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s390: fix irq state tracing
With commit58c644ba51
("sched/idle: Fix arch_cpu_idle() vs tracing") common code calls arch_cpu_idle() with a lockdep state that tells irqs are on. This doesn't work very well for s390: psw_idle() will enable interrupts to wait for an interrupt. As soon as an interrupt occurs the interrupt handler will verify if the old context was psw_idle(). If that is the case the interrupt enablement bits in the old program status word will be cleared. A subsequent test in both the external as well as the io interrupt handler checks if in the old context interrupts were enabled. Due to the above patching of the old program status word it is assumed the old context had interrupts disabled, and therefore a call to TRACE_IRQS_OFF (aka trace_hardirqs_off_caller) is skipped. Which in turn makes lockdep incorrectly "think" that interrupts are enabled within the interrupt handler. Fix this by unconditionally calling TRACE_IRQS_OFF when entering interrupt handlers. Also call unconditionally TRACE_IRQS_ON when leaving interrupts handlers. This leaves the special psw_idle() case, which now returns with interrupts disabled, but has an "irqs on" lockdep state. So callers of psw_idle() must adjust the state on their own, if required. This is currently only __udelay_disabled(). Fixes:58c644ba51
("sched/idle: Fix arch_cpu_idle() vs tracing") Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
parent
a2bd4097b3
commit
b1cae1f84a
2 changed files with 2 additions and 18 deletions
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@ -763,12 +763,7 @@ ENTRY(io_int_handler)
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xc __PT_FLAGS(8,%r11),__PT_FLAGS(%r11)
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TSTMSK __LC_CPU_FLAGS,_CIF_IGNORE_IRQ
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jo .Lio_restore
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#if IS_ENABLED(CONFIG_TRACE_IRQFLAGS)
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tmhh %r8,0x300
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jz 1f
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TRACE_IRQS_OFF
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1:
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#endif
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xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
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.Lio_loop:
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lgr %r2,%r11 # pass pointer to pt_regs
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@ -791,12 +786,7 @@ ENTRY(io_int_handler)
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TSTMSK __LC_CPU_FLAGS,_CIF_WORK
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jnz .Lio_work
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.Lio_restore:
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#if IS_ENABLED(CONFIG_TRACE_IRQFLAGS)
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tm __PT_PSW(%r11),3
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jno 0f
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TRACE_IRQS_ON
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0:
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#endif
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mvc __LC_RETURN_PSW(16),__PT_PSW(%r11)
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tm __PT_PSW+1(%r11),0x01 # returning to user ?
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jno .Lio_exit_kernel
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@ -976,12 +966,7 @@ ENTRY(ext_int_handler)
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xc __PT_FLAGS(8,%r11),__PT_FLAGS(%r11)
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TSTMSK __LC_CPU_FLAGS,_CIF_IGNORE_IRQ
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jo .Lio_restore
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#if IS_ENABLED(CONFIG_TRACE_IRQFLAGS)
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tmhh %r8,0x300
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jz 1f
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TRACE_IRQS_OFF
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1:
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#endif
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xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
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lgr %r2,%r11 # pass pointer to pt_regs
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lghi %r3,EXT_INTERRUPT
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@ -33,7 +33,7 @@ EXPORT_SYMBOL(__delay);
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static void __udelay_disabled(unsigned long long usecs)
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{
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unsigned long cr0, cr0_new, psw_mask, flags;
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unsigned long cr0, cr0_new, psw_mask;
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struct s390_idle_data idle;
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u64 end;
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@ -45,9 +45,8 @@ static void __udelay_disabled(unsigned long long usecs)
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psw_mask = __extract_psw() | PSW_MASK_EXT | PSW_MASK_WAIT;
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set_clock_comparator(end);
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set_cpu_flag(CIF_IGNORE_IRQ);
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local_irq_save(flags);
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psw_idle(&idle, psw_mask);
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local_irq_restore(flags);
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trace_hardirqs_off();
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clear_cpu_flag(CIF_IGNORE_IRQ);
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set_clock_comparator(S390_lowcore.clock_comparator);
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__ctl_load(cr0, 0, 0);
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