797245f5da
This avoids races in the VFP code where the dead thread may have state on another CPU. By moving this code to exit_thread(), we will be running as the thread, and therefore be running on the current CPU. This means that we can ensure that the only local state is accessed in the thread notifiers. Acked-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
88 lines
2.1 KiB
C
88 lines
2.1 KiB
C
/*
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* arch/arm/kernel/crunch.c
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* Cirrus MaverickCrunch context switching and handling
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*
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* Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/init.h>
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#include <linux/io.h>
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#include <mach/ep93xx-regs.h>
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#include <asm/thread_notify.h>
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struct crunch_state *crunch_owner;
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void crunch_task_release(struct thread_info *thread)
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{
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local_irq_disable();
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if (crunch_owner == &thread->crunchstate)
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crunch_owner = NULL;
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local_irq_enable();
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}
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static int crunch_enabled(u32 devcfg)
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{
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return !!(devcfg & EP93XX_SYSCON_DEVCFG_CPENA);
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}
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static int crunch_do(struct notifier_block *self, unsigned long cmd, void *t)
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{
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struct thread_info *thread = (struct thread_info *)t;
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struct crunch_state *crunch_state;
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u32 devcfg;
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crunch_state = &thread->crunchstate;
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switch (cmd) {
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case THREAD_NOTIFY_FLUSH:
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memset(crunch_state, 0, sizeof(*crunch_state));
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/*
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* FALLTHROUGH: Ensure we don't try to overwrite our newly
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* initialised state information on the first fault.
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*/
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case THREAD_NOTIFY_EXIT:
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crunch_task_release(thread);
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break;
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case THREAD_NOTIFY_SWITCH:
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devcfg = __raw_readl(EP93XX_SYSCON_DEVCFG);
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if (crunch_enabled(devcfg) || crunch_owner == crunch_state) {
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/*
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* We don't use ep93xx_syscon_swlocked_write() here
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* because we are on the context switch path and
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* preemption is already disabled.
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*/
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devcfg ^= EP93XX_SYSCON_DEVCFG_CPENA;
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__raw_writel(0xaa, EP93XX_SYSCON_SWLOCK);
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__raw_writel(devcfg, EP93XX_SYSCON_DEVCFG);
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}
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break;
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}
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return NOTIFY_DONE;
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}
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static struct notifier_block crunch_notifier_block = {
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.notifier_call = crunch_do,
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};
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static int __init crunch_init(void)
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{
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thread_register_notifier(&crunch_notifier_block);
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elf_hwcap |= HWCAP_CRUNCH;
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return 0;
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}
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late_initcall(crunch_init);
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