72 lines
2.0 KiB
C
72 lines
2.0 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (c) 2021 Keith Packard <keithp@keithp.com>
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* Copyright (c) 2021 Google, LLC <ardb@kernel.org>
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*/
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#ifndef _ASM_ARM_CURRENT_H
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#define _ASM_ARM_CURRENT_H
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#ifndef __ASSEMBLY__
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#include <asm/insn.h>
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struct task_struct;
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extern struct task_struct *__current;
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static __always_inline __attribute_const__ struct task_struct *get_current(void)
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{
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struct task_struct *cur;
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#if __has_builtin(__builtin_thread_pointer) && \
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defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) && \
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!(defined(CONFIG_THUMB2_KERNEL) && \
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defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 130001)
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/*
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* Use the __builtin helper when available - this results in better
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* code, especially when using GCC in combination with the per-task
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* stack protector, as the compiler will recognize that it needs to
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* load the TLS register only once in every function.
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*
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* Clang < 13.0.1 gets this wrong for Thumb2 builds:
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* https://github.com/ClangBuiltLinux/linux/issues/1485
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*/
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cur = __builtin_thread_pointer();
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#elif defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP)
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asm("0: mrc p15, 0, %0, c13, c0, 3 \n\t"
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#ifdef CONFIG_CPU_V6
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"1: \n\t"
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" .subsection 1 \n\t"
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#if defined(CONFIG_ARM_HAS_GROUP_RELOCS) && \
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!(defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS))
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"2: " LOAD_SYM_ARMV6(%0, __current) " \n\t"
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" b 1b \n\t"
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#else
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"2: ldr %0, 3f \n\t"
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" ldr %0, [%0] \n\t"
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" b 1b \n\t"
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"3: .long __current \n\t"
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#endif
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" .previous \n\t"
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" .pushsection \".alt.smp.init\", \"a\" \n\t"
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" .long 0b - . \n\t"
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" b . + (2b - 0b) \n\t"
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" .popsection \n\t"
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#endif
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: "=r"(cur));
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#elif __LINUX_ARM_ARCH__>= 7 || \
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!defined(CONFIG_ARM_HAS_GROUP_RELOCS) || \
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(defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS))
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cur = __current;
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#else
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asm(LOAD_SYM_ARMV6(%0, __current) : "=r"(cur));
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#endif
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return cur;
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}
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#define current get_current()
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#endif /* __ASSEMBLY__ */
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#endif /* _ASM_ARM_CURRENT_H */
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