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1fee9db9b4
Since d4a45c68dc ("irqdomain: Protect the linear revmap with RCU"),
any irqdomain lookup requires the RCU read lock to be held.
This assumes that the architecture code will be structured such as
irq_enter() will be called *before* the interrupt is looked up
in the irq domain. However, this isn't the case for MIPS, and a number
of drivers are structured to do it the other way around when handling
an interrupt in their root irqchip (secondary irqchips are OK by
construction).
This results in a RCU splat on a lockdep-enabled kernel when the kernel
takes an interrupt from idle, as reported by Guenter Roeck.
Note that this could have fired previously if any driver had used
tree-based irqdomain, which always had the RCU requirement.
To solve this, provide a MIPS-specific helper (do_domain_IRQ())
as the pendent of do_IRQ() that will do thing in the right order
(and maybe save some cycles in the process).
Ideally, MIPS would be moved over to using handle_domain_irq(),
but that's much more ambitious.
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
[maz: add dependency on CONFIG_IRQ_DOMAIN after report from the kernelci bot]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Serge Semin <fancer.lancer@gmail.com>
Link: https://lore.kernel.org/r/20210705172352.GA56304@roeck-us.net
Link: https://lore.kernel.org/r/20210706110647.3979002-1-maz@kernel.org
126 lines
2.7 KiB
C
126 lines
2.7 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Code to handle x86 style IRQs plus some generic interrupt stuff.
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*
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* Copyright (C) 1992 Linus Torvalds
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* Copyright (C) 1994 - 2000 Ralf Baechle
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*/
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#include <linux/kernel.h>
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/kernel_stat.h>
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#include <linux/proc_fs.h>
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#include <linux/mm.h>
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#include <linux/random.h>
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#include <linux/sched.h>
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#include <linux/seq_file.h>
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#include <linux/kallsyms.h>
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#include <linux/kgdb.h>
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#include <linux/ftrace.h>
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#include <linux/irqdomain.h>
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#include <linux/atomic.h>
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#include <linux/uaccess.h>
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void *irq_stack[NR_CPUS];
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/*
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* 'what should we do if we get a hw irq event on an illegal vector'.
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* each architecture has to answer this themselves.
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*/
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void ack_bad_irq(unsigned int irq)
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{
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printk("unexpected IRQ # %d\n", irq);
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}
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atomic_t irq_err_count;
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int arch_show_interrupts(struct seq_file *p, int prec)
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{
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seq_printf(p, "%*s: %10u\n", prec, "ERR", atomic_read(&irq_err_count));
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return 0;
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}
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asmlinkage void spurious_interrupt(void)
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{
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atomic_inc(&irq_err_count);
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}
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void __init init_IRQ(void)
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{
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int i;
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unsigned int order = get_order(IRQ_STACK_SIZE);
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for (i = 0; i < NR_IRQS; i++)
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irq_set_noprobe(i);
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if (cpu_has_veic)
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clear_c0_status(ST0_IM);
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arch_init_irq();
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for_each_possible_cpu(i) {
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void *s = (void *)__get_free_pages(GFP_KERNEL, order);
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irq_stack[i] = s;
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pr_debug("CPU%d IRQ stack at 0x%p - 0x%p\n", i,
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irq_stack[i], irq_stack[i] + IRQ_STACK_SIZE);
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}
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}
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#ifdef CONFIG_DEBUG_STACKOVERFLOW
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static inline void check_stack_overflow(void)
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{
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unsigned long sp;
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__asm__ __volatile__("move %0, $sp" : "=r" (sp));
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sp &= THREAD_MASK;
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/*
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* Check for stack overflow: is there less than STACK_WARN free?
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* STACK_WARN is defined as 1/8 of THREAD_SIZE by default.
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*/
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if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) {
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printk("do_IRQ: stack overflow: %ld\n",
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sp - sizeof(struct thread_info));
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dump_stack();
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}
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}
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#else
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static inline void check_stack_overflow(void) {}
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#endif
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/*
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* do_IRQ handles all normal device IRQ's (the special
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* SMP cross-CPU interrupts have their own specific
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* handlers).
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*/
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void __irq_entry do_IRQ(unsigned int irq)
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{
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irq_enter();
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check_stack_overflow();
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generic_handle_irq(irq);
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irq_exit();
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}
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#ifdef CONFIG_IRQ_DOMAIN
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void __irq_entry do_domain_IRQ(struct irq_domain *domain, unsigned int hwirq)
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{
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struct irq_desc *desc;
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irq_enter();
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check_stack_overflow();
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desc = irq_resolve_mapping(domain, hwirq);
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if (likely(desc))
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handle_irq_desc(desc);
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irq_exit();
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}
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#endif
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