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[binutils-gdb/binutils-2_29-branch] Import patch from mainline to improve padding of .eh_frame sections.
- From: Nick Clifton <nickc at sourceware dot org>
- To: bfd-cvs at sourceware dot org
- Date: 4 Sep 2017 16:30:18 -0000
- Subject: [binutils-gdb/binutils-2_29-branch] Import patch from mainline to improve padding of .eh_frame sections.
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=35e01275b59ac867d342379d457e732b5acda6a3
commit 35e01275b59ac867d342379d457e732b5acda6a3
Author: Nick Clifton <nickc@redhat.com>
Date: Mon Sep 4 17:28:17 2017 +0100
Import patch from mainline to improve padding of .eh_frame sections.
PR 21441
bfd * elf-eh-frame.c (_bfd_elf_discard_section_eh_frame): Don't add
alignment padding here.
* elflink.c (bfd_elf_discard_info): Add .eh_frame padding here
in a reverse pass over sections.
ld * testsuite/ld-elf/eh3.d: Update.
* testsuite/ld-elf/eh4.d: Update.
PR 21441
* testsuite/ld-x86-64/pr21038a.d: Adjust.
* testsuite/ld-x86-64/pr21038a-now.d: Adjust.
Diff:
---
bfd/ChangeLog | 6 ++++++
bfd/elf-eh-frame.c | 31 +++++++++----------------------
bfd/elflink.c | 32 ++++++++++++++++++++++++++++++++
ld/ChangeLog | 11 +++++++++++
ld/testsuite/ld-elf/eh3.d | 12 ++----------
ld/testsuite/ld-elf/eh4.d | 4 +---
ld/testsuite/ld-x86-64/pr21038a-now.d | 8 ++------
ld/testsuite/ld-x86-64/pr21038a.d | 8 ++------
8 files changed, 65 insertions(+), 47 deletions(-)
diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 226aea9..db9d0a9 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -60,6 +60,12 @@
(elfcore_grok_freebsd_prstatus): Add checks to make sure that
there is enough data present in the note.
+ PR 21441
+ * elf-eh-frame.c (_bfd_elf_discard_section_eh_frame): Don't add
+ alignment padding here.
+ * elflink.c (bfd_elf_discard_info): Add .eh_frame padding here
+ in a reverse pass over sections.
+
2017-09-04 Alan Modra <amodra@gmail.com>
PR 22067
diff --git a/bfd/elf-eh-frame.c b/bfd/elf-eh-frame.c
index 52ba9c6..cd81b60 100644
--- a/bfd/elf-eh-frame.c
+++ b/bfd/elf-eh-frame.c
@@ -619,15 +619,6 @@ _bfd_elf_parse_eh_frame (bfd *abfd, struct bfd_link_info *info,
REQUIRE (bfd_malloc_and_get_section (abfd, sec, &ehbuf));
- if (sec->size >= 4
- && bfd_get_32 (abfd, ehbuf) == 0
- && cookie->rel == cookie->relend)
- {
- /* Empty .eh_frame section. */
- free (ehbuf);
- return;
- }
-
/* If .eh_frame section size doesn't fit into int, we cannot handle
it (it would need to use 64-bit .eh_frame format anyway). */
REQUIRE (sec->size == (unsigned int) sec->size);
@@ -669,8 +660,11 @@ _bfd_elf_parse_eh_frame (bfd *abfd, struct bfd_link_info *info,
REQUIRE (sec_info);
/* We need to have a "struct cie" for each CIE in this section. */
- local_cies = (struct cie *) bfd_zmalloc (num_cies * sizeof (*local_cies));
- REQUIRE (local_cies);
+ if (num_cies)
+ {
+ local_cies = (struct cie *) bfd_zmalloc (num_cies * sizeof (*local_cies));
+ REQUIRE (local_cies);
+ }
/* FIXME: octets_per_byte. */
#define ENSURE_NO_RELOCS(buf) \
@@ -724,7 +718,9 @@ _bfd_elf_parse_eh_frame (bfd *abfd, struct bfd_link_info *info,
if (hdr_length == 0)
{
/* A zero-length CIE should only be found at the end of
- the section. */
+ the section, but allow multiple terminators. */
+ while (skip_bytes (&buf, ehbuf + sec->size, 4))
+ REQUIRE (bfd_get_32 (abfd, buf - 4) == 0);
REQUIRE ((bfd_size_type) (buf - ehbuf) == sec->size);
ENSURE_NO_RELOCS (buf);
sec_info->count++;
@@ -1339,7 +1335,7 @@ offset_adjust (bfd_vma offset, const asection *sec)
struct eh_frame_sec_info *sec_info
= (struct eh_frame_sec_info *) elf_section_data (sec)->sec_info;
unsigned int lo, hi, mid;
- struct eh_cie_fde *ent;
+ struct eh_cie_fde *ent = NULL;
bfd_signed_vma delta;
lo = 0;
@@ -1594,16 +1590,7 @@ _bfd_elf_discard_section_eh_frame
offset += size_of_output_cie_fde (ent);
}
- /* Pad the last FDE out to the output section alignment if there are
- following sections, in order to ensure no padding between this
- section and the next. (Relies on the output section alignment
- being the maximum of all input sections alignments, which is the
- case unless someone is overriding alignment via scripts.) */
eh_alignment = 4;
- if (sec->map_head.s != NULL
- && (sec->map_head.s->size != 4
- || sec->map_head.s->map_head.s != NULL))
- eh_alignment = 1 << sec->output_section->alignment_power;
offset = (offset + eh_alignment - 1) & -eh_alignment;
sec->rawsize = sec->size;
sec->size = offset;
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 736fb4c..301cf03 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -13831,6 +13831,7 @@ bfd_elf_discard_info (bfd *output_bfd, struct bfd_link_info *info)
{
asection *i;
int eh_changed = 0;
+ unsigned int eh_alignment;
for (i = o->map_head.s; i != NULL; i = i->map_head.s)
{
@@ -13856,6 +13857,37 @@ bfd_elf_discard_info (bfd *output_bfd, struct bfd_link_info *info)
fini_reloc_cookie_for_section (&cookie, i);
}
+
+ eh_alignment = 1 << o->alignment_power;
+ /* Skip over zero terminator, and prevent empty sections from
+ adding alignment padding at the end. */
+ for (i = o->map_tail.s; i != NULL; i = i->map_tail.s)
+ if (i->size == 0)
+ i->flags |= SEC_EXCLUDE;
+ else if (i->size > 4)
+ break;
+ /* The last non-empty eh_frame section doesn't need padding. */
+ if (i != NULL)
+ i = i->map_tail.s;
+ /* Any prior sections must pad the last FDE out to the output
+ section alignment. Otherwise we might have zero padding
+ between sections, which would be seen as a terminator. */
+ for (; i != NULL; i = i->map_tail.s)
+ if (i->size == 4)
+ /* All but the last zero terminator should have been removed. */
+ BFD_FAIL ();
+ else
+ {
+ bfd_size_type size
+ = (i->size + eh_alignment - 1) & -eh_alignment;
+ if (i->size != size)
+ {
+ i->size = size;
+ changed = 1;
+ eh_changed = 1;
+ }
+ }
+
if (eh_changed)
elf_link_hash_traverse (elf_hash_table (info),
_bfd_elf_adjust_eh_frame_global_symbol, NULL);
diff --git a/ld/ChangeLog b/ld/ChangeLog
index 24d0ed2..e8ee459 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,14 @@
+2017-09-04 Nick Clifton <nickc@redhat.com>
+
+ Import from mainline:
+
+ * testsuite/ld-elf/eh3.d: Update.
+ * testsuite/ld-elf/eh4.d: Update.
+
+ PR 21441
+ * testsuite/ld-x86-64/pr21038a.d: Adjust.
+ * testsuite/ld-x86-64/pr21038a-now.d: Adjust.
+
2017-09-01 H.J. Lu <hongjiu.lu@intel.com>
PR ld/22064
diff --git a/ld/testsuite/ld-elf/eh3.d b/ld/testsuite/ld-elf/eh3.d
index 3811341..6ac584a 100644
--- a/ld/testsuite/ld-elf/eh3.d
+++ b/ld/testsuite/ld-elf/eh3.d
@@ -23,20 +23,12 @@ Contents of the .eh_frame section:
DW_CFA_nop
DW_CFA_nop
-0+0018 0+0024 0+001c FDE cie=0+0000 pc=0+400078\.\.0+400090
+0+0018 0+001c 0+001c FDE cie=0+0000 pc=0+400078\.\.0+400090
DW_CFA_advance_loc: 8 to 0+400080
DW_CFA_def_cfa_offset: 16
DW_CFA_offset: r6 \(rbp\) at cfa-16
DW_CFA_advance_loc: 8 to 0+400088
DW_CFA_def_cfa_register: r6 \(rbp\)
- DW_CFA_nop
- DW_CFA_nop
- DW_CFA_nop
- DW_CFA_nop
- DW_CFA_nop
- DW_CFA_nop
- DW_CFA_nop
- DW_CFA_nop
-0+0040 ZERO terminator
+0+0038 ZERO terminator
#pass
diff --git a/ld/testsuite/ld-elf/eh4.d b/ld/testsuite/ld-elf/eh4.d
index b5eec2f..6c1cb32 100644
--- a/ld/testsuite/ld-elf/eh4.d
+++ b/ld/testsuite/ld-elf/eh4.d
@@ -28,14 +28,12 @@ Contents of the .eh_frame section:
DW_CFA_set_loc: 0+0417
DW_CFA_def_cfa_offset: 80
-0+0048 0+0024 0+004c FDE cie=0+0000 pc=[0-9a-f]+\.\.[0-9a-f]+
+0+0048 0+002[04] 0+004c FDE cie=0+0000 pc=[0-9a-f]+\.\.[0-9a-f]+
DW_CFA_def_cfa_offset: 16
DW_CFA_advance_loc: [0-9a-f]+ to [0-9a-f]+
DW_CFA_def_cfa_offset: 24
DW_CFA_advance_loc: [0-9a-f]+ to [0-9a-f]+
DW_CFA_def_cfa_expression \(DW_OP_breg7 \(rsp\): 8; DW_OP_breg16 \(rip\): 0;.*
- DW_CFA_nop
#...
-
[0-9a-f]+ ZERO terminator
#pass
diff --git a/ld/testsuite/ld-x86-64/pr21038a-now.d b/ld/testsuite/ld-x86-64/pr21038a-now.d
index ebc5128..1d5bec1 100644
--- a/ld/testsuite/ld-x86-64/pr21038a-now.d
+++ b/ld/testsuite/ld-x86-64/pr21038a-now.d
@@ -1,7 +1,7 @@
#name: PR ld/21038 (.plt.got, -z now)
#source: pr21038a.s
#as: --64
-#ld: -z now -z bndplt -melf_x86_64 -shared -z relro --ld-generated-unwind-info
+#ld: -z now -z bndplt -melf_x86_64 -shared -z relro --ld-generated-unwind-info --hash-style=sysv
#objdump: -dw -Wf
.*: +file format .*
@@ -41,11 +41,7 @@ Contents of the .eh_frame section:
DW_CFA_nop
DW_CFA_nop
-0+58 0000000000000014 0000005c FDE cie=00000000 pc=0000000000000230..0000000000000238
- DW_CFA_nop
- DW_CFA_nop
- DW_CFA_nop
- DW_CFA_nop
+0+58 0000000000000010 0000005c FDE cie=00000000 pc=0000000000000230..0000000000000238
DW_CFA_nop
DW_CFA_nop
DW_CFA_nop
diff --git a/ld/testsuite/ld-x86-64/pr21038a.d b/ld/testsuite/ld-x86-64/pr21038a.d
index 81b26cb..01770ec 100644
--- a/ld/testsuite/ld-x86-64/pr21038a.d
+++ b/ld/testsuite/ld-x86-64/pr21038a.d
@@ -1,6 +1,6 @@
#name: PR ld/21038 (.plt.got)
#as: --64
-#ld: -z bndplt -melf_x86_64 -shared -z relro --ld-generated-unwind-info
+#ld: -z bndplt -melf_x86_64 -shared -z relro --ld-generated-unwind-info --hash-style=sysv
#objdump: -dw -Wf
.*: +file format .*
@@ -40,11 +40,7 @@ Contents of the .eh_frame section:
DW_CFA_nop
DW_CFA_nop
-0+58 0000000000000014 0000005c FDE cie=00000000 pc=0000000000000230..0000000000000238
- DW_CFA_nop
- DW_CFA_nop
- DW_CFA_nop
- DW_CFA_nop
+0+58 0000000000000010 0000005c FDE cie=00000000 pc=0000000000000230..0000000000000238
DW_CFA_nop
DW_CFA_nop
DW_CFA_nop