| /* POSIX.1 `sigaction' call for Linux/x86-64. |
| Copyright (C) 2001-2018 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/>. */ |
| |
| #include <sysdep.h> |
| #include <errno.h> |
| #include <stddef.h> |
| #include <signal.h> |
| #include <string.h> |
| |
| #include <sysdep.h> |
| #include <sys/syscall.h> |
| |
| /* The difference here is that the sigaction structure used in the |
| kernel is not the same as we use in the libc. Therefore we must |
| translate it here. */ |
| #include <kernel_sigaction.h> |
| |
| #include "ucontext_i.h" |
| |
| /* We do not globally define the SA_RESTORER flag so do it here. */ |
| #define SA_RESTORER 0x04000000 |
| |
| /* Using the hidden attribute here does not change the code but it |
| helps to avoid warnings. */ |
| extern void restore_rt (void) asm ("__restore_rt") attribute_hidden; |
| |
| |
| /* If ACT is not NULL, change the action for SIG to *ACT. |
| If OACT is not NULL, put the old action for SIG in *OACT. */ |
| int |
| __libc_sigaction (int sig, const struct sigaction *act, struct sigaction *oact) |
| { |
| int result; |
| struct kernel_sigaction kact, koact; |
| |
| if (act) |
| { |
| kact.k_sa_handler = act->sa_handler; |
| memcpy (&kact.sa_mask, &act->sa_mask, sizeof (sigset_t)); |
| kact.sa_flags = act->sa_flags | SA_RESTORER; |
| |
| kact.sa_restorer = &restore_rt; |
| } |
| |
| /* XXX The size argument hopefully will have to be changed to the |
| real size of the user-level sigset_t. */ |
| result = INLINE_SYSCALL (rt_sigaction, 4, |
| sig, act ? &kact : NULL, |
| oact ? &koact : NULL, _NSIG / 8); |
| if (oact && result >= 0) |
| { |
| oact->sa_handler = koact.k_sa_handler; |
| memcpy (&oact->sa_mask, &koact.sa_mask, sizeof (sigset_t)); |
| oact->sa_flags = koact.sa_flags; |
| oact->sa_restorer = koact.sa_restorer; |
| } |
| return result; |
| } |
| libc_hidden_def (__libc_sigaction) |
| |
| #include <nptl/sigaction.c> |
| |
| |
| /* NOTE: Please think twice before making any changes to the bits of |
| code below. GDB needs some intimate knowledge about it to |
| recognize them as signal trampolines, and make backtraces through |
| signal handlers work right. Important are both the names |
| (__restore_rt) and the exact instruction sequence. |
| If you ever feel the need to make any changes, please notify the |
| appropriate GDB maintainer. |
| |
| The unwind information starts a byte before __restore_rt, so that |
| it is found when unwinding, to get an address the unwinder assumes |
| will be in the middle of a call instruction. See the Linux kernel |
| (the i386 vsyscall, in particular) for an explanation of the complex |
| unwind information used here in order to get the traditional CFA. |
| We do not restore cs - it's only stored as two bytes here so that's |
| a bit tricky. We don't use the gas cfi directives, so that we can |
| reliably add .cfi_signal_frame. */ |
| |
| #define do_cfa_expr \ |
| " .byte 0x0f\n" /* DW_CFA_def_cfa_expression */ \ |
| " .uleb128 2f-1f\n" /* length */ \ |
| "1: .byte 0x77\n" /* DW_OP_breg7 */ \ |
| " .sleb128 " CFI_STRINGIFY (oRSP) "\n" \ |
| " .byte 0x06\n" /* DW_OP_deref */ \ |
| "2:" |
| |
| #define do_expr(regno, offset) \ |
| " .byte 0x10\n" /* DW_CFA_expression */ \ |
| " .uleb128 " CFI_STRINGIFY (regno) "\n" \ |
| " .uleb128 2f-1f\n" /* length */ \ |
| "1: .byte 0x77\n" /* DW_OP_breg7 */ \ |
| " .sleb128 " CFI_STRINGIFY (offset) "\n" \ |
| "2:" |
| |
| #define RESTORE(name, syscall) RESTORE2 (name, syscall) |
| # define RESTORE2(name, syscall) \ |
| asm \ |
| ( \ |
| /* `nop' for debuggers assuming `call' should not disalign the code. */ \ |
| " nop\n" \ |
| ".align 16\n" \ |
| ".LSTART_" #name ":\n" \ |
| " .type __" #name ",@function\n" \ |
| "__" #name ":\n" \ |
| " movq $" #syscall ", %rax\n" \ |
| " syscall\n" \ |
| ".LEND_" #name ":\n" \ |
| ".section .eh_frame,\"a\",@progbits\n" \ |
| ".LSTARTFRAME_" #name ":\n" \ |
| " .long .LENDCIE_" #name "-.LSTARTCIE_" #name "\n" \ |
| ".LSTARTCIE_" #name ":\n" \ |
| " .long 0\n" /* CIE ID */ \ |
| " .byte 1\n" /* Version number */ \ |
| " .string \"zRS\"\n" /* NUL-terminated augmentation string */ \ |
| " .uleb128 1\n" /* Code alignment factor */ \ |
| " .sleb128 -8\n" /* Data alignment factor */ \ |
| " .uleb128 16\n" /* Return address register column (rip) */ \ |
| /* Augmentation value length */ \ |
| " .uleb128 .LENDAUGMNT_" #name "-.LSTARTAUGMNT_" #name "\n" \ |
| ".LSTARTAUGMNT_" #name ":\n" \ |
| " .byte 0x1b\n" /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */ \ |
| ".LENDAUGMNT_" #name ":\n" \ |
| " .align " LP_SIZE "\n" \ |
| ".LENDCIE_" #name ":\n" \ |
| " .long .LENDFDE_" #name "-.LSTARTFDE_" #name "\n" /* FDE len */ \ |
| ".LSTARTFDE_" #name ":\n" \ |
| " .long .LSTARTFDE_" #name "-.LSTARTFRAME_" #name "\n" /* CIE */ \ |
| /* `LSTART_' is subtracted 1 as debuggers assume a `call' here. */ \ |
| " .long (.LSTART_" #name "-1)-.\n" /* PC-relative start addr. */ \ |
| " .long .LEND_" #name "-(.LSTART_" #name "-1)\n" \ |
| " .uleb128 0\n" /* FDE augmentation length */ \ |
| do_cfa_expr \ |
| do_expr (8 /* r8 */, oR8) \ |
| do_expr (9 /* r9 */, oR9) \ |
| do_expr (10 /* r10 */, oR10) \ |
| do_expr (11 /* r11 */, oR11) \ |
| do_expr (12 /* r12 */, oR12) \ |
| do_expr (13 /* r13 */, oR13) \ |
| do_expr (14 /* r14 */, oR14) \ |
| do_expr (15 /* r15 */, oR15) \ |
| do_expr (5 /* rdi */, oRDI) \ |
| do_expr (4 /* rsi */, oRSI) \ |
| do_expr (6 /* rbp */, oRBP) \ |
| do_expr (3 /* rbx */, oRBX) \ |
| do_expr (1 /* rdx */, oRDX) \ |
| do_expr (0 /* rax */, oRAX) \ |
| do_expr (2 /* rcx */, oRCX) \ |
| do_expr (7 /* rsp */, oRSP) \ |
| do_expr (16 /* rip */, oRIP) \ |
| /* libgcc-4.1.1 has only `DWARF_FRAME_REGISTERS == 17'. */ \ |
| /* do_expr (49 |* rflags *|, oEFL) */ \ |
| /* `cs'/`ds'/`fs' are unaligned and a different size. */ \ |
| /* gas: Error: register save offset not a multiple of 8 */ \ |
| " .align " LP_SIZE "\n" \ |
| ".LENDFDE_" #name ":\n" \ |
| " .previous\n" \ |
| ); |
| /* The return code for realtime-signals. */ |
| RESTORE (restore_rt, __NR_rt_sigreturn) |
