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Diffstat (limited to 'gcc-4.9/libgcc/config/i386/w32-unwind.h')
| -rw-r--r-- | gcc-4.9/libgcc/config/i386/w32-unwind.h | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/gcc-4.9/libgcc/config/i386/w32-unwind.h b/gcc-4.9/libgcc/config/i386/w32-unwind.h new file mode 100644 index 000000000..17ad2379b --- /dev/null +++ b/gcc-4.9/libgcc/config/i386/w32-unwind.h @@ -0,0 +1,207 @@ +/* Definitions for Dwarf2 EH unwind support for Windows32 targets + Copyright (C) 2007-2014 Free Software Foundation, Inc. + Contributed by Pascal Obry <obry@adacore.com> + +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/>. */ + + +/* This file implements the md_fallback_frame_state_for routine for + Windows, triggered when the GCC table based unwinding process hits a + frame for which no unwind info has been registered. This typically + occurs when raising an exception from a signal handler, because the + handler is actually called from the OS kernel. + + The basic idea is to detect that we are indeed trying to unwind past a + signal handler and to fill out the GCC internal unwinding structures for + the OS kernel frame as if it had been directly called from the + interrupted context. + + This is all assuming that the code to set the handler asked the kernel + to pass a pointer to such context information. + + There is three main parts. + + 1) The first thing to do is to check if we are in a signal context. If + not we can just return as there is nothing to do. We are probably on + some foreign code for which no unwind frame can be found. If this is + a call from the Windows signal handler, then: + + 2) We must get the signal context information. + + * With the standard exception filter: + + This is on Windows pointed to by an EXCEPTION_POINTERS. We know that + the signal handle will call an UnhandledExceptionFilter with this + parameter. The spec for this routine is: + + LONG WINAPI UnhandledExceptionFilter(struct _EXCEPTION_POINTERS*); + + So the pointer to struct _EXCEPTION_POINTERS must be somewhere on the + stack. + + This was found experimentally to always be at offset 0 of the context + frame in all cases handled by this implementation. + + * With the SEH exception handler: + + In this case the signal context is directly on the stack as the SEH + exception handler has the following prototype: + + DWORD + SEH_error_handler (PEXCEPTION_RECORD ExceptionRecord, + PVOID EstablisherFrame, + PCONTEXT ContextRecord, + PVOID DispatcherContext) + + This was found experimentally to always be at offset 56 of the + context frame in all cases handled by this implementation. + + 3) When we have the signal context we just have to save some registers + and set the return address based on the program counter (Eip). + + Note that this implementation follows closely the same principles as the + GNU/Linux and OSF ones. */ + +#ifndef __MINGW64__ + +#define WIN32_MEAN_AND_LEAN +#include <windows.h> +/* Patterns found experimentally to be on a Windows signal handler */ + +/* In a standard exception filter */ + +#define SIG_PAT1 \ + (pc_[-2] == 0xff && pc_[-1] == 0xd0 /* call %eax */ \ + && pc_[0] == 0x83 && pc_[1] == 0xf8) /* cmp 0xdepl,%eax */ + +#define SIG_PAT2 \ + (pc_[-5] == 0xe8 && pc_[-4] == 0x68 /* call (depl16) */ \ + && pc_[0] == 0xc3) /* ret */ + +/* In a Win32 SEH handler */ + +#define SIG_SEH1 \ + (pc_[-5] == 0xe8 /* call addr */ \ + && pc_[0] == 0x83 && pc_[1] == 0xc4 /* add 0xval,%esp */ \ + && pc_[3] == 0xb8) /* mov 0xval,%eax */ + +#define SIG_SEH2 \ + (pc_[-5] == 0x8b && pc_[-4] == 0x4d /* mov depl(%ebp),%ecx */ \ + && pc_[0] == 0x64 && pc_[1] == 0x8b) /* mov %fs:(0),<reg> */ \ + +/* In the GCC alloca (stack probing) */ + +#define SIG_ALLOCA \ + (pc_[-1] == 0x83 /* orl $0x0,(%ecx) */ \ + && pc_[0] == 0x9 && pc_[1] == 0 \ + && pc_[2] == 0x2d && pc_[3] == 0 /* subl $0x1000,%eax */ \ + && pc_[4] == 0x10 && pc_[5] == 0) + + +#define MD_FALLBACK_FRAME_STATE_FOR i386_w32_fallback_frame_state + +static _Unwind_Reason_Code +i386_w32_fallback_frame_state (struct _Unwind_Context *context, + _Unwind_FrameState *fs) + +{ + void * ctx_ra_ = (void *)(context->ra); /* return address */ + void * ctx_cfa_ = (void *)(context->cfa); /* context frame address */ + unsigned char * pc_ = (unsigned char *) ctx_ra_; + + /* In the test below we look for two specific patterns found + experimentally to be in the Windows signal handler. */ + if (SIG_PAT1 || SIG_PAT2 || SIG_SEH1 || SIG_SEH2) + { + PEXCEPTION_POINTERS weinfo_; + PCONTEXT proc_ctx_; + long new_cfa_; + + if (SIG_SEH1) + proc_ctx_ = (PCONTEXT) (*(int*)(ctx_cfa_ + 56)); + else if (SIG_SEH2) + proc_ctx_ = (PCONTEXT) (*(int*)(ctx_cfa_ + 8)); + else + { + weinfo_ = (PEXCEPTION_POINTERS) (*(int*)ctx_cfa_); + proc_ctx_ = weinfo_->ContextRecord; + } + + /* The new context frame address is the stack pointer. */ + new_cfa_ = proc_ctx_->Esp; + fs->regs.cfa_how = CFA_REG_OFFSET; + fs->regs.cfa_reg = __builtin_dwarf_sp_column(); + fs->regs.cfa_offset = new_cfa_ - (long) ctx_cfa_; + + /* Restore registers. */ + fs->regs.reg[0].how = REG_SAVED_OFFSET; + fs->regs.reg[0].loc.offset = (long)&proc_ctx_->Eax - new_cfa_; + fs->regs.reg[3].how = REG_SAVED_OFFSET; + fs->regs.reg[3].loc.offset = (long)&proc_ctx_->Ebx - new_cfa_; + fs->regs.reg[1].how = REG_SAVED_OFFSET; + fs->regs.reg[1].loc.offset = (long)&proc_ctx_->Ecx - new_cfa_; + fs->regs.reg[2].how = REG_SAVED_OFFSET; + fs->regs.reg[2].loc.offset = (long)&proc_ctx_->Edx - new_cfa_; + fs->regs.reg[6].how = REG_SAVED_OFFSET; + fs->regs.reg[6].loc.offset = (long)&proc_ctx_->Esi - new_cfa_; + fs->regs.reg[7].how = REG_SAVED_OFFSET; + fs->regs.reg[7].loc.offset = (long)&proc_ctx_->Edi - new_cfa_; + fs->regs.reg[5].how = REG_SAVED_OFFSET; + fs->regs.reg[5].loc.offset = (long)&proc_ctx_->Ebp - new_cfa_; + fs->regs.reg[8].how = REG_SAVED_OFFSET; + fs->regs.reg[8].loc.offset = (long)&proc_ctx_->Eip - new_cfa_; + fs->retaddr_column = 8; + fs->signal_frame = 1; + + return _URC_NO_REASON; + } + + /* Unwinding through _alloca, propagating from a trap triggered by + one of it's probes prior to the real SP adjustment. The only + operations of interest performed is "pushl %ecx", followed by + ecx clobbering. */ + else if (SIG_ALLOCA) + { + /* Only one push between entry in _alloca and the probe trap. */ + long new_cfa_ = (long) ctx_cfa_ + 4; + + fs->regs.cfa_how = CFA_REG_OFFSET; + fs->regs.cfa_reg = __builtin_dwarf_sp_column(); + fs->regs.cfa_offset = new_cfa_ - (long) ctx_cfa_; + + /* The saved value of %ecx is at CFA - 4 */ + fs->regs.reg[1].how = REG_SAVED_OFFSET; + fs->regs.reg[1].loc.offset = -4; + + /* and what is stored at the CFA is the return address. */ + fs->retaddr_column = 8; + fs->regs.reg[8].how = REG_SAVED_OFFSET; + fs->regs.reg[8].loc.offset = 0; + fs->signal_frame = 1; + + return _URC_NO_REASON; + } + else + return _URC_END_OF_STACK; +} + +#endif /* !__MINGW64__ */ |