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) 2000-2012 Julian Seward 11 jseward (at) 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) 80 ML_(do_syscall_for_client_WRK): 81 /* save callee-saved regs */ 82 push %esi 83 push %edi 84 push %ebx 85 push %ebp 86 #define FSZ ((4+1)*4) /* 4 args + ret addr */ 87 88 1: /* Even though we can't take a signal until the sigprocmask completes, 89 start the range early. 90 If eip is in the range [1,2), the syscall hasn't been started yet */ 91 92 /* Set the signal mask which should be current during the syscall. */ 93 movl $ __NR_rt_sigprocmask, %eax 94 movl $ VKI_SIG_SETMASK, %ebx 95 movl 8+FSZ(%esp), %ecx 96 movl 12+FSZ(%esp), %edx 97 movl 16+FSZ(%esp), %esi 98 int $0x80 99 testl %eax, %eax 100 js 7f /* sigprocmask failed */ 101 102 movl 4+FSZ(%esp), %eax /* eax == ThreadState * */ 103 104 movl OFFSET_x86_EBX(%eax), %ebx 105 movl OFFSET_x86_ECX(%eax), %ecx 106 movl OFFSET_x86_EDX(%eax), %edx 107 movl OFFSET_x86_ESI(%eax), %esi 108 movl OFFSET_x86_EDI(%eax), %edi 109 movl OFFSET_x86_EBP(%eax), %ebp 110 movl 0+FSZ(%esp), %eax /* use syscallno argument rather than thread EAX */ 111 112 /* If eip==2, then the syscall was either just about to start, 113 or was interrupted and the kernel was restarting it. */ 114 2: int $0x80 115 3: /* In the range [3, 4), the syscall result is in %eax, but hasn't been 116 committed to EAX. */ 117 movl 4+FSZ(%esp), %ebx 118 movl %eax, OFFSET_x86_EAX(%ebx) /* save back to EAX */ 119 120 4: /* Re-block signals. If eip is in [4,5), then the syscall is complete and 121 we needn't worry about it. */ 122 movl $ __NR_rt_sigprocmask, %eax 123 movl $ VKI_SIG_SETMASK, %ebx 124 movl 12+FSZ(%esp), %ecx 125 xorl %edx, %edx 126 movl 16+FSZ(%esp), %esi 127 int $0x80 128 testl %eax, %eax 129 js 7f /* sigprocmask failed */ 130 131 5: /* now safe from signals */ 132 movl $0, %eax /* SUCCESS */ 133 popl %ebp 134 popl %ebx 135 popl %edi 136 popl %esi 137 ret 138 139 7: /* failure: return 0x8000 | error code */ 140 negl %eax 141 andl $0x7FFF, %eax 142 orl $0x8000, %eax 143 popl %ebp 144 popl %ebx 145 popl %edi 146 popl %esi 147 ret 148 #undef FSZ 149 150 151 .section .rodata 152 /* export the ranges so that 153 VG_(fixup_guest_state_after_syscall_interrupted) can do the 154 right thing */ 155 156 .globl ML_(blksys_setup) 157 .globl ML_(blksys_restart) 158 .globl ML_(blksys_complete) 159 .globl ML_(blksys_committed) 160 .globl ML_(blksys_finished) 161 ML_(blksys_setup): .long 1b 162 ML_(blksys_restart): .long 2b 163 ML_(blksys_complete): .long 3b 164 ML_(blksys_committed): .long 4b 165 ML_(blksys_finished): .long 5b 166 .previous 167 168 /* Let the linker know we don't need an executable stack */ 169 .section .note.GNU-stack,"",@progbits 170 171 #endif // defined(VGP_x86_linux) 172 173 /*--------------------------------------------------------------------*/ 174 /*--- end ---*/ 175 /*--------------------------------------------------------------------*/ 176
