1/* DWARF2 EH unwinding support for PA Linux. 2 Copyright (C) 2004, 2005 Free Software Foundation, Inc. 3 4This file is part of GCC. 5 6GCC is free software; you can redistribute it and/or modify 7it under the terms of the GNU General Public License as published by 8the Free Software Foundation; either version 2, or (at your option) 9any later version. 10 11In addition to the permissions in the GNU General Public License, the 12Free Software Foundation gives you unlimited permission to link the 13compiled version of this file with other programs, and to distribute 14those programs without any restriction coming from the use of this 15file. (The General Public License restrictions do apply in other 16respects; for example, they cover modification of the file, and 17distribution when not linked into another program.) 18 19GCC is distributed in the hope that it will be useful, 20but WITHOUT ANY WARRANTY; without even the implied warranty of 21MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 22GNU General Public License for more details. 23 24You should have received a copy of the GNU General Public License 25along with GCC; see the file COPYING. If not, write to 26the Free Software Foundation, 51 Franklin Street, Fifth Floor, 27Boston, MA 02110-1301, USA. */ 28 29/* Do code reading to identify a signal frame, and set the frame 30 state data appropriately. See unwind-dw2.c for the structs. */ 31 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 55static _Unwind_Reason_Code 56pa32_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 struct siginfo 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->cfa_how = CFA_REG_OFFSET; 115 fs->cfa_reg = 30; 116 fs->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 return _URC_NO_REASON; 139} 140