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 13 struct task_struct; 14 15 extern struct task_struct *__current; 16 17 static __always_inline __attribute_const__ struct task_struct *get_current(void) 18 { 19 struct task_struct *cur; 20 21 #if __has_builtin(__builtin_thread_pointer) && defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) 22 /* 23 * Use the __builtin helper when available - this results in better 24 * code, especially when using GCC in combination with the per-task 25 * stack protector, as the compiler will recognize that it needs to 26 * load the TLS register only once in every function. 27 */ 28 cur = __builtin_thread_pointer(); 29 #elif defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP) 30 asm("0: mrc p15, 0, %0, c13, c0, 3 \n\t" 31 #ifdef CONFIG_CPU_V6 32 "1: \n\t" 33 " .subsection 1 \n\t" 34 #if defined(CONFIG_ARM_HAS_GROUP_RELOCS) && \ 35 !(defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS)) 36 "2: " LOAD_SYM_ARMV6(%0, __current) " \n\t" 37 " b 1b \n\t" 38 #else 39 "2: ldr %0, 3f \n\t" 40 " ldr %0, [%0] \n\t" 41 " b 1b \n\t" 42 "3: .long __current \n\t" 43 #endif 44 " .previous \n\t" 45 " .pushsection \".alt.smp.init\", \"a\" \n\t" 46 " .long 0b - . \n\t" 47 " b . + (2b - 0b) \n\t" 48 " .popsection \n\t" 49 #endif 50 : "=r"(cur)); 51 #elif __LINUX_ARM_ARCH__>= 7 || \ 52 !defined(CONFIG_ARM_HAS_GROUP_RELOCS) || \ 53 (defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS)) 54 cur = __current; 55 #else 56 asm(LOAD_SYM_ARMV6(%0, __current) : "=r"(cur)); 57 #endif 58 return cur; 59 } 60 61 #define current get_current() 62 63 #endif /* __ASSEMBLY__ */ 64 65 #endif /* _ASM_ARM_CURRENT_H */ 66