Messages in this thread Patch in this message | | | Date | Thu, 27 Aug 2009 00:31:26 +0200 | From | Jan Kratochvil <> | Subject | [patch] Fix vdso32 relocation for paddr |
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Hi,
`readelf -Wl file-dumped-from-/proc/self/maps-[vdso]' for x86_64 process prints: Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align LOAD 0x000000 0xffffffffff700000 0xffffffffff700000 0x000890 0x000890 R E 0x1000 DYNAMIC 0x000410 0xffffffffff700410 0xffffffffff700410 0x0000f0 0x0000f0 R 0x8 NOTE 0x0002d0 0xffffffffff7002d0 0xffffffffff7002d0 0x00003c 0x00003c R 0x4 GNU_EH_FRAME 0x00030c 0xffffffffff70030c 0xffffffffff70030c 0x000034 0x000034 R 0x4
while such dump for i386 process prints: Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align LOAD 0x000000 0xffffe000 0x00000000 0x00434 0x00434 R E 0x1000 DYNAMIC 0x000350 0xffffe350 0x00000350 0x00078 0x00078 R 0x4 NOTE 0x0001c4 0xffffe1c4 0x000001c4 0x00060 0x00060 R 0x4 GNU_EH_FRAME 0x000224 0xffffe224 0x00000224 0x00024 0x00024 R 0x4
The mapped location can be arbirary (according to the rules of PIC - Position Independent Code) but currently the i386 vdso (vdso32) looks as an overlayed code as it has LMA != VMA (rule contained in GDB function section_is_overlay, as suggested by Daniel Jacobowitz).
Fixed vdso32 prints: Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align LOAD 0x000000 0xffffe000 0xffffe000 0x00434 0x00434 R E 0x1000 DYNAMIC 0x000350 0xffffe350 0xffffe350 0x00078 0x00078 R 0x4 NOTE 0x0001c4 0xffffe1c4 0xffffe1c4 0x00060 0x00060 R 0x4 GNU_EH_FRAME 0x000224 0xffffe224 0xffffe224 0x00024 0x00024 R 0x4
It required now a workaround in GDB patch so at least to fix it in Linux kernel: http://sourceware.org/ml/gdb-patches/2009-08/msg00437.html
Thanks, Jan
Signed-off-by: Jan Kratochvil <jan.kratochvil@redhat.com>
--- linux-2.6.30.x86_64/arch/x86/vdso/vdso32-setup.c-orig 2009-08-26 22:23:08.000000000 +0200 +++ linux-2.6.30.x86_64/arch/x86/vdso/vdso32-setup.c 2009-08-26 22:38:10.000000000 +0200 @@ -172,6 +172,7 @@ static __init void relocate_vdso(Elf32_E phdr = (void *)ehdr + ehdr->e_phoff; for (i = 0; i < ehdr->e_phnum; i++) { phdr[i].p_vaddr += VDSO_ADDR_ADJUST; + phdr[i].p_paddr += VDSO_ADDR_ADJUST; /* relocate dynamic stuff */ if (phdr[i].p_type == PT_DYNAMIC)
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