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Re: [PATCH] x86: Don't set eh->local_ref to 1 for linker defined symbols
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Binutils <binutils at sourceware dot org>
- Date: Mon, 21 May 2018 07:43:20 -0700
- Subject: Re: [PATCH] x86: Don't set eh->local_ref to 1 for linker defined symbols
- References: <20180517233054.GA8864@intel.com>
On Thu, May 17, 2018 at 4:30 PM, H.J. Lu <hongjiu.lu@intel.com> wrote:
> Since symbols created by HIDDEN and PROVIDE_HIDDEN assignments in
> linker script may be marked as defined, but not hidden, we can't
> set eh->local_ref to 1 in _bfd_x86_elf_link_symbol_references_local.
>
> Also R_386_GOT32X should be handled as just like R_386_GOT32 when
> relocating a section. The input R_386_GOT32X relocations, which
> can be relaxed, should have been converted to R_386_PC32, R_386_32
> or R_386_GOTOFF.
>
> Any comments?
>
> H.J.
> ---
> bfd/
>
> PR ld/23189
> * elf32-i386.c (elf_i386_relocate_section): Handle R_386_GOT32X
> like R_386_GOT32.
> * elfxx-x86.c (_bfd_x86_elf_link_symbol_references_local): Don't
> set eh->local_ref to 1 for linker defined symbols.
>
> ld/
>
> PR ld/23189
> * testsuite/ld-i386/i386.exp: Run pr23189.
> * testsuite/ld-x86-64/x86-64.exp: Likewise.
> * testsuite/ld-i386/pr23189.d: New file.
> * testsuite/ld-i386/pr23189.s: Likewise.
> * testsuite/ld-i386/pr23189.t: Likewise.
> * testsuite/ld-x86-64/pr23189.d: Likewise.
> * testsuite/ld-x86-64/pr23189.s: Likewise.
> * testsuite/ld-x86-64/pr23189.t: Likewise.
I am backporting it to binutils 2.30 branch.
> ---
> bfd/elf32-i386.c | 59 -------------------------------
> bfd/elfxx-x86.c | 6 +++-
> ld/testsuite/ld-i386/i386.exp | 1 +
> ld/testsuite/ld-i386/pr23189.d | 7 ++++
> ld/testsuite/ld-i386/pr23189.s | 5 +++
> ld/testsuite/ld-i386/pr23189.t | 11 ++++++
> ld/testsuite/ld-x86-64/pr23189.d | 7 ++++
> ld/testsuite/ld-x86-64/pr23189.s | 5 +++
> ld/testsuite/ld-x86-64/pr23189.t | 11 ++++++
> ld/testsuite/ld-x86-64/x86-64.exp | 1 +
> 10 files changed, 53 insertions(+), 60 deletions(-)
> create mode 100644 ld/testsuite/ld-i386/pr23189.d
> create mode 100644 ld/testsuite/ld-i386/pr23189.s
> create mode 100644 ld/testsuite/ld-i386/pr23189.t
> create mode 100644 ld/testsuite/ld-x86-64/pr23189.d
> create mode 100644 ld/testsuite/ld-x86-64/pr23189.s
> create mode 100644 ld/testsuite/ld-x86-64/pr23189.t
>
> diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
> index 580a591816..3dd709a10e 100644
> --- a/bfd/elf32-i386.c
> +++ b/bfd/elf32-i386.c
> @@ -2451,66 +2451,7 @@ skip_ifunc:
> switch (r_type)
> {
> case R_386_GOT32X:
> - /* Avoid optimizing _DYNAMIC since ld.so may use its
> - link-time address. */
> - if (h == htab->elf.hdynamic)
> - goto r_386_got32;
> -
> - if (bfd_link_pic (info))
> - {
> - /* It is OK to convert mov to lea and convert indirect
> - branch to direct branch. It is OK to convert adc,
> - add, and, cmp, or, sbb, sub, test, xor only when PIC
> - is false. */
> - unsigned int opcode, addend;
> - addend = bfd_get_32 (input_bfd, contents + rel->r_offset);
> - if (addend != 0)
> - goto r_386_got32;
> - opcode = bfd_get_8 (input_bfd, contents + rel->r_offset - 2);
> - if (opcode != 0x8b && opcode != 0xff)
> - goto r_386_got32;
> - }
> -
> - /* Resolve "mov GOT[(%reg)], %reg",
> - "call/jmp *GOT[(%reg)]", "test %reg, foo@GOT[(%reg)]"
> - and "binop foo@GOT[(%reg)], %reg". */
> - if (h == NULL
> - || (h->plt.offset == (bfd_vma) -1
> - && h->got.offset == (bfd_vma) -1)
> - || htab->elf.sgotplt == NULL)
> - abort ();
> -
> - offplt = (htab->elf.sgotplt->output_section->vma
> - + htab->elf.sgotplt->output_offset);
> -
> - /* It is relative to .got.plt section. */
> - if (h->got.offset != (bfd_vma) -1)
> - /* Use GOT entry. Mask off the least significant bit in
> - GOT offset which may be set by R_386_GOT32 processing
> - below. */
> - relocation = (htab->elf.sgot->output_section->vma
> - + htab->elf.sgot->output_offset
> - + (h->got.offset & ~1) - offplt);
> - else
> - /* Use GOTPLT entry. */
> - relocation = (h->plt.offset / plt_entry_size
> - - htab->plt.has_plt0 + 3) * 4;
> -
> - if (!bfd_link_pic (info))
> - {
> - /* If not PIC, add the .got.plt section address for
> - baseless addressing. */
> - unsigned int modrm;
> - modrm = bfd_get_8 (input_bfd, contents + rel->r_offset - 1);
> - if ((modrm & 0xc7) == 0x5)
> - relocation += offplt;
> - }
> -
> - unresolved_reloc = FALSE;
> - break;
> -
> case R_386_GOT32:
> -r_386_got32:
> /* Relocation is to the entry for this symbol in the global
> offset table. */
> if (htab->elf.sgot == NULL)
> diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c
> index 936b4c67d2..f4dbddf15e 100644
> --- a/bfd/elfxx-x86.c
> +++ b/bfd/elfxx-x86.c
> @@ -2047,7 +2047,11 @@ _bfd_x86_elf_link_symbol_references_local (struct bfd_link_info *info,
> return TRUE;
> }
>
> - eh->local_ref = 1;
> + /* Symbols created by HIDDEN and PROVIDE_HIDDEN assignments in linker
> + script aren't forced local here yet. */
> + if (!h->root.ldscript_def)
> + eh->local_ref = 1;
> +
> return FALSE;
> }
>
> diff --git a/ld/testsuite/ld-i386/i386.exp b/ld/testsuite/ld-i386/i386.exp
> index 0d50b63d44..7aec5345cf 100644
> --- a/ld/testsuite/ld-i386/i386.exp
> +++ b/ld/testsuite/ld-i386/i386.exp
> @@ -479,6 +479,7 @@ run_dump_test "pr18815"
> run_dump_test "pr19939a"
> run_dump_test "pr19939b"
> run_dump_test "tlsdesc2"
> +run_dump_test "pr23189"
>
> proc undefined_weak {cflags ldflags} {
> set testname "Undefined weak symbol"
> diff --git a/ld/testsuite/ld-i386/pr23189.d b/ld/testsuite/ld-i386/pr23189.d
> new file mode 100644
> index 0000000000..9345b42bd0
> --- /dev/null
> +++ b/ld/testsuite/ld-i386/pr23189.d
> @@ -0,0 +1,7 @@
> +#as: --32 -mrelax-relocations=yes
> +#ld: -shared -melf_i386 -T pr23189.t
> +#readelf: -r --wide
> +
> +Relocation section '.rel.dyn' at offset 0x[0-9a-f]+ contains 1 entry:
> + Offset Info Type Sym. Value Symbol's Name
> +[0-9a-f]+ +[0-9a-f]+ +R_386_RELATIVE +
> diff --git a/ld/testsuite/ld-i386/pr23189.s b/ld/testsuite/ld-i386/pr23189.s
> new file mode 100644
> index 0000000000..4a6c9cd078
> --- /dev/null
> +++ b/ld/testsuite/ld-i386/pr23189.s
> @@ -0,0 +1,5 @@
> + .globl _start
> + .type _start, @function
> +_start:
> + movl __hidden_sym@GOT(%eax), %eax
> + .size _start, .-_start
> diff --git a/ld/testsuite/ld-i386/pr23189.t b/ld/testsuite/ld-i386/pr23189.t
> new file mode 100644
> index 0000000000..0e6ff655b2
> --- /dev/null
> +++ b/ld/testsuite/ld-i386/pr23189.t
> @@ -0,0 +1,11 @@
> +EXTERN(_start)
> +ENTRY(_start)
> +
> +SECTIONS
> +{
> + .text :
> + {
> + HIDDEN (__hidden_sym = .);
> + *(.text*)
> + }
> +}
> diff --git a/ld/testsuite/ld-x86-64/pr23189.d b/ld/testsuite/ld-x86-64/pr23189.d
> new file mode 100644
> index 0000000000..7951c7acc3
> --- /dev/null
> +++ b/ld/testsuite/ld-x86-64/pr23189.d
> @@ -0,0 +1,7 @@
> +#as: --64 -mrelax-relocations=yes
> +#ld: -shared -melf_x86_64 -T pr23189.t
> +#readelf: -r --wide
> +
> +Relocation section '.rela.dyn' at offset 0x[0-9a-f]+ contains 1 entry:
> + Offset Info Type Symbol's Value Symbol's Name \+ Addend
> +[0-9a-f]+ +[0-9a-f]+ +R_X86_64_RELATIVE +[0-9a-f]+
> diff --git a/ld/testsuite/ld-x86-64/pr23189.s b/ld/testsuite/ld-x86-64/pr23189.s
> new file mode 100644
> index 0000000000..971ad8f892
> --- /dev/null
> +++ b/ld/testsuite/ld-x86-64/pr23189.s
> @@ -0,0 +1,5 @@
> + .globl _start
> + .type _start, @function
> +_start:
> + movq __hidden_sym@GOTPCREL(%rip), %rax
> + .size _start, .-_start
> diff --git a/ld/testsuite/ld-x86-64/pr23189.t b/ld/testsuite/ld-x86-64/pr23189.t
> new file mode 100644
> index 0000000000..0e6ff655b2
> --- /dev/null
> +++ b/ld/testsuite/ld-x86-64/pr23189.t
> @@ -0,0 +1,11 @@
> +EXTERN(_start)
> +ENTRY(_start)
> +
> +SECTIONS
> +{
> + .text :
> + {
> + HIDDEN (__hidden_sym = .);
> + *(.text*)
> + }
> +}
> diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp
> index 5a06947057..563e782e2e 100644
> --- a/ld/testsuite/ld-x86-64/x86-64.exp
> +++ b/ld/testsuite/ld-x86-64/x86-64.exp
> @@ -606,6 +606,7 @@ run_dump_test "pr20253-5b"
> run_dump_test "tlsdesc2"
> run_dump_test "pr22048"
> run_dump_test "pr22929"
> +run_dump_test "pr23189"
>
> proc undefined_weak {cflags ldflags} {
> set testname "Undefined weak symbol"
> --
> 2.17.0
>
--
H.J.