[patch] Support core files with 0 < p_filesz < p_memsz (build-id)
Jan Kratochvil
jan.kratochvil@redhat.com
Wed Aug 1 16:22:00 GMT 2007
Hi,
there is now a pending patch for Linux kernels producing core files with the
first page of the ELF file for the build-id note identification (to find the
original versions/builds of the binaries used to produce the core file).
So far GDB handled either p_filesz == 0 or p_filesz == p_memsz. Patch handles
the case 0 < p_filesz < p_memsz (p_filesz == PAGE_SIZE for the build-id case).
`0 < p_filesz < p_memsz' meaning was so far undefined for the ET_CORE files.
(Testsuite run verified.)
The IMO more appropriate patch for BFD to flag the p_filesz..p_memsz part the
same way as the former (0==p_filesz)..(p_memsz) core part has been rejected:
http://sourceware.org/ml/binutils/2007-08/msg00013.html
Referencing former BFD patch (where no GDB modifications were needed):
http://sourceware.org/ml/binutils/2007-07/msg00520.html
Regards,
Jan
New build-id enhanced Linux kernels produce core files:
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
NOTE 0x000660 0x0000000000000000 0x0000000000000000 0x000324 0x000000 0x0
LOAD 0x001000 0x0000000000400000 0x0000000000000000 0x001000 0x0b1000 R E 0x1000
^^^^^^^^ ^^^^^^^^
LOAD 0x002000 0x00000000006b1000 0x0000000000000000 0x00a000 0x00a000 RW 0x1000
GDB-patched gdb `info files'
0x0000000000400000 - 0x0000000000401000 is load1a
0x00000000006b1000 - 0x00000000006bb000 is load2
0x0000000000419f00 <main+0>: push %r15
0x0000000000419f02 <main+2>: push %r14
BROKEN: original gdb `info files' (it sees the code sections zeroed)
0x0000000000400000 - 0x0000000000401000 is load1a
0x0000000000401000 - 0x00000000004b1000 is load1b
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
0x00000000006b1000 - 0x00000000006bb000 is load2
0x0000000000419f00 <main+0>: add %al,(%rax)
0x0000000000419f02 <main+2>: add %al,(%rax)
(as 0x419f00 >= 0x401000)
Legacy kernel core files:
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
NOTE 0x000660 0x0000000000000000 0x0000000000000000 0x000324 0x000000 0x0
LOAD 0x001000 0x0000000000400000 0x0000000000000000 0x000000 0x0b1000 R E 0x1000
^^^^^^^^ ^^^^^^^^
LOAD 0x001000 0x00000000006b1000 0x0000000000000000 0x00a000 0x00a000 RW 0x1000
original gdb `info files'
# `load1' completely missing
0x00000000006b1000 - 0x00000000006bb000 is load2
0x0000000000419f00 <main+0>: push %r15
0x0000000000419f02 <main+2>: push %r14
-------------- next part --------------
2007-08-01 Jan Kratochvil <jan.kratochvil@redhat.com>
* exec.c (add_to_section_table): Ignore the BFD_CORE `loadXb' segments.
--- ./gdb/exec.c 31 Jul 2007 21:49:21 -0000 1.67
+++ ./gdb/exec.c 1 Aug 2007 14:24:51 -0000
@@ -354,6 +354,13 @@ add_to_section_table (bfd *abfd, struct
if (!(aflag & SEC_ALLOC))
return;
+ /* Core files with 0 < p_filesz < p_memsz have the p_filesz..p_memsz section
+ without these flags. It would be considered as .bss otherwise. It would
+ mask out the real EXEC_BFD loaded code by its zeroes. */
+ if (bfd_get_format (abfd) == bfd_core
+ && !(aflag & (SEC_LOAD | SEC_HAS_CONTENTS)))
+ return;
+
(*table_pp)->bfd = abfd;
(*table_pp)->the_bfd_section = asect;
(*table_pp)->addr = bfd_section_vma (abfd, asect);
More information about the Gdb-patches
mailing list