Re: [review] Fix resolving of PC in overlapping non-zero sized functions

[Daniel Jacobowitz <drow at false dot org>]

Sorry for not getting back to this one sooner.  I definitely broke
this case when I rewrote lookup_minimal_symbol_by_pc_section; thanks
for fixing it.

On Mon, Oct 30, 2006 at 01:48:16PM +0100, Jan Kratochvil wrote:
> 2006-10-30  Jan Kratochvil  <jan.kratochvil@redhat.com>
> 
> 	* gdb/minsyms.c (lookup_minimal_symbol_by_pc_section): Handle
> 	overlapping non-zero sized functions (for glibc `__nanosleep').
> 
> 2006-10-30  Jan Kratochvil  <jan.kratochvil@redhat.com>
> 
> 	* gdb.arch/i386-size-overlap.c, gdb.arch/i386-size-overlap.exp: New
> 	file, provide nested (overlapping) functions for the PC resolving.

The patch and testcase look fine.  I adjusted the comments and
changelog entries, and checked in this copy.  Briefer comments have
a better chance of staying accurate as the code changes, and it's
easy enough to find the submission on the mailing list later.

-- 
Daniel Jacobowitz
CodeSourcery

2007-01-09  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* minsyms.c (lookup_minimal_symbol_by_pc_section): Handle
	nested symbols.

2007-01-09  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.arch/i386-size-overlap.c, gdb.arch/i386-size-overlap.exp: New.

Index: minsyms.c
===================================================================
RCS file: /cvs/src/src/gdb/minsyms.c,v
retrieving revision 1.48
diff -u -p -r1.48 minsyms.c
--- minsyms.c	9 Jan 2007 17:58:52 -0000	1.48
+++ minsyms.c	9 Jan 2007 22:10:48 -0000
@@ -510,6 +510,22 @@ lookup_minimal_symbol_by_pc_section (COR
 		      continue;
 		    }
 
+		  /* If we are past the end of the current symbol, try
+		     the previous symbol if it has a larger overlapping
+		     size.  This happens on i686-pc-linux-gnu with glibc;
+		     the nocancel variants of system calls are inside
+		     the cancellable variants, but both have sizes.  */
+		  if (hi > 0
+		      && MSYMBOL_SIZE (&msymbol[hi]) != 0
+		      && pc >= (SYMBOL_VALUE_ADDRESS (&msymbol[hi])
+				+ MSYMBOL_SIZE (&msymbol[hi]))
+		      && pc < (SYMBOL_VALUE_ADDRESS (&msymbol[hi - 1])
+			       + MSYMBOL_SIZE (&msymbol[hi - 1])))
+		    {
+		      hi--;
+		      continue;
+		    }
+
 		  /* Otherwise, this symbol must be as good as we're going
 		     to get.  */
 		  break;
Index: testsuite/gdb.arch/i386-size-overlap.c
===================================================================
RCS file: testsuite/gdb.arch/i386-size-overlap.c
diff -N testsuite/gdb.arch/i386-size-overlap.c
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.arch/i386-size-overlap.c	9 Jan 2007 22:10:48 -0000
@@ -0,0 +1,53 @@
+/* Overlapping symbol sizes test program.
+
+   Copyright 2007 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program 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 of the License, or
+   (at your option) any later version.
+   
+   This program 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 this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#ifdef SYMBOL_PREFIX
+#define SYMBOL(str)	SYMBOL_PREFIX #str
+#else
+#define SYMBOL(str)	#str
+#endif
+
+void
+trap (void)
+{
+  asm ("int $0x03");
+}
+
+/* Jump from a function with its symbol size set, to a function
+   named by a local label.  GDB should report the `main' function
+   even for the rest, after the global `inner' ends.  */
+
+asm(".text\n"
+    "    .align 8\n"
+    "    .globl " SYMBOL (main) "\n"
+    SYMBOL (main) ":\n"
+    "    pushl %ebp\n"
+    "    mov   %esp, %ebp\n"
+    "    call  .Lfunc\n"
+    "    ret\n"
+    SYMBOL (inner) ":\n"
+    "    ret\n"
+    "    .size " SYMBOL (inner) ", .-" SYMBOL (inner) "\n"
+    ".Lfunc:\n"
+    "    pushl %ebp\n"
+    "    mov   %esp, %ebp\n"
+    "    call  " SYMBOL (trap) "\n"
+    "    .size " SYMBOL (main) ", .-" SYMBOL (main) "\n");
Index: testsuite/gdb.arch/i386-size-overlap.exp
===================================================================
RCS file: testsuite/gdb.arch/i386-size-overlap.exp
diff -N testsuite/gdb.arch/i386-size-overlap.exp
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ testsuite/gdb.arch/i386-size-overlap.exp	9 Jan 2007 22:10:48 -0000
@@ -0,0 +1,76 @@
+# Copyright 2007 Free Software Foundation, Inc.
+
+# This program 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 of the License, or
+# (at your option) any later version.
+#
+# This program 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 this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  
+
+# This file is part of the gdb testsuite.
+
+if $tracelevel {
+    strace $tracelevel
+}
+
+# Test that GDB can handle overlapping sizes of symbols.
+
+if ![istarget "i?86-*-*"] then {
+    verbose "Skipping i386 unwinder tests."
+    return
+}
+
+set testfile "i386-size-overlap"
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+
+# some targets have leading underscores on assembly symbols.
+# TODO: detect this automatically
+set additional_flags ""
+if [istarget "i?86-*-cygwin*"] then {
+  set additional_flags "additional_flags=-DSYMBOL_PREFIX=\"_\""
+}
+
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" \
+	  executable [list debug $additional_flags]] != "" } {
+    untested "i386-size"
+    return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+# We use gdb_run_cmd so this stands a chance to work for remote
+# targets too.
+gdb_run_cmd
+
+gdb_expect {
+    -re "Program received signal SIGTRAP.*$gdb_prompt $" {
+	pass "run past main"
+    }
+    -re ".*$gdb_prompt $" {
+	fail "run past main"
+    }
+    timeout {
+	fail "run past main (timeout)"
+    }
+}
+
+set message "backtrace shows the outer function"
+gdb_test_multiple "backtrace 10" $message {
+    -re "#1\[ \t]*$hex in inner.*$gdb_prompt $" {
+	fail $message
+    }
+    -re "#1\[ \t]*$hex in main.*$gdb_prompt $" {
+	pass $message
+    }
+}