1 2 /*--------------------------------------------------------------------*/ 3 /*--- Support for doing system calls. syscall-arm-linux.S ---*/ 4 /*--------------------------------------------------------------------*/ 5 6 /* 7 This file is part of Valgrind, a dynamic binary instrumentation 8 framework. 9 10 Copyright (C) 2008-2015 Evan Geller (gaze (at) bea.ms) 11 12 This program is free software; you can redistribute it and/or 13 modify it under the terms of the GNU General Public License as 14 published by the Free Software Foundation; either version 2 of the 15 License, or (at your option) any later version. 16 17 This program is distributed in the hope that it will be useful, but 18 WITHOUT ANY WARRANTY; without even the implied warranty of 19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 20 General Public License for more details. 21 22 You should have received a copy of the GNU General Public License 23 along with this program; if not, write to the Free Software 24 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 25 02111-1307, USA. 26 27 The GNU General Public License is contained in the file COPYING. 28 */ 29 30 #include "pub_core_basics_asm.h" 31 32 #if defined(VGP_arm_linux) 33 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 IP 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_R7. The syscall result is written 53 back to regs->m_R0 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, // r0 69 void* guest_state, // r1 70 const vki_sigset_t *sysmask, // r2 71 const vki_sigset_t *postmask, // r3 72 Int nsigwords) // [sp, #0] 73 */ 74 /* from vki_arch.h */ 75 #define VKI_SIG_SETMASK 2 76 77 .globl ML_(do_syscall_for_client_WRK) 78 ML_(do_syscall_for_client_WRK): 79 80 /* Stash callee-saves and our args on the stack */ 81 push {r0, r1, r3, r4, r5, r7, fp, lr} 82 83 1: 84 85 mov r7, #__NR_rt_sigprocmask 86 mov r0, #VKI_SIG_SETMASK 87 mov r1, r2 /* sysmask */ 88 mov r2, r3 /* postmask */ 89 ldr r3, [sp, #32] /* nsigwords */ 90 svc 0x00000000 91 92 93 ldr r5, [sp, #4] /* guest_state */ 94 95 ldr r7, [sp, #0] /* syscall# */ 96 ldr r0, [r5, #OFFSET_arm_R0] 97 ldr r1, [r5, #OFFSET_arm_R1] 98 ldr r2, [r5, #OFFSET_arm_R2] 99 ldr r3, [r5, #OFFSET_arm_R3] 100 ldr r4, [r5, #OFFSET_arm_R4] 101 ldr r5, [r5, #OFFSET_arm_R5] 102 103 2: svc 0x00000000 104 3: 105 ldr r5, [sp, #4] /* guest_state */ 106 str r0, [r5, #OFFSET_arm_R0] 107 108 4: 109 mov r7, #__NR_rt_sigprocmask 110 mov r0, #VKI_SIG_SETMASK 111 ldr r1, [sp, #8] /* postmask */ 112 mov r2, #0 113 ldr r3, [sp, #32] /* nsigwords */ 114 svc 0x00000000 115 116 cmp r0, #0 117 blt 7f 118 add sp, sp, #4 /* r0 contains return value */ 119 120 5: /* Success */ 121 mov r0, #0 122 pop {r1, r3, r4, r5, r7, fp, pc} 123 124 7: /* Failure: return 0x8000 | error code */ 125 orr r0, r0, #0x8000 126 pop {r1, r3, r4, r5, r7, fp, pc} 127 128 129 .section .rodata 130 /* export the ranges so that 131 VG_(fixup_guest_state_after_syscall_interrupted) can do the 132 right thing */ 133 134 .globl ML_(blksys_setup) 135 .globl ML_(blksys_restart) 136 .globl ML_(blksys_complete) 137 .globl ML_(blksys_committed) 138 .globl ML_(blksys_finished) 139 ML_(blksys_setup): .long 1b 140 ML_(blksys_restart): .long 2b 141 ML_(blksys_complete): .long 3b 142 ML_(blksys_committed): .long 4b 143 ML_(blksys_finished): .long 5b 144 145 #endif // defined(VGP_arm_linux) 146 147 /* Let the linker know we don't need an executable stack */ 148 MARK_STACK_NO_EXEC 149 150 /*--------------------------------------------------------------------*/ 151 /*--- end ---*/ 152 /*--------------------------------------------------------------------*/ 153