/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (c) 2021 Keith Packard <keithp@keithp.com>
 * Copyright (c) 2021 Google, LLC <ardb@kernel.org>
 */

#ifndef _ASM_ARM_CURRENT_H
#define _ASM_ARM_CURRENT_H

#ifndef __ASSEMBLY__
#include <asm/insn.h>

struct task_struct;

extern struct task_struct *__current;

static __always_inline __attribute_const__ struct task_struct *get_current(void)
{
        struct task_struct *cur;

#if __has_builtin(__builtin_thread_pointer) && defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO)
        /*
         * Use the __builtin helper when available - this results in better
         * code, especially when using GCC in combination with the per-task
         * stack protector, as the compiler will recognize that it needs to
         * load the TLS register only once in every function.
         */
        cur = __builtin_thread_pointer();
#elif defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP)
        asm("0: mrc p15, 0, %0, c13, c0, 3                      \n\t"
#ifdef CONFIG_CPU_V6
            "1:                                                 \n\t"
            "   .subsection 1                                   \n\t"
#if defined(CONFIG_ARM_HAS_GROUP_RELOCS) && \
    !(defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS))
            "2: " LOAD_SYM_ARMV6(%0, __current) "               \n\t"
            "   b       1b                                      \n\t"
#else
            "2: ldr     %0, 3f                                  \n\t"
            "   ldr     %0, [%0]                                \n\t"
            "   b       1b                                      \n\t"
            "3: .long   __current                               \n\t"
#endif
            "   .previous                                       \n\t"
            "   .pushsection \".alt.smp.init\", \"a\"           \n\t"
            "   .long   0b - .                                  \n\t"
            "   b       . + (2b - 0b)                           \n\t"
            "   .popsection                                     \n\t"
#endif
            : "=r"(cur));
#elif __LINUX_ARM_ARCH__>= 7 || \
      !defined(CONFIG_ARM_HAS_GROUP_RELOCS) || \
      (defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS))
        cur = __current;
#else
        asm(LOAD_SYM_ARMV6(%0, __current) : "=r"(cur));
#endif
        return cur;
}

#define current get_current()

#endif /* __ASSEMBLY__ */

#endif /* _ASM_ARM_CURRENT_H */