| /* DWARF2 EH unwinding support for MIPS Linux. |
| Copyright (C) 2004-2022 Free Software Foundation, Inc. |
| |
| This file is part of GCC. |
| |
| GCC is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3, or (at your option) |
| any later version. |
| |
| GCC is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| Under Section 7 of GPL version 3, you are granted additional |
| permissions described in the GCC Runtime Library Exception, version |
| 3.1, as published by the Free Software Foundation. |
| |
| You should have received a copy of the GNU General Public License and |
| a copy of the GCC Runtime Library Exception along with this program; |
| see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #ifndef inhibit_libc |
| /* Do code reading to identify a signal frame, and set the frame |
| state data appropriately. See unwind-dw2.c for the structs. */ |
| |
| #include <signal.h> |
| #include <sys/syscall.h> |
| |
| /* The third parameter to the signal handler points to something with |
| * this structure defined in asm/ucontext.h, but the name clashes with |
| * struct ucontext from sys/ucontext.h so this private copy is used. */ |
| typedef struct _sig_ucontext { |
| unsigned long uc_flags; |
| struct _sig_ucontext *uc_link; |
| stack_t uc_stack; |
| struct sigcontext uc_mcontext; |
| sigset_t uc_sigmask; |
| } _sig_ucontext_t; |
| |
| #define MD_FALLBACK_FRAME_STATE_FOR mips_fallback_frame_state |
| |
| static _Unwind_Reason_Code |
| mips_fallback_frame_state (struct _Unwind_Context *context, |
| _Unwind_FrameState *fs) |
| { |
| u_int32_t *pc = (u_int32_t *) context->ra; |
| struct sigcontext *sc; |
| _Unwind_Ptr new_cfa, reg_offset; |
| int i; |
| |
| /* A MIPS16 or microMIPS frame. Signal frames always use the standard |
| ISA encoding. */ |
| if ((_Unwind_Ptr) pc & 3) |
| return _URC_END_OF_STACK; |
| |
| /* 24021061 li v0, 0x1061 (rt_sigreturn)*/ |
| /* 0000000c syscall */ |
| /* or */ |
| /* 24021017 li v0, 0x1017 (sigreturn) */ |
| /* 0000000c syscall */ |
| if (pc[1] != 0x0000000c) |
| return _URC_END_OF_STACK; |
| #if _MIPS_SIM == _ABIO32 |
| if (pc[0] == (0x24020000 | __NR_sigreturn)) |
| { |
| struct sigframe { |
| u_int32_t ass[4]; /* Argument save space for o32. */ |
| u_int32_t trampoline[2]; |
| struct sigcontext sigctx; |
| } *rt_ = context->cfa; |
| sc = &rt_->sigctx; |
| } |
| else |
| #endif |
| if (pc[0] == (0x24020000 | __NR_rt_sigreturn)) |
| { |
| struct rt_sigframe { |
| u_int32_t ass[4]; /* Argument save space for o32. */ |
| u_int32_t trampoline[2]; |
| siginfo_t info; |
| _sig_ucontext_t uc; |
| } *rt_ = context->cfa; |
| sc = &rt_->uc.uc_mcontext; |
| } |
| else |
| return _URC_END_OF_STACK; |
| |
| new_cfa = (_Unwind_Ptr) sc; |
| fs->regs.cfa_how = CFA_REG_OFFSET; |
| fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__; |
| fs->regs.cfa_offset = new_cfa - (_Unwind_Ptr) context->cfa; |
| |
| /* On o32 Linux, the register save slots in the sigcontext are |
| eight bytes. We need the lower half of each register slot, |
| so slide our view of the structure back four bytes. */ |
| #if _MIPS_SIM == _ABIO32 && defined __MIPSEB__ |
| reg_offset = 4; |
| #else |
| reg_offset = 0; |
| #endif |
| |
| for (i = 0; i < 32; i++) { |
| fs->regs.reg[i].how = REG_SAVED_OFFSET; |
| fs->regs.reg[i].loc.offset |
| = (_Unwind_Ptr)&(sc->sc_regs[i]) + reg_offset - new_cfa; |
| } |
| /* "PC & -2" points to the faulting instruction, but the unwind code |
| searches for "(ADDR & -2) - 1". (See MASK_RETURN_ADDR for the source |
| of the -2 mask.) Adding 2 here ensures that "(ADDR & -2) - 1" is the |
| address of the second byte of the faulting instruction. |
| |
| Note that setting fs->signal_frame would not work. As the comment |
| above MASK_RETURN_ADDR explains, MIPS unwinders must earch for an |
| odd-valued address. */ |
| fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].how |
| = REG_SAVED_VAL_OFFSET; |
| fs->regs.reg[__LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__].loc.offset |
| = (_Unwind_Ptr)(sc->sc_pc) + 2 - new_cfa; |
| fs->retaddr_column = __LIBGCC_DWARF_ALT_FRAME_RETURN_COLUMN__; |
| |
| return _URC_NO_REASON; |
| } |
| #endif |