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Re: [PATCH] x86: Add -z print-local-ifuncs to ELF linker
- 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: Thu, 8 Jun 2017 03:55:07 -0700
- Subject: Re: [PATCH] x86: Add -z print-local-ifuncs to ELF linker
- Authentication-results: sourceware.org; auth=none
- References: <20170607130555.GA31495@lucon.org> <20170608013336.GZ8842@bubble.grove.modra.org>
On Wed, Jun 7, 2017 at 6:33 PM, Alan Modra <amodra@gmail.com> wrote:
> On Wed, Jun 07, 2017 at 06:05:55AM -0700, H.J. Lu wrote:
>> Add -z print-local-ifuncs to x86 ELF linker to list local IFUNC functions
>> when generating executables and shared objects.
>>
>> Any comments?
>
> I'm wondering if it would be better to dump this output to a map file,
> using minfo rather than einfo. If you do that then there is possibly
> no need to have an option to control the output; If a mapfile is
> requested then you will see a list of these symbols. In any case, I
> don't see a need for -z noprint-local-ifuncs.
>
Thanks for your suggestion. This is what I checked in.
--
H.J.
From 6322e5c5cb7ffe1c26c50f117765503717b0431c Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 7 Jun 2017 21:18:01 -0700
Subject: [PATCH] x86: Dump local IFUNC functions in the map file
Dump local IFUNC functions in the map file when generating IRELATIVE
relocations if -Map is used.
bfd/
* elf32-i386.c (elf_i386_check_relocs): Set local IFUNC symbol
name. Use local IFUNC symbol name string to report unsupported
non-PIC call to IFUNC function.
(elf_i386_relocate_section): Dump local IFUNC name with minfo
when generating R_386_IRELATIVE relocation.
(elf_i386_finish_dynamic_symbol): Likewise.
* elf_x86_64_check_relocs (elf_x86_64_check_relocs): Set local
IFUNC symbol name.
(elf_x86_64_relocate_section): Dump local IFUNC name with minfo
when generating R_X86_64_IRELATIVE relocation.
(elf_x86_64_finish_dynamic_symbol): Likewise.
ld/
* testsuite/ld-ifunc/ifunc-1-local-x86.d: Pass
"-Map tmpdir/ifunc-1-local-x86.map" to ld and check
ifunc-1-local-x86.map.
* testsuite/ld-ifunc/ifunc-1-x86.d: Pass
"-Map tmpdir/ifunc-1-x86.map" to ld and check ifunc-1-x86.map.
* testsuite/ld-ifunc/ifunc-1-local-x86.map: New file.
* testsuite/ld-ifunc/ifunc-1-x86.map: Likewise.
---
bfd/elf32-i386.c | 27 ++++++++++++++++++---------
bfd/elf64-x86-64.c | 15 +++++++++++++++
ld/testsuite/ld-ifunc/ifunc-1-local-x86.d | 3 ++-
ld/testsuite/ld-ifunc/ifunc-1-local-x86.map | 3 +++
ld/testsuite/ld-ifunc/ifunc-1-x86.d | 3 ++-
ld/testsuite/ld-ifunc/ifunc-1-x86.map | 3 +++
6 files changed, 43 insertions(+), 11 deletions(-)
create mode 100644 ld/testsuite/ld-ifunc/ifunc-1-local-x86.map
create mode 100644 ld/testsuite/ld-ifunc/ifunc-1-x86.map
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index 1fdc06c..e447e3d 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -1945,6 +1945,8 @@ elf_i386_check_relocs (bfd *abfd,
goto error_return;
/* Fake a STT_GNU_IFUNC symbol. */
+ h->root.root.string = bfd_elf_sym_name (abfd, symtab_hdr,
+ isym, NULL);
h->type = STT_GNU_IFUNC;
h->def_regular = 1;
h->ref_regular = 1;
@@ -2181,15 +2183,10 @@ do_relocation:
else if (h->type == STT_GNU_IFUNC
&& bfd_link_pic (info))
{
- if (isym == NULL)
- name = h->root.root.string;
- else
- name = bfd_elf_sym_name (abfd, symtab_hdr, isym,
- NULL);
- _bfd_error_handler
- /* xgettext:c-format */
- (_("%B: unsupported non-PIC call to IFUNC `%s'"),
- abfd, name);
+ _bfd_error_handler
+ /* xgettext:c-format */
+ (_("%B: unsupported non-PIC call to IFUNC `%s'"),
+ abfd, h->root.root.string);
bfd_set_error (bfd_error_bad_value);
goto error_return;
}
@@ -4081,6 +4078,10 @@ do_ifunc_pointer:
|| h->forced_local
|| bfd_link_executable (info))
{
+ info->callbacks->minfo (_("Local IFUNC function `%s' in %B\n"),
+ h->root.root.string,
+ h->root.u.def.section->owner);
+
/* This symbol is resolved locally. */
outrel.r_info = ELF32_R_INFO (0, R_386_IRELATIVE);
bfd_put_32 (output_bfd,
@@ -5413,6 +5414,10 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
&& h->def_regular
&& h->type == STT_GNU_IFUNC))
{
+ info->callbacks->minfo (_("Local IFUNC function `%s' in %B\n"),
+ h->root.root.string,
+ h->root.u.def.section->owner);
+
/* If an STT_GNU_IFUNC symbol is locally defined, generate
R_386_IRELATIVE instead of R_386_JUMP_SLOT. Store addend
in the .got.plt section. */
@@ -5548,6 +5553,10 @@ elf_i386_finish_dynamic_symbol (bfd *output_bfd,
}
if (SYMBOL_REFERENCES_LOCAL (info, h))
{
+ info->callbacks->minfo (_("Local IFUNC function `%s' in %B\n"),
+ h->root.root.string,
+ h->root.u.def.section->owner);
+
bfd_put_32 (output_bfd,
(h->root.u.def.value
+ h->root.u.def.section->output_section->vma
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 7beb78e..c94d7ff 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -2281,6 +2281,8 @@ elf_x86_64_check_relocs (bfd *abfd, struct bfd_link_info *info,
goto error_return;
/* Fake a STT_GNU_IFUNC symbol. */
+ h->root.root.string = bfd_elf_sym_name (abfd, symtab_hdr,
+ isym, NULL);
h->type = STT_GNU_IFUNC;
h->def_regular = 1;
h->ref_regular = 1;
@@ -4422,6 +4424,10 @@ do_ifunc_pointer:
|| h->forced_local
|| bfd_link_executable (info))
{
+ info->callbacks->minfo (_("Local IFUNC function `%s' in %B\n"),
+ h->root.root.string,
+ h->root.u.def.section->owner);
+
/* This symbol is resolved locally. */
outrel.r_info = htab->r_info (0, R_X86_64_IRELATIVE);
outrel.r_addend = (h->root.u.def.value
@@ -5791,6 +5797,10 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
&& h->def_regular
&& h->type == STT_GNU_IFUNC))
{
+ info->callbacks->minfo (_("Local IFUNC function `%s' in %B\n"),
+ h->root.root.string,
+ h->root.u.def.section->owner);
+
/* If an STT_GNU_IFUNC symbol is locally defined, generate
R_X86_64_IRELATIVE instead of R_X86_64_JUMP_SLOT. */
rela.r_info = htab->r_info (0, R_X86_64_IRELATIVE);
@@ -5941,6 +5951,11 @@ elf_x86_64_finish_dynamic_symbol (bfd *output_bfd,
}
if (SYMBOL_REFERENCES_LOCAL (info, h))
{
+ info->callbacks->minfo (_("Local IFUNC function `%s' in %B\n"),
+ output_bfd,
+ h->root.root.string,
+ h->root.u.def.section->owner);
+
rela.r_info = htab->r_info (0,
R_X86_64_IRELATIVE);
rela.r_addend = (h->root.u.def.value
diff --git a/ld/testsuite/ld-ifunc/ifunc-1-local-x86.d b/ld/testsuite/ld-ifunc/ifunc-1-local-x86.d
index 00bc474..c14cd28 100644
--- a/ld/testsuite/ld-ifunc/ifunc-1-local-x86.d
+++ b/ld/testsuite/ld-ifunc/ifunc-1-local-x86.d
@@ -1,6 +1,7 @@
-#ld: -shared
+#ld: -shared -Map tmpdir/ifunc-1-local-x86.map
#objdump: -dw
#target: x86_64-*-* i?86-*-*
+#map: ifunc-1-local-x86.map
#...
[ \t0-9a-f]+:[ \t0-9a-f]+call[ \t0-9a-fq]+<\*ABS\*(\+0x160|\+0x170|\+0x1e0|)@plt>
diff --git a/ld/testsuite/ld-ifunc/ifunc-1-local-x86.map b/ld/testsuite/ld-ifunc/ifunc-1-local-x86.map
new file mode 100644
index 0000000..557a446
--- /dev/null
+++ b/ld/testsuite/ld-ifunc/ifunc-1-local-x86.map
@@ -0,0 +1,3 @@
+#...
+Local IFUNC function `__GI_foo' in tmpdir/ifunc-1-local-x86.o
+#pass
diff --git a/ld/testsuite/ld-ifunc/ifunc-1-x86.d b/ld/testsuite/ld-ifunc/ifunc-1-x86.d
index f9dee1b..c245758 100644
--- a/ld/testsuite/ld-ifunc/ifunc-1-x86.d
+++ b/ld/testsuite/ld-ifunc/ifunc-1-x86.d
@@ -1,6 +1,7 @@
-#ld: -shared
+#ld: -shared -Map tmpdir/ifunc-1-x86.map
#objdump: -dw
#target: x86_64-*-* i?86-*-*
+#map: ifunc-1-x86.map
#...
[ \t0-9a-f]+:[ \t0-9a-f]+call[ \t0-9a-fq]+<\*ABS\*(\+0x170|\+0x190|\+0x210|)@plt>
diff --git a/ld/testsuite/ld-ifunc/ifunc-1-x86.map b/ld/testsuite/ld-ifunc/ifunc-1-x86.map
new file mode 100644
index 0000000..98bbb7a
--- /dev/null
+++ b/ld/testsuite/ld-ifunc/ifunc-1-x86.map
@@ -0,0 +1,3 @@
+#...
+Local IFUNC function `__GI_foo' in tmpdir/ifunc-1-x86.o
+#pass
--
2.9.4