cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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current.h (2079B)

      1/* SPDX-License-Identifier: GPL-2.0-only */
      2/*
      3 * Copyright (c) 2021 Keith Packard <keithp@keithp.com>
      4 * Copyright (c) 2021 Google, LLC <ardb@kernel.org>
      5 */
      6
      7#ifndef _ASM_ARM_CURRENT_H
      8#define _ASM_ARM_CURRENT_H
      9
     10#ifndef __ASSEMBLY__
     11#include <asm/insn.h>
     12
     13struct task_struct;
     14
     15extern struct task_struct *__current;
     16
     17static __always_inline __attribute_const__ struct task_struct *get_current(void)
     18{
     19	struct task_struct *cur;
     20
     21#if __has_builtin(__builtin_thread_pointer) && \
     22    defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) && \
     23    !(defined(CONFIG_THUMB2_KERNEL) && \
     24      defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 130001)
     25	/*
     26	 * Use the __builtin helper when available - this results in better
     27	 * code, especially when using GCC in combination with the per-task
     28	 * stack protector, as the compiler will recognize that it needs to
     29	 * load the TLS register only once in every function.
     30	 *
     31	 * Clang < 13.0.1 gets this wrong for Thumb2 builds:
     32	 * https://github.com/ClangBuiltLinux/linux/issues/1485
     33	 */
     34	cur = __builtin_thread_pointer();
     35#elif defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP)
     36	asm("0:	mrc p15, 0, %0, c13, c0, 3			\n\t"
     37#ifdef CONFIG_CPU_V6
     38	    "1:							\n\t"
     39	    "	.subsection 1					\n\t"
     40#if defined(CONFIG_ARM_HAS_GROUP_RELOCS) && \
     41    !(defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS))
     42	    "2: " LOAD_SYM_ARMV6(%0, __current) "		\n\t"
     43	    "	b	1b					\n\t"
     44#else
     45	    "2:	ldr	%0, 3f					\n\t"
     46	    "	ldr	%0, [%0]				\n\t"
     47	    "	b	1b					\n\t"
     48	    "3:	.long	__current				\n\t"
     49#endif
     50	    "	.previous					\n\t"
     51	    "	.pushsection \".alt.smp.init\", \"a\"		\n\t"
     52	    "	.long	0b - .					\n\t"
     53	    "	b	. + (2b - 0b)				\n\t"
     54	    "	.popsection					\n\t"
     55#endif
     56	    : "=r"(cur));
     57#elif __LINUX_ARM_ARCH__>= 7 || \
     58      !defined(CONFIG_ARM_HAS_GROUP_RELOCS) || \
     59      (defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS))
     60	cur = __current;
     61#else
     62	asm(LOAD_SYM_ARMV6(%0, __current) : "=r"(cur));
     63#endif
     64	return cur;
     65}
     66
     67#define current get_current()
     68
     69#endif /* __ASSEMBLY__ */
     70
     71#endif /* _ASM_ARM_CURRENT_H */