVAL(SYMBOL) PSEUDO_END_ERRVAL (SYMBOL) |
| |
| #if SYSCALL_NOERRNO |
| |
| /* This kind of system call stub never returns an error. |
| We return the return value register to the caller unexamined. */ |
| |
| T_PSEUDO_NOERRNO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS) |
| ret_NOERRNO |
| T_PSEUDO_END_NOERRNO (SYSCALL_SYMBOL) |
| |
| #elif SYSCALL_ERRVAL |
| |
| /* This kind of system call stub returns the errno code as its return |
| value, or zero for success. We may massage the kernel's return value |
| to meet that ABI, but we never set errno here. */ |
| |
| T_PSEUDO_ERRVAL (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS) |
| ret_ERRVAL |
| T_PSEUDO_END_ERRVAL (SYSCALL_SYMBOL) |
| |
| #else |
| |
| /* This is a "normal" system call stub: if there is an error, |
| it returns -1 and sets errno. */ |
| |
| T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS) |
| ret |
| T_PSEUDO_END (SYSCALL_SYMBOL) |
| |
| #endif |
| |
| syscall_hidden_def (SYSCALL_SYMBOL) |