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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * arch/arm/kernel/thumbee.c
- *
- * Copyright (C) 2008 ARM Limited
- */
- #include <linux/kernel.h>
- #include <linux/init.h>
- #include <asm/cputype.h>
- #include <asm/system_info.h>
- #include <asm/thread_notify.h>
- /*
- * Access to the ThumbEE Handler Base register
- */
- static inline unsigned long teehbr_read(void)
- {
- unsigned long v;
- asm("mrc p14, 6, %0, c1, c0, 0\n" : "=r" (v));
- return v;
- }
- static inline void teehbr_write(unsigned long v)
- {
- asm("mcr p14, 6, %0, c1, c0, 0\n" : : "r" (v));
- }
- static int thumbee_notifier(struct notifier_block *self, unsigned long cmd, void *t)
- {
- struct thread_info *thread = t;
- switch (cmd) {
- case THREAD_NOTIFY_FLUSH:
- teehbr_write(0);
- break;
- case THREAD_NOTIFY_SWITCH:
- current_thread_info()->thumbee_state = teehbr_read();
- teehbr_write(thread->thumbee_state);
- break;
- }
- return NOTIFY_DONE;
- }
- static struct notifier_block thumbee_notifier_block = {
- .notifier_call = thumbee_notifier,
- };
- static int __init thumbee_init(void)
- {
- unsigned long pfr0;
- unsigned int cpu_arch = cpu_architecture();
- if (cpu_arch < CPU_ARCH_ARMv7)
- return 0;
- pfr0 = read_cpuid_ext(CPUID_EXT_PFR0);
- if ((pfr0 & 0x0000f000) != 0x00001000)
- return 0;
- pr_info("ThumbEE CPU extension supported.\n");
- elf_hwcap |= HWCAP_THUMBEE;
- thread_register_notifier(&thumbee_notifier_block);
- return 0;
- }
- late_initcall(thumbee_init);
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