kernel.git/arch/s390/kernel/vdso64, branch linux-4.6.y

s390/vdso: optimize getcpu system call

2016-01-11T12:01:24Z

Add the CPU number to the per-cpu vdso data page and add the __kernel_getcpu function to the vdso object to retrieve the CPU number in user space. Suggested-by: Heiko Carstens Reviewed-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/vdso: emit a GNU hash

2015-08-07T07:57:39Z

As proposed by Andy Lutomirski create the SysV and the GNU hash for the vdso objects. This may make some dynamic loaders a bit faster. Signed-off-by: Martin Schwidefsky

s390/vdso: fix clock_gettime for CLOCK_THREAD_CPUTIME_ID, -2 and -3

2015-02-12T08:37:21Z

Git commit 8d8f2e18a6dbd3d09dd918788422e6ac8c878e96 "s390/vdso: ectg gettime support for CLOCK_THREAD_CPUTIME_ID" broke clock_gettime for CLOCK_THREAD_CPUTIME_ID. Git commit c742b31c03f37c5c499178f09f57381aa6c70131 "fast vdso implementation for CLOCK_THREAD_CPUTIME_ID" introduced the ECTG for clock id -2. Correct would have been clock id -3. Fix the whole mess, CLOCK_THREAD_CPUTIME_ID is based on CPUCLOCK_SCHED and can not be speed up by the vdso. A speedup is only available for clock id -3 which is CPUCLOCK_VIRT for the task currently running on the CPU. Signed-off-by: Martin Schwidefsky

s390/vdso: fix stack corruption

2014-10-27T12:27:02Z

The kernel provided vdso functions do not get a stack frame from the calling function and therefore may not change the stack contents, unless they allocate space on their own. This problem was exposed with 070b7be633dc "s390/vdso: replace stck with stcke" which writes 16 bytes instead of 8 bytes into the stack frame. These additional 8 bytes however were indeed used by the caller (glibc) to save data and therefore this data was corrupted by the vdso code. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/vdso: add vdso support for coarse clocks

2014-09-09T06:53:27Z

Add CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE optimization to the 64-bit and 31-bit vdso. Signed-off-by: Martin Schwidefsky

s390/vdso: replace stck with stcke

2014-09-09T06:53:27Z

If gettimeofday / clock_gettime are called multiple times in a row the STCK instruction will stall until a difference in the result is visible. This unnecessarily slows down the vdso calls, use stcke instead of stck to get rid of the stall. Signed-off-by: Martin Schwidefsky

s390/vdso: remove NULL pointer check from clock_gettime

2014-09-01T07:56:29Z

The explicit NULL pointer check on the timespec argument is only required for clock_getres but not for clock_gettime. Signed-off-by: Martin Schwidefsky

s390/time,vdso: fix clock_gettime for CLOCK_MONOTONIC

2013-12-02T17:15:25Z

With git commit 79c74ecbebf76732f91b82a62ce7fc8a88326962 "s390/time,vdso: convert to the new update_vsyscall interface" the new update_vsyscall function already does the sum of xtime and wall_to_monotonic. The old update_vsyscall function only copied the wall_to_monotonic offset. The vdso code needs to be modified to take this into consideration. Signed-off-by: Martin Schwidefsky

s390/vdso: ectg gettime support for CLOCK_THREAD_CPUTIME_ID

2013-12-02T14:31:10Z

The code to use the ECTG instruction to calculate the cputime for the current thread is currently used only for the per-thread CPU-clock with the clockid -2 (PID=0, VIRT=1). Use the same code for the clockid CLOCK_THREAD_CPUTIME_ID to speed up the more common clockid as well. Reported-by: Heiko Carstens Signed-off-by: Martin Schwidefsky

s390/time,vdso: convert to the new update_vsyscall interface

2013-11-25T08:15:39Z

Switch to the improved update_vsyscall interface that provides sub-nanosecond precision for gettimeofday and clock_gettime. Signed-off-by: Martin Schwidefsky