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Re: [PATCH] ld: Lookup section in output with the same name
On Fri, Aug 31, 2018 at 8:39 AM, Alan Modra <amodra@gmail.com> wrote:
> On Thu, Aug 30, 2018 at 01:51:37PM -0700, H.J. Lu wrote:
>> --- a/ld/ldlang.c
>> +++ b/ld/ldlang.c
>> @@ -6097,6 +6097,24 @@ undef_start_stop (struct bfd_link_hash_entry *h)
>> || strcmp (h->u.def.section->name,
>> h->u.def.section->output_section->name) != 0)
>> {
>> + asection *sec = bfd_get_section_by_name (link_info.output_bfd,
>> + h->u.def.section->name);
>> + if (sec != NULL)
>> + {
>> + /* When there are more than one input sections with the same
>> + section name, SECNAME, linker picks the first one to define
>> + __start_SECNAME and __stop_SECNAME symbols. When the first
>> + input section is removed by comdat group, we need to check
>> + if there is still an output section with section name
>> + SECNAME. */
>> + asection *i;
>> + for (i = sec->map_head.s; i != NULL; i = i->map_head.s)
>> + if (i->size != 0)
>
> I think you should check that i->name matches h->u.def.section->name
> here. At one stage we only defined start/stop symbols on orphans,
> but now we do so whenever input section name matches output section
> name and the name is alphanumeric. That means a linker script might
> be involved in which case differently named input sections might map
> to the output section.
>
> Also, why do you check i->size? We define start/stop symbols on zero
> sized sections!
Like this?
--
H.J.
From bd9d34b72f3f3b338521d0ca58384eb0fba0cf44 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Thu, 30 Aug 2018 09:21:57 -0700
Subject: [PATCH] ld: Lookup section in output with the same name
When there are more than one input sections with the same section name,
SECNAME, linker picks the first one to define __start_SECNAME and
__stop_SECNAME symbols. When the first input section is removed by
comdat group, we need to check if there is still an output section
with section name SECNAME.
PR ld/23591
* ldlang.c (undef_start_stop): Lookup section in output with
the same name.
* testsuite/ld-elf/pr23591.d: New file.
* testsuite/ld-elf/pr23591a.s: Likewise.
* testsuite/ld-elf/pr23591b.s: Likewise.
* testsuite/ld-elf/pr23591c.s: Likewise.
---
ld/ldlang.c | 18 ++++++++++++++++++
ld/testsuite/ld-elf/pr23591.d | 9 +++++++++
ld/testsuite/ld-elf/pr23591a.s | 14 ++++++++++++++
ld/testsuite/ld-elf/pr23591b.s | 11 +++++++++++
ld/testsuite/ld-elf/pr23591c.s | 26 ++++++++++++++++++++++++++
5 files changed, 78 insertions(+)
create mode 100644 ld/testsuite/ld-elf/pr23591.d
create mode 100644 ld/testsuite/ld-elf/pr23591a.s
create mode 100644 ld/testsuite/ld-elf/pr23591b.s
create mode 100644 ld/testsuite/ld-elf/pr23591c.s
diff --git a/ld/ldlang.c b/ld/ldlang.c
index 8878ccdb63..d644b56812 100644
--- a/ld/ldlang.c
+++ b/ld/ldlang.c
@@ -6097,6 +6097,24 @@ undef_start_stop (struct bfd_link_hash_entry *h)
|| strcmp (h->u.def.section->name,
h->u.def.section->output_section->name) != 0)
{
+ asection *sec = bfd_get_section_by_name (link_info.output_bfd,
+ h->u.def.section->name);
+ if (sec != NULL)
+ {
+ /* When there are more than one input sections with the same
+ section name, SECNAME, linker picks the first one to define
+ __start_SECNAME and __stop_SECNAME symbols. When the first
+ input section is removed by comdat group, we need to check
+ if there is still an output section with section name
+ SECNAME. */
+ asection *i;
+ for (i = sec->map_head.s; i != NULL; i = i->map_head.s)
+ if (strcmp (h->u.def.section->name, i->name) == 0)
+ {
+ h->u.def.section = i;
+ return;
+ }
+ }
h->type = bfd_link_hash_undefined;
h->u.undef.abfd = NULL;
}
diff --git a/ld/testsuite/ld-elf/pr23591.d b/ld/testsuite/ld-elf/pr23591.d
new file mode 100644
index 0000000000..e002d73044
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr23591.d
@@ -0,0 +1,9 @@
+#source: pr23591a.s
+#source: pr23591b.s
+#source: pr23591c.s
+#ld: -e _start
+#readelf: -sW
+
+#...
+ +[0-9]+: +[a-f0-9]+ +0 +NOTYPE +GLOBAL +HIDDEN +[0-9]+ +___?start___sancov_cntrs
+#pass
diff --git a/ld/testsuite/ld-elf/pr23591a.s b/ld/testsuite/ld-elf/pr23591a.s
new file mode 100644
index 0000000000..ebdb7f8abb
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr23591a.s
@@ -0,0 +1,14 @@
+.ifdef UNDERSCORE
+ .hidden ___start___sancov_cntrs
+.else
+ .hidden __start___sancov_cntrs
+.endif
+ .text
+ .globl _start
+ .type _start, %function
+_start:
+.ifdef UNDERSCORE
+ .dc.a ___start___sancov_cntrs
+.else
+ .dc.a __start___sancov_cntrs
+.endif
diff --git a/ld/testsuite/ld-elf/pr23591b.s b/ld/testsuite/ld-elf/pr23591b.s
new file mode 100644
index 0000000000..646e681cc5
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr23591b.s
@@ -0,0 +1,11 @@
+ .section .text,"axG",%progbits,foo1,comdat
+.ifdef UNDERSCORE
+ .globl _foo1
+ .type _foo1, %function
+_foo1:
+.else
+ .globl foo1
+ .type foo1, %function
+foo1:
+.endif
+ .byte 0
diff --git a/ld/testsuite/ld-elf/pr23591c.s b/ld/testsuite/ld-elf/pr23591c.s
new file mode 100644
index 0000000000..338671ceb7
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr23591c.s
@@ -0,0 +1,26 @@
+ .section __sancov_cntrs,"aG",%progbits,foo1,comdat
+ .long 0
+ .section .text,"axG",%progbits,foo1,comdat
+.ifdef UNDERSCORE
+ .globl _foo1
+ .type _foo1, %function
+_foo1:
+.else
+ .globl foo1
+ .type foo1, %function
+foo1:
+.endif
+ .long 0
+ .section __sancov_cntrs,"aG",%progbits,foo2,comdat
+ .long 1
+ .section .text,"axG",%progbits,foo2,comdat
+.ifdef UNDERSCORE
+ .globl _foo2
+ .type _foo2, %function
+_foo2:
+ .long 1
+.else
+ .globl foo2
+ .type foo2, %function
+foo2:
+.endif
--
2.17.1