1 /* DWARF2 EH unwinding support for PA Linux. 2 Copyright (C) 2004-2013 Free Software Foundation, Inc. 3 4 This file is part of GCC. 5 6 GCC is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 3, or (at your option) 9 any later version. 10 11 GCC is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 Under Section 7 of GPL version 3, you are granted additional 17 permissions described in the GCC Runtime Library Exception, version 18 3.1, as published by the Free Software Foundation. 19 20 You should have received a copy of the GNU General Public License and 21 a copy of the GCC Runtime Library Exception along with this program; 22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 <http://www.gnu.org/licenses/>. */ 24 25 26 /* Do code reading to identify a signal frame, and set the frame 27 state data appropriately. See unwind-dw2.c for the structs. */ 28 29 /* Don't use this if inhibit_libc is set. 30 The build for this target will fail trying to include missing headers. */ 31 #ifndef inhibit_libc 32 #include <signal.h> 33 #include <sys/ucontext.h> 34 35 /* Unfortunately, because of various bugs and changes to the kernel, 36 we have several cases to deal with. 37 38 In 2.4, the signal trampoline is 4 words, and (CONTEXT)->ra should 39 point directly at the beginning of the trampoline and struct rt_sigframe. 40 41 In <= 2.6.5-rc2-pa3, the signal trampoline is 9 words, and 42 (CONTEXT)->ra points at the 4th word in the trampoline structure. This 43 is wrong, it should point at the 5th word. This is fixed in 2.6.5-rc2-pa4. 44 45 To detect these cases, we first take (CONTEXT)->ra, align it to 64-bytes 46 to get the beginning of the signal frame, and then check offsets 0, 4 47 and 5 to see if we found the beginning of the trampoline. This will 48 tell us how to locate the sigcontext structure. 49 50 Note that with a 2.4 64-bit kernel, the signal context is not properly 51 passed back to userspace so the unwind will not work correctly. */ 52 53 #define MD_FALLBACK_FRAME_STATE_FOR pa32_fallback_frame_state 54 55 static _Unwind_Reason_Code 56 pa32_fallback_frame_state (struct _Unwind_Context *context, 57 _Unwind_FrameState *fs) 58 { 59 unsigned long sp = (unsigned long)context->ra & ~63; 60 unsigned int *pc = (unsigned int *)sp; 61 unsigned long off; 62 _Unwind_Ptr new_cfa; 63 int i; 64 struct sigcontext *sc; 65 struct rt_sigframe { 66 siginfo_t info; 67 struct ucontext uc; 68 } *frame; 69 70 /* rt_sigreturn trampoline: 71 3419000x ldi 0, %r25 or ldi 1, %r25 (x = 0 or 2) 72 3414015a ldi __NR_rt_sigreturn, %r20 73 e4008200 be,l 0x100(%sr2, %r0), %sr0, %r31 74 08000240 nop */ 75 76 if (pc[0] == 0x34190000 || pc[0] == 0x34190002) 77 off = 4*4; 78 else if (pc[4] == 0x34190000 || pc[4] == 0x34190002) 79 { 80 pc += 4; 81 off = 10 * 4; 82 } 83 else if (pc[5] == 0x34190000 || pc[5] == 0x34190002) 84 { 85 pc += 5; 86 off = 10 * 4; 87 } 88 else 89 { 90 /* We may have to unwind through an alternate signal stack. 91 We assume that the alignment of the alternate signal stack 92 is BIGGEST_ALIGNMENT (i.e., that it has been allocated using 93 malloc). As a result, we can't distinguish trampolines 94 used prior to 2.6.5-rc2-pa4. However after 2.6.5-rc2-pa4, 95 the return address of a signal trampoline will be on an odd 96 word boundary and we can then determine the frame offset. */ 97 sp = (unsigned long)context->ra; 98 pc = (unsigned int *)sp; 99 if ((pc[0] == 0x34190000 || pc[0] == 0x34190002) && (sp & 4)) 100 off = 5 * 4; 101 else 102 return _URC_END_OF_STACK; 103 } 104 105 if (pc[1] != 0x3414015a 106 || pc[2] != 0xe4008200 107 || pc[3] != 0x08000240) 108 return _URC_END_OF_STACK; 109 110 frame = (struct rt_sigframe *)(sp + off); 111 sc = &frame->uc.uc_mcontext; 112 113 new_cfa = sc->sc_gr[30]; 114 fs->regs.cfa_how = CFA_REG_OFFSET; 115 fs->regs.cfa_reg = 30; 116 fs->regs.cfa_offset = new_cfa - (long) context->cfa; 117 for (i = 1; i <= 31; i++) 118 { 119 fs->regs.reg[i].how = REG_SAVED_OFFSET; 120 fs->regs.reg[i].loc.offset = (long)&sc->sc_gr[i] - new_cfa; 121 } 122 for (i = 4; i <= 31; i++) 123 { 124 /* FP regs have left and right halves */ 125 fs->regs.reg[2*i+24].how = REG_SAVED_OFFSET; 126 fs->regs.reg[2*i+24].loc.offset 127 = (long)&sc->sc_fr[i] - new_cfa; 128 fs->regs.reg[2*i+24+1].how = REG_SAVED_OFFSET; 129 fs->regs.reg[2*i+24+1].loc.offset 130 = (long)&sc->sc_fr[i] + 4 - new_cfa; 131 } 132 fs->regs.reg[88].how = REG_SAVED_OFFSET; 133 fs->regs.reg[88].loc.offset = (long) &sc->sc_sar - new_cfa; 134 fs->regs.reg[DWARF_ALT_FRAME_RETURN_COLUMN].how = REG_SAVED_OFFSET; 135 fs->regs.reg[DWARF_ALT_FRAME_RETURN_COLUMN].loc.offset 136 = (long) &sc->sc_iaoq[0] - new_cfa; 137 fs->retaddr_column = DWARF_ALT_FRAME_RETURN_COLUMN; 138 fs->signal_frame = 1; 139 return _URC_NO_REASON; 140 } 141 #endif /* inhibit_libc */ 142