mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-28 11:18:45 +07:00
db7e007fd6
When using systemtap it was observed that our udelay implementation is rather suboptimal if being called from a kprobe handler installed by systemtap. The problem observed when a kprobe was installed on lock_acquired(). When the probe was hit the kprobe handler did call udelay, which set up an (internal) timer and reenabled interrupts (only the clock comparator interrupt) and waited for the interrupt. This is an optimization to avoid that the cpu is busy looping while waiting that enough time passes. The problem is that the interrupt handler still does call irq_enter()/irq_exit() which then again can lead to a deadlock, since some accounting functions may take locks as well. If one of these locks is the same, which caused lock_acquired() to be called, we have a nice deadlock. This patch reworks the udelay code for the interrupts disabled case to immediately leave the low level interrupt handler when the clock comparator interrupt happens. That way no C code is being called and the deadlock cannot happen anymore. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
120 lines
2.6 KiB
C
120 lines
2.6 KiB
C
#ifndef _ASM_IRQ_H
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#define _ASM_IRQ_H
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#define EXT_INTERRUPT 0
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#define IO_INTERRUPT 1
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#define THIN_INTERRUPT 2
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#define NR_IRQS_BASE 3
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#ifdef CONFIG_PCI_NR_MSI
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# define NR_IRQS (NR_IRQS_BASE + CONFIG_PCI_NR_MSI)
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#else
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# define NR_IRQS NR_IRQS_BASE
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#endif
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/* External interruption codes */
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#define EXT_IRQ_INTERRUPT_KEY 0x0040
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#define EXT_IRQ_CLK_COMP 0x1004
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#define EXT_IRQ_CPU_TIMER 0x1005
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#define EXT_IRQ_WARNING_TRACK 0x1007
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#define EXT_IRQ_MALFUNC_ALERT 0x1200
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#define EXT_IRQ_EMERGENCY_SIG 0x1201
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#define EXT_IRQ_EXTERNAL_CALL 0x1202
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#define EXT_IRQ_TIMING_ALERT 0x1406
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#define EXT_IRQ_MEASURE_ALERT 0x1407
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#define EXT_IRQ_SERVICE_SIG 0x2401
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#define EXT_IRQ_CP_SERVICE 0x2603
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#define EXT_IRQ_IUCV 0x4000
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#ifndef __ASSEMBLY__
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#include <linux/hardirq.h>
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#include <linux/percpu.h>
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#include <linux/cache.h>
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#include <linux/types.h>
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enum interruption_class {
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IRQEXT_CLK,
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IRQEXT_EXC,
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IRQEXT_EMS,
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IRQEXT_TMR,
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IRQEXT_TLA,
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IRQEXT_PFL,
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IRQEXT_DSD,
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IRQEXT_VRT,
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IRQEXT_SCP,
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IRQEXT_IUC,
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IRQEXT_CMS,
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IRQEXT_CMC,
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IRQEXT_CMR,
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IRQEXT_FTP,
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IRQIO_CIO,
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IRQIO_QAI,
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IRQIO_DAS,
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IRQIO_C15,
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IRQIO_C70,
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IRQIO_TAP,
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IRQIO_VMR,
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IRQIO_LCS,
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IRQIO_CTC,
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IRQIO_APB,
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IRQIO_ADM,
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IRQIO_CSC,
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IRQIO_PCI,
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IRQIO_MSI,
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IRQIO_VIR,
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IRQIO_VAI,
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NMI_NMI,
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CPU_RST,
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NR_ARCH_IRQS
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};
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struct irq_stat {
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unsigned int irqs[NR_ARCH_IRQS];
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};
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DECLARE_PER_CPU_SHARED_ALIGNED(struct irq_stat, irq_stat);
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static __always_inline void inc_irq_stat(enum interruption_class irq)
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{
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__this_cpu_inc(irq_stat.irqs[irq]);
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}
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struct ext_code {
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unsigned short subcode;
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unsigned short code;
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};
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typedef void (*ext_int_handler_t)(struct ext_code, unsigned int, unsigned long);
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int register_external_irq(u16 code, ext_int_handler_t handler);
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int unregister_external_irq(u16 code, ext_int_handler_t handler);
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enum irq_subclass {
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IRQ_SUBCLASS_MEASUREMENT_ALERT = 5,
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IRQ_SUBCLASS_SERVICE_SIGNAL = 9,
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};
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#define CR0_IRQ_SUBCLASS_MASK \
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((1UL << (63 - 30)) /* Warning Track */ | \
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(1UL << (63 - 48)) /* Malfunction Alert */ | \
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(1UL << (63 - 49)) /* Emergency Signal */ | \
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(1UL << (63 - 50)) /* External Call */ | \
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(1UL << (63 - 52)) /* Clock Comparator */ | \
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(1UL << (63 - 53)) /* CPU Timer */ | \
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(1UL << (63 - 54)) /* Service Signal */ | \
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(1UL << (63 - 57)) /* Interrupt Key */ | \
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(1UL << (63 - 58)) /* Measurement Alert */ | \
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(1UL << (63 - 59)) /* Timing Alert */ | \
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(1UL << (63 - 62))) /* IUCV */
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void irq_subclass_register(enum irq_subclass subclass);
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void irq_subclass_unregister(enum irq_subclass subclass);
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#define irq_canonicalize(irq) (irq)
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#endif /* __ASSEMBLY__ */
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#endif /* _ASM_IRQ_H */
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