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author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2012-03-11 15:59:27 (GMT) |
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committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2012-03-11 15:59:28 (GMT) |
commit | 4c1051e37a0e2a941115c6fb7ba08c318f25a0f9 (patch) | |
tree | f228f1a90c0d7abb8308f275d0906dd7d1588ba3 /arch/s390/kernel/entry64.S | |
parent | 8b646bd759086f6090fe27acf414c0b5faa737f4 (diff) | |
download | linux-4c1051e37a0e2a941115c6fb7ba08c318f25a0f9.tar.xz |
[S390] rework idle code
Whenever the cpu loads an enabled wait PSW it will appear as idle to the
underlying host system. The code in default_idle calls vtime_stop_cpu
which does the necessary voodoo to get the cpu time accounting right.
The udelay code just loads an enabled wait PSW. To correct this rework
the vtime_stop_cpu/vtime_start_cpu logic and move the difficult parts
to entry[64].S, vtime_stop_cpu can now be called from anywhere and
vtime_start_cpu is gone. The correction of the cpu time during wakeup
from an enabled wait PSW is done with a critical section in entry[64].S.
As vtime_start_cpu is gone, s390_idle_check can be removed as well.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/entry64.S')
-rw-r--r-- | arch/s390/kernel/entry64.S | 65 |
1 files changed, 62 insertions, 3 deletions
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S index e33789a..4e1c292 100644 --- a/arch/s390/kernel/entry64.S +++ b/arch/s390/kernel/entry64.S @@ -489,7 +489,6 @@ io_restore: lg %r14,__LC_VDSO_PER_CPU lmg %r0,%r10,__PT_R0(%r11) mvc __LC_RETURN_PSW(16),__PT_PSW(%r11) - ni __LC_RETURN_PSW+1,0xfd # clear wait state bit stpt __LC_EXIT_TIMER mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER lmg %r11,%r15,__PT_R11(%r11) @@ -631,6 +630,24 @@ ext_skip: brasl %r14,do_extint j io_return +/* + * Load idle PSW. The second "half" of this function is in cleanup_idle. + */ +ENTRY(psw_idle) + stg %r4,__SF_EMPTY(%r15) + larl %r1,psw_idle_lpsw+4 + stg %r1,__SF_EMPTY+8(%r15) + larl %r1,.Lvtimer_max + stck __IDLE_ENTER(%r2) + ltr %r5,%r5 + stpt __VQ_IDLE_ENTER(%r3) + jz psw_idle_lpsw + spt 0(%r1) +psw_idle_lpsw: + lpswe __SF_EMPTY(%r15) + br %r14 +psw_idle_end: + __critical_end: /* @@ -696,7 +713,6 @@ mcck_return: lg %r14,__LC_VDSO_PER_CPU lmg %r0,%r10,__PT_R0(%r11) mvc __LC_RETURN_MCCK_PSW(16),__PT_PSW(%r11) # move return PSW - ni __LC_RETURN_MCCK_PSW+1,0xfd # clear wait state bit tm __LC_RETURN_MCCK_PSW+1,0x01 # returning to user ? jno 0f stpt __LC_EXIT_TIMER @@ -770,6 +786,8 @@ cleanup_table: .quad io_tif .quad io_restore .quad io_done + .quad psw_idle + .quad psw_idle_end cleanup_critical: clg %r9,BASED(cleanup_table) # system_call @@ -788,6 +806,10 @@ cleanup_critical: jl cleanup_io_tif clg %r9,BASED(cleanup_table+56) # io_done jl cleanup_io_restore + clg %r9,BASED(cleanup_table+64) # psw_idle + jl 0f + clg %r9,BASED(cleanup_table+72) # psw_idle_end + jl cleanup_idle 0: br %r14 @@ -877,7 +899,6 @@ cleanup_io_restore: je 0f lg %r9,24(%r11) # get saved r11 pointer to pt_regs mvc __LC_RETURN_PSW(16),__PT_PSW(%r9) - ni __LC_RETURN_PSW+1,0xfd # clear wait state bit mvc 0(64,%r11),__PT_R8(%r9) lmg %r0,%r7,__PT_R0(%r9) 0: lmg %r8,%r9,__LC_RETURN_PSW @@ -885,6 +906,42 @@ cleanup_io_restore: cleanup_io_restore_insn: .quad io_done - 4 +cleanup_idle: + # copy interrupt clock & cpu timer + mvc __IDLE_EXIT(8,%r2),__LC_INT_CLOCK + mvc __VQ_IDLE_EXIT(8,%r3),__LC_ASYNC_ENTER_TIMER + cghi %r11,__LC_SAVE_AREA_ASYNC + je 0f + mvc __IDLE_EXIT(8,%r2),__LC_MCCK_CLOCK + mvc __VQ_IDLE_EXIT(8,%r3),__LC_MCCK_ENTER_TIMER +0: # check if stck & stpt have been executed + clg %r9,BASED(cleanup_idle_insn) + jhe 1f + mvc __IDLE_ENTER(8,%r2),__IDLE_EXIT(%r2) + mvc __VQ_IDLE_ENTER(8,%r3),__VQ_IDLE_EXIT(%r3) + j 2f +1: # check if the cpu timer has been reprogrammed + ltr %r5,%r5 + jz 2f + spt __VQ_IDLE_ENTER(%r3) +2: # account system time going idle + lg %r9,__LC_STEAL_TIMER + alg %r9,__IDLE_ENTER(%r2) + slg %r9,__LC_LAST_UPDATE_CLOCK + stg %r9,__LC_STEAL_TIMER + mvc __LC_LAST_UPDATE_CLOCK(8),__IDLE_EXIT(%r2) + lg %r9,__LC_SYSTEM_TIMER + alg %r9,__LC_LAST_UPDATE_TIMER + slg %r9,__VQ_IDLE_ENTER(%r3) + stg %r9,__LC_SYSTEM_TIMER + mvc __LC_LAST_UPDATE_TIMER(8),__VQ_IDLE_EXIT(%r3) + # prepare return psw + nihh %r8,0xfffd # clear wait state bit + lg %r9,48(%r11) # return from psw_idle + br %r14 +cleanup_idle_insn: + .quad psw_idle_lpsw + /* * Integer constants */ @@ -893,6 +950,8 @@ cleanup_io_restore_insn: .quad __critical_start .Lcritical_length: .quad __critical_end - __critical_start +.Lvtimer_max: + .quad 0x7fffffffffffffff #if defined(CONFIG_KVM) || defined(CONFIG_KVM_MODULE) |