[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Bug ld/13621] New: dangling global hidden symbol in symtab
From: |
mjw at redhat dot com |
Subject: |
[Bug ld/13621] New: dangling global hidden symbol in symtab |
Date: |
Tue, 24 Jan 2012 23:13:17 +0000 |
http://sourceware.org/bugzilla/show_bug.cgi?id=13621
Bug #: 13621
Summary: dangling global hidden symbol in symtab
Product: binutils
Version: unspecified
Status: NEW
Severity: normal
Priority: P2
Component: ld
AssignedTo: address@hidden
ReportedBy: address@hidden
CC: address@hidden
Classification: Unclassified
gcc 4.7 (not yet released) introduces a new __TMC_END__ global hidden symbol to
mark the end of a .tm_clone_table section. When linking a program that doesn't
use any tm_clone_table entries the __TMC_END__ symbol is left in .symtab
pointing outside any section. For example just compiling an empty program int
main(int argc, char **argv) { return 0; } produces on x86_64 with gcc (GCC)
4.7.0 20120119
(Red Hat 4.7.0-0.8) and binutils-2.22-4.fc17.x86_64 a __TMC_END__ symbol in
.symtab that looks as follows:
66: 0000000000600850 0 OBJECT GLOBAL HIDDEN 24 __TMC_END__
Section 24 is:
[24] .data PROGBITS 0000000000600848 00000848 00000004 0 WA
0 0 4
So the address of __TMC_END__ is outside that section.
With gcc < 4.7 the following mimics what happens:
$ cat attrsec.c
typedef void (*func_ptr) (void);
static func_ptr __TMC_LIST__[]
__attribute__((used, section(".tm_clone_table"), aligned(sizeof(void*))))
= { };
extern func_ptr __TMC_END__[] __attribute__((__visibility__ ("hidden")));
void
deregister_tm_clones (void)
{
if (__TMC_END__ - __TMC_LIST__ == 0)
return;
}
func_ptr __TMC_END__[]
__attribute__((used, section(".tm_clone_table"), aligned(sizeof(void *))))
__attribute__((__visibility__ ("hidden"))) = { };
$ gcc -c attrsec.c
$ readelf -a attrsec.o
[...]
[ 5] .tm_clone_table PROGBITS 0000000000000000 00000068
0000000000000000 0000000000000000 WA 0 0 8
[...]
Symbol table '.symtab' contains 12 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 FILE LOCAL DEFAULT ABS attrsec.c
2: 0000000000000000 0 SECTION LOCAL DEFAULT 1
3: 0000000000000000 0 SECTION LOCAL DEFAULT 3
4: 0000000000000000 0 SECTION LOCAL DEFAULT 4
5: 0000000000000000 0 SECTION LOCAL DEFAULT 5
6: 0000000000000000 0 OBJECT LOCAL DEFAULT 5 __TMC_LIST__
7: 0000000000000000 0 SECTION LOCAL DEFAULT 7
8: 0000000000000000 0 SECTION LOCAL DEFAULT 8
9: 0000000000000000 0 SECTION LOCAL DEFAULT 6
10: 0000000000000000 34 FUNC GLOBAL DEFAULT 1 deregister_tm_clones
11: 0000000000000000 0 OBJECT GLOBAL HIDDEN 5 __TMC_END__
$ cat attrsecmain.c
int main (int argc, char **argv)
{
deregister_tm_clones ();
return 0;
}
$ gcc -o attrsec attrsec.o attrsecmain.c
$ readelf -a attrsec
[...]
[24] .data PROGBITS 0000000000600898 00000898
0000000000000004 0000000000000000 WA 0 0 4
[...]
64: 00000000006008a0 0 OBJECT GLOBAL HIDDEN 24 __TMC_END__
--
Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are on the CC list for the bug.
- [Bug ld/13621] New: dangling global hidden symbol in symtab,
mjw at redhat dot com <=
- [Bug ld/13621] dangling global hidden symbol in symtab, hjl.tools at gmail dot com, 2012/01/25
- [Bug ld/13621] dangling global hidden symbol in symtab, mjw at redhat dot com, 2012/01/26
- [Bug ld/13621] dangling global hidden symbol in symtab, rth at gcc dot gnu.org, 2012/01/27
- [Bug ld/13621] dangling global hidden symbol in symtab, rth at gcc dot gnu.org, 2012/01/27
- [Bug ld/13621] dangling global hidden symbol in symtab, rth at gcc dot gnu.org, 2012/01/27
- [Bug ld/13621] dangling global hidden symbol in symtab, ian at airs dot com, 2012/01/27
- [Bug ld/13621] dangling global hidden symbol in symtab, rth at gcc dot gnu.org, 2012/01/29