From: "H.J. Lu" <hjl.tools@gmail.com>
To: Alan Modra <amodra@gmail.com>
Cc: Binutils <binutils@sourceware.org>
Subject: Re: [PATCH] PR ld/21402: Skip PIE indirect5 and indirect6 tests on i386
Date: Mon, 24 Apr 2017 21:43:00 -0000 [thread overview]
Message-ID: <CAMe9rOpzNQs9OEogG1arCjSYnfLEy7V1Heoizfascnk=CYeALQ@mail.gmail.com> (raw)
In-Reply-To: <20170424040944.GN24006@bubble.grove.modra.org>
[-- Attachment #1: Type: text/plain, Size: 3424 bytes --]
On Sun, Apr 23, 2017 at 9:09 PM, Alan Modra <amodra@gmail.com> wrote:
> On Fri, Apr 21, 2017 at 11:37:34AM -0700, H.J. Lu wrote:
>> @@ -2863,10 +2867,14 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
>> int tls_type = elf_i386_hash_entry(h)->tls_type;
>>
>> /* Make sure this symbol is output as a dynamic symbol.
>> - Undefined weak syms won't yet be marked as dynamic. */
>> + Undefined weak syms won't yet be marked as dynamic.
>> + PR ld/21402: If this symbol isn't undefined weak symbol,
>> + don't make it dynamic in PIE. */
>> if (h->dynindx == -1
>> && !h->forced_local
>> - && !resolved_to_zero)
>> + && !resolved_to_zero
>> + && (h->root.type == bfd_link_hash_undefweak
>> + || !bfd_link_pie (info)))
>> {
>> if (! bfd_elf_link_record_dynamic_symbol (info, h))
>> return FALSE;
>
> This doesn't look correct to me. Sure, it fixes the particular
> testcase, but why do you make non-pie non-undefweak symbols dynamic
> here? I believe that only undefweak symbols should be made dynamic
> here, and in all the other places in allocate_dynrelocs.
>
> x86_64 too, but fixing allocate_dynrelocs for x86_64 causes no-plt-1e
> to fail due to lack of a relative GOT dynamic reloc on
> cmpq func@GOTPCREL(%rip), %rax
> in no-plt-check1.S. Seems like x86_64 would need something like your
> change to elf32-i386.c to emit relative GOT dynamic relocs in
> relocate_section. (For powerpc I decided to only handle plt and copy
> relocs in finish_dynamic_symbol. GOT dynamic relocs are all handled
> in relocate_section as otherwise there is a lot of duplication and IMO
> less comprehensible code.)
This sounds a goo idea. I will keep it in mind.
>> @@ -3818,6 +3826,7 @@ elf_i386_relocate_section (bfd *output_bfd,
>> bfd_vma st_size;
>> asection *resolved_plt;
>> bfd_boolean resolved_to_zero;
>> + bfd_boolean relative_reloc;
>>
>> r_type = ELF32_R_TYPE (rel->r_info);
>> if (r_type == R_386_GNU_VTINHERIT
>> @@ -4268,6 +4277,7 @@ r_386_got32:
>> if (htab->elf.sgot == NULL)
>> abort ();
>>
>> + relative_reloc = FALSE;
>> if (h != NULL)
>> {
>> bfd_boolean dyn;
>> @@ -4301,6 +4311,17 @@ r_386_got32:
>> bfd_put_32 (output_bfd, relocation,
>> htab->elf.sgot->contents + off);
>> h->got.offset |= 1;
>> +
>> + if (h->dynindx == -1
>> + && !h->forced_local
>> + && h->root.type != bfd_link_hash_undefweak
>> + && bfd_link_pie (info))
>> + {
>> + /* PR ld/21402: If this symbol isn't dynamic
>> + in PIE, generate R_386_RELATIVE here. */
>> + eh->no_finish_dynamic_symbol = 1;
>> + relative_reloc = TRUE;
>> + }
>> }
>> }
>> else
>
> This also looks odd. Surely you need a relative reloc when pic, not
> pie? It seems to me you need one any time you won't be calling
> finish_dynamic_symbol (which is where x86 sets most dynamic GOT
> relocs) and have a symbol that doesn't resolve to zero.
>
I checked in this patch for x86-64.
Thanks.
--
H.J.
[-- Attachment #2: 0001-x86-64-Force-symbol-dynamic-if-it-isn-t-undefined-we.patch --]
[-- Type: text/x-patch, Size: 8053 bytes --]
From 9e9821ddd80c0d0b3dda54d34cc8867f256d4583 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Mon, 24 Apr 2017 14:37:12 -0700
Subject: [PATCH] x86-64: Force symbol dynamic if it isn't undefined weak
Force symbol dynamic if it isn't undefined weak. Generate relative
relocation for GOT reference against non-dynamic symbol in PIC to
avoid unnecessary dynamic symbols.
bfd/
* elf64-x86-64.c (elf_x86_64_link_hash_entry): Add
no_finish_dynamic_symbol.
(elf_x86_64_link_hash_newfunc): Set no_finish_dynamic_symbol to
0.
(elf_x86_64_allocate_dynrelocs): If a symbol isn't undefined
weak symbol, don't make it dynamic.
(elf_x86_64_relocate_section): If a symbol isn't dynamic in PIC,
set no_finish_dynamic_symbol and generate R_X86_64_RELATIVE
relocation for GOT reference.
(elf_x86_64_finish_dynamic_symbol): Abort if
no_finish_dynamic_symbol isn't 0.
ld/
* testsuite/ld-x86-64/no-plt.exp: Also check no-plt-1e.nd.
* testsuite/ld-x86-64/no-plt-1e.nd: New file.
---
bfd/ChangeLog | 14 ++++++++
bfd/elf64-x86-64.c | 66 +++++++++++++++++++++++++------------
ld/ChangeLog | 5 +++
ld/testsuite/ld-x86-64/no-plt-1e.nd | 7 ++++
ld/testsuite/ld-x86-64/no-plt.exp | 2 +-
5 files changed, 72 insertions(+), 22 deletions(-)
create mode 100644 ld/testsuite/ld-x86-64/no-plt-1e.nd
diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 54e2f0d..b902a76 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,5 +1,19 @@
2017-04-24 H.J. Lu <hongjiu.lu@intel.com>
+ * elf64-x86-64.c (elf_x86_64_link_hash_entry): Add
+ no_finish_dynamic_symbol.
+ (elf_x86_64_link_hash_newfunc): Set no_finish_dynamic_symbol to
+ 0.
+ (elf_x86_64_allocate_dynrelocs): If a symbol isn't undefined
+ weak symbol, don't make it dynamic.
+ (elf_x86_64_relocate_section): If a symbol isn't dynamic in PIC,
+ set no_finish_dynamic_symbol and generate R_X86_64_RELATIVE
+ relocation for GOT reference.
+ (elf_x86_64_finish_dynamic_symbol): Abort if
+ no_finish_dynamic_symbol isn't 0.
+
+2017-04-24 H.J. Lu <hongjiu.lu@intel.com>
+
PR ld/21402
* elf32-i386.c (elf_i386_allocate_dynrelocs): If a symbol isn't
undefined weak symbol, don't make it dynamic.
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 746b847..965ceb2 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -867,6 +867,9 @@ struct elf_x86_64_link_hash_entry
/* TRUE if symbol has non-GOT/non-PLT relocations in text sections. */
unsigned int has_non_got_reloc : 1;
+ /* Don't call finish_dynamic_symbol on this symbol. */
+ unsigned int no_finish_dynamic_symbol : 1;
+
/* 0: symbol isn't __tls_get_addr.
1: symbol is __tls_get_addr.
2: symbol is unknown. */
@@ -1022,6 +1025,7 @@ elf_x86_64_link_hash_newfunc (struct bfd_hash_entry *entry,
eh->has_bnd_reloc = 0;
eh->has_got_reloc = 0;
eh->has_non_got_reloc = 0;
+ eh->no_finish_dynamic_symbol = 0;
eh->tls_get_addr = 2;
eh->func_pointer_refcount = 0;
eh->plt_bnd.offset = (bfd_vma) -1;
@@ -3218,7 +3222,8 @@ elf_x86_64_allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf)
Undefined weak syms won't yet be marked as dynamic. */
if (h->dynindx == -1
&& !h->forced_local
- && !resolved_to_zero)
+ && !resolved_to_zero
+ && h->root.type == bfd_link_hash_undefweak)
{
if (! bfd_elf_link_record_dynamic_symbol (info, h))
return FALSE;
@@ -3338,7 +3343,8 @@ elf_x86_64_allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf)
Undefined weak syms won't yet be marked as dynamic. */
if (h->dynindx == -1
&& !h->forced_local
- && !resolved_to_zero)
+ && !resolved_to_zero
+ && h->root.type == bfd_link_hash_undefweak)
{
if (! bfd_elf_link_record_dynamic_symbol (info, h))
return FALSE;
@@ -3475,6 +3481,7 @@ elf_x86_64_allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf)
if (h->dynindx == -1
&& ! h->forced_local
&& ! resolved_to_zero
+ && h->root.type == bfd_link_hash_undefweak
&& ! bfd_elf_link_record_dynamic_symbol (info, h))
return FALSE;
@@ -4270,6 +4277,7 @@ elf_x86_64_relocate_section (bfd *output_bfd,
asection *base_got, *resolved_plt;
bfd_vma st_size;
bfd_boolean resolved_to_zero;
+ bfd_boolean relative_reloc;
r_type = ELF32_R_TYPE (rel->r_info);
if (r_type == (int) R_X86_64_GNU_VTINHERIT
@@ -4637,6 +4645,7 @@ do_ifunc_pointer:
if (htab->elf.sgot == NULL)
abort ();
+ relative_reloc = FALSE;
if (h != NULL)
{
bfd_boolean dyn;
@@ -4683,6 +4692,17 @@ do_ifunc_pointer:
/* Note that this is harmless for the GOTPLT64 case,
as -1 | 1 still is -1. */
h->got.offset |= 1;
+
+ if (h->dynindx == -1
+ && !h->forced_local
+ && h->root.type != bfd_link_hash_undefweak
+ && bfd_link_pic (info))
+ {
+ /* If this symbol isn't dynamic in PIC,
+ generate R_X86_64_RELATIVE here. */
+ eh->no_finish_dynamic_symbol = 1;
+ relative_reloc = TRUE;
+ }
}
}
else
@@ -4704,30 +4724,32 @@ do_ifunc_pointer:
{
bfd_put_64 (output_bfd, relocation,
base_got->contents + off);
+ local_got_offsets[r_symndx] |= 1;
if (bfd_link_pic (info))
- {
- asection *s;
- Elf_Internal_Rela outrel;
-
- /* We need to generate a R_X86_64_RELATIVE reloc
- for the dynamic linker. */
- s = htab->elf.srelgot;
- if (s == NULL)
- abort ();
-
- outrel.r_offset = (base_got->output_section->vma
- + base_got->output_offset
- + off);
- outrel.r_info = htab->r_info (0, R_X86_64_RELATIVE);
- outrel.r_addend = relocation;
- elf_append_rela (output_bfd, s, &outrel);
- }
-
- local_got_offsets[r_symndx] |= 1;
+ relative_reloc = TRUE;
}
}
+ if (relative_reloc)
+ {
+ asection *s;
+ Elf_Internal_Rela outrel;
+
+ /* We need to generate a R_X86_64_RELATIVE reloc
+ for the dynamic linker. */
+ s = htab->elf.srelgot;
+ if (s == NULL)
+ abort ();
+
+ outrel.r_offset = (base_got->output_section->vma
+ + base_got->output_offset
+ + off);
+ outrel.r_info = htab->r_info (0, R_X86_64_RELATIVE);
+ outrel.r_addend = relocation;
+ elf_append_rela (output_bfd, s, &outrel);
+ }
+
if (off >= (bfd_vma) -2)
abort ();
@@ -5797,6 +5819,8 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
: get_elf_x86_64_backend_data (output_bfd));
eh = (struct elf_x86_64_link_hash_entry *) h;
+ if (eh->no_finish_dynamic_symbol)
+ abort ();
/* We keep PLT/GOT entries without dynamic PLT/GOT relocations for
resolved undefined weak symbols in executable so that their
diff --git a/ld/ChangeLog b/ld/ChangeLog
index d40086e..ed3797e 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,5 +1,10 @@
2017-04-24 H.J. Lu <hongjiu.lu@intel.com>
+ * testsuite/ld-x86-64/no-plt.exp: Also check no-plt-1e.nd.
+ * testsuite/ld-x86-64/no-plt-1e.nd: New file.
+
+2017-04-24 H.J. Lu <hongjiu.lu@intel.com>
+
* testsuite/ld-i386/pr12570a.d: Skip for nacl targets.
* testsuite/ld-i386/pr12570b.d: Likewise.
diff --git a/ld/testsuite/ld-x86-64/no-plt-1e.nd b/ld/testsuite/ld-x86-64/no-plt-1e.nd
new file mode 100644
index 0000000..c96760c
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/no-plt-1e.nd
@@ -0,0 +1,7 @@
+#nm: -g -D
+#target: x86_64-*-*
+
+#failif
+#...
+[0-9]+ +T +func
+#...
diff --git a/ld/testsuite/ld-x86-64/no-plt.exp b/ld/testsuite/ld-x86-64/no-plt.exp
index 5b5c817..9cecd03 100644
--- a/ld/testsuite/ld-x86-64/no-plt.exp
+++ b/ld/testsuite/ld-x86-64/no-plt.exp
@@ -111,7 +111,7 @@ run_cc_link_tests [list \
tmpdir/no-plt-func1.o tmpdir/no-plt-extern1.o" \
"" \
{dummy.s} \
- {{readelf -Wr no-plt-1e.rd} {objdump -dwrj.text no-plt-1e.dd}} \
+ {{readelf -Wr no-plt-1e.rd} {nm -gD no-plt-1e.nd} {objdump -dwrj.text no-plt-1e.dd}} \
"no-plt-1e" \
] \
[list \
--
2.9.3
prev parent reply other threads:[~2017-04-24 21:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-20 19:41 H.J. Lu
2017-04-21 1:09 ` Alan Modra
2017-04-21 18:37 ` H.J. Lu
2017-04-24 4:10 ` Alan Modra
2017-04-24 20:51 ` H.J. Lu
2017-04-24 21:43 ` H.J. Lu [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAMe9rOpzNQs9OEogG1arCjSYnfLEy7V1Heoizfascnk=CYeALQ@mail.gmail.com' \
--to=hjl.tools@gmail.com \
--cc=amodra@gmail.com \
--cc=binutils@sourceware.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).