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authorH.J. Lu <hjl.tools@gmail.com>2015-12-14 19:09:13 -0800
committerH.J. Lu <hjl.tools@gmail.com>2015-12-16 05:46:20 -0800
commit4c0dfefbdf950080746e48f6f95f449922bb5d0c (patch)
tree39de519307330b9de1d58381daaad28d489cf448 /nptl/DESIGN-systemtap-probes.txt
parentd29d57eed9a6acb646663a02b7eb2bece2c433dc (diff)
downloadglibc-hjl/pr19363/master.tar.gz
glibc-hjl/pr19363/master.tar.xz
glibc-hjl/pr19363/master.zip
Use INTERNAL_SYSCALL_TIMES* macros for Linux times hjl/pr19363/master
The Linux times function, which returns clock_t, is implemented with
INTERNAL_SYSCALL_DECL, INTERNAL_SYSCALL, INTERNAL_SYSCALL_ERROR_P and
INTERNAL_SYSCALL_ERRNO.  Since INTERNAL_SYSCALL* macros use 32-bit
integer and clock_t is 64-bit on x32, this is a mismatch on x32.  All
system calls returning 64-bit integer, which are lseek, time and times,
must be handled specially for x32.  lseek is handled by x32 lseek.S and
time doesn't check syscall return.  times is the only missed one.

This patch replaces INTERNAL_SYSCALL* macros in Linux times.c with
INTERNAL_SYSCALL_TIMES* macros which are default to INTERNAL_SYSCALL*
macros and provides x32 times.c with proper INTERNAL_SYSCALL_TIMES*
macros.

There is no code change on times for i686 nor x86-64.  For x32, before
this patch, there are

0000000 <__times>:
   0:	b8 64 00 00 40       	mov    $0x40000064,%eax
   5:	0f 05                	syscall
   7:	48 63 d0             	movslq %eax,%rdx
                                ^^^^^^^^^^ Incorrect signed extension
   a:	48 83 fa f2          	cmp    $0xfffffffffffffff2,%rdx
   e:	75 07                	jne    17 <__times+0x17>
  10:	3d 00 f0 ff ff       	cmp    $0xfffff000,%eax
                                ^^^^^^^^^^^^^^^^^^^^^ 32-bit compare
  15:	77 11                	ja     28 <__times+0x28>
  17:	48 83 fa ff          	cmp    $0xffffffffffffffff,%rdx
  1b:	b8 00 00 00 00       	mov    $0x0,%eax
  20:	48 0f 45 c2          	cmovne %rdx,%rax
  24:	c3                   	retq

After this patch, there are

00000000 <__times>:
   0:	b8 64 00 00 40       	mov    $0x40000064,%eax
   5:	0f 05                	syscall
   7:	48 83 f8 f2          	cmp    $0xfffffffffffffff2,%rax
   b:	75 08                	jne    15 <__times+0x15>
   d:	48 3d 00 f0 ff ff    	cmp    $0xfffffffffffff000,%rax
  13:	77 13                	ja     28 <__times+0x28>
  15:	48 83 f8 ff          	cmp    $0xffffffffffffffff,%rax
  19:	ba 00 00 00 00       	mov    $0x0,%edx
  1e:	48 0f 44 c2          	cmove  %rdx,%rax
  22:	c3                   	retq

The incorrect signed extension and 32-bit compare are gone.

	[BZ #19363]
	* sysdeps/unix/sysv/linux/times.c (INTERNAL_SYSCALL_TIMES_DECL):
	New.
	(INTERNAL_SYSCALL_TIMES): Likewise.
	(INTERNAL_SYSCALL_TIMES_ERROR_P): Likewise.
	(INTERNAL_SYSCALL_TIMES_ERRNO): Likewise.
	(__times): Replace INTERNAL_SYSCALL* macros with
	INTERNAL_SYSCALL_TIMES* macros.
	* sysdeps/unix/sysv/linux/x86_64/x32/times.c: New file.
Diffstat (limited to 'nptl/DESIGN-systemtap-probes.txt')
0 files changed, 0 insertions, 0 deletions