/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (c) 2021 Keith Packard <[email protected]>
 * Copyright (c) 2021 Google, LLC <[email protected]>
 */

#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) && \
    !(defined(CONFIG_THUMB2_KERNEL) && \
      defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 130001)
    /*
     * 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.
     *
     * Clang < 13.0.1 gets this wrong for Thumb2 builds:
     * https://github.com/ClangBuiltLinux/linux/issues/1485
     */
    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 */