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) 2006-2010 OpenWorks Ltd
12 info@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_threadstate.h"
38 #include "pub_core_aspacemgr.h"
39 #include "pub_core_libcbase.h"
40 #include "pub_core_libcassert.h"
41 #include "pub_core_libcprint.h"
42 #include "pub_core_machine.h"
43 #include "pub_core_options.h"
44 #include "pub_core_signals.h"
45 #include "pub_core_tooliface.h"
46 #include "pub_core_trampoline.h"
47 #include "pub_core_sigframe.h" /* self */
48
49
50 /* Cheap-ass hack copied from ppc32-aix5 code, just to get started.
51 Produce a frame with layout entirely of our own choosing. */
52
53 /* This module creates and removes signal frames for signal deliveries
54 on x86-darwin. Kludgey; the machine state ought to be saved in a
55 ucontext and retrieved from it later, so the handler can modify it
56 and return. However .. for now .. just stick the vex guest state
57 in the frame and snarf it again later.
58
59 Also, don't bother with creating siginfo and ucontext in the
60 handler, although do point them somewhere non-faulting.
61
62 Frame should have a 16-aligned size, just in case that turns out to
63 be important for Darwin. (be conservative)
64 */
65 struct hacky_sigframe {
66 /* first four words look like a call to a 3-arg x86 function */
67 UInt returnAddr;
68 UInt a1_signo;
69 UInt a2_siginfo;
70 UInt a3_ucontext;
71 UChar lower_guardzone[512]; // put nothing here
72 VexGuestX86State gst;
73 VexGuestX86State gshadow1;
74 VexGuestX86State gshadow2;
75 vki_siginfo_t fake_siginfo;
76 struct vki_ucontext fake_ucontext;
77 UInt magicPI;
78 UInt sigNo_private;
79 vki_sigset_t mask; // saved sigmask; restore when hdlr returns
80 UInt __pad[1];
81 UChar upper_guardzone[512]; // put nothing here
82 // and don't zero it, since that might overwrite the client's
83 // stack redzone, at least on archs which have one
84 };
85
86
87 /* Extend the stack segment downwards if needed so as to ensure the
88 new signal frames are mapped to something. Return a Bool
89 indicating whether or not the operation was successful.
90 */
extend(ThreadState * tst,Addr addr,SizeT size)91 static Bool extend ( ThreadState *tst, Addr addr, SizeT size )
92 {
93 ThreadId tid = tst->tid;
94 /* For tracking memory events, indicate the entire frame has been
95 allocated. Except, don't mess with the area which
96 overlaps the previous frame's redzone. */
97 /* XXX is the following call really right? compared with the
98 amd64-linux version, this doesn't appear to handle the redzone
99 in the same way. */
100 VG_TRACK( new_mem_stack_signal,
101 addr - VG_STACK_REDZONE_SZB, size, tid );
102 return True;
103 }
104
105
106 /* Create a signal frame for thread 'tid'. Make a 3-arg frame
107 regardless of whether the client originally requested a 1-arg
108 version (no SA_SIGINFO) or a 3-arg one (SA_SIGINFO) since in the
109 former case, the x86 calling conventions will simply cause the
110 extra 2 args to be ignored (inside the handler). */
VG_(sigframe_create)111 void VG_(sigframe_create) ( ThreadId tid,
112 Addr sp_top_of_frame,
113 const vki_siginfo_t *siginfo,
114 const struct vki_ucontext *siguc,
115 void *handler,
116 UInt flags,
117 const vki_sigset_t *mask,
118 void *restorer )
119 {
120 ThreadState* tst;
121 Addr esp;
122 struct hacky_sigframe* frame;
123 Int sigNo = siginfo->si_signo;
124
125 vg_assert(VG_IS_16_ALIGNED(sizeof(struct hacky_sigframe)));
126
127 sp_top_of_frame &= ~0xf;
128 esp = sp_top_of_frame - sizeof(struct hacky_sigframe);
129
130 tst = VG_(get_ThreadState)(tid);
131 if (!extend(tst, esp, sp_top_of_frame - esp))
132 return;
133
134 vg_assert(VG_IS_16_ALIGNED(esp));
135
136 frame = (struct hacky_sigframe *) esp;
137
138 /* clear it (very conservatively) (why so conservatively??) */
139 VG_(memset)(&frame->lower_guardzone, 0, 512);
140 VG_(memset)(&frame->gst, 0, sizeof(VexGuestX86State));
141 VG_(memset)(&frame->gshadow1, 0, sizeof(VexGuestX86State));
142 VG_(memset)(&frame->gshadow2, 0, sizeof(VexGuestX86State));
143 VG_(memset)(&frame->fake_siginfo, 0, sizeof(frame->fake_siginfo));
144 VG_(memset)(&frame->fake_ucontext, 0, sizeof(frame->fake_ucontext));
145
146 /* save stuff in frame */
147 frame->gst = tst->arch.vex;
148 frame->gshadow1 = tst->arch.vex_shadow1;
149 frame->gshadow2 = tst->arch.vex_shadow2;
150 frame->sigNo_private = sigNo;
151 frame->mask = tst->sig_mask;
152 frame->magicPI = 0x31415927;
153
154 /* Minimally fill in the siginfo and ucontext. Note, utter
155 lameness prevails. Be underwhelmed, be very underwhelmed. */
156 frame->fake_siginfo.si_signo = sigNo;
157 frame->fake_siginfo.si_code = siginfo->si_code;
158
159 /* Set up stack pointer */
160 vg_assert(esp == (Addr)&frame->returnAddr);
161 VG_(set_SP)(tid, esp);
162 VG_TRACK( post_reg_write, Vg_CoreSignal, tid, VG_O_STACK_PTR, sizeof(UInt));
163
164 /* Set up program counter */
165 VG_(set_IP)(tid, (UInt)handler);
166 VG_TRACK( post_reg_write, Vg_CoreSignal, tid, VG_O_INSTR_PTR, sizeof(UInt));
167
168 /* Set up RA and args for the frame */
169 VG_TRACK( pre_mem_write, Vg_CoreSignal, tid, "signal handler frame",
170 (Addr)frame, 4*sizeof(UInt) );
171 frame->returnAddr = (UInt)&VG_(x86_darwin_SUBST_FOR_sigreturn);
172 frame->a1_signo = sigNo;
173 frame->a2_siginfo = (UInt)&frame->fake_siginfo; /* oh well */
174 frame->a3_ucontext = (UInt)&frame->fake_ucontext; /* oh well */
175 VG_TRACK( post_mem_write, Vg_CoreSignal, tid,
176 (Addr)frame, 4*sizeof(UInt) );
177 VG_TRACK( post_mem_write, Vg_CoreSignal, tid,
178 (Addr)&frame->fake_siginfo, sizeof(frame->fake_siginfo));
179 VG_TRACK( post_mem_write, Vg_CoreSignal, tid,
180 (Addr)&frame->fake_ucontext, sizeof(frame->fake_ucontext));
181
182 if (VG_(clo_trace_signals))
183 VG_(message)(Vg_DebugMsg,
184 "sigframe_create (thread %d): next EIP=%#lx, next ESP=%#lx",
185 tid, (Addr)handler, (Addr)frame );
186 }
187
188
189 /* Remove a signal frame from thread 'tid's stack, and restore the CPU
190 state from it. Note, isRT is irrelevant here. */
VG_(sigframe_destroy)191 void VG_(sigframe_destroy)( ThreadId tid, Bool isRT )
192 {
193 ThreadState *tst;
194 Addr esp;
195 Int sigNo;
196 struct hacky_sigframe* frame;
197
198 vg_assert(VG_(is_valid_tid)(tid));
199 tst = VG_(get_ThreadState)(tid);
200
201 /* Check that the stack frame looks valid */
202 esp = VG_(get_SP)(tid);
203
204 /* why -4 ? because the signal handler's return will have popped
205 the return address of the stack; and the return address is the
206 lowest-addressed element of hacky_sigframe. */
207 frame = (struct hacky_sigframe*)(esp - 4);
208 vg_assert(frame->magicPI == 0x31415927);
209 vg_assert(VG_IS_16_ALIGNED(frame));
210
211 /* restore the entire guest state, and shadows, from the
212 frame. Note, as per comments above, this is a kludge - should
213 restore it from saved ucontext. Oh well. */
214 tst->arch.vex = frame->gst;
215 tst->arch.vex_shadow1 = frame->gshadow1;
216 tst->arch.vex_shadow2 = frame->gshadow2;
217 tst->sig_mask = frame->mask;
218 tst->tmp_sig_mask = frame->mask;
219 sigNo = frame->sigNo_private;
220
221 if (VG_(clo_trace_signals))
222 VG_(message)(Vg_DebugMsg,
223 "sigframe_destroy (thread %d): valid magic; next EIP=%#x",
224 tid, tst->arch.vex.guest_EIP);
225
226 VG_TRACK( die_mem_stack_signal,
227 (Addr)frame - VG_STACK_REDZONE_SZB,
228 sizeof(struct hacky_sigframe) );
229
230 /* tell the tools */
231 VG_TRACK( post_deliver_signal, tid, sigNo );
232 }
233
234 #endif // defined(VGP_x86_darwin)
235
236 /*--------------------------------------------------------------------*/
237 /*--- end ---*/
238 /*--------------------------------------------------------------------*/
239