This is the mail archive of the
gdb-patches@sourceware.org
mailing list for the GDB project.
[patch] Parse DW_AT_ranges into PSYMTABS (for childless CU, for vDSO32)
- From: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- To: gdb-patches at sourceware dot org
- Date: Tue, 9 Oct 2007 20:02:46 +0200
- Subject: [patch] Parse DW_AT_ranges into PSYMTABS (for childless CU, for vDSO32)
Hi,
currently on GNU/Linux running i386 inferior on x86_64 host you do not see some
of the debug info for the vDSO32 provided by the kernel.
Unpatched:
------------------------------------------------------------------------------
0xffffe410 in __kernel_vsyscall ()
(gdb) bt
#0 0xffffe410 in __kernel_vsyscall ()
#1 0x00c7a853 in __read_nocancel () from /lib/libc.so.6
#2 0x0804b263 in ?? ()
#3 0x0804941f in ?? ()
#4 0x00bcd3a0 in __libc_start_main () from /lib/libc.so.6
#5 0x08048c61 in ?? ()
(gdb) info line *0xffffe410
No line number information available for address 0xffffe410 <__kernel_vsyscall+16>
------------------------------------------------------------------------------
Patched:
------------------------------------------------------------------------------
__kernel_vsyscall () at arch/x86_64/ia32/vsyscall-sysenter.S:26
26 pop %ebp
Current language: auto; currently asm
(gdb) bt
#0 __kernel_vsyscall () at arch/x86_64/ia32/vsyscall-sysenter.S:26
#1 0x00c7a853 in __read_nocancel () from /lib/libc.so.6
#2 0x0804b263 in ?? ()
#3 0x0804941f in ?? ()
#4 0x00bcd3a0 in __libc_start_main () from /lib/libc.so.6
#5 0x08048c61 in ?? ()
(gdb) info line $eip
Convenience variables used in line specs must have integer values.
(gdb) info line $rip
Convenience variables used in line specs must have integer values.
(gdb) p/x $eip
$1 = 0xffffe410
(gdb) info line *0xffffe410
Line 26 of "arch/x86_64/ia32/vsyscall-sysenter.S" starts at address 0xffffe410 <__kernel_vsyscall+16>
and ends at 0xffffe411 <__kernel_vsyscall+17>.
------------------------------------------------------------------------------
The problem is this vDSO is in assembly language, therefore its
<0><b>: Abbrev Number: 1 (DW_TAG_compile_unit)
< c> DW_AT_stmt_list : 0
<10> DW_AT_ranges : 0
<14> DW_AT_name : arch/x86_64/ia32/vsyscall-sysenter.S
<39> DW_AT_comp_dir : /usr/src/debug////////kernel-2.6.22/linux-2.6.22.x86_64
<71> DW_AT_producer : GNU AS 2.17.50.0.18
<85> DW_AT_language : 32769 (MIPS assembler)
Contents of the .debug_ranges section:
Offset Begin End
00000000 ffffffff 00000000 (start > end)
00000000 ffffe400 ffffe414
00000000 ffffe500 ffffe508
00000000 ffffe600 ffffe607
00000000 <End of list>
DW_TAG_compile_unit has no children and it has neither DW_AT_low_pc nor
DW_AT_high_pc but it has DW_AT_ranges instead. So far DW_AT_ranges was not
parsed into PSYMTABS and so this file was ignored during the debug info search
later. Reasons for the discontinuous vDSO32 layout/hack are in the Linux
kernel sources.
Thanks to Roland McGrath for pointing out this .debug_info is not broken for
`.S'.
Regards,
Jan
2007-10-09 Jan Kratochvil <jan.kratochvil@redhat.com>
* dwarf2read.c (dwarf2_get_pc_bounds): Moved the `DW_AT_ranges' parsing
code with its variables OBJFILE, CU_HEADER and OBFD into ...
(dwarf2_ranges_read): ... a new function.
(read_partial_die): Implemented the parsing of `DW_AT_ranges'.
2007-10-09 Jan Kratochvil <jan.kratochvil@redhat.com>
* gdb.dwarf2/dw2-ranges.S, gdb.dwarf2/dw2-ranges.exp,
gdb.dwarf2/dw2-ranges.lds: New files.
--- ./gdb/dwarf2read.c 26 Sep 2007 13:59:54 -0000 1.232
+++ ./gdb/dwarf2read.c 9 Oct 2007 15:03:09 -0000
@@ -3075,6 +3075,124 @@ read_lexical_block_scope (struct die_inf
local_symbols = new->locals;
}
+/* Get low and high pc attributes from DW_AT_ranges attribute value OFFSET.
+ Return 1 if the attributes are present and valid, otherwise, return 0. */
+
+static int
+dwarf2_ranges_read (unsigned offset, CORE_ADDR *low_return,
+ CORE_ADDR *high_return, struct dwarf2_cu *cu)
+{
+ struct objfile *objfile = cu->objfile;
+ struct comp_unit_head *cu_header = &cu->header;
+ bfd *obfd = objfile->obfd;
+ unsigned int addr_size = cu_header->addr_size;
+ CORE_ADDR mask = ~(~(CORE_ADDR)1 << (addr_size * 8 - 1));
+ /* Base address selection entry. */
+ CORE_ADDR base;
+ int found_base;
+ unsigned int dummy;
+ gdb_byte *buffer;
+ CORE_ADDR marker;
+ int low_set;
+ CORE_ADDR low = 0;
+ CORE_ADDR high = 0;
+
+ found_base = cu_header->base_known;
+ base = cu_header->base_address;
+
+ if (offset >= dwarf2_per_objfile->ranges_size)
+ {
+ complaint (&symfile_complaints,
+ _("Offset %d out of bounds for DW_AT_ranges attribute"),
+ offset);
+ return 0;
+ }
+ buffer = dwarf2_per_objfile->ranges_buffer + offset;
+
+ /* Read in the largest possible address. */
+ marker = read_address (obfd, buffer, cu, &dummy);
+ if ((marker & mask) == mask)
+ {
+ /* If we found the largest possible address, then
+ read the base address. */
+ base = read_address (obfd, buffer + addr_size, cu, &dummy);
+ buffer += 2 * addr_size;
+ offset += 2 * addr_size;
+ found_base = 1;
+ }
+
+ low_set = 0;
+
+ while (1)
+ {
+ CORE_ADDR range_beginning, range_end;
+
+ range_beginning = read_address (obfd, buffer, cu, &dummy);
+ buffer += addr_size;
+ range_end = read_address (obfd, buffer, cu, &dummy);
+ buffer += addr_size;
+ offset += 2 * addr_size;
+
+ /* An end of list marker is a pair of zero addresses. */
+ if (range_beginning == 0 && range_end == 0)
+ /* Found the end of list entry. */
+ break;
+
+ /* Each base address selection entry is a pair of 2 values.
+ The first is the largest possible address, the second is
+ the base address. Check for a base address here. */
+ if ((range_beginning & mask) == mask)
+ {
+ /* If we found the largest possible address, then
+ read the base address. */
+ base = read_address (obfd, buffer + addr_size, cu, &dummy);
+ found_base = 1;
+ continue;
+ }
+
+ if (!found_base)
+ {
+ /* We have no valid base address for the ranges
+ data. */
+ complaint (&symfile_complaints,
+ _("Invalid .debug_ranges data (no base address)"));
+ return 0;
+ }
+
+ range_beginning += base;
+ range_end += base;
+
+ /* FIXME: This is recording everything as a low-high
+ segment of consecutive addresses. We should have a
+ data structure for discontiguous block ranges
+ instead. */
+ if (! low_set)
+ {
+ low = range_beginning;
+ high = range_end;
+ low_set = 1;
+ }
+ else
+ {
+ if (range_beginning < low)
+ low = range_beginning;
+ if (range_end > high)
+ high = range_end;
+ }
+ }
+
+ if (! low_set)
+ /* If the first entry is an end-of-list marker, the range
+ describes an empty scope, i.e. no instructions. */
+ return 0;
+
+ if (low_return)
+ *low_return = low;
+ if (high_return)
+ *high_return = high;
+ return 1;
+}
+
/* Get low and high pc attributes from a die. Return 1 if the attributes
are present and valid, otherwise, return 0. Return -1 if the range is
discontinuous, i.e. derived from DW_AT_ranges information. */
@@ -3082,10 +3200,7 @@ static int
dwarf2_get_pc_bounds (struct die_info *die, CORE_ADDR *lowpc,
CORE_ADDR *highpc, struct dwarf2_cu *cu)
{
- struct objfile *objfile = cu->objfile;
- struct comp_unit_head *cu_header = &cu->header;
struct attribute *attr;
- bfd *obfd = objfile->obfd;
CORE_ADDR low = 0;
CORE_ADDR high = 0;
int ret = 0;
@@ -3109,108 +3224,11 @@ dwarf2_get_pc_bounds (struct die_info *d
attr = dwarf2_attr (die, DW_AT_ranges, cu);
if (attr != NULL)
{
- unsigned int addr_size = cu_header->addr_size;
- CORE_ADDR mask = ~(~(CORE_ADDR)1 << (addr_size * 8 - 1));
/* Value of the DW_AT_ranges attribute is the offset in the
.debug_ranges section. */
- unsigned int offset = DW_UNSND (attr);
- /* Base address selection entry. */
- CORE_ADDR base;
- int found_base;
- unsigned int dummy;
- gdb_byte *buffer;
- CORE_ADDR marker;
- int low_set;
-
- found_base = cu_header->base_known;
- base = cu_header->base_address;
-
- if (offset >= dwarf2_per_objfile->ranges_size)
- {
- complaint (&symfile_complaints,
- _("Offset %d out of bounds for DW_AT_ranges attribute"),
- offset);
- return 0;
- }
- buffer = dwarf2_per_objfile->ranges_buffer + offset;
-
- /* Read in the largest possible address. */
- marker = read_address (obfd, buffer, cu, &dummy);
- if ((marker & mask) == mask)
- {
- /* If we found the largest possible address, then
- read the base address. */
- base = read_address (obfd, buffer + addr_size, cu, &dummy);
- buffer += 2 * addr_size;
- offset += 2 * addr_size;
- found_base = 1;
- }
-
- low_set = 0;
-
- while (1)
- {
- CORE_ADDR range_beginning, range_end;
-
- range_beginning = read_address (obfd, buffer, cu, &dummy);
- buffer += addr_size;
- range_end = read_address (obfd, buffer, cu, &dummy);
- buffer += addr_size;
- offset += 2 * addr_size;
-
- /* An end of list marker is a pair of zero addresses. */
- if (range_beginning == 0 && range_end == 0)
- /* Found the end of list entry. */
- break;
-
- /* Each base address selection entry is a pair of 2 values.
- The first is the largest possible address, the second is
- the base address. Check for a base address here. */
- if ((range_beginning & mask) == mask)
- {
- /* If we found the largest possible address, then
- read the base address. */
- base = read_address (obfd, buffer + addr_size, cu, &dummy);
- found_base = 1;
- continue;
- }
-
- if (!found_base)
- {
- /* We have no valid base address for the ranges
- data. */
- complaint (&symfile_complaints,
- _("Invalid .debug_ranges data (no base address)"));
- return 0;
- }
-
- range_beginning += base;
- range_end += base;
-
- /* FIXME: This is recording everything as a low-high
- segment of consecutive addresses. We should have a
- data structure for discontiguous block ranges
- instead. */
- if (! low_set)
- {
- low = range_beginning;
- high = range_end;
- low_set = 1;
- }
- else
- {
- if (range_beginning < low)
- low = range_beginning;
- if (range_end > high)
- high = range_end;
- }
- }
-
- if (! low_set)
- /* If the first entry is an end-of-list marker, the range
- describes an empty scope, i.e. no instructions. */
+ if (!dwarf2_ranges_read (DW_UNSND (attr), &low, &high, cu))
return 0;
-
+ /* Found discontinuous range of addresses. */
ret = -1;
}
}
@@ -5571,6 +5589,11 @@ read_partial_die (struct partial_die_inf
has_high_pc_attr = 1;
part_die->highpc = DW_ADDR (&attr);
break;
+ case DW_AT_ranges:
+ if (dwarf2_ranges_read (DW_UNSND (&attr), &part_die->lowpc,
+ &part_die->highpc, cu))
+ has_low_pc_attr = has_high_pc_attr = 1;
+ break;
case DW_AT_location:
/* Support the .debug_loc offsets */
if (attr_form_is_block (&attr))
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ ./gdb/testsuite/gdb.dwarf2/dw2-ranges.S 9 Oct 2007 15:03:10 -0000
@@ -0,0 +1,33 @@
+/*
+ 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 3 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, see <http://www.gnu.org/licenses/>.
+ */
+
+ .text
+
+ .section .text._start, "ax", @progbits
+ .globl _start
+ .func _start
+_start: call func
+ .endfunc
+ .size _start, . - _start
+
+ .section .text.func, "ax", @progbits
+ .globl func
+ .func func
+func: int3
+ nop
+ .endfunc
+ .size func, . - func
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ ./gdb/testsuite/gdb.dwarf2/dw2-ranges.exp 9 Oct 2007 15:03:10 -0000
@@ -0,0 +1,82 @@
+# 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 3 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, see <http://www.gnu.org/licenses/>.
+
+# Test DW_TAG_compile_unit with no children and with neither DW_AT_low_pc nor
+# DW_AT_high_pc but with DW_AT_ranges instead. We created the hole there for
+# DW_AT_ranges by the linker script.
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+# For now pick a sampling of likely targets.
+if {![istarget *-*-linux*]
+ && ![istarget *-*-gnu*]
+ && ![istarget *-*-elf*]
+ && ![istarget *-*-openbsd*]
+ && ![istarget arm-*-eabi*]
+ && ![istarget powerpc-*-eabi*]} {
+ verbose "Skipping i386/amd64 DW_AT_ranges test."
+ return 0
+}
+if { ![istarget "i?86-*-*"] && ![istarget "x86_64-*-*"] } then {
+ verbose "Skipping i386/amd64 DW_AT_ranges test."
+ return 0
+}
+
+set testfile "dw2-ranges"
+set srcfile ${testfile}.S
+set ldsfile ${testfile}.lds
+set binfile ${objdir}/${subdir}/${testfile}
+
+# Avoid `-lm' from `lib/ada.exp' as it would fail with out `-nostdlib'.
+# Provide BOARD for SET_BOARD_INFO.
+set board [target_info name]
+set_board_info mathlib ""
+
+if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable [list debug "additional_flags=-Wl,--script=${srcdir}/${subdir}/${ldsfile} -nostdlib"]] != "" } {
+ return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+# Former wrong output:
+# Program received signal SIGTRAP, Trace/breakpoint trap.
+# 0x000000000000002b in func ()
+# (gdb) bt
+# #0 0x000000000000002b in func ()
+# #1 0x0000000000000029 in _start ()
+# (gdb) _
+# Correct output:
+# Program received signal SIGTRAP, Trace/breakpoint trap.
+# func () at dw2-ranges.S:14
+# 14 nop
+# Current language: auto; currently asm
+# (gdb) bt
+# #0 func () at dw2-ranges.S:14
+# #1 0x0000000000000029 in _start () at dw2-ranges.S:6
+# (gdb) _
+# The entry #1 is missing on i386.
+# "#0 +func \\(\\) at .*dw2-ranges.S:\[0-9\]+\r\n#1 .*in _start \\(\\) at .*dw2-ranges.S:\[0-9\]+"
+
+gdb_run_cmd
+set test "run"
+gdb_test_multiple "" "$test" {
+ -re "Program received signal SIGTRAP,.*$gdb_prompt $" {
+ pass $test
+ }
+}
+
+gdb_test "backtrace" "#0 +func \\(\\) at .*dw2-ranges.S:\[0-9\]+"
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ ./gdb/testsuite/gdb.dwarf2/dw2-ranges.lds 9 Oct 2007 15:03:10 -0000
@@ -0,0 +1,25 @@
+/*
+ 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 3 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, see <http://www.gnu.org/licenses/>.
+ */
+
+SECTIONS
+{
+ .text._start : { *(.text._start) }
+ /* Create the hole. */
+ . = . + 1;
+ .text.func : { *(.text.func) }
+}
+ENTRY(_start)