1 2/*--------------------------------------------------------------------*/ 3/*--- Support for doing system calls. syscall-x86-linux.S ---*/ 4/*--------------------------------------------------------------------*/ 5 6/* 7 This file is part of Valgrind, a dynamic binary instrumentation 8 framework. 9 10 Copyright (C) 2000-2013 Julian Seward 11 jseward@acm.org 12 13 This program is free software; you can redistribute it and/or 14 modify it under the terms of the GNU General Public License as 15 published by the Free Software Foundation; either version 2 of the 16 License, or (at your option) any later version. 17 18 This program is distributed in the hope that it will be useful, but 19 WITHOUT ANY WARRANTY; without even the implied warranty of 20 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 21 General Public License for more details. 22 23 You should have received a copy of the GNU General Public License 24 along with this program; if not, write to the Free Software 25 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 26 02111-1307, USA. 27 28 The GNU General Public License is contained in the file COPYING. 29*/ 30 31#if defined(VGP_x86_linux) 32 33#include "pub_core_basics_asm.h" 34#include "pub_core_vkiscnums_asm.h" 35#include "libvex_guest_offsets.h" 36 37 38/*----------------------------------------------------------------*/ 39/* 40 Perform a syscall for the client. This will run a syscall 41 with the client's specific per-thread signal mask. 42 43 The structure of this function is such that, if the syscall is 44 interrupted by a signal, we can determine exactly what 45 execution state we were in with respect to the execution of 46 the syscall by examining the value of %eip in the signal 47 handler. This means that we can always do the appropriate 48 thing to precisely emulate the kernel's signal/syscall 49 interactions. 50 51 The syscall number is taken from the argument, even though it 52 should also be in regs->m_eax. The syscall result is written 53 back to regs->m_eax on completion. 54 55 Returns 0 if the syscall was successfully called (even if the 56 syscall itself failed), or a nonzero error code in the lowest 57 8 bits if one of the sigprocmasks failed (there's no way to 58 determine which one failed). And there's no obvious way to 59 recover from that either, but nevertheless we want to know. 60 61 VG_(fixup_guest_state_after_syscall_interrupted) does the 62 thread state fixup in the case where we were interrupted by a 63 signal. 64 65 Prototype: 66 67 UWord ML_(do_syscall_for_client_WRK)( 68 Int syscallno, // 0 69 void* guest_state, // 4 70 const vki_sigset_t *sysmask, // 8 71 const vki_sigset_t *postmask, // 12 72 Int sigsetSzB) // 16 73 74*/ 75 76/* from vki_arch.h */ 77#define VKI_SIG_SETMASK 2 78 79.globl ML_(do_syscall_for_client_WRK) 80ML_(do_syscall_for_client_WRK): 81 .cfi_startproc 82 /* save callee-saved regs */ 83 push %esi 84 .cfi_adjust_cfa_offset 4 85 .cfi_offset %esi, -8 86 push %edi 87 .cfi_adjust_cfa_offset 4 88 .cfi_offset %esi, -12 89 push %ebx 90 .cfi_adjust_cfa_offset 4 91 .cfi_offset %esi, -16 92 push %ebp 93 .cfi_adjust_cfa_offset 4 94 .cfi_offset %esi, -20 95#define FSZ ((4+1)*4) /* 4 args + ret addr */ 96 971: /* Even though we can't take a signal until the sigprocmask completes, 98 start the range early. 99 If eip is in the range [1,2), the syscall hasn't been started yet */ 100 101 /* Set the signal mask which should be current during the syscall. */ 102 movl $ __NR_rt_sigprocmask, %eax 103 movl $ VKI_SIG_SETMASK, %ebx 104 movl 8+FSZ(%esp), %ecx 105 movl 12+FSZ(%esp), %edx 106 movl 16+FSZ(%esp), %esi 107 int $0x80 108 testl %eax, %eax 109 js 7f /* sigprocmask failed */ 110 111 movl 4+FSZ(%esp), %eax /* eax == ThreadState * */ 112 113 movl OFFSET_x86_EBX(%eax), %ebx 114 movl OFFSET_x86_ECX(%eax), %ecx 115 movl OFFSET_x86_EDX(%eax), %edx 116 movl OFFSET_x86_ESI(%eax), %esi 117 movl OFFSET_x86_EDI(%eax), %edi 118 movl OFFSET_x86_EBP(%eax), %ebp 119 movl 0+FSZ(%esp), %eax /* use syscallno argument rather than thread EAX */ 120 121 /* If eip==2, then the syscall was either just about to start, 122 or was interrupted and the kernel was restarting it. */ 1232: int $0x80 1243: /* In the range [3, 4), the syscall result is in %eax, but hasn't been 125 committed to EAX. */ 126 movl 4+FSZ(%esp), %ebx 127 movl %eax, OFFSET_x86_EAX(%ebx) /* save back to EAX */ 128 1294: /* Re-block signals. If eip is in [4,5), then the syscall is complete and 130 we needn't worry about it. */ 131 movl $ __NR_rt_sigprocmask, %eax 132 movl $ VKI_SIG_SETMASK, %ebx 133 movl 12+FSZ(%esp), %ecx 134 xorl %edx, %edx 135 movl 16+FSZ(%esp), %esi 136 int $0x80 137 testl %eax, %eax 138 js 7f /* sigprocmask failed */ 139 1405: /* now safe from signals */ 141 movl $0, %eax /* SUCCESS */ 142 popl %ebp 143 .cfi_adjust_cfa_offset -4 144 popl %ebx 145 .cfi_adjust_cfa_offset -4 146 popl %edi 147 .cfi_adjust_cfa_offset -4 148 popl %esi 149 .cfi_adjust_cfa_offset -4 150 ret 151 .cfi_adjust_cfa_offset 4*4 152 1537: /* failure: return 0x8000 | error code */ 154 negl %eax 155 andl $0x7FFF, %eax 156 orl $0x8000, %eax 157 popl %ebp 158 .cfi_adjust_cfa_offset -4 159 popl %ebx 160 .cfi_adjust_cfa_offset -4 161 popl %edi 162 .cfi_adjust_cfa_offset -4 163 popl %esi 164 .cfi_adjust_cfa_offset -4 165 ret 166 .cfi_endproc 167#undef FSZ 168 169 170.section .rodata 171/* export the ranges so that 172 VG_(fixup_guest_state_after_syscall_interrupted) can do the 173 right thing */ 174 175.globl ML_(blksys_setup) 176.globl ML_(blksys_restart) 177.globl ML_(blksys_complete) 178.globl ML_(blksys_committed) 179.globl ML_(blksys_finished) 180ML_(blksys_setup): .long 1b 181ML_(blksys_restart): .long 2b 182ML_(blksys_complete): .long 3b 183ML_(blksys_committed): .long 4b 184ML_(blksys_finished): .long 5b 185.previous 186 187/* Let the linker know we don't need an executable stack */ 188.section .note.GNU-stack,"",@progbits 189 190#endif // defined(VGP_x86_linux) 191 192/*--------------------------------------------------------------------*/ 193/*--- end ---*/ 194/*--------------------------------------------------------------------*/ 195