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[PATCH] fast vdso implementation for CLOCK_THREAD_CPUTIME_ID

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The extract cpu time instruction (ectg) instruction allows the user
process to get the current thread cputime without calling into the
kernel. The code that uses the instruction needs to switch to the
access registers mode to get access to the per-cpu info page that
contains the two base values that are needed to calculate the current
cputime from the CPU timer with the ectg instruction.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky
2008-12-31 15:11:42 +01:00
parent 9cfb9b3c3a
commit c742b31c03
10 changed files with 222 additions and 32 deletions
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45
arch/s390/kernel/entry64.S
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@ -177,8 +177,11 @@ _TIF_WORK_INT = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \
.if !\sync
ni \psworg+1,0xfd # clear wait state bit
.endif
lmg %r0,%r15,SP_R0(%r15) # load gprs 0-15 of user
lg %r14,__LC_VDSO_PER_CPU
lmg %r0,%r13,SP_R0(%r15) # load gprs 0-13 of user
stpt __LC_EXIT_TIMER
mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER
lmg %r14,%r15,SP_R14(%r15) # load grps 14-15 of user
lpswe \psworg # back to caller
.endm
@ -980,23 +983,23 @@ cleanup_sysc_return:
cleanup_sysc_leave:
clc 8(8,%r12),BASED(cleanup_sysc_leave_insn)
je 2f
mvc __LC_EXIT_TIMER(8),__LC_ASYNC_ENTER_TIMER
je 3f
clc 8(8,%r12),BASED(cleanup_sysc_leave_insn+8)
je 2f
mvc __LC_RETURN_PSW(16),SP_PSW(%r15)
jhe 0f
mvc __LC_EXIT_TIMER(8),__LC_ASYNC_ENTER_TIMER
0: mvc __LC_RETURN_PSW(16),SP_PSW(%r15)
cghi %r12,__LC_MCK_OLD_PSW
jne 0f
jne 1f
mvc __LC_SAVE_AREA+64(32),SP_R12(%r15)
j 1f
0: mvc __LC_SAVE_AREA+32(32),SP_R12(%r15)
1: lmg %r0,%r11,SP_R0(%r15)
j 2f
1: mvc __LC_SAVE_AREA+32(32),SP_R12(%r15)
2: lmg %r0,%r11,SP_R0(%r15)
lg %r15,SP_R15(%r15)
2: la %r12,__LC_RETURN_PSW
3: la %r12,__LC_RETURN_PSW
br %r14
cleanup_sysc_leave_insn:
.quad sysc_done - 4
.quad sysc_done - 8
.quad sysc_done - 16
cleanup_io_return:
mvc __LC_RETURN_PSW(8),0(%r12)
@ -1006,23 +1009,23 @@ cleanup_io_return:
cleanup_io_leave:
clc 8(8,%r12),BASED(cleanup_io_leave_insn)
je 2f
mvc __LC_EXIT_TIMER(8),__LC_ASYNC_ENTER_TIMER
je 3f
clc 8(8,%r12),BASED(cleanup_io_leave_insn+8)
je 2f
mvc __LC_RETURN_PSW(16),SP_PSW(%r15)
jhe 0f
mvc __LC_EXIT_TIMER(8),__LC_ASYNC_ENTER_TIMER
0: mvc __LC_RETURN_PSW(16),SP_PSW(%r15)
cghi %r12,__LC_MCK_OLD_PSW
jne 0f
jne 1f
mvc __LC_SAVE_AREA+64(32),SP_R12(%r15)
j 1f
0: mvc __LC_SAVE_AREA+32(32),SP_R12(%r15)
1: lmg %r0,%r11,SP_R0(%r15)
j 2f
1: mvc __LC_SAVE_AREA+32(32),SP_R12(%r15)
2: lmg %r0,%r11,SP_R0(%r15)
lg %r15,SP_R15(%r15)
2: la %r12,__LC_RETURN_PSW
3: la %r12,__LC_RETURN_PSW
br %r14
cleanup_io_leave_insn:
.quad io_done - 4
.quad io_done - 8
.quad io_done - 16
/*
* Integer constants