Commit Graph

12 Commits

Author SHA1 Message Date
H.J. Lu
5b736bc9b5 x86-64: Check PIC instead of SHARED in start.S
Since start.o may be compiled as PIC, we should check PIC instead of
SHARED.

	* sysdeps/x86_64/start.S (_start): Check PIC instead of SHARED.
2017-08-02 10:27:34 -07:00
Joseph Myers
bfff8b1bec Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
H.J. Lu
ac187dc4ab Always indirect branch to __libc_start_main via GOT
Since __libc_start_main in libc.so is called very early, lazy binding
isn't relevant.  Always call __libc_start_main with indirect branch via
GOT to avoid extra branch to PLT slot.  In case of static executable,
ld in binutils 2.26 or above can convert indirect branch into direct
branch:

0000000000400a80 <_start>:
  400a80:       31 ed                   xor    %ebp,%ebp
  400a82:       49 89 d1                mov    %rdx,%r9
  400a85:       5e                      pop    %rsi
  400a86:       48 89 e2                mov    %rsp,%rdx
  400a89:       48 83 e4 f0             and    $0xfffffffffffffff0,%rsp
  400a8d:       50                      push   %rax
  400a8e:       54                      push   %rsp
  400a8f:       49 c7 c0 20 1b 40 00    mov    $0x401b20,%r8
  400a96:       48 c7 c1 90 1a 40 00    mov    $0x401a90,%rcx
  400a9d:       48 c7 c7 c0 03 40 00    mov    $0x4003c0,%rdi
  400aa4:       67 e8 96 09 00 00       addr32 callq 401440 <__libc_start_main>
  400aaa:       f4                      hlt

	* sysdeps/x86_64/start.S (_start): Always indirect branch to
	__libc_start_main via GOT.
2016-06-09 04:43:31 -07:00
H.J. Lu
21683b5a7d Replace @PLT with @GOTPCREL(%rip) in call
Since __libc_start_main is called very early, lazy binding isn't relevant
here.  Use indirect branch via GOT to avoid extra branch to PLT slot.

	[BZ #19745]
	* sysdeps/x86_64/start.S (_start): __libc_start_main@PLT
	with *__libc_start_main@GOTPCREL(%rip) in call.
2016-03-04 16:15:41 -08:00
Joseph Myers
f7a9f785e5 Update copyright dates with scripts/update-copyrights. 2016-01-04 16:05:18 +00:00
Joseph Myers
b168057aaa Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
Brooks Moses
467fec0bb4 sysdeps/x86_64/start.S doesn't have a .size elf directive for _start.
This tripped up some analysis I was doing.

This patch is the straightforward fix.

I see no regressions on a "make check" using ENTRY and END.
2014-11-24 16:26:58 -08:00
Allan McRae
d4697bc93d Update copyright notices with scripts/update-copyrights 2014-01-01 22:00:23 +10:00
Joseph Myers
2969121014 Remove bounded-pointers handling from x86_64 assembly sources. 2013-02-17 21:57:26 +00:00
Joseph Myers
568035b787 Update copyright notices with scripts/update-copyrights. 2013-01-02 19:05:09 +00:00
H.J. Lu
6cdef1ab36 Update sysdeps/x86_64/start.S for x32 2012-05-14 17:50:41 -07:00
Andreas Jaeger
9d639b9918 Move x86_64/elf files to x86_64 2012-03-19 20:55:26 +01:00