Quellcode-Bibliothek current.h   Sprache: C

/* 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 */