From 92c9bcd479e4cb388a7f286fc42414b115cfc656 Mon Sep 17 00:00:00 2001 From: Jan Kratochvil Date: Thu, 18 Sep 2014 08:21:40 +0200 Subject: [PATCH] Fix regression for Linux vDSO in GDB (PR gdb/17407). since 5979d6b69b20a8355ea94b75fad97415fce4788c https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=5979d6b69b20a8355ea94b75fad97415fce4788c vdso handling https://sourceware.org/ml/binutils/2014-03/msg00082.html https://sourceware.org/ml/binutils/2014-04/msg00003.html Message-ID: I get on kernel-3.16.2-200.fc20.x86_64 https://koji.fedoraproject.org/koji/buildinfo?buildID=575860 attaching its vdso.bin.gz GDB (FSF HEAD 5e43d46791c4c66fd83947a12d4f716b561a9103) regression: reproducer: ./gdb -ex start ./gdb actual result / FAIL: Got object file from memory but can't read symbols: File truncated. expected result / PASS: or / PASS: warning: Could not load shared library symbols for linux-vdso.so.1. Do you need "set solib-search-path" or "set sysroot"? That "warning: Could not load shared library..." is mostly harmless (it is a bug in GDB), in the FAIL case it is not printed just because bfd_check_format() fails there. It seems logical to me this way when the 'size' parameter has been already added. Alan Modra: I was wrongly thinking that the section headers were always last when I wrote that code. (They are now! If you relink that vdso with current binutils master you won't hit this problem, but that of course doesn't help existing kernels.) I do not see a regression for add-symbol-file-from-memory for libncurses.so.5 from the original thread above. Start of section headers: 1080 (bytes into file) Size of section headers: 64 (bytes) Number of section headers: 13 Section header string table index: 8 Section Headers: [Nr] Name Type Address Off Size ES Flg Lk Inf Al [ 8] .fake_shstrtab STRTAB 0000000000000780 000780 000076 00 A 0 0 32 Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align LOAD 0x000000 0x0000000000000000 0x0000000000000000 0x0012fe 0x0012fe R E 0x1000 size == 0x2000 shdr_end == 0x778 == 1080 + 13 * 64 high_offset == 0x12fe else if (size >= shdr_end) - high_offset = shdr_end; + high_offset = size; But then 0x778 < 0x780 for "Section header string table index" so whole bfd_check_format() fails because section headers were not cleared here: /* If the segments visible in memory didn't include the section headers, then clear them from the file header. */ if (high_offset < shdr_end) bfd/ChangeLog 2014-09-18 Jan Kratochvil PR gdb/17407 * elfcode.h (bfd_from_remote_memory): Use SIZE for HIGH_OFFSET. --- bfd/ChangeLog | 5 +++++ bfd/elfcode.h | 2 +- 2 files changed, 6 insertions(+), 1 deletion(-) diff --git a/bfd/ChangeLog b/bfd/ChangeLog index 7076ff4..b2e6140 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,3 +1,8 @@ +2014-09-18 Jan Kratochvil + + PR gdb/17407 + * elfcode.h (bfd_from_remote_memory): Use SIZE for HIGH_OFFSET. + 2014-09-16 Terry Guo * elf32-arm.c (elf32_arm_merge_eabi_attributes): Return false if diff --git a/bfd/elfcode.h b/bfd/elfcode.h index a49a708..ec53c3b 100644 --- a/bfd/elfcode.h +++ b/bfd/elfcode.h @@ -1749,7 +1749,7 @@ NAME(_bfd_elf,bfd_from_remote_memory) headers. */ } else if (size >= shdr_end) - high_offset = shdr_end; + high_offset = size; else { bfd_vma page_size = get_elf_backend_data (templ)->minpagesize; -- 2.7.4