1 2 /*--------------------------------------------------------------------*/ 3 /*--- Create/destroy signal delivery frames. ---*/ 4 /*--- sigframe-x86-darwin.c ---*/ 5 /*--------------------------------------------------------------------*/ 6 7 /* 8 This file is part of Valgrind, a dynamic binary instrumentation 9 framework. 10 11 Copyright (C) 2006-2013 OpenWorks Ltd 12 info (at) open-works.co.uk 13 14 This program is free software; you can redistribute it and/or 15 modify it under the terms of the GNU General Public License as 16 published by the Free Software Foundation; either version 2 of the 17 License, or (at your option) any later version. 18 19 This program is distributed in the hope that it will be useful, but 20 WITHOUT ANY WARRANTY; without even the implied warranty of 21 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 22 General Public License for more details. 23 24 You should have received a copy of the GNU General Public License 25 along with this program; if not, write to the Free Software 26 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 27 02111-1307, USA. 28 29 The GNU General Public License is contained in the file COPYING. 30 */ 31 32 #if defined(VGP_x86_darwin) 33 34 #include "pub_core_basics.h" 35 #include "pub_core_vki.h" 36 #include "pub_core_vkiscnums.h" 37 #include "pub_core_libcsetjmp.h" // to keep _threadstate.h happy 38 #include "pub_core_threadstate.h" 39 #include "pub_core_aspacemgr.h" 40 #include "pub_core_libcbase.h" 41 #include "pub_core_libcassert.h" 42 #include "pub_core_libcprint.h" 43 #include "pub_core_machine.h" 44 #include "pub_core_options.h" 45 #include "pub_core_signals.h" 46 #include "pub_core_tooliface.h" 47 #include "pub_core_trampoline.h" 48 #include "pub_core_sigframe.h" /* self */ 49 50 51 /* Cheap-ass hack copied from ppc32-aix5 code, just to get started. 52 Produce a frame with layout entirely of our own choosing. */ 53 54 /* This module creates and removes signal frames for signal deliveries 55 on x86-darwin. Kludgey; the machine state ought to be saved in a 56 ucontext and retrieved from it later, so the handler can modify it 57 and return. However .. for now .. just stick the vex guest state 58 in the frame and snarf it again later. 59 60 Also, don't bother with creating siginfo and ucontext in the 61 handler, although do point them somewhere non-faulting. 62 63 Frame should have a 16-aligned size, just in case that turns out to 64 be important for Darwin. (be conservative) 65 */ 66 struct hacky_sigframe { 67 /* first four words look like a call to a 3-arg x86 function */ 68 UInt returnAddr; 69 UInt a1_signo; 70 UInt a2_siginfo; 71 UInt a3_ucontext; 72 UChar lower_guardzone[512]; // put nothing here 73 VexGuestX86State gst; 74 VexGuestX86State gshadow1; 75 VexGuestX86State gshadow2; 76 vki_siginfo_t fake_siginfo; 77 struct vki_ucontext fake_ucontext; 78 UInt magicPI; 79 UInt sigNo_private; 80 vki_sigset_t mask; // saved sigmask; restore when hdlr returns 81 UInt __pad[1]; 82 UChar upper_guardzone[512]; // put nothing here 83 // and don't zero it, since that might overwrite the client's 84 // stack redzone, at least on archs which have one 85 }; 86 87 88 /* Extend the stack segment downwards if needed so as to ensure the 89 new signal frames are mapped to something. Return a Bool 90 indicating whether or not the operation was successful. 91 */ 92 static Bool extend ( ThreadState *tst, Addr addr, SizeT size ) 93 { 94 ThreadId tid = tst->tid; 95 /* For tracking memory events, indicate the entire frame has been 96 allocated. Except, don't mess with the area which 97 overlaps the previous frame's redzone. */ 98 /* XXX is the following call really right? compared with the 99 amd64-linux version, this doesn't appear to handle the redzone 100 in the same way. */ 101 VG_TRACK( new_mem_stack_signal, 102 addr - VG_STACK_REDZONE_SZB, size, tid ); 103 return True; 104 } 105 106 107 /* Create a signal frame for thread 'tid'. Make a 3-arg frame 108 regardless of whether the client originally requested a 1-arg 109 version (no SA_SIGINFO) or a 3-arg one (SA_SIGINFO) since in the 110 former case, the x86 calling conventions will simply cause the 111 extra 2 args to be ignored (inside the handler). */ 112 void VG_(sigframe_create) ( ThreadId tid, 113 Addr sp_top_of_frame, 114 const vki_siginfo_t *siginfo, 115 const struct vki_ucontext *siguc, 116 void *handler, 117 UInt flags, 118 const vki_sigset_t *mask, 119 void *restorer ) 120 { 121 ThreadState* tst; 122 Addr esp; 123 struct hacky_sigframe* frame; 124 Int sigNo = siginfo->si_signo; 125 126 vg_assert(VG_IS_16_ALIGNED(sizeof(struct hacky_sigframe))); 127 128 sp_top_of_frame &= ~0xf; 129 esp = sp_top_of_frame - sizeof(struct hacky_sigframe); 130 esp -= 4; /* ELF ABI says that esp+4 must be 16 aligned on 131 entry to a function. */ 132 133 tst = VG_(get_ThreadState)(tid); 134 if (!extend(tst, esp, sp_top_of_frame - esp)) 135 return; 136 137 vg_assert(VG_IS_16_ALIGNED(esp+4)); 138 139 frame = (struct hacky_sigframe *) esp; 140 141 /* clear it (very conservatively) (why so conservatively??) */ 142 VG_(memset)(&frame->lower_guardzone, 0, 512); 143 VG_(memset)(&frame->gst, 0, sizeof(VexGuestX86State)); 144 VG_(memset)(&frame->gshadow1, 0, sizeof(VexGuestX86State)); 145 VG_(memset)(&frame->gshadow2, 0, sizeof(VexGuestX86State)); 146 VG_(memset)(&frame->fake_siginfo, 0, sizeof(frame->fake_siginfo)); 147 VG_(memset)(&frame->fake_ucontext, 0, sizeof(frame->fake_ucontext)); 148 149 /* save stuff in frame */ 150 frame->gst = tst->arch.vex; 151 frame->gshadow1 = tst->arch.vex_shadow1; 152 frame->gshadow2 = tst->arch.vex_shadow2; 153 frame->sigNo_private = sigNo; 154 frame->mask = tst->sig_mask; 155 frame->magicPI = 0x31415927; 156 157 /* Minimally fill in the siginfo and ucontext. Note, utter 158 lameness prevails. Be underwhelmed, be very underwhelmed. */ 159 frame->fake_siginfo.si_signo = sigNo; 160 frame->fake_siginfo.si_code = siginfo->si_code; 161 162 /* Set up stack pointer */ 163 vg_assert(esp == (Addr)&frame->returnAddr); 164 VG_(set_SP)(tid, esp); 165 VG_TRACK( post_reg_write, Vg_CoreSignal, tid, VG_O_STACK_PTR, sizeof(UInt)); 166 167 /* Set up program counter */ 168 VG_(set_IP)(tid, (UInt)handler); 169 VG_TRACK( post_reg_write, Vg_CoreSignal, tid, VG_O_INSTR_PTR, sizeof(UInt)); 170 171 /* Set up RA and args for the frame */ 172 VG_TRACK( pre_mem_write, Vg_CoreSignal, tid, "signal handler frame", 173 (Addr)frame, 4*sizeof(UInt) ); 174 frame->returnAddr = (UInt)&VG_(x86_darwin_SUBST_FOR_sigreturn); 175 frame->a1_signo = sigNo; 176 frame->a2_siginfo = (UInt)&frame->fake_siginfo; /* oh well */ 177 frame->a3_ucontext = (UInt)&frame->fake_ucontext; /* oh well */ 178 VG_TRACK( post_mem_write, Vg_CoreSignal, tid, 179 (Addr)frame, 4*sizeof(UInt) ); 180 VG_TRACK( post_mem_write, Vg_CoreSignal, tid, 181 (Addr)&frame->fake_siginfo, sizeof(frame->fake_siginfo)); 182 VG_TRACK( post_mem_write, Vg_CoreSignal, tid, 183 (Addr)&frame->fake_ucontext, sizeof(frame->fake_ucontext)); 184 185 if (VG_(clo_trace_signals)) 186 VG_(message)(Vg_DebugMsg, 187 "sigframe_create (thread %d): " 188 "next EIP=%#lx, next ESP=%#lx\n", 189 tid, (Addr)handler, (Addr)frame ); 190 } 191 192 193 /* Remove a signal frame from thread 'tid's stack, and restore the CPU 194 state from it. Note, isRT is irrelevant here. */ 195 void VG_(sigframe_destroy)( ThreadId tid, Bool isRT ) 196 { 197 ThreadState *tst; 198 Addr esp; 199 Int sigNo; 200 struct hacky_sigframe* frame; 201 202 vg_assert(VG_(is_valid_tid)(tid)); 203 tst = VG_(get_ThreadState)(tid); 204 205 /* Check that the stack frame looks valid */ 206 esp = VG_(get_SP)(tid); 207 208 /* why -4 ? because the signal handler's return will have popped 209 the return address off the stack; and the return address is the 210 lowest-addressed element of hacky_sigframe. */ 211 frame = (struct hacky_sigframe*)(esp - 4); 212 vg_assert(frame->magicPI == 0x31415927); 213 214 /* This +8 is because of the -4 referred to in the ELF ABI comment 215 in VG_(sigframe_create) just above. */ 216 vg_assert(VG_IS_16_ALIGNED((Addr)frame + 4)); 217 218 /* restore the entire guest state, and shadows, from the 219 frame. Note, as per comments above, this is a kludge - should 220 restore it from saved ucontext. Oh well. */ 221 tst->arch.vex = frame->gst; 222 tst->arch.vex_shadow1 = frame->gshadow1; 223 tst->arch.vex_shadow2 = frame->gshadow2; 224 tst->sig_mask = frame->mask; 225 tst->tmp_sig_mask = frame->mask; 226 sigNo = frame->sigNo_private; 227 228 if (VG_(clo_trace_signals)) 229 VG_(message)(Vg_DebugMsg, 230 "sigframe_destroy (thread %d): " 231 "valid magic; next EIP=%#x\n", 232 tid, tst->arch.vex.guest_EIP); 233 234 VG_TRACK( die_mem_stack_signal, 235 (Addr)frame - VG_STACK_REDZONE_SZB, 236 sizeof(struct hacky_sigframe) ); 237 238 /* tell the tools */ 239 VG_TRACK( post_deliver_signal, tid, sigNo ); 240 } 241 242 #endif // defined(VGP_x86_darwin) 243 244 /*--------------------------------------------------------------------*/ 245 /*--- end ---*/ 246 /*--------------------------------------------------------------------*/ 247
