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PATCH: Properly handle protected function for ia32 and x86_64
On Thu, Jan 20, 2005 at 09:33:54AM -0800, H. J. Lu wrote:
> On Thu, Jan 20, 2005 at 11:17:55AM +0100, Andreas Schwab wrote:
> > "H. J. Lu" <hjl@lucon.org> writes:
> >
> > > I don't think we should worry about anything, like wrong insn, r_offset
> > > == 0, jump table or data section.
> >
> > At least we shouldn't crash.
>
> How about this patch?
>
>
I updated the patch to make ia32 and x86_64 the same in dealing with
protected function symbols. On ia32, I disallow R_386_GOTOFF on
protected function and on x86_64, I allow 32bit relative branch on
protected function. Since we only warn global symbols, there is no
need to check if h is NULL. Also I updated error message.
H.J.
----
2005-01-24 H.J. Lu <hongjiu.lu@intel.com>
* elf32-i386.c (elf_i386_relocate_section): Disallow R_386_GOTOFF
against protected function when building shared library.
PR 584
* elf64-x86-64.c (is_32bit_relative_branch): New.
(elf64_x86_64_relocate_section): Alllow R_X86_64_PC32 on a
protected function symbol when building shared library for
32bit relative branch instruction.
--- bfd/elf32-i386.c.prot 2005-01-11 09:09:27.000000000 -0800
+++ bfd/elf32-i386.c 2005-01-24 12:52:26.233408808 -0800
@@ -2274,6 +2274,22 @@ elf_i386_relocate_section (bfd *output_b
/* Relocation is relative to the start of the global offset
table. */
+ /* Check to make sure it isn't a protected function symbol
+ for shared library since it may not be local when used
+ as function address. */
+ if (info->shared
+ && h
+ && h->def_regular
+ && h->type == STT_FUNC
+ && ELF_ST_VISIBILITY (h->other) == STV_PROTECTED)
+ {
+ (*_bfd_error_handler)
+ (_("%B: relocation R_386_GOTOFF against protected function `%s' can not be used when making a shared object"),
+ input_bfd, h->root.root.string);
+ bfd_set_error (bfd_error_bad_value);
+ return FALSE;
+ }
+
/* Note that sgot is not involved in this
calculation. We always want the start of .got.plt. If we
defined _GLOBAL_OFFSET_TABLE_ in a different way, as is
--- bfd/elf64-x86-64.c.prot 2005-01-11 09:10:28.000000000 -0800
+++ bfd/elf64-x86-64.c 2005-01-24 13:08:28.622633929 -0800
@@ -1745,6 +1745,24 @@ tpoff (struct bfd_link_info *info, bfd_v
return address - htab->tls_size - htab->tls_sec->vma;
}
+/* Is the instruction before OFFSET in CONTENTS a 32bit relative
+ branch? */
+
+static bfd_boolean
+is_32bit_relative_branch (bfd_byte *contents, bfd_vma offset)
+{
+ /* Opcode Instruction
+ 0xe8 call
+ 0xe9 jump
+ 0x0f 0x8x conditional jump */
+ return ((offset > 0
+ && (contents [offset - 1] == 0xe8
+ || contents [offset - 1] == 0xe9))
+ || (offset > 1
+ && contents [offset - 2] == 0x0f
+ && (contents [offset - 1] & 0xf0) == 0x80));
+}
+
/* Relocate an x86_64 ELF section. */
static bfd_boolean
@@ -1950,13 +1968,26 @@ elf64_x86_64_relocate_section (bfd *outp
if (info->shared
&& !SYMBOL_REFERENCES_LOCAL (info, h)
&& (input_section->flags & SEC_ALLOC) != 0
- && (input_section->flags & SEC_READONLY) != 0)
+ && (input_section->flags & SEC_READONLY) != 0
+ && (!h->def_regular
+ || r_type != R_X86_64_PC32
+ || h->type != STT_FUNC
+ || ELF_ST_VISIBILITY (h->other) != STV_PROTECTED
+ || !is_32bit_relative_branch (contents,
+ rel->r_offset)))
{
- (*_bfd_error_handler)
- (_("%B: relocation %s against `%s' can not be used when making a shared object; recompile with -fPIC"),
- input_bfd,
- x86_64_elf_howto_table[r_type].name,
- (h) ? h->root.root.string : "a local symbol");
+ if (h->def_regular
+ && r_type == R_X86_64_PC32
+ && h->type == STT_FUNC
+ && ELF_ST_VISIBILITY (h->other) == STV_PROTECTED)
+ (*_bfd_error_handler)
+ (_("%B: relocation R_X86_64_PC32 against protected function `%s' can not be used when making a shared object"),
+ input_bfd, h->root.root.string);
+ else
+ (*_bfd_error_handler)
+ (_("%B: relocation %s against `%s' can not be used when making a shared object; recompile with -fPIC"),
+ input_bfd, x86_64_elf_howto_table[r_type].name,
+ h->root.root.string);
bfd_set_error (bfd_error_bad_value);
return FALSE;
}