unwind-dw2-xtensa.h (_Unwind_FrameState): Remove pc field and add signal_ra.

	* config/xtensa/unwind-dw2-xtensa.h (_Unwind_FrameState): Remove pc
	field and add signal_ra.
	* config/xtensa/unwind-dw2-xtensa.c (uw_frame_state_for): Remove
	assignments to frame state pc.  Move end of stack check after
	MD_FALLBACK_FRAME_STATE_FOR.
	(uw_update_context_1): Use frame state signal_regs if set, instead
	of checking signal_frame flag.
	(uw_update_context): Use frame state signal_ra if set.
	* config/xtensa/linux.h (MD_UNWIND_SUPPORT): Define.
	* config/xtensa/linux-unwind.h: New file.

From-SVN: r131622

gcc/ChangeLog

+2007-01-17  Bob Wilson  <bob.wilson@acm.org>
+
+	* config/xtensa/unwind-dw2-xtensa.h (_Unwind_FrameState): Remove pc
+	field and add signal_ra.
+	* config/xtensa/unwind-dw2-xtensa.c (uw_frame_state_for): Remove
+	assignments to frame state pc.  Move end of stack check after
+	MD_FALLBACK_FRAME_STATE_FOR.
+	(uw_update_context_1): Use frame state signal_regs if set, instead
+	of checking signal_frame flag.
+	(uw_update_context): Use frame state signal_ra if set.
+	* config/xtensa/linux.h (MD_UNWIND_SUPPORT): Define.
+	* config/xtensa/linux-unwind.h: New file.
+
 2007-01-18  Bernhard Fischer  <aldot@gcc.gnu.org>
 
 	* modulo-sched.c (get_sched_window): Fix comment typo.

gcc/config/xtensa/linux-unwind.h

+/* DWARF2 EH unwinding support for Xtensa.
+   Copyright (C) 2008 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 2, or (at your option)
+any later version.
+
+In addition to the permissions in the GNU General Public License, the
+Free Software Foundation gives you unlimited permission to link the
+compiled version of this file with other programs, and to distribute
+those programs without any restriction coming from the use of this
+file.  (The General Public License restrictions do apply in other
+respects; for example, they cover modification of the file, and
+distribution when not linked into another program.)
+
+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.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING.  If not, write to
+the Free Software Foundation, 51 Franklin Street, Fifth Floor,
+Boston, MA 02110-1301, USA.  */
+
+/* Do code reading to identify a signal frame, and set the frame
+   state data appropriately.  See unwind-dw2-xtensa.c for the structs.
+   Don't use this at all if inhibit_libc is used.  */
+
+#ifndef inhibit_libc
+
+#include <signal.h>
+#include <sys/ucontext.h>
+
+/* Encoded bytes for Xtensa instructions:
+	movi a2, __NR_rt_sigreturn
+	syscall
+	entry (first byte only)
+   Some of the bytes are endian-dependent.  */
+
+#define MOVI_BYTE0 0x22
+#define MOVI_BYTE2 225 /* __NR_rt_sigreturn */
+#define SYSC_BYTE0 0
+#define SYSC_BYTE2 0
+
+#ifdef __XTENSA_EB__
+#define MOVI_BYTE1 0x0a
+#define SYSC_BYTE1 0x05
+#define ENTRY_BYTE 0x6c
+#else
+#define MOVI_BYTE1 0xa0
+#define SYSC_BYTE1 0x50
+#define ENTRY_BYTE 0x36
+#endif
+
+#define MD_FALLBACK_FRAME_STATE_FOR xtensa_fallback_frame_state
+
+static _Unwind_Reason_Code
+xtensa_fallback_frame_state (struct _Unwind_Context *context,
+			     _Unwind_FrameState *fs)
+{
+  unsigned char *pc = context->ra;
+  struct sigcontext *sc;
+
+  struct rt_sigframe {
+    struct siginfo info;
+    struct ucontext uc;
+  } *rt_;
+
+  /* movi a2, __NR_rt_sigreturn; syscall */
+  if (pc[0] != MOVI_BYTE0
+      || pc[1] != MOVI_BYTE1
+      || pc[2] != MOVI_BYTE2
+      || pc[3] != SYSC_BYTE0
+      || pc[4] != SYSC_BYTE1
+      || pc[5] != SYSC_BYTE2)
+    return _URC_END_OF_STACK;
+
+  rt_ = context->sp;
+  sc = &rt_->uc.uc_mcontext;
+  fs->signal_regs = (_Unwind_Word *) sc->sc_a;
+
+  /* If the signal arrived just before an ENTRY instruction, find the return
+     address and pretend the signal arrived before executing the CALL.  */
+  if (*(unsigned char *) sc->sc_pc == ENTRY_BYTE)
+   {
+     unsigned callinc = (sc->sc_ps >> 16) & 3;
+     fs->signal_ra = ((sc->sc_a[callinc << 2] & XTENSA_RA_FIELD_MASK)
+		      | context->ra_high_bits) - 3;
+   }
+  else
+    fs->signal_ra = sc->sc_pc;
+
+  fs->signal_frame = 1;
+  return _URC_NO_REASON;
+}
+
+#endif /* ifdef inhibit_libc  */

gcc/config/xtensa/linux.h

 /* Xtensa Linux configuration.
    Derived from the configuration for GCC for Intel i386 running Linux.
-   Copyright (C) 2001, 2002, 2003, 2006, 2007 Free Software Foundation, Inc.
+   Copyright (C) 2001, 2002, 2003, 2006, 2007, 2008
+   Free Software Foundation, Inc.
 
 This file is part of GCC.
 
@@ -59,3 +60,6 @@ along with GCC; see the file COPYING3.  If not see
 
 /* Always enable "-fpic" for Xtensa Linux.  */
 #define XTENSA_ALWAYS_PIC 1
+
+#define MD_UNWIND_SUPPORT "config/xtensa/linux-unwind.h"
+

gcc/config/xtensa/unwind-dw2-xtensa.c

 /* DWARF2 exception handling and frame unwinding for Xtensa.
    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
-   2007
+   2007, 2008
    Free Software Foundation, Inc.
 
    This file is part of GCC.
@@ -325,10 +325,6 @@ uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs)
   memset (fs, 0, sizeof (*fs));
   context->lsda = 0;
 
-  ra_ptr = context->reg[0];
-  if (ra_ptr && *ra_ptr == 0)
-    return _URC_END_OF_STACK;
-
   fde = _Unwind_Find_FDE (context->ra + _Unwind_IsSignalFrame (context) - 1,
 			  &context->bases);
   if (fde == NULL)
@@ -341,16 +337,13 @@ uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs)
       reason = MD_FALLBACK_FRAME_STATE_FOR (context, fs);
       if (reason != _URC_END_OF_STACK)
 	return reason;
+#endif
       /* The frame was not recognized and handled by the fallback function,
 	 but it is not really the end of the stack.  Fall through here and
 	 unwind it anyway.  */
-#endif
-      fs->pc = context->ra;
     }
   else
     {
-      fs->pc = context->bases.func;
-
       cie = get_cie (fde);
       if (extract_cie_info (cie, context, fs) == NULL)
 	/* CIE contained unknown augmentation.  */
@@ -373,6 +366,15 @@ uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs)
 	}
     }
 
+  /* Check for the end of the stack.  This needs to be checked after
+     the MD_FALLBACK_FRAME_STATE_FOR check for signal frames because
+     the contents of context->reg[0] are undefined at a signal frame,
+     and register a0 may appear to be zero.  (The return address in
+     context->ra comes from register a4 or a8).  */
+  ra_ptr = context->reg[0];
+  if (ra_ptr && *ra_ptr == 0)
+    return _URC_END_OF_STACK;
+
   /* Find the window size from the high bits of the return address.  */
   if (ra_ptr)
     window_size = (*ra_ptr >> 30) * 4;
@@ -391,7 +393,7 @@ uw_update_context_1 (struct _Unwind_Context *context, _Unwind_FrameState *fs)
   _Unwind_Word *sp, *cfa, *next_cfa;
   int i;
 
-  if (fs->signal_frame)
+  if (fs->signal_regs)
     {
       cfa = (_Unwind_Word *) fs->signal_regs[1];
       next_cfa = (_Unwind_Word *) cfa[-3];
@@ -437,8 +439,11 @@ uw_update_context (struct _Unwind_Context *context, _Unwind_FrameState *fs)
 
   /* Compute the return address now, since the return address column
      can change from frame to frame.  */
-  context->ra = (void *) ((_Unwind_GetGR (context, fs->retaddr_column)
-			   & XTENSA_RA_FIELD_MASK) | context->ra_high_bits);
+  if (fs->signal_ra != 0)
+    context->ra = (void *) fs->signal_ra;
+  else
+    context->ra = (void *) ((_Unwind_GetGR (context, fs->retaddr_column)
+			     & XTENSA_RA_FIELD_MASK) | context->ra_high_bits);
 }
 
 static void

gcc/config/xtensa/unwind-dw2-xtensa.h

 /* DWARF2 frame unwind data structure for Xtensa.
-   Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2007
+   Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2007, 2008
    Free Software Foundation, Inc.
 
    This file is part of GCC.
@@ -39,9 +39,6 @@
    _Unwind_FrameState.  */
 typedef struct
 {
-  /* The PC described by the current frame state.  */
-  void *pc;
-
   /* The information we care about from the CIE/FDE.  */
   _Unwind_Personality_Fn personality;
   _Unwind_Word retaddr_column;
@@ -53,5 +50,6 @@ typedef struct
 
   /* Saved registers for a signal frame.  */
   _Unwind_Word *signal_regs;
+  _Unwind_Word signal_ra;
 } _Unwind_FrameState;