diff options
author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2012-03-11 15:59:27 (GMT) |
---|---|---|
committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2012-03-11 15:59:28 (GMT) |
commit | 4c1051e37a0e2a941115c6fb7ba08c318f25a0f9 (patch) | |
tree | f228f1a90c0d7abb8308f275d0906dd7d1588ba3 /arch/s390/kernel | |
parent | 8b646bd759086f6090fe27acf414c0b5faa737f4 (diff) | |
download | linux-fsl-qoriq-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')
-rw-r--r-- | arch/s390/kernel/asm-offsets.c | 8 | ||||
-rw-r--r-- | arch/s390/kernel/entry.S | 76 | ||||
-rw-r--r-- | arch/s390/kernel/entry.h | 5 | ||||
-rw-r--r-- | arch/s390/kernel/entry64.S | 65 | ||||
-rw-r--r-- | arch/s390/kernel/irq.c | 2 | ||||
-rw-r--r-- | arch/s390/kernel/nmi.c | 2 | ||||
-rw-r--r-- | arch/s390/kernel/process.c | 7 | ||||
-rw-r--r-- | arch/s390/kernel/smp.c | 46 | ||||
-rw-r--r-- | arch/s390/kernel/vtime.c | 163 |
9 files changed, 193 insertions, 181 deletions
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c index aeeaf89..ed8c913 100644 --- a/arch/s390/kernel/asm-offsets.c +++ b/arch/s390/kernel/asm-offsets.c @@ -8,6 +8,8 @@ #include <linux/kbuild.h> #include <linux/sched.h> +#include <asm/cputime.h> +#include <asm/timer.h> #include <asm/vdso.h> #include <asm/pgtable.h> #include <asm/system.h> @@ -70,6 +72,12 @@ int main(void) DEFINE(__CLOCK_MONOTONIC, CLOCK_MONOTONIC); DEFINE(__CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC); BLANK(); + /* idle data offsets */ + DEFINE(__IDLE_ENTER, offsetof(struct s390_idle_data, idle_enter)); + DEFINE(__IDLE_EXIT, offsetof(struct s390_idle_data, idle_exit)); + /* vtimer queue offsets */ + DEFINE(__VQ_IDLE_ENTER, offsetof(struct vtimer_queue, idle_enter)); + DEFINE(__VQ_IDLE_EXIT, offsetof(struct vtimer_queue, idle_exit)); /* lowcore offsets */ DEFINE(__LC_EXT_PARAMS, offsetof(struct _lowcore, ext_params)); DEFINE(__LC_EXT_CPU_ADDR, offsetof(struct _lowcore, ext_cpu_addr)); diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 6143521..74ee563 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -105,14 +105,14 @@ STACK_SIZE = 1 << STACK_SHIFT .macro ADD64 high,low,timer al \high,\timer - al \low,\timer+4 + al \low,4+\timer brc 12,.+8 ahi \high,1 .endm .macro SUB64 high,low,timer sl \high,\timer - sl \low,\timer+4 + sl \low,4+\timer brc 3,.+8 ahi \high,-1 .endm @@ -471,7 +471,6 @@ io_tif: jnz io_work # there is work to do (signals etc.) io_restore: mvc __LC_RETURN_PSW(8),__PT_PSW(%r11) - ni __LC_RETURN_PSW+1,0xfd # clean wait state bit stpt __LC_EXIT_TIMER lm %r0,%r15,__PT_R0(%r11) lpsw __LC_RETURN_PSW @@ -612,6 +611,26 @@ ext_skip: basr %r14,%r1 # call do_extint j io_return +/* + * Load idle PSW. The second "half" of this function is in cleanup_idle. + */ +ENTRY(psw_idle) + st %r4,__SF_EMPTY(%r15) + basr %r1,0 + la %r1,psw_idle_lpsw+4-.(%r1) + st %r1,__SF_EMPTY+4(%r15) + oi __SF_EMPTY+4(%r15),0x80 + la %r1,.Lvtimer_max-psw_idle_lpsw-4(%r1) + stck __IDLE_ENTER(%r2) + ltr %r5,%r5 + stpt __VQ_IDLE_ENTER(%r3) + jz psw_idle_lpsw + spt 0(%r1) +psw_idle_lpsw: + lpsw __SF_EMPTY(%r15) + br %r14 +psw_idle_end: + __critical_end: /* @@ -673,7 +692,6 @@ mcck_skip: TRACE_IRQS_ON mcck_return: mvc __LC_RETURN_MCCK_PSW(8),__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 lm %r0,%r15,__PT_R0(%r11) @@ -748,6 +766,8 @@ cleanup_table: .long io_tif + 0x80000000 .long io_restore + 0x80000000 .long io_done + 0x80000000 + .long psw_idle + 0x80000000 + .long psw_idle_end + 0x80000000 cleanup_critical: cl %r9,BASED(cleanup_table) # system_call @@ -766,6 +786,10 @@ cleanup_critical: jl cleanup_io_tif cl %r9,BASED(cleanup_table+28) # io_done jl cleanup_io_restore + cl %r9,BASED(cleanup_table+32) # psw_idle + jl 0f + cl %r9,BASED(cleanup_table+36) # psw_idle_end + jl cleanup_idle 0: br %r14 cleanup_system_call: @@ -849,7 +873,6 @@ cleanup_io_restore: jhe 0f l %r9,12(%r11) # get saved r11 pointer to pt_regs mvc __LC_RETURN_PSW(8),__PT_PSW(%r9) - ni __LC_RETURN_PSW+1,0xfd # clear wait state bit mvc 0(32,%r11),__PT_R8(%r9) lm %r0,%r7,__PT_R0(%r9) 0: lm %r8,%r9,__LC_RETURN_PSW @@ -857,11 +880,52 @@ cleanup_io_restore: cleanup_io_restore_insn: .long io_done - 4 + 0x80000000 +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 + chi %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 has been executed + cl %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 + lm %r9,%r10,__LC_STEAL_TIMER + ADD64 %r9,%r10,__IDLE_ENTER(%r2) + SUB64 %r9,%r10,__LC_LAST_UPDATE_CLOCK + stm %r9,%r10,__LC_STEAL_TIMER + mvc __LC_LAST_UPDATE_CLOCK(8),__IDLE_EXIT(%r2) + lm %r9,%r10,__LC_SYSTEM_TIMER + ADD64 %r9,%r10,__LC_LAST_UPDATE_TIMER + SUB64 %r9,%r10,__VQ_IDLE_ENTER(%r3) + stm %r9,%r10,__LC_SYSTEM_TIMER + mvc __LC_LAST_UPDATE_TIMER(8),__VQ_IDLE_EXIT(%r3) + # prepare return psw + n %r8,BASED(cleanup_idle_wait) # clear wait state bit + l %r9,24(%r11) # return from psw_idle + br %r14 +cleanup_idle_insn: + .long psw_idle_lpsw + 0x80000000 +cleanup_idle_wait: + .long 0xfffdffff + /* * Integer constants */ .align 4 -.Lnr_syscalls: .long NR_syscalls +.Lnr_syscalls: + .long NR_syscalls +.Lvtimer_max: + .quad 0x7fffffffffffffff /* * Symbol constants diff --git a/arch/s390/kernel/entry.h b/arch/s390/kernel/entry.h index 92b1617..4984785 100644 --- a/arch/s390/kernel/entry.h +++ b/arch/s390/kernel/entry.h @@ -4,7 +4,8 @@ #include <linux/types.h> #include <linux/signal.h> #include <asm/ptrace.h> - +#include <asm/cputime.h> +#include <asm/timer.h> extern void (*pgm_check_table[128])(struct pt_regs *); extern void *restart_stack; @@ -16,6 +17,8 @@ void io_int_handler(void); void mcck_int_handler(void); void restart_int_handler(void); void restart_call_handler(void); +void psw_idle(struct s390_idle_data *, struct vtimer_queue *, + unsigned long, int); asmlinkage long do_syscall_trace_enter(struct pt_regs *regs); asmlinkage void do_syscall_trace_exit(struct pt_regs *regs); 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) diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c index b9a7fdd..09a014c 100644 --- a/arch/s390/kernel/irq.c +++ b/arch/s390/kernel/irq.c @@ -219,8 +219,6 @@ void __irq_entry do_extint(struct pt_regs *regs, unsigned int ext_int_code, code = (unsigned short) ext_int_code; old_regs = set_irq_regs(regs); - s390_idle_check(regs, S390_lowcore.int_clock, - S390_lowcore.async_enter_timer); irq_enter(); if (S390_lowcore.int_clock >= S390_lowcore.clock_comparator) /* Serve timer interrupts first. */ diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c index 0fd2e86..8c372ca 100644 --- a/arch/s390/kernel/nmi.c +++ b/arch/s390/kernel/nmi.c @@ -254,8 +254,6 @@ void notrace s390_do_machine_check(struct pt_regs *regs) int umode; nmi_enter(); - s390_idle_check(regs, S390_lowcore.mcck_clock, - S390_lowcore.mcck_enter_timer); kstat_cpu(smp_processor_id()).irqs[NMI_NMI]++; mci = (struct mci *) &S390_lowcore.mcck_interruption_code; mcck = &__get_cpu_var(cpu_mcck); diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c index e795933..78b3c14 100644 --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -77,13 +77,8 @@ static void default_idle(void) local_irq_enable(); return; } - trace_hardirqs_on(); - /* Don't trace preempt off for idle. */ - stop_critical_timings(); - /* Stop virtual timer and halt the cpu. */ + /* Halt the cpu and keep track of cpu time accounting. */ vtime_stop_cpu(); - /* Reenable preemption tracer. */ - start_critical_timings(); } void cpu_idle(void) diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index 6db8526..afd6e51 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -972,22 +972,16 @@ static DEVICE_ATTR(capability, 0444, show_capability, NULL); static ssize_t show_idle_count(struct device *dev, struct device_attribute *attr, char *buf) { - struct s390_idle_data *idle; + struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id); unsigned long long idle_count; unsigned int sequence; - idle = &per_cpu(s390_idle, dev->id); -repeat: - sequence = idle->sequence; - smp_rmb(); - if (sequence & 1) - goto repeat; - idle_count = idle->idle_count; - if (idle->idle_enter) - idle_count++; - smp_rmb(); - if (idle->sequence != sequence) - goto repeat; + do { + sequence = ACCESS_ONCE(idle->sequence); + idle_count = ACCESS_ONCE(idle->idle_count); + if (ACCESS_ONCE(idle->idle_enter)) + idle_count++; + } while ((sequence & 1) || (idle->sequence != sequence)); return sprintf(buf, "%llu\n", idle_count); } static DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL); @@ -995,24 +989,18 @@ static DEVICE_ATTR(idle_count, 0444, show_idle_count, NULL); static ssize_t show_idle_time(struct device *dev, struct device_attribute *attr, char *buf) { - struct s390_idle_data *idle; - unsigned long long now, idle_time, idle_enter; + struct s390_idle_data *idle = &per_cpu(s390_idle, dev->id); + unsigned long long now, idle_time, idle_enter, idle_exit; unsigned int sequence; - idle = &per_cpu(s390_idle, dev->id); - now = get_clock(); -repeat: - sequence = idle->sequence; - smp_rmb(); - if (sequence & 1) - goto repeat; - idle_time = idle->idle_time; - idle_enter = idle->idle_enter; - if (idle_enter != 0ULL && idle_enter < now) - idle_time += now - idle_enter; - smp_rmb(); - if (idle->sequence != sequence) - goto repeat; + do { + now = get_clock(); + sequence = ACCESS_ONCE(idle->sequence); + idle_time = ACCESS_ONCE(idle->idle_time); + idle_enter = ACCESS_ONCE(idle->idle_enter); + idle_exit = ACCESS_ONCE(idle->idle_exit); + } while ((sequence & 1) || (idle->sequence != sequence)); + idle_time += idle_enter ? ((idle_exit ? : now) - idle_enter) : 0; return sprintf(buf, "%llu\n", idle_time >> 12); } static DEVICE_ATTR(idle_time_us, 0444, show_idle_time, NULL); diff --git a/arch/s390/kernel/vtime.c b/arch/s390/kernel/vtime.c index 7bacee9..277ea71 100644 --- a/arch/s390/kernel/vtime.c +++ b/arch/s390/kernel/vtime.c @@ -26,6 +26,7 @@ #include <asm/irq_regs.h> #include <asm/cputime.h> #include <asm/irq.h> +#include "entry.h" static DEFINE_PER_CPU(struct vtimer_queue, virt_cpu_timer); @@ -123,153 +124,53 @@ void account_system_vtime(struct task_struct *tsk) } EXPORT_SYMBOL_GPL(account_system_vtime); -void __kprobes vtime_start_cpu(__u64 int_clock, __u64 enter_timer) +void __kprobes vtime_stop_cpu(void) { struct s390_idle_data *idle = &__get_cpu_var(s390_idle); struct vtimer_queue *vq = &__get_cpu_var(virt_cpu_timer); - __u64 idle_time, expires; + unsigned long long idle_time; + unsigned long psw_mask; - if (idle->idle_enter == 0ULL) - return; + trace_hardirqs_on(); + /* Don't trace preempt off for idle. */ + stop_critical_timings(); - /* Account time spent with enabled wait psw loaded as idle time. */ - idle_time = int_clock - idle->idle_enter; - account_idle_time(idle_time); - S390_lowcore.steal_timer += - idle->idle_enter - S390_lowcore.last_update_clock; - S390_lowcore.last_update_clock = int_clock; - - /* Account system time spent going idle. */ - S390_lowcore.system_timer += S390_lowcore.last_update_timer - vq->idle; - S390_lowcore.last_update_timer = enter_timer; - - /* Restart vtime CPU timer */ - if (vq->do_spt) { - /* Program old expire value but first save progress. */ - expires = vq->idle - enter_timer; - expires += get_vtimer(); - set_vtimer(expires); - } else { - /* Don't account the CPU timer delta while the cpu was idle. */ - vq->elapsed -= vq->idle - enter_timer; - } + /* Wait for external, I/O or machine check interrupt. */ + psw_mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_DAT | + PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK; + idle->nohz_delay = 0; + /* Call the assembler magic in entry.S */ + psw_idle(idle, vq, psw_mask, !list_empty(&vq->list)); + + /* Reenable preemption tracer. */ + start_critical_timings(); + + /* Account time spent with enabled wait psw loaded as idle time. */ idle->sequence++; smp_wmb(); + idle_time = idle->idle_exit - idle->idle_enter; idle->idle_time += idle_time; - idle->idle_enter = 0ULL; + idle->idle_enter = idle->idle_exit = 0ULL; idle->idle_count++; + account_idle_time(idle_time); smp_wmb(); idle->sequence++; } -void __kprobes vtime_stop_cpu(void) -{ - struct s390_idle_data *idle = &__get_cpu_var(s390_idle); - struct vtimer_queue *vq = &__get_cpu_var(virt_cpu_timer); - psw_t psw; - - /* Wait for external, I/O or machine check interrupt. */ - psw.mask = psw_kernel_bits | PSW_MASK_WAIT | - PSW_MASK_DAT | PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK; - - idle->nohz_delay = 0; - - /* Check if the CPU timer needs to be reprogrammed. */ - if (vq->do_spt) { - __u64 vmax = VTIMER_MAX_SLICE; - /* - * The inline assembly is equivalent to - * vq->idle = get_cpu_timer(); - * set_cpu_timer(VTIMER_MAX_SLICE); - * idle->idle_enter = get_clock(); - * __load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT | - * PSW_MASK_DAT | PSW_MASK_IO | - * PSW_MASK_EXT | PSW_MASK_MCHECK); - * The difference is that the inline assembly makes sure that - * the last three instruction are stpt, stck and lpsw in that - * order. This is done to increase the precision. - */ - asm volatile( -#ifndef CONFIG_64BIT - " basr 1,0\n" - "0: ahi 1,1f-0b\n" - " st 1,4(%2)\n" -#else /* CONFIG_64BIT */ - " larl 1,1f\n" - " stg 1,8(%2)\n" -#endif /* CONFIG_64BIT */ - " stpt 0(%4)\n" - " spt 0(%5)\n" - " stck 0(%3)\n" -#ifndef CONFIG_64BIT - " lpsw 0(%2)\n" -#else /* CONFIG_64BIT */ - " lpswe 0(%2)\n" -#endif /* CONFIG_64BIT */ - "1:" - : "=m" (idle->idle_enter), "=m" (vq->idle) - : "a" (&psw), "a" (&idle->idle_enter), - "a" (&vq->idle), "a" (&vmax), "m" (vmax), "m" (psw) - : "memory", "cc", "1"); - } else { - /* - * The inline assembly is equivalent to - * vq->idle = get_cpu_timer(); - * idle->idle_enter = get_clock(); - * __load_psw_mask(psw_kernel_bits | PSW_MASK_WAIT | - * PSW_MASK_DAT | PSW_MASK_IO | - * PSW_MASK_EXT | PSW_MASK_MCHECK); - * The difference is that the inline assembly makes sure that - * the last three instruction are stpt, stck and lpsw in that - * order. This is done to increase the precision. - */ - asm volatile( -#ifndef CONFIG_64BIT - " basr 1,0\n" - "0: ahi 1,1f-0b\n" - " st 1,4(%2)\n" -#else /* CONFIG_64BIT */ - " larl 1,1f\n" - " stg 1,8(%2)\n" -#endif /* CONFIG_64BIT */ - " stpt 0(%4)\n" - " stck 0(%3)\n" -#ifndef CONFIG_64BIT - " lpsw 0(%2)\n" -#else /* CONFIG_64BIT */ - " lpswe 0(%2)\n" -#endif /* CONFIG_64BIT */ - "1:" - : "=m" (idle->idle_enter), "=m" (vq->idle) - : "a" (&psw), "a" (&idle->idle_enter), - "a" (&vq->idle), "m" (psw) - : "memory", "cc", "1"); - } -} - cputime64_t s390_get_idle_time(int cpu) { - struct s390_idle_data *idle; - unsigned long long now, idle_time, idle_enter; + struct s390_idle_data *idle = &per_cpu(s390_idle, cpu); + unsigned long long now, idle_enter, idle_exit; unsigned int sequence; - idle = &per_cpu(s390_idle, cpu); - - now = get_clock(); -repeat: - sequence = idle->sequence; - smp_rmb(); - if (sequence & 1) - goto repeat; - idle_time = 0; - idle_enter = idle->idle_enter; - if (idle_enter != 0ULL && idle_enter < now) - idle_time = now - idle_enter; - smp_rmb(); - if (idle->sequence != sequence) - goto repeat; - return idle_time; + do { + now = get_clock(); + sequence = ACCESS_ONCE(idle->sequence); + idle_enter = ACCESS_ONCE(idle->idle_enter); + idle_exit = ACCESS_ONCE(idle->idle_exit); + } while ((sequence & 1) || (idle->sequence != sequence)); + return idle_enter ? ((idle_exit ? : now) - idle_enter) : 0; } /* @@ -346,7 +247,6 @@ static void do_cpu_timer_interrupt(unsigned int ext_int_code, } spin_unlock(&vq->lock); - vq->do_spt = list_empty(&cb_list); do_callbacks(&cb_list); /* next event is first in list */ @@ -355,8 +255,7 @@ static void do_cpu_timer_interrupt(unsigned int ext_int_code, if (!list_empty(&vq->list)) { event = list_first_entry(&vq->list, struct vtimer_list, entry); next = event->expires; - } else - vq->do_spt = 0; + } spin_unlock(&vq->lock); /* * To improve precision add the time spent by the |