--- /dev/null
+/* Definitions for Dwarf2 EH unwind support for Windows32 targets
+ Copyright (C) 2007, 2009
+ 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. */
+
+#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_;
+
+ /* Save some 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[9].how = REG_SAVED_OFFSET;
+ fs->regs.reg[9].loc.offset = (long)&proc_ctx_->Eip - new_cfa_;
+ fs->regs.reg[4].how = REG_SAVED_OFFSET;
+ fs->regs.reg[4].loc.offset = (long)&proc_ctx_->Ebp - new_cfa_;
+
+ /* Set the return address to Eip + 1. As we can be called multiple
+ times we use another register for this. */
+
+ proc_ctx_->Dr0 = proc_ctx_->Eip + 1;
+ fs->regs.reg[8].how = REG_SAVED_OFFSET;
+ fs->regs.reg[8].loc.offset = (long)&proc_ctx_->Dr0 - new_cfa_;
+ fs->retaddr_column = 8;
+ 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;
+
+ return _URC_NO_REASON;
+ }
+ else
+ return _URC_END_OF_STACK;
+}
projects / msp430-gcc.git / blobdiff