1  /* POSIX.1 `sigaction' call for Linux/i386.
       2     Copyright (C) 1991-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <signal.h>
      20  #include <ldsodefs.h>
      21  
      22  #define SA_RESTORER 0x04000000
      23  
      24  extern void restore_rt (void) asm ("__restore_rt") attribute_hidden;
      25  extern void restore (void) asm ("__restore") attribute_hidden;
      26  
      27  #define SET_SA_RESTORER(kact, act)				\
      28    ({								\
      29       if (GLRO(dl_sysinfo_dso) == NULL)				\
      30         {							\
      31  	 (kact)->sa_flags |= SA_RESTORER;			\
      32           (kact)->sa_restorer = (((act)->sa_flags & SA_SIGINFO)	\
      33  			       ? &restore_rt : &restore);	\
      34         }							\
      35       else							\
      36         (kact)->sa_restorer = NULL;				\
      37    })
      38  
      39  #define RESET_SA_RESTORER(act, kact) \
      40    (act)->sa_restorer = (kact)->sa_restorer
      41  
      42  #include <sysdeps/unix/sysv/linux/libc_sigaction.c>
      43  
      44  /* NOTE: Please think twice before making any changes to the bits of
      45     code below.  GDB needs some intimate knowledge about it to
      46     recognize them as signal trampolines, and make backtraces through
      47     signal handlers work right.  Important are both the names
      48     (__restore and __restore_rt) and the exact instruction sequence.
      49     If you ever feel the need to make any changes, please notify the
      50     appropriate GDB maintainer.  */
      51  
      52  #define RESTORE(name, syscall) RESTORE2 (name, syscall)
      53  #define RESTORE2(name, syscall) \
      54  asm						\
      55    (						\
      56     ".text\n"					\
      57     "	.align 16\n"				\
      58     "__" #name ":\n"				\
      59     "	movl $" #syscall ", %eax\n"		\
      60     "	int  $0x80"				\
      61     );
      62  
      63  /* The return code for realtime-signals.  */
      64  RESTORE (restore_rt, __NR_rt_sigreturn)
      65  
      66  /* For the boring old signals.  */
      67  #undef RESTORE2
      68  #define RESTORE2(name, syscall) \
      69  asm						\
      70    (						\
      71     ".text\n"					\
      72     "	.align 8\n"				\
      73     "__" #name ":\n"				\
      74     "	popl %eax\n"				\
      75     "	movl $" #syscall ", %eax\n"		\
      76     "	int  $0x80"				\
      77     );
      78  
      79  RESTORE (restore, __NR_sigreturn)