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Re: [PATCH] PR ld/16322: ld fails to generate GNU_RELRO segment
- From: Alan Modra <amodra at gmail dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: Binutils <binutils at sourceware dot org>, Nick Clifton <nickc at redhat dot com>
- Date: Fri, 10 Jan 2014 15:19:30 +1030
- Subject: Re: [PATCH] PR ld/16322: ld fails to generate GNU_RELRO segment
- Authentication-results: sourceware.org; auth=none
- References: <20131212185803 dot GA2434 at intel dot com> <CAMe9rOo+hnJPNUwb3fWqx=HjWvBs+Ekrv+zRgu3F_Rr0KZ1Cjw at mail dot gmail dot com> <CAMe9rOpN28KDu8JzYoaK1b5G12S6DuGAkxOxYnyMk6T2y8iv3A at mail dot gmail dot com> <20140109041304 dot GF31693 at bubble dot grove dot modra dot org> <CAMe9rOpcNEtd6uFUeVKm7S59FxmcFEtaSH1tAzqUQj3pF8a0qQ at mail dot gmail dot com> <20140109145002 dot GG31693 at bubble dot grove dot modra dot org> <CAMe9rOpunwqvsfHxY4pH3=43tzt5j22K1erV9QdsK5xK72SKmA at mail dot gmail dot com> <CAMe9rOqOB9NqzHwHWcPDK_nL3Z8b6yCaQ_h+P-xeQt+95sXRQg at mail dot gmail dot com>
On Thu, Jan 09, 2014 at 09:07:43AM -0800, H.J. Lu wrote:
> It is OK to have another PT_LOAD segment.
Not when the second PT_LOAD segment is also in relro area.
But let's leave that aside for the moment. Why is it necessary to
adjust the PT_LOAD segment in assign_file_positions_for_load_sections?
It seems to me this is quite bogus. The end of the loaded part or the
alloced part of the PT_LOAD segment really has nothing to do with the
PT_GNU_RELRO segment end.
I think what we should do instead is fix Jakub's original code setting
up the PR_GNU_RELRO segment from the PT_LOAD segment.. I'm testing
the following along with the ldlang.c changes.
bfd/
PR ld/14207
PR ld/16322
PR binutils/16323
* elf.c (assign_file_positions_for_load_sections): Revert last change.
(assign_file_positions_for_non_load_sections): When setting up
PT_GNU_RELRO header, don't require a corresponding PT_LOAD
header that completely covers the relro region.
ld/testsuite/
* ld-x86-64/pr14207.d: Adjust.
diff --git a/bfd/elf.c b/bfd/elf.c
index 870e281..3815e32 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -4376,7 +4376,6 @@ assign_file_positions_for_load_sections (bfd *abfd,
unsigned int alloc;
unsigned int i, j;
bfd_vma header_pad = 0;
- bfd_vma relro_start = 0, relro_end = 0;
if (link_info == NULL
&& !_bfd_elf_map_sections_to_segments (abfd, link_info))
@@ -4447,23 +4446,6 @@ assign_file_positions_for_load_sections (bfd *abfd,
header_pad -= off;
off += header_pad;
- /* Get start and end of PT_GNU_RELRO segment. */
- if (link_info != NULL)
- {
- relro_start = link_info->relro_start;
- relro_end = link_info->relro_end;
- }
- else
- {
- for (m = elf_seg_map (abfd); m != NULL; m = m->next)
- if (m->p_type == PT_GNU_RELRO)
- {
- relro_start = m->p_paddr;
- relro_end = relro_start + m->p_size;
- break;
- }
- }
-
for (m = elf_seg_map (abfd), p = phdrs, j = 0;
m != NULL;
m = m->next, p++, j++)
@@ -4807,22 +4789,6 @@ assign_file_positions_for_load_sections (bfd *abfd,
}
}
- if (relro_start != 0
- && p->p_type == PT_LOAD
- && p->p_vaddr >= relro_start)
- {
- /* If PT_LOAD segment doesn't fit PT_GNU_RELRO segment,
- adjust its p_filesz and p_memsz. */
- if (p->p_vaddr + p->p_filesz < relro_end)
- {
- bfd_vma adjust = relro_end - (p->p_vaddr + p->p_filesz);
- p->p_filesz += adjust;
- off += adjust;
- }
- if (p->p_vaddr + p->p_memsz < relro_end)
- p->p_memsz += relro_end - (p->p_vaddr + p->p_memsz);
- }
-
off -= off_adjust;
/* Check that all sections are in a PT_LOAD segment.
@@ -5024,14 +4990,11 @@ assign_file_positions_for_non_load_sections (bfd *abfd,
{
if (lp->p_type == PT_LOAD
&& lp->p_vaddr < link_info->relro_end
- && lp->p_vaddr + lp->p_filesz >= link_info->relro_end
&& lm->count != 0
&& lm->sections[0]->vma >= link_info->relro_start)
break;
}
- /* PR ld/14207. If the RELRO segment doesn't fit in the
- LOAD segment, it should be removed. */
BFD_ASSERT (lm != NULL);
}
else
diff --git a/ld/testsuite/ld-x86-64/pr14207.d b/ld/testsuite/ld-x86-64/pr14207.d
index b1e2d5a..d4e22a1 100644
--- a/ld/testsuite/ld-x86-64/pr14207.d
+++ b/ld/testsuite/ld-x86-64/pr14207.d
@@ -11,7 +11,7 @@ There are 4 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000000 0x0000000000000000 0x0000000000000000 0x0001e0 0x0001e0 R 0x200000
- LOAD 0x000b48 0x0000000000200b48 0x0000000000200b48 0x0004b8 0x000cf8 RW 0x200000
+ LOAD 0x000b48 0x0000000000200b48 0x0000000000200b48 0x0004b0 0x000cf8 RW 0x200000
DYNAMIC 0x000b90 0x0000000000200b90 0x0000000000200b90 0x0001c0 0x0001c0 RW 0x8
GNU_RELRO 0x000b48 0x0000000000200b48 0x0000000000200b48 0x0004b8 0x0004b8 R 0x1
--
Alan Modra
Australia Development Lab, IBM