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aarch64: fix static pie enabled libc when main is in a shared library

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In the static pie enabled libc, crt1.o uses the same position independent
code as rcrt1.o and crt1.o is used instead of Scrt1.o when -no-pie
executables are linked.  When main is not defined in the executable, but
in a shared library crt1.o is currently broken, it assumes main is local.
(glibc has a test for this but i missed it in my previous testing.)

To make both rcrt1.o and crt1.o happy with the same code, a wrapper is
introduced around main: with this crt1.o works with extern main symbol
while rcrt1.o does not depend on GOT relocations. (The change only
affects static pie enabled libc. Further simplification of start.S is
possible in the future by using the same approach for Scrt1.o too.)

	* aarch64/start.S (_start): Use __wrap_main.
	(__wrap_main): New local symbol.
This commit is contained in:
Szabolcs Nagy 2017-12-19 18:43:04 +00:00
parent 52a713fdd0
commit 3d1d79283e
2 changed files with 16 additions and 2 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
2018-01-12 Szabolcs Nagy <szabolcs.nagy@arm.com>
* aarch64/start.S (_start): Use __wrap_main.
(__wrap_main): New local symbol.
2018-01-12 Dmitry V. Levin <ldv@altlinux.org>
[BZ #22679]

13
sysdeps/aarch64/start.S
View File

@ -71,8 +71,8 @@ _start:
adrp x4, :got:__libc_csu_fini
ldr PTR_REG (4), [x4, #:got_lo12:__libc_csu_fini]
# else
adrp x0, main
add x0, x0, :lo12:main
adrp x0, __wrap_main
add x0, x0, :lo12:__wrap_main
adrp x3, __libc_csu_init
add x3, x3, :lo12:__libc_csu_init
adrp x4, __libc_csu_fini
@ -94,6 +94,15 @@ _start:
/* should never get here....*/
bl abort
#if defined PIC && !defined SHARED
/* When main is not defined in the executable but in a shared library
then a wrapper is needed in crt1.o of the static-pie enabled libc,
because crt1.o and rcrt1.o share code and the later must avoid the
use of GOT relocations before __libc_start_main is called. */
__wrap_main:
b main
#endif
/* Define a symbol for the first piece of initialized data. */
.data
.globl __data_start