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1 /* libunwind - a platform-independent unwind library
2    Copyright (C) 2008 CodeSourcery
3 
4 This file is part of libunwind.
5 
6 Permission is hereby granted, free of charge, to any person obtaining
7 a copy of this software and associated documentation files (the
8 "Software"), to deal in the Software without restriction, including
9 without limitation the rights to use, copy, modify, merge, publish,
10 distribute, sublicense, and/or sell copies of the Software, and to
11 permit persons to whom the Software is furnished to do so, subject to
12 the following conditions:
13 
14 The above copyright notice and this permission notice shall be
15 included in all copies or substantial portions of the Software.
16 
17 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
18 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
19 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
20 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
21 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
22 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
23 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
24 
25 #include "unwind_i.h"
26 #include "offsets.h"
27 
28 PROTECTED int
unw_handle_signal_frame(unw_cursor_t * cursor)29 unw_handle_signal_frame (unw_cursor_t *cursor)
30 {
31   struct cursor *c = (struct cursor *) cursor;
32   unw_word_t sc_addr, sp, sp_addr = c->dwarf.cfa;
33   unw_word_t ra, fp;
34   int ret;
35 
36   /* FIXME (simon): Save the SP and PC to be able to return execution
37      at this point later in time (unw_resume). */
38   // c->sigcontext_sp = c->dwarf.cfa;
39   // c->sigcontext_pc = c->dwarf.ip;
40 
41   switch (unw_is_signal_frame (cursor)) {
42   case 1:
43     sc_addr = sp_addr + LINUX_SF_TRAMP_SIZE + sizeof (siginfo_t) +
44 	    LINUX_UC_MCONTEXT_OFF;
45     break;
46   case 2:
47     sc_addr = sp_addr + LINUX_UC_MCONTEXT_OFF;
48     break;
49   default:
50     return -UNW_EUNSPEC;
51   }
52 
53   if (tdep_big_endian(c->dwarf.as))
54     sc_addr += 4;
55 
56   c->sigcontext_addr = sc_addr;
57 
58   /* Update the dwarf cursor. */
59   c->dwarf.loc[UNW_MIPS_R0]  = DWARF_LOC (sc_addr + LINUX_SC_R0_OFF, 0);
60   c->dwarf.loc[UNW_MIPS_R1]  = DWARF_LOC (sc_addr + LINUX_SC_R1_OFF, 0);
61   c->dwarf.loc[UNW_MIPS_R2]  = DWARF_LOC (sc_addr + LINUX_SC_R2_OFF, 0);
62   c->dwarf.loc[UNW_MIPS_R3]  = DWARF_LOC (sc_addr + LINUX_SC_R3_OFF, 0);
63   c->dwarf.loc[UNW_MIPS_R4]  = DWARF_LOC (sc_addr + LINUX_SC_R4_OFF, 0);
64   c->dwarf.loc[UNW_MIPS_R5]  = DWARF_LOC (sc_addr + LINUX_SC_R5_OFF, 0);
65   c->dwarf.loc[UNW_MIPS_R6]  = DWARF_LOC (sc_addr + LINUX_SC_R6_OFF, 0);
66   c->dwarf.loc[UNW_MIPS_R7]  = DWARF_LOC (sc_addr + LINUX_SC_R7_OFF, 0);
67   c->dwarf.loc[UNW_MIPS_R8]  = DWARF_LOC (sc_addr + LINUX_SC_R8_OFF, 0);
68   c->dwarf.loc[UNW_MIPS_R9]  = DWARF_LOC (sc_addr + LINUX_SC_R9_OFF, 0);
69   c->dwarf.loc[UNW_MIPS_R10] = DWARF_LOC (sc_addr + LINUX_SC_R10_OFF, 0);
70   c->dwarf.loc[UNW_MIPS_R11] = DWARF_LOC (sc_addr + LINUX_SC_R11_OFF, 0);
71   c->dwarf.loc[UNW_MIPS_R12] = DWARF_LOC (sc_addr + LINUX_SC_R12_OFF, 0);
72   c->dwarf.loc[UNW_MIPS_R13] = DWARF_LOC (sc_addr + LINUX_SC_R13_OFF, 0);
73   c->dwarf.loc[UNW_MIPS_R14] = DWARF_LOC (sc_addr + LINUX_SC_R14_OFF, 0);
74   c->dwarf.loc[UNW_MIPS_R15] = DWARF_LOC (sc_addr + LINUX_SC_R15_OFF, 0);
75   c->dwarf.loc[UNW_MIPS_R16] = DWARF_LOC (sc_addr + LINUX_SC_R16_OFF, 0);
76   c->dwarf.loc[UNW_MIPS_R17] = DWARF_LOC (sc_addr + LINUX_SC_R17_OFF, 0);
77   c->dwarf.loc[UNW_MIPS_R18] = DWARF_LOC (sc_addr + LINUX_SC_R18_OFF, 0);
78   c->dwarf.loc[UNW_MIPS_R19] = DWARF_LOC (sc_addr + LINUX_SC_R19_OFF, 0);
79   c->dwarf.loc[UNW_MIPS_R20] = DWARF_LOC (sc_addr + LINUX_SC_R20_OFF, 0);
80   c->dwarf.loc[UNW_MIPS_R21] = DWARF_LOC (sc_addr + LINUX_SC_R21_OFF, 0);
81   c->dwarf.loc[UNW_MIPS_R22] = DWARF_LOC (sc_addr + LINUX_SC_R22_OFF, 0);
82   c->dwarf.loc[UNW_MIPS_R23] = DWARF_LOC (sc_addr + LINUX_SC_R23_OFF, 0);
83   c->dwarf.loc[UNW_MIPS_R24] = DWARF_LOC (sc_addr + LINUX_SC_R24_OFF, 0);
84   c->dwarf.loc[UNW_MIPS_R25] = DWARF_LOC (sc_addr + LINUX_SC_R25_OFF, 0);
85   c->dwarf.loc[UNW_MIPS_R26] = DWARF_LOC (sc_addr + LINUX_SC_R26_OFF, 0);
86   c->dwarf.loc[UNW_MIPS_R27] = DWARF_LOC (sc_addr + LINUX_SC_R27_OFF, 0);
87   c->dwarf.loc[UNW_MIPS_R28] = DWARF_LOC (sc_addr + LINUX_SC_R28_OFF, 0);
88   c->dwarf.loc[UNW_MIPS_R29] = DWARF_LOC (sc_addr + LINUX_SC_R29_OFF, 0);
89   c->dwarf.loc[UNW_MIPS_R30] = DWARF_LOC (sc_addr + LINUX_SC_R30_OFF, 0);
90   c->dwarf.loc[UNW_MIPS_R31] = DWARF_LOC (sc_addr + LINUX_SC_R31_OFF, 0);
91   c->dwarf.loc[UNW_MIPS_PC] = DWARF_LOC (sc_addr + LINUX_SC_PC_OFF, 0);
92 
93   /* Set SP/CFA and PC/IP. */
94   dwarf_get (&c->dwarf, c->dwarf.loc[UNW_MIPS_R29], &c->dwarf.cfa);
95   //dwarf_get (&c->dwarf, c->dwarf.loc[UNW_MIPS_R31], &c->dwarf.ip);
96 
97   if ((ret = dwarf_get(&c->dwarf, DWARF_LOC(sc_addr + LINUX_SC_PC_OFF, 0),
98 		       &c->dwarf.ip)) < 0)
99     return ret;
100 
101   if ((ret = dwarf_get(&c->dwarf, DWARF_LOC(sc_addr + LINUX_SC_R31_OFF, 0),
102 		       &ra)) < 0)
103     return ret;
104   if ((ret = dwarf_get(&c->dwarf, DWARF_LOC(sc_addr + LINUX_SC_R30_OFF, 0),
105 		       &fp)) < 0)
106     return ret;
107 
108   Debug (2, "SH (ip=0x%016llx, ra=0x%016llx, sp=0x%016llx, fp=0x%016llx)\n",
109          (unsigned long long)c->dwarf.ip, (unsigned long long)ra,
110 	 (unsigned long long)c->dwarf.cfa, (unsigned long long)fp);
111 
112   c->dwarf.pi_valid = 0;
113   c->dwarf.use_prev_instr = 0;
114 
115   return 1;
116 }
117 
118 PROTECTED int
unw_step(unw_cursor_t * cursor)119 unw_step (unw_cursor_t *cursor)
120 {
121   struct cursor *c = (struct cursor *) cursor;
122   int ret;
123 
124   unw_word_t old_ip = c->dwarf.ip;
125   unw_word_t old_cfa = c->dwarf.cfa;
126 
127   ret = unw_handle_signal_frame (cursor);
128   if (ret < 0)
129     /* Not a signal frame, try DWARF-based unwinding. */
130     ret = dwarf_step (&c->dwarf);
131 
132   if (unlikely (ret == -UNW_ESTOPUNWIND))
133     return ret;
134 
135   /* Dwarf unwinding didn't work, stop.  */
136   if (unlikely (ret < 0))
137     return 0;
138 
139   /* If the decode yields the exact same ip/cfa as before, then indicate
140      the unwind is complete. */
141   if (c->dwarf.ip == old_ip && c->dwarf.cfa == old_cfa)
142     {
143       Dprintf ("%s: ip and cfa unchanged; stopping here (ip=0x%lx)\n",
144                __FUNCTION__, (long) c->dwarf.ip);
145       return -UNW_EBADFRAME;
146     }
147 
148   return (c->dwarf.ip == 0) ? 0 : 1;
149 }
150