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Re: [PATCH] tile: Remove the __tls_get_addr check from gc_mark_hook
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Alan Modra <amodra at gmail dot com>
- Cc: Binutils <binutils at sourceware dot org>
- Date: Tue, 17 Oct 2017 18:20:27 -0700
- Subject: Re: [PATCH] tile: Remove the __tls_get_addr check from gc_mark_hook
- Authentication-results: sourceware.org; auth=none
- References: <20171017212736.GB32374@intel.com> <20171017231923.GP27132@bubble.grove.modra.org>
On Tue, Oct 17, 2017 at 4:19 PM, Alan Modra <amodra@gmail.com> wrote:
> On Tue, Oct 17, 2017 at 02:27:36PM -0700, H.J. Lu wrote:
>> Reference to __tls_get_addr is created by check_relocs. Since check_relocs
>> is called after garbage collection now, the __tls_get_addr check should be
>> removed from gc_mark_hook.
>
> What happens if the only reference to __tls_get_addr is an implicit
> one via TLS_GD_CALL? Imagine a static --gc-sections link with
> __tls_get_addr in its own section. Shouldn't you instead be creating
> the __tls_get_addr reference in gcc_mark_hook?
>
Here is the updated patch. Tested with glibc build-many-glibcs.py.
OK for master?
--
H.J.
From 0ccde551af515ceaab49f4423c0de168dd67676f Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Tue, 17 Oct 2017 13:07:50 -0700
Subject: [PATCH] tile: Mark __tls_get_addr in gc_mark_hook
TLS_GD_CALL relocations implicitly reference __tls_get_addr. Since
elf_gc_mark_hook is called before check_relocs now, we need to call
_bfd_generic_link_add_one_symbol to mark __tls_get_addr for garbage
collection.
* elf32-tilepro.c (tilepro_elf_gc_mark_hook): Call
_bfd_generic_link_add_one_symbol to mark __tls_get_addr.
* elfxx-tilegx.c (tilegx_elf_gc_mark_hook): Likewise.
---
bfd/elf32-tilepro.c | 20 +++++++++++++-------
bfd/elfxx-tilegx.c | 20 +++++++++++++-------
2 files changed, 26 insertions(+), 14 deletions(-)
diff --git a/bfd/elf32-tilepro.c b/bfd/elf32-tilepro.c
index 7ab60bbaca..d9e282bc72 100644
--- a/bfd/elf32-tilepro.c
+++ b/bfd/elf32-tilepro.c
@@ -1864,16 +1864,22 @@ tilepro_elf_gc_mark_hook (asection *sec,
dealing with TLS optimization, ought to be !bfd_link_executable (info). */
if (bfd_link_pic (info))
{
+ struct bfd_link_hash_entry *bh;
+
switch (ELF32_R_TYPE (rel->r_info))
{
case R_TILEPRO_TLS_GD_CALL:
- /* This reloc implicitly references __tls_get_addr. We know
- another reloc will reference the same symbol as the one
- on this reloc, so the real symbol and section will be
- gc marked when processing the other reloc. That lets
- us handle __tls_get_addr here. */
- h = elf_link_hash_lookup (elf_hash_table (info), "__tls_get_addr",
- FALSE, FALSE, TRUE);
+ /* This reloc implicitly references __tls_get_addr. This
+ function is called before check_relocs. Mark it for
+ garbage collection here. */
+ bh = NULL;
+ if (! _bfd_generic_link_add_one_symbol (info, sec->owner,
+ "__tls_get_addr", 0,
+ bfd_und_section_ptr,
+ 0, NULL, FALSE,
+ FALSE, &bh))
+ return NULL;
+ h = (struct elf_link_hash_entry *) bh;
BFD_ASSERT (h != NULL);
h->mark = 1;
if (h->u.weakdef != NULL)
diff --git a/bfd/elfxx-tilegx.c b/bfd/elfxx-tilegx.c
index c9e860a70c..5ae0c53ea4 100644
--- a/bfd/elfxx-tilegx.c
+++ b/bfd/elfxx-tilegx.c
@@ -2103,16 +2103,22 @@ tilegx_elf_gc_mark_hook (asection *sec,
dealing with TLS optimization, ought to be !bfd_link_executable (info). */
if (bfd_link_pic (info))
{
+ struct bfd_link_hash_entry *bh;
+
switch (TILEGX_ELF_R_TYPE (rel->r_info))
{
case R_TILEGX_TLS_GD_CALL:
- /* This reloc implicitly references __tls_get_addr. We know
- another reloc will reference the same symbol as the one
- on this reloc, so the real symbol and section will be
- gc marked when processing the other reloc. That lets
- us handle __tls_get_addr here. */
- h = elf_link_hash_lookup (elf_hash_table (info), "__tls_get_addr",
- FALSE, FALSE, TRUE);
+ /* This reloc implicitly references __tls_get_addr. This
+ function is called before check_relocs. Mark it for
+ garbage collection here. */
+ bh = NULL;
+ if (! _bfd_generic_link_add_one_symbol (info, sec->owner,
+ "__tls_get_addr", 0,
+ bfd_und_section_ptr,
+ 0, NULL, FALSE,
+ FALSE, &bh))
+ return NULL;
+ h = (struct elf_link_hash_entry *) bh;
BFD_ASSERT (h != NULL);
h->mark = 1;
if (h->u.weakdef != NULL)
--
2.13.6