Commit 6377981f authored by Martin Schwidefsky's avatar Martin Schwidefsky Committed by Martin Schwidefsky
Browse files

[S390] idle time accounting vs. machine checks 



A machine check can interrupt the i/o and external interrupt handler
anytime. If the machine check occurs while the interrupt handler is
waking up from idle vtime_start_cpu can get executed a second time
and the int_clock / async_enter_timer values in the lowcore get
clobbered. This can confuse the cpu time accounting.
To fix this problem two changes are needed. First the machine check
handler has to use its own copies of int_clock and async_enter_timer,
named mcck_clock and mcck_enter_timer. Second the nested execution
of vtime_start_cpu has to be prevented. This is done in s390_idle_check
by checking the wait bit in the program status word.

Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 6a2df3a8

arch/s390/include/asm/cputime.h

+5 −4
Original line number Diff line number Diff line
@@ -188,15 +188,16 @@ struct s390_idle_data { 


DECLARE_PER_CPU(struct s390_idle_data, s390_idle);



void vtime_start_cpu(void);

void vtime_start_cpu(__u64 int_clock, __u64 enter_timer);

cputime64_t s390_get_idle_time(int cpu);



#define arch_idle_time(cpu) s390_get_idle_time(cpu)



static inline void s390_idle_check(void)

static inline void s390_idle_check(struct pt_regs *regs, __u64 int_clock,

				   __u64 enter_timer)

{

	if ((&__get_cpu_var(s390_idle))->idle_enter != 0ULL)

		vtime_start_cpu();

	if (regs->psw.mask & PSW_MASK_WAIT)

		vtime_start_cpu(int_clock, enter_timer);

}



static inline int s390_nohz_delay(int cpu)

arch/s390/include/asm/lowcore.h

+51 −47
Original line number Diff line number Diff line
@@ -104,37 +104,39 @@ struct _lowcore { 
	/* CPU time accounting values */

	__u64	sync_enter_timer;		/* 0x0250 */

	__u64	async_enter_timer;		/* 0x0258 */

	__u64	exit_timer;			/* 0x0260 */

	__u64	user_timer;			/* 0x0268 */

	__u64	system_timer;			/* 0x0270 */

	__u64	steal_timer;			/* 0x0278 */

	__u64	last_update_timer;		/* 0x0280 */

	__u64	last_update_clock;		/* 0x0288 */

	__u64	mcck_enter_timer;		/* 0x0260 */

	__u64	exit_timer;			/* 0x0268 */

	__u64	user_timer;			/* 0x0270 */

	__u64	system_timer;			/* 0x0278 */

	__u64	steal_timer;			/* 0x0280 */

	__u64	last_update_timer;		/* 0x0288 */

	__u64	last_update_clock;		/* 0x0290 */



	/* Current process. */

	__u32	current_task;			/* 0x0290 */

	__u32	thread_info;			/* 0x0294 */

	__u32	kernel_stack;			/* 0x0298 */

	__u32	current_task;			/* 0x0298 */

	__u32	thread_info;			/* 0x029c */

	__u32	kernel_stack;			/* 0x02a0 */



	/* Interrupt and panic stack. */

	__u32	async_stack;			/* 0x029c */

	__u32	panic_stack;			/* 0x02a0 */

	__u32	async_stack;			/* 0x02a4 */

	__u32	panic_stack;			/* 0x02a8 */



	/* Address space pointer. */

	__u32	kernel_asce;			/* 0x02a4 */

	__u32	user_asce;			/* 0x02a8 */

	__u32	user_exec_asce;			/* 0x02ac */

	__u32	kernel_asce;			/* 0x02ac */

	__u32	user_asce;			/* 0x02b0 */

	__u32	user_exec_asce;			/* 0x02b4 */



	/* SMP info area */

	__u32	cpu_nr;				/* 0x02b0 */

	__u32	softirq_pending;		/* 0x02b4 */

	__u32	percpu_offset;			/* 0x02b8 */

	__u32	ext_call_fast;			/* 0x02bc */

	__u64	int_clock;			/* 0x02c0 */

	__u64	clock_comparator;		/* 0x02c8 */

	__u32	machine_flags;			/* 0x02d0 */

	__u32	ftrace_func;			/* 0x02d4 */

	__u8	pad_0x02d8[0x0300-0x02d8];	/* 0x02d8 */

	__u32	cpu_nr;				/* 0x02b8 */

	__u32	softirq_pending;		/* 0x02bc */

	__u32	percpu_offset;			/* 0x02c0 */

	__u32	ext_call_fast;			/* 0x02c4 */

	__u64	int_clock;			/* 0x02c8 */

	__u64	mcck_clock;			/* 0x02d0 */

	__u64	clock_comparator;		/* 0x02d8 */

	__u32	machine_flags;			/* 0x02e0 */

	__u32	ftrace_func;			/* 0x02e4 */

	__u8	pad_0x02e8[0x0300-0x02e8];	/* 0x02e8 */



	/* Interrupt response block */

	__u8	irb[64];			/* 0x0300 */
@@ -232,38 +234,40 @@ struct _lowcore { 
	/* CPU accounting and timing values. */

	__u64	sync_enter_timer;		/* 0x02a0 */

	__u64	async_enter_timer;		/* 0x02a8 */

	__u64	exit_timer;			/* 0x02b0 */

	__u64	user_timer;			/* 0x02b8 */

	__u64	system_timer;			/* 0x02c0 */

	__u64	steal_timer;			/* 0x02c8 */

	__u64	last_update_timer;		/* 0x02d0 */

	__u64	last_update_clock;		/* 0x02d8 */

	__u64	mcck_enter_timer;		/* 0x02b0 */

	__u64	exit_timer;			/* 0x02b8 */

	__u64	user_timer;			/* 0x02c0 */

	__u64	system_timer;			/* 0x02c8 */

	__u64	steal_timer;			/* 0x02d0 */

	__u64	last_update_timer;		/* 0x02d8 */

	__u64	last_update_clock;		/* 0x02e0 */



	/* Current process. */

	__u64	current_task;			/* 0x02e0 */

	__u64	thread_info;			/* 0x02e8 */

	__u64	kernel_stack;			/* 0x02f0 */

	__u64	current_task;			/* 0x02e8 */

	__u64	thread_info;			/* 0x02f0 */

	__u64	kernel_stack;			/* 0x02f8 */



	/* Interrupt and panic stack. */

	__u64	async_stack;			/* 0x02f8 */

	__u64	panic_stack;			/* 0x0300 */

	__u64	async_stack;			/* 0x0300 */

	__u64	panic_stack;			/* 0x0308 */



	/* Address space pointer. */

	__u64	kernel_asce;			/* 0x0308 */

	__u64	user_asce;			/* 0x0310 */

	__u64	user_exec_asce;			/* 0x0318 */

	__u64	kernel_asce;			/* 0x0310 */

	__u64	user_asce;			/* 0x0318 */

	__u64	user_exec_asce;			/* 0x0320 */



	/* SMP info area */

	__u32	cpu_nr;				/* 0x0320 */

	__u32	softirq_pending;		/* 0x0324 */

	__u64	percpu_offset;			/* 0x0328 */

	__u64	ext_call_fast;			/* 0x0330 */

	__u64	int_clock;			/* 0x0338 */

	__u64	clock_comparator;		/* 0x0340 */

	__u64	vdso_per_cpu_data;		/* 0x0348 */

	__u64	machine_flags;			/* 0x0350 */

	__u64	ftrace_func;			/* 0x0358 */

	__u8	pad_0x0368[0x0380-0x0360];	/* 0x0360 */

	__u32	cpu_nr;				/* 0x0328 */

	__u32	softirq_pending;		/* 0x032c */

	__u64	percpu_offset;			/* 0x0330 */

	__u64	ext_call_fast;			/* 0x0338 */

	__u64	int_clock;			/* 0x0340 */

	__u64	mcck_clock;			/* 0x0348 */

	__u64	clock_comparator;		/* 0x0350 */

	__u64	vdso_per_cpu_data;		/* 0x0358 */

	__u64	machine_flags;			/* 0x0360 */

	__u64	ftrace_func;			/* 0x0368 */

	__u8	pad_0x0370[0x0380-0x0370];	/* 0x0370 */



	/* Interrupt response block. */

	__u8	irb[64];			/* 0x0380 */

arch/s390/kernel/asm-offsets.c

+2 −0
Original line number Diff line number Diff line
@@ -112,6 +112,7 @@ int main(void) 
	DEFINE(__LC_RETURN_MCCK_PSW, offsetof(struct _lowcore, return_mcck_psw));

	DEFINE(__LC_SYNC_ENTER_TIMER, offsetof(struct _lowcore, sync_enter_timer));

	DEFINE(__LC_ASYNC_ENTER_TIMER, offsetof(struct _lowcore, async_enter_timer));

	DEFINE(__LC_MCCK_ENTER_TIMER, offsetof(struct _lowcore, mcck_enter_timer));

	DEFINE(__LC_EXIT_TIMER, offsetof(struct _lowcore, exit_timer));

	DEFINE(__LC_USER_TIMER, offsetof(struct _lowcore, user_timer));

	DEFINE(__LC_SYSTEM_TIMER, offsetof(struct _lowcore, system_timer));
@@ -127,6 +128,7 @@ int main(void) 
	DEFINE(__LC_USER_ASCE, offsetof(struct _lowcore, user_asce));

	DEFINE(__LC_USER_EXEC_ASCE, offsetof(struct _lowcore, user_exec_asce));

	DEFINE(__LC_INT_CLOCK, offsetof(struct _lowcore, int_clock));

	DEFINE(__LC_MCCK_CLOCK, offsetof(struct _lowcore, mcck_clock));

	DEFINE(__LC_MACHINE_FLAGS, offsetof(struct _lowcore, machine_flags));

	DEFINE(__LC_FTRACE_FUNC, offsetof(struct _lowcore, ftrace_func));

	DEFINE(__LC_IRB, offsetof(struct _lowcore, irb));

arch/s390/kernel/entry.S

+26 −28
Original line number Diff line number Diff line
@@ -742,15 +742,14 @@ __critical_end: 


	.globl mcck_int_handler

mcck_int_handler:

	stck	__LC_INT_CLOCK

	stck	__LC_MCCK_CLOCK

	spt	__LC_CPU_TIMER_SAVE_AREA	# revalidate cpu timer

	lm	%r0,%r15,__LC_GPREGS_SAVE_AREA	# revalidate gprs

	SAVE_ALL_BASE __LC_SAVE_AREA+32

	la	%r12,__LC_MCK_OLD_PSW

	tm	__LC_MCCK_CODE,0x80	# system damage?

	bo	BASED(mcck_int_main)	# yes -> rest of mcck code invalid

	mvc	__LC_SAVE_AREA+52(8),__LC_ASYNC_ENTER_TIMER

	mvc	__LC_ASYNC_ENTER_TIMER(8),__LC_CPU_TIMER_SAVE_AREA

	mvc	__LC_MCCK_ENTER_TIMER(8),__LC_CPU_TIMER_SAVE_AREA

	tm	__LC_MCCK_CODE+5,0x02	# stored cpu timer value valid?

	bo	BASED(1f)

	la	%r14,__LC_SYNC_ENTER_TIMER
@@ -764,7 +763,7 @@ mcck_int_handler: 
	bl	BASED(0f)

	la	%r14,__LC_LAST_UPDATE_TIMER

0:	spt	0(%r14)

	mvc	__LC_ASYNC_ENTER_TIMER(8),0(%r14)

	mvc	__LC_MCCK_ENTER_TIMER(8),0(%r14)

1:	tm	__LC_MCCK_CODE+2,0x09	# mwp + ia of old psw valid?

	bno	BASED(mcck_int_main)	# no -> skip cleanup critical

	tm	__LC_MCK_OLD_PSW+1,0x01	# test problem state bit
@@ -786,9 +785,9 @@ mcck_int_main: 
	bno	BASED(mcck_no_vtime)	# no -> skip cleanup critical

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?

	bz	BASED(mcck_no_vtime)

	UPDATE_VTIME __LC_EXIT_TIMER,__LC_ASYNC_ENTER_TIMER,__LC_USER_TIMER

	UPDATE_VTIME __LC_EXIT_TIMER,__LC_MCCK_ENTER_TIMER,__LC_USER_TIMER

	UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER

	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_ASYNC_ENTER_TIMER

	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_MCCK_ENTER_TIMER

mcck_no_vtime:

	l	%r9,__LC_THREAD_INFO	# load pointer to thread_info struct

	la	%r2,SP_PTREGS(%r15)	# load pt_regs
@@ -811,7 +810,6 @@ mcck_no_vtime: 
mcck_return:

	mvc	__LC_RETURN_MCCK_PSW(8),SP_PSW(%r15) # move return PSW

	ni	__LC_RETURN_MCCK_PSW+1,0xfd # clear wait state bit

	mvc	__LC_ASYNC_ENTER_TIMER(8),__LC_SAVE_AREA+52

	tm	__LC_RETURN_MCCK_PSW+1,0x01 # returning to user ?

	bno	BASED(0f)

	lm	%r0,%r15,SP_R0(%r15)	# load gprs 0-15
@@ -934,15 +932,16 @@ cleanup_critical: 


cleanup_system_call:

	mvc	__LC_RETURN_PSW(8),0(%r12)

	c	%r12,BASED(.Lmck_old_psw)

	be	BASED(0f)

	la	%r12,__LC_SAVE_AREA+16

	b	BASED(1f)

0:	la	%r12,__LC_SAVE_AREA+32

1:

	clc	__LC_RETURN_PSW+4(4),BASED(cleanup_system_call_insn+4)

	bh	BASED(0f)

	mvc	__LC_SYNC_ENTER_TIMER(8),__LC_MCCK_ENTER_TIMER

	c	%r12,BASED(.Lmck_old_psw)

	be	BASED(0f)

	mvc	__LC_SYNC_ENTER_TIMER(8),__LC_ASYNC_ENTER_TIMER

0:	c	%r12,BASED(.Lmck_old_psw)

	la	%r12,__LC_SAVE_AREA+32

	be	BASED(0f)

	la	%r12,__LC_SAVE_AREA+16

0:	clc	__LC_RETURN_PSW+4(4),BASED(cleanup_system_call_insn+8)

	bhe	BASED(cleanup_vtime)

	clc	__LC_RETURN_PSW+4(4),BASED(cleanup_system_call_insn)
@@ -984,16 +983,19 @@ cleanup_sysc_tif: 
cleanup_sysc_restore:

	clc	4(4,%r12),BASED(cleanup_sysc_restore_insn)

	be	BASED(2f)

	mvc	__LC_EXIT_TIMER(8),__LC_MCCK_ENTER_TIMER

	c	%r12,BASED(.Lmck_old_psw)

	be	BASED(0f)

	mvc	__LC_EXIT_TIMER(8),__LC_ASYNC_ENTER_TIMER

	clc	4(4,%r12),BASED(cleanup_sysc_restore_insn+4)

0:	clc	4(4,%r12),BASED(cleanup_sysc_restore_insn+4)

	be	BASED(2f)

	mvc	__LC_RETURN_PSW(8),SP_PSW(%r15)

	c	%r12,BASED(.Lmck_old_psw)

	bne	BASED(0f)

	mvc	__LC_SAVE_AREA+32(16),SP_R12(%r15)

	b	BASED(1f)

0:	mvc	__LC_SAVE_AREA+16(16),SP_R12(%r15)

1:	lm	%r0,%r11,SP_R0(%r15)

	la	%r12,__LC_SAVE_AREA+32

	be	BASED(1f)

	la	%r12,__LC_SAVE_AREA+16

1:	mvc	0(16,%r12),SP_R12(%r15)

	lm	%r0,%r11,SP_R0(%r15)

	l	%r15,SP_R15(%r15)

2:	la	%r12,__LC_RETURN_PSW

	br	%r14
@@ -1009,19 +1011,15 @@ cleanup_io_tif: 


cleanup_io_restore:

	clc	4(4,%r12),BASED(cleanup_io_restore_insn)

	be	BASED(2f)

	mvc	__LC_EXIT_TIMER(8),__LC_ASYNC_ENTER_TIMER

	be	BASED(1f)

	mvc	__LC_EXIT_TIMER(8),__LC_MCCK_ENTER_TIMER

	clc	4(4,%r12),BASED(cleanup_io_restore_insn+4)

	be	BASED(2f)

	be	BASED(1f)

	mvc	__LC_RETURN_PSW(8),SP_PSW(%r15)

	c	%r12,BASED(.Lmck_old_psw)

	bne	BASED(0f)

	mvc	__LC_SAVE_AREA+32(16),SP_R12(%r15)

	b	BASED(1f)

0:	mvc	__LC_SAVE_AREA+16(16),SP_R12(%r15)

1:	lm	%r0,%r11,SP_R0(%r15)

	lm	%r0,%r11,SP_R0(%r15)

	l	%r15,SP_R15(%r15)

2:	la	%r12,__LC_RETURN_PSW

1:	la	%r12,__LC_RETURN_PSW

	br	%r14

cleanup_io_restore_insn:

	.long	io_done - 4 + 0x80000000

arch/s390/kernel/entry64.S

+26 −28
Original line number Diff line number Diff line
@@ -725,7 +725,7 @@ __critical_end: 
 */

	.globl mcck_int_handler

mcck_int_handler:

	stck	__LC_INT_CLOCK

	stck	__LC_MCCK_CLOCK

	la	%r1,4095		# revalidate r1

	spt	__LC_CPU_TIMER_SAVE_AREA-4095(%r1)	# revalidate cpu timer

	lmg	%r0,%r15,__LC_GPREGS_SAVE_AREA-4095(%r1)# revalidate gprs
@@ -734,8 +734,7 @@ mcck_int_handler: 
	tm	__LC_MCCK_CODE,0x80	# system damage?

	jo	mcck_int_main		# yes -> rest of mcck code invalid

	la	%r14,4095

	mvc	__LC_SAVE_AREA+104(8),__LC_ASYNC_ENTER_TIMER

	mvc	__LC_ASYNC_ENTER_TIMER(8),__LC_CPU_TIMER_SAVE_AREA-4095(%r14)

	mvc	__LC_MCCK_ENTER_TIMER(8),__LC_CPU_TIMER_SAVE_AREA-4095(%r14)

	tm	__LC_MCCK_CODE+5,0x02	# stored cpu timer value valid?

	jo	1f

	la	%r14,__LC_SYNC_ENTER_TIMER
@@ -749,7 +748,7 @@ mcck_int_handler: 
	jl	0f

	la	%r14,__LC_LAST_UPDATE_TIMER

0:	spt	0(%r14)

	mvc	__LC_ASYNC_ENTER_TIMER(8),0(%r14)

	mvc	__LC_MCCK_ENTER_TIMER(8),0(%r14)

1:	tm	__LC_MCCK_CODE+2,0x09	# mwp + ia of old psw valid?

	jno	mcck_int_main		# no -> skip cleanup critical

	tm	__LC_MCK_OLD_PSW+1,0x01 # test problem state bit
@@ -770,9 +769,9 @@ mcck_int_main: 
	jno	mcck_no_vtime		# no -> no timer update

	tm	SP_PSW+1(%r15),0x01	# interrupting from user ?

	jz	mcck_no_vtime

	UPDATE_VTIME __LC_EXIT_TIMER,__LC_ASYNC_ENTER_TIMER,__LC_USER_TIMER

	UPDATE_VTIME __LC_EXIT_TIMER,__LC_MCCK_ENTER_TIMER,__LC_USER_TIMER

	UPDATE_VTIME __LC_LAST_UPDATE_TIMER,__LC_EXIT_TIMER,__LC_SYSTEM_TIMER

	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_ASYNC_ENTER_TIMER

	mvc	__LC_LAST_UPDATE_TIMER(8),__LC_MCCK_ENTER_TIMER

mcck_no_vtime:

	lg	%r9,__LC_THREAD_INFO	# load pointer to thread_info struct

	la	%r2,SP_PTREGS(%r15)	# load pt_regs
@@ -794,7 +793,6 @@ mcck_return: 
	mvc	__LC_RETURN_MCCK_PSW(16),SP_PSW(%r15) # move return PSW

	ni	__LC_RETURN_MCCK_PSW+1,0xfd # clear wait state bit

	lmg	%r0,%r15,SP_R0(%r15)	# load gprs 0-15

	mvc	__LC_ASYNC_ENTER_TIMER(8),__LC_SAVE_AREA+104

	tm	__LC_RETURN_MCCK_PSW+1,0x01 # returning to user ?

	jno	0f

	stpt	__LC_EXIT_TIMER
@@ -909,15 +907,16 @@ cleanup_critical: 


cleanup_system_call:

	mvc	__LC_RETURN_PSW(16),0(%r12)

	cghi	%r12,__LC_MCK_OLD_PSW

	je	0f

	la	%r12,__LC_SAVE_AREA+32

	j	1f

0:	la	%r12,__LC_SAVE_AREA+64

1:

	clc	__LC_RETURN_PSW+8(8),BASED(cleanup_system_call_insn+8)

	jh	0f

	mvc	__LC_SYNC_ENTER_TIMER(8),__LC_MCCK_ENTER_TIMER

	cghi	%r12,__LC_MCK_OLD_PSW

	je	0f

	mvc	__LC_SYNC_ENTER_TIMER(8),__LC_ASYNC_ENTER_TIMER

0:	cghi	%r12,__LC_MCK_OLD_PSW

	la	%r12,__LC_SAVE_AREA+64

	je	0f

	la	%r12,__LC_SAVE_AREA+32

0:	clc	__LC_RETURN_PSW+8(8),BASED(cleanup_system_call_insn+16)

	jhe	cleanup_vtime

	clc	__LC_RETURN_PSW+8(8),BASED(cleanup_system_call_insn)
@@ -958,19 +957,22 @@ cleanup_sysc_tif: 


cleanup_sysc_restore:

	clc	8(8,%r12),BASED(cleanup_sysc_restore_insn)

	je	3f

	je	2f

	clc	8(8,%r12),BASED(cleanup_sysc_restore_insn+8)

	jhe	0f

	mvc	__LC_EXIT_TIMER(8),__LC_MCCK_ENTER_TIMER

	cghi	%r12,__LC_MCK_OLD_PSW

	je	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	1f

	mvc	__LC_SAVE_AREA+64(32),SP_R12(%r15)

	j	2f

1:	mvc	__LC_SAVE_AREA+32(32),SP_R12(%r15)

2:	lmg	%r0,%r11,SP_R0(%r15)

	la	%r12,__LC_SAVE_AREA+64

	je	1f

	la	%r12,__LC_SAVE_AREA+32

1:	mvc	0(32,%r12),SP_R12(%r15)

	lmg	%r0,%r11,SP_R0(%r15)

	lg	%r15,SP_R15(%r15)

3:	la	%r12,__LC_RETURN_PSW

2:	la	%r12,__LC_RETURN_PSW

	br	%r14

cleanup_sysc_restore_insn:

	.quad	sysc_done - 4
@@ -984,19 +986,15 @@ cleanup_io_tif: 


cleanup_io_restore:

	clc	8(8,%r12),BASED(cleanup_io_restore_insn)

	je	3f

	je	1f

	clc	8(8,%r12),BASED(cleanup_io_restore_insn+8)

	jhe	0f

	mvc	__LC_EXIT_TIMER(8),__LC_ASYNC_ENTER_TIMER

	mvc	__LC_EXIT_TIMER(8),__LC_MCCK_ENTER_TIMER

0:	mvc	__LC_RETURN_PSW(16),SP_PSW(%r15)

	cghi	%r12,__LC_MCK_OLD_PSW

	jne	1f

	mvc	__LC_SAVE_AREA+64(32),SP_R12(%r15)

	j	2f

1:	mvc	__LC_SAVE_AREA+32(32),SP_R12(%r15)

2:	lmg	%r0,%r11,SP_R0(%r15)

	lmg	%r0,%r11,SP_R0(%r15)

	lg	%r15,SP_R15(%r15)

3:	la	%r12,__LC_RETURN_PSW

1:	la	%r12,__LC_RETURN_PSW

	br	%r14

cleanup_io_restore_insn:

	.quad	io_done - 4

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