CFI support: lookup by PC and translate into DWARF location per register

7 files changed, 127 insertions, 6 deletions

diff --git a/libebl/ChangeLog b/libebl/ChangeLog
index 12e94f42..837a4d16 100644
--- a/libebl/ChangeLog
+++ b/libebl/ChangeLog
@@ -1,3 +1,12 @@
+2009-07-08  Roland McGrath  <roland@redhat.com>
+
+	* ebl-hooks.h: Add abi_cfi hook.
+	* eblopenbackend.c (default_abi_cfi): New function.
+	(fill_defaults): Add initializer.
+	* eblabicfi.c: New file.
+	* Makefile.am (gen_SOURCES): Add it.
+	* libebl.h: Declare ebl_abi_cfi.
+
 2009-07-08  Ulrich Drepper  <drepper@redhat.com>
 
 	* eblsymbolbindingname.c (ebl_symbol_binding_name): Handle
diff --git a/libebl/Makefile.am b/libebl/Makefile.am
index c4e4a076..a95e66d6 100644
--- a/libebl/Makefile.am
+++ b/libebl/Makefile.am
@@ -1,6 +1,6 @@
 ## Process this file with automake to create Makefile.in
 ##
-## Copyright (C) 2000,2001,2002,2003,2004,2005,2006,2007,2008 Red Hat, Inc.
+## Copyright (C) 2000-2009 Red Hat, Inc.
 ## This file is part of Red Hat elfutils.
 ##
 ## Red Hat elfutils is free software; you can redistribute it and/or modify
@@ -59,7 +59,7 @@ gen_SOURCES = eblopenbackend.c eblclosebackend.c eblstrtab.c \
 	      ebl_check_special_symbol.c eblbsspltp.c eblretval.c \
 	      eblreginfo.c eblnonerelocp.c eblrelativerelocp.c \
 	      eblsysvhashentrysize.c eblauxvinfo.c eblcheckobjattr.c \
-	      ebl_check_special_section.c ebl_syscall_abi.c
+	      ebl_check_special_section.c ebl_syscall_abi.c eblabicfi.c
 
 libebl_a_SOURCES = $(gen_SOURCES)
 
diff --git a/libebl/ebl-hooks.h b/libebl/ebl-hooks.h
index 2db1e208..d483f2a3 100644
--- a/libebl/ebl-hooks.h
+++ b/libebl/ebl-hooks.h
@@ -1,5 +1,5 @@
 /* Backend hook signatures internal interface for libebl.
-   Copyright (C) 2000,2001,2002,2004,2005,2006,2007,2008 Red Hat, Inc.
+   Copyright (C) 2000-2009 Red Hat, Inc.
    This file is part of Red Hat elfutils.
 
    Red Hat elfutils is free software; you can redistribute it and/or modify
@@ -167,6 +167,8 @@ int EBLHOOK(disasm) (const uint8_t **startp, const uint8_t *end,
 		     GElf_Addr addr, const char *fmt, DisasmOutputCB_t outcb,
 		     DisasmGetSymCB_t symcb, void *outcbarg, void *symcbarg);
 
+/* Supply the machine-specific state of CFI before CIE initial programs.  */
+int EBLHOOK(abi_cfi) (Ebl *ebl, Dwarf_CIE *abi_info);
 
 /* Destructor for ELF backend handle.  */
 void EBLHOOK(destr) (struct ebl *);
diff --git a/libebl/eblabicfi.c b/libebl/eblabicfi.c
new file mode 100644
index 00000000..221e83fc
--- /dev/null
+++ b/libebl/eblabicfi.c
@@ -0,0 +1,63 @@
+/* Return ABI-specific DWARF CFI details.
+   Copyright (C) 2009 Red Hat, Inc.
+   This file is part of Red Hat elfutils.
+
+   Red Hat elfutils 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; version 2 of the License.
+
+   Red Hat elfutils 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 Red Hat elfutils; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
+
+   In addition, as a special exception, Red Hat, Inc. gives You the
+   additional right to link the code of Red Hat elfutils with code licensed
+   under any Open Source Initiative certified open source license
+   (http://www.opensource.org/licenses/index.php) which requires the
+   distribution of source code with any binary distribution and to
+   distribute linked combinations of the two.  Non-GPL Code permitted under
+   this exception must only link to the code of Red Hat elfutils through
+   those well defined interfaces identified in the file named EXCEPTION
+   found in the source code files (the "Approved Interfaces").  The files
+   of Non-GPL Code may instantiate templates or use macros or inline
+   functions from the Approved Interfaces without causing the resulting
+   work to be covered by the GNU General Public License.  Only Red Hat,
+   Inc. may make changes or additions to the list of Approved Interfaces.
+   Red Hat's grant of this exception is conditioned upon your not adding
+   any new exceptions.  If you wish to add a new Approved Interface or
+   exception, please contact Red Hat.  You must obey the GNU General Public
+   License in all respects for all of the Red Hat elfutils code and other
+   code used in conjunction with Red Hat elfutils except the Non-GPL Code
+   covered by this exception.  If you modify this file, you may extend this
+   exception to your version of the file, but you are not obligated to do
+   so.  If you do not wish to provide this exception without modification,
+   you must delete this exception statement from your version and license
+   this file solely under the GPL without exception.
+
+   Red Hat elfutils is an included package of the Open Invention Network.
+   An included package of the Open Invention Network is a package for which
+   Open Invention Network licensees cross-license their patents.  No patent
+   license is granted, either expressly or impliedly, by designation as an
+   included package.  Should you wish to participate in the Open Invention
+   Network licensing program, please visit www.openinventionnetwork.com
+   <http://www.openinventionnetwork.com>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <libeblP.h>
+
+
+int
+ebl_abi_cfi (ebl, abi_info)
+     Ebl *ebl;
+     Dwarf_CIE *abi_info;
+{
+  return ebl == NULL ? -1 : ebl->abi_cfi (ebl, abi_info);
+}
diff --git a/libebl/eblopenbackend.c b/libebl/eblopenbackend.c
index 8cf42189..cb17f03f 100644
--- a/libebl/eblopenbackend.c
+++ b/libebl/eblopenbackend.c
@@ -1,5 +1,5 @@
 /* Generate ELF backend handle.
-   Copyright (C) 2000,2001,2002,2003,2004,2005,2006,2007,2008 Red Hat, Inc.
+   Copyright (C) 2000-2009 Red Hat, Inc.
    This file is part of Red Hat elfutils.
 
    Red Hat elfutils is free software; you can redistribute it and/or modify
@@ -218,6 +218,7 @@ static bool default_check_object_attribute (Ebl *ebl, const char *vendor,
 					    int tag, uint64_t value,
 					    const char **tag_name,
 					    const char **value_name);
+static int default_abi_cfi (Ebl *ebl, Dwarf_CIE *abi_info);
 
 
 static void
@@ -258,6 +259,7 @@ fill_defaults (Ebl *result)
   result->syscall_abi = default_syscall_abi;
   result->check_object_attribute = default_check_object_attribute;
   result->disasm = NULL;
+  result->abi_cfi = default_abi_cfi;
   result->destr = default_destr;
   result->sysvhash_entrysize = sizeof (Elf32_Word);
 }
@@ -746,3 +748,10 @@ default_check_object_attribute (Ebl *ebl __attribute__ ((unused)),
   *value_name = NULL;
   return false;
 }
+
+static int
+default_abi_cfi (Ebl *ebl __attribute__ ((unused)),
+		 Dwarf_CIE *abi_info __attribute__ ((unused)))
+{
+  return 0;
+}
diff --git a/libebl/libebl.h b/libebl/libebl.h
index 50258690..1a56b966 100644
--- a/libebl/libebl.h
+++ b/libebl/libebl.h
@@ -1,5 +1,5 @@
 /* Interface for libebl.
-   Copyright (C) 2000, 2001, 2002, 2004, 2005, 2006, 2007, 2008 Red Hat, Inc.
+   Copyright (C) 2000, 2001-2009 Red Hat, Inc.
    This file is part of Red Hat elfutils.
 
    Red Hat elfutils is free software; you can redistribute it and/or modify
@@ -256,6 +256,38 @@ extern ssize_t ebl_register_info (Ebl *ebl,
 extern int ebl_syscall_abi (Ebl *ebl, int *sp, int *pc,
 			    int *callno, int args[6]);
 
+/* Supply the ABI-specified state of DWARF CFI before CIE initial programs.
+
+   The DWARF 3.0 spec says that the default initial states of all registers
+   are "undefined", unless otherwise specified by the machine/compiler ABI.
+
+   This default is wrong for every machine with the CFI generated by GCC.
+   The EH unwinder does not really distinguish "same_value" and "undefined",
+   since it doesn't matter for unwinding (in either case there is no change
+   to make for that register).  GCC generates CFI that says nothing at all
+   about registers it hasn't spilled somewhere.  For our unwinder to give
+   the true story, the backend must supply an initial state that uses
+   "same_value" rules for all the callee-saves registers.
+
+   This can fill in the initial_instructions, initial_instructions_end
+   members of *ABI_INFO to point at a CFI instruction stream to process
+   before each CIE's initial instructions.  It should set the
+   data_alignment_factor member if it affects the initial instructions.
+
+   As a shorthand for some common cases, for this instruction stream
+   we overload some CFI instructions that cannot be used in a CIE:
+
+	DW_CFA_restore		-- Change default rule for all unmentioned
+				   registers from undefined to same_value.
+
+   This function can also fill in ABI_INFO->return_address_register with the
+   DWARF register number that identifies the actual PC in machine state.
+   If there is no canonical DWARF register number with that meaning, it's
+   left unchanged (callers usually initialize with (Dwarf_Word) -1).
+   This value is not used by CFI per se.  */
+extern int ebl_abi_cfi (Ebl *ebl, Dwarf_CIE *abi_info)
+  __nonnull_attribute__ (2);
+
 /* ELF string table handling.  */
 struct Ebl_Strtab;
 struct Ebl_Strent;
diff --git a/libebl/libeblP.h b/libebl/libeblP.h
index 7bfa650f..32a43728 100644
--- a/libebl/libeblP.h
+++ b/libebl/libeblP.h
@@ -1,5 +1,5 @@
 /* Internal definitions for interface for libebl.
-   Copyright (C) 2000, 2001, 2002, 2004, 2005, 2006 Red Hat, Inc.
+   Copyright (C) 2000-2009 Red Hat, Inc.
    This file is part of Red Hat elfutils.
 
    Red Hat elfutils is free software; you can redistribute it and/or modify
@@ -94,4 +94,10 @@ typedef const char *(*ebl_bhinit_t) (Elf *, GElf_Half, Ebl *, size_t);
 #undef _
 #define _(Str) dgettext ("elfutils", Str)
 
+
+/* LEB128 constant helper macros.  */
+#define ULEB128_7(x)	(BUILD_BUG_ON_ZERO ((x) >= (1U << 7)) + (x))
+
+#define BUILD_BUG_ON_ZERO(x) (sizeof (char [(x) ? -1 : 1]) - 1)
+
 #endif	/* libeblP.h */