1/* libunwind - a platform-independent unwind library
2   Copyright (C) 2002-2004 Hewlett-Packard Co
3	Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
4
5This file is part of libunwind.
6
7Permission is hereby granted, free of charge, to any person obtaining
8a copy of this software and associated documentation files (the
9"Software"), to deal in the Software without restriction, including
10without limitation the rights to use, copy, modify, merge, publish,
11distribute, sublicense, and/or sell copies of the Software, and to
12permit persons to whom the Software is furnished to do so, subject to
13the following conditions:
14
15The above copyright notice and this permission notice shall be
16included in all copies or substantial portions of the Software.
17
18THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
19EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
21NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
22LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
23OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
24WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
25
26#include "unwind_i.h"
27#include "offsets.h"
28
29PROTECTED int
30unw_is_signal_frame (unw_cursor_t *cursor)
31{
32  struct cursor *c = (struct cursor *) cursor;
33  unw_word_t w0, w1, ip;
34  unw_addr_space_t as;
35  unw_accessors_t *a;
36  void *arg;
37  int ret;
38
39  as = c->dwarf.as;
40  a = unw_get_accessors (as);
41  arg = c->dwarf.as_arg;
42
43  /* Check if EIP points at sigreturn() sequence.  On Linux, this is:
44
45    __restore:
46	0x58				pop %eax
47	0xb8 0x77 0x00 0x00 0x00	movl 0x77,%eax
48	0xcd 0x80			int 0x80
49
50     without SA_SIGINFO, and
51
52    __restore_rt:
53       0xb8 0xad 0x00 0x00 0x00        movl 0xad,%eax
54       0xcd 0x80                       int 0x80
55       0x00
56
57     if SA_SIGINFO is specified.
58  */
59  ip = c->dwarf.ip;
60  if ((*a->access_mem) (as, ip, &w0, 0, arg) < 0
61      || (*a->access_mem) (as, ip + 4, &w1, 0, arg) < 0)
62    ret = 0;
63  else
64    ret = ((w0 == 0x0077b858 && w1 == 0x80cd0000)
65	 || (w0 == 0x0000adb8 && (w1 & 0xffffff) == 0x80cd00));
66  Debug (16, "returning %d\n", ret);
67  return ret;
68}
69
70PROTECTED int
71unw_handle_signal_frame (unw_cursor_t *cursor)
72{
73  struct cursor *c = (struct cursor *) cursor;
74  int ret;
75
76  /* c->esp points at the arguments to the handler.  Without
77     SA_SIGINFO, the arguments consist of a signal number
78     followed by a struct sigcontext.  With SA_SIGINFO, the
79     arguments consist a signal number, a siginfo *, and a
80     ucontext *. */
81  unw_word_t sc_addr;
82  unw_word_t siginfo_ptr_addr = c->dwarf.cfa + 4;
83  unw_word_t sigcontext_ptr_addr = c->dwarf.cfa + 8;
84  unw_word_t siginfo_ptr, sigcontext_ptr;
85  struct dwarf_loc esp_loc, siginfo_ptr_loc, sigcontext_ptr_loc;
86
87  siginfo_ptr_loc = DWARF_LOC (siginfo_ptr_addr, 0);
88  sigcontext_ptr_loc = DWARF_LOC (sigcontext_ptr_addr, 0);
89  ret = (dwarf_get (&c->dwarf, siginfo_ptr_loc, &siginfo_ptr)
90	 | dwarf_get (&c->dwarf, sigcontext_ptr_loc, &sigcontext_ptr));
91  if (ret < 0)
92    {
93      Debug (2, "returning 0\n");
94      return 0;
95    }
96  if (siginfo_ptr < c->dwarf.cfa
97      || siginfo_ptr > c->dwarf.cfa + 256
98      || sigcontext_ptr < c->dwarf.cfa
99      || sigcontext_ptr > c->dwarf.cfa + 256)
100    {
101      /* Not plausible for SA_SIGINFO signal */
102      c->sigcontext_format = X86_SCF_LINUX_SIGFRAME;
103      c->sigcontext_addr = sc_addr = c->dwarf.cfa + 4;
104    }
105  else
106    {
107      /* If SA_SIGINFO were not specified, we actually read
108	 various segment pointers instead.  We believe that at
109	 least fs and _fsh are always zero for linux, so it is
110	 not just unlikely, but impossible that we would end
111	 up here. */
112      c->sigcontext_format = X86_SCF_LINUX_RT_SIGFRAME;
113      c->sigcontext_addr = sigcontext_ptr;
114      sc_addr = sigcontext_ptr + LINUX_UC_MCONTEXT_OFF;
115    }
116  esp_loc = DWARF_LOC (sc_addr + LINUX_SC_ESP_OFF, 0);
117  ret = dwarf_get (&c->dwarf, esp_loc, &c->dwarf.cfa);
118  if (ret < 0)
119    {
120      Debug (2, "returning 0\n");
121      return 0;
122    }
123
124  c->dwarf.loc[EAX] = DWARF_LOC (sc_addr + LINUX_SC_EAX_OFF, 0);
125  c->dwarf.loc[ECX] = DWARF_LOC (sc_addr + LINUX_SC_ECX_OFF, 0);
126  c->dwarf.loc[EDX] = DWARF_LOC (sc_addr + LINUX_SC_EDX_OFF, 0);
127  c->dwarf.loc[EBX] = DWARF_LOC (sc_addr + LINUX_SC_EBX_OFF, 0);
128  c->dwarf.loc[EBP] = DWARF_LOC (sc_addr + LINUX_SC_EBP_OFF, 0);
129  c->dwarf.loc[ESI] = DWARF_LOC (sc_addr + LINUX_SC_ESI_OFF, 0);
130  c->dwarf.loc[EDI] = DWARF_LOC (sc_addr + LINUX_SC_EDI_OFF, 0);
131  c->dwarf.loc[EFLAGS] = DWARF_NULL_LOC;
132  c->dwarf.loc[TRAPNO] = DWARF_NULL_LOC;
133  c->dwarf.loc[ST0] = DWARF_NULL_LOC;
134  c->dwarf.loc[EIP] = DWARF_LOC (sc_addr + LINUX_SC_EIP_OFF, 0);
135  c->dwarf.loc[ESP] = DWARF_LOC (sc_addr + LINUX_SC_ESP_OFF, 0);
136
137  return 0;
138}
139
140HIDDEN dwarf_loc_t
141x86_get_scratch_loc (struct cursor *c, unw_regnum_t reg)
142{
143  unw_word_t addr = c->sigcontext_addr, fpstate_addr, off;
144  int ret, is_fpstate = 0;
145
146  switch (c->sigcontext_format)
147    {
148    case X86_SCF_NONE:
149      return DWARF_REG_LOC (&c->dwarf, reg);
150
151    case X86_SCF_LINUX_SIGFRAME:
152      break;
153
154    case X86_SCF_LINUX_RT_SIGFRAME:
155      addr += LINUX_UC_MCONTEXT_OFF;
156      break;
157
158    default:
159      return DWARF_NULL_LOC;
160    }
161
162  switch (reg)
163    {
164    case UNW_X86_GS: off = LINUX_SC_GS_OFF; break;
165    case UNW_X86_FS: off = LINUX_SC_FS_OFF; break;
166    case UNW_X86_ES: off = LINUX_SC_ES_OFF; break;
167    case UNW_X86_DS: off = LINUX_SC_DS_OFF; break;
168    case UNW_X86_EDI: off = LINUX_SC_EDI_OFF; break;
169    case UNW_X86_ESI: off = LINUX_SC_ESI_OFF; break;
170    case UNW_X86_EBP: off = LINUX_SC_EBP_OFF; break;
171    case UNW_X86_ESP: off = LINUX_SC_ESP_OFF; break;
172    case UNW_X86_EBX: off = LINUX_SC_EBX_OFF; break;
173    case UNW_X86_EDX: off = LINUX_SC_EDX_OFF; break;
174    case UNW_X86_ECX: off = LINUX_SC_ECX_OFF; break;
175    case UNW_X86_EAX: off = LINUX_SC_EAX_OFF; break;
176    case UNW_X86_TRAPNO: off = LINUX_SC_TRAPNO_OFF; break;
177    case UNW_X86_EIP: off = LINUX_SC_EIP_OFF; break;
178    case UNW_X86_CS: off = LINUX_SC_CS_OFF; break;
179    case UNW_X86_EFLAGS: off = LINUX_SC_EFLAGS_OFF; break;
180    case UNW_X86_SS: off = LINUX_SC_SS_OFF; break;
181
182      /* The following is probably not correct for all possible cases.
183	 Somebody who understands this better should review this for
184	 correctness.  */
185
186    case UNW_X86_FCW: is_fpstate = 1; off = LINUX_FPSTATE_CW_OFF; break;
187    case UNW_X86_FSW: is_fpstate = 1; off = LINUX_FPSTATE_SW_OFF; break;
188    case UNW_X86_FTW: is_fpstate = 1; off = LINUX_FPSTATE_TAG_OFF; break;
189    case UNW_X86_FCS: is_fpstate = 1; off = LINUX_FPSTATE_CSSEL_OFF; break;
190    case UNW_X86_FIP: is_fpstate = 1; off = LINUX_FPSTATE_IPOFF_OFF; break;
191    case UNW_X86_FEA: is_fpstate = 1; off = LINUX_FPSTATE_DATAOFF_OFF; break;
192    case UNW_X86_FDS: is_fpstate = 1; off = LINUX_FPSTATE_DATASEL_OFF; break;
193    case UNW_X86_MXCSR: is_fpstate = 1; off = LINUX_FPSTATE_MXCSR_OFF; break;
194
195      /* stacked fp registers */
196    case UNW_X86_ST0: case UNW_X86_ST1: case UNW_X86_ST2: case UNW_X86_ST3:
197    case UNW_X86_ST4: case UNW_X86_ST5: case UNW_X86_ST6: case UNW_X86_ST7:
198      is_fpstate = 1;
199      off = LINUX_FPSTATE_ST0_OFF + 10*(reg - UNW_X86_ST0);
200      break;
201
202     /* SSE fp registers */
203    case UNW_X86_XMM0_lo: case UNW_X86_XMM0_hi:
204    case UNW_X86_XMM1_lo: case UNW_X86_XMM1_hi:
205    case UNW_X86_XMM2_lo: case UNW_X86_XMM2_hi:
206    case UNW_X86_XMM3_lo: case UNW_X86_XMM3_hi:
207    case UNW_X86_XMM4_lo: case UNW_X86_XMM4_hi:
208    case UNW_X86_XMM5_lo: case UNW_X86_XMM5_hi:
209    case UNW_X86_XMM6_lo: case UNW_X86_XMM6_hi:
210    case UNW_X86_XMM7_lo: case UNW_X86_XMM7_hi:
211      is_fpstate = 1;
212      off = LINUX_FPSTATE_XMM0_OFF + 8*(reg - UNW_X86_XMM0_lo);
213      break;
214    case UNW_X86_XMM0:
215    case UNW_X86_XMM1:
216    case UNW_X86_XMM2:
217    case UNW_X86_XMM3:
218    case UNW_X86_XMM4:
219    case UNW_X86_XMM5:
220    case UNW_X86_XMM6:
221    case UNW_X86_XMM7:
222      is_fpstate = 1;
223      off = LINUX_FPSTATE_XMM0_OFF + 16*(reg - UNW_X86_XMM0);
224      break;
225
226    case UNW_X86_FOP:
227    case UNW_X86_TSS:
228    case UNW_X86_LDT:
229    default:
230      return DWARF_REG_LOC (&c->dwarf, reg);
231    }
232
233  if (is_fpstate)
234    {
235      if ((ret = dwarf_get (&c->dwarf,
236			    DWARF_MEM_LOC (&c->dwarf,
237					   addr + LINUX_SC_FPSTATE_OFF),
238			    &fpstate_addr)) < 0)
239	return DWARF_NULL_LOC;
240
241      if (!fpstate_addr)
242	return DWARF_NULL_LOC;
243
244      return DWARF_MEM_LOC (c, fpstate_addr + off);
245    }
246  else
247    return DWARF_MEM_LOC (c, addr + off);
248}
249
250#ifndef UNW_REMOTE_ONLY
251HIDDEN void *
252x86_r_uc_addr (ucontext_t *uc, int reg)
253{
254  void *addr;
255
256  switch (reg)
257    {
258    case UNW_X86_GS:  addr = &uc->uc_mcontext.gregs[REG_GS]; break;
259    case UNW_X86_FS:  addr = &uc->uc_mcontext.gregs[REG_FS]; break;
260    case UNW_X86_ES:  addr = &uc->uc_mcontext.gregs[REG_ES]; break;
261    case UNW_X86_DS:  addr = &uc->uc_mcontext.gregs[REG_DS]; break;
262    case UNW_X86_EAX: addr = &uc->uc_mcontext.gregs[REG_EAX]; break;
263    case UNW_X86_EBX: addr = &uc->uc_mcontext.gregs[REG_EBX]; break;
264    case UNW_X86_ECX: addr = &uc->uc_mcontext.gregs[REG_ECX]; break;
265    case UNW_X86_EDX: addr = &uc->uc_mcontext.gregs[REG_EDX]; break;
266    case UNW_X86_ESI: addr = &uc->uc_mcontext.gregs[REG_ESI]; break;
267    case UNW_X86_EDI: addr = &uc->uc_mcontext.gregs[REG_EDI]; break;
268    case UNW_X86_EBP: addr = &uc->uc_mcontext.gregs[REG_EBP]; break;
269    case UNW_X86_EIP: addr = &uc->uc_mcontext.gregs[REG_EIP]; break;
270    case UNW_X86_ESP: addr = &uc->uc_mcontext.gregs[REG_ESP]; break;
271    case UNW_X86_TRAPNO:  addr = &uc->uc_mcontext.gregs[REG_TRAPNO]; break;
272    case UNW_X86_CS:  addr = &uc->uc_mcontext.gregs[REG_CS]; break;
273    case UNW_X86_EFLAGS:  addr = &uc->uc_mcontext.gregs[REG_EFL]; break;
274    case UNW_X86_SS:  addr = &uc->uc_mcontext.gregs[REG_SS]; break;
275
276    default:
277      addr = NULL;
278    }
279  return addr;
280}
281
282HIDDEN int
283x86_local_resume (unw_addr_space_t as, unw_cursor_t *cursor, void *arg)
284{
285  struct cursor *c = (struct cursor *) cursor;
286#if !defined(__ANDROID__)
287  ucontext_t *uc = c->uc;
288#endif
289
290  /* Ensure c->pi is up-to-date.  On x86, it's relatively common to be
291     missing DWARF unwind info.  We don't want to fail in that case,
292     because the frame-chain still would let us do a backtrace at
293     least.  */
294  dwarf_make_proc_info (&c->dwarf);
295
296  if (unlikely (c->sigcontext_format != X86_SCF_NONE))
297    {
298      struct sigcontext *sc = (struct sigcontext *) c->sigcontext_addr;
299      (void)sc;
300
301      Debug (8, "resuming at ip=%x via sigreturn(%p)\n", c->dwarf.ip, sc);
302
303#if !defined(__ANDROID__)
304      sigreturn (sc);
305#endif
306    }
307  else
308    {
309      Debug (8, "resuming at ip=%x via setcontext()\n", c->dwarf.ip);
310#if !defined(__ANDROID__)
311      setcontext (uc);
312#endif
313    }
314  return -UNW_EINVAL;
315}
316#endif
317