150596b75SArd Biesheuvel /* SPDX-License-Identifier: GPL-2.0-only */ 250596b75SArd Biesheuvel /* 350596b75SArd Biesheuvel * Copyright (c) 2021 Keith Packard <keithp@keithp.com> 450596b75SArd Biesheuvel * Copyright (c) 2021 Google, LLC <ardb@kernel.org> 550596b75SArd Biesheuvel */ 650596b75SArd Biesheuvel 750596b75SArd Biesheuvel #ifndef _ASM_ARM_CURRENT_H 850596b75SArd Biesheuvel #define _ASM_ARM_CURRENT_H 950596b75SArd Biesheuvel 1050596b75SArd Biesheuvel #ifndef __ASSEMBLY__ 119c46929eSArd Biesheuvel #include <asm/insn.h> 1250596b75SArd Biesheuvel 1350596b75SArd Biesheuvel struct task_struct; 1450596b75SArd Biesheuvel 159c46929eSArd Biesheuvel extern struct task_struct *__current; 1650596b75SArd Biesheuvel 179c46929eSArd Biesheuvel static inline __attribute_const__ struct task_struct *get_current(void) 1850596b75SArd Biesheuvel { 1950596b75SArd Biesheuvel struct task_struct *cur; 2050596b75SArd Biesheuvel 21c1e42efaSArd Biesheuvel #if __has_builtin(__builtin_thread_pointer) && \ 229c46929eSArd Biesheuvel defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) && \ 23c1e42efaSArd Biesheuvel !(defined(CONFIG_THUMB2_KERNEL) && \ 24c1e42efaSArd Biesheuvel defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 130001) 2550596b75SArd Biesheuvel /* 2650596b75SArd Biesheuvel * Use the __builtin helper when available - this results in better 2750596b75SArd Biesheuvel * code, especially when using GCC in combination with the per-task 2850596b75SArd Biesheuvel * stack protector, as the compiler will recognize that it needs to 2950596b75SArd Biesheuvel * load the TLS register only once in every function. 30c1e42efaSArd Biesheuvel * 31c1e42efaSArd Biesheuvel * Clang < 13.0.1 gets this wrong for Thumb2 builds: 32c1e42efaSArd Biesheuvel * https://github.com/ClangBuiltLinux/linux/issues/1485 3350596b75SArd Biesheuvel */ 3450596b75SArd Biesheuvel cur = __builtin_thread_pointer(); 359c46929eSArd Biesheuvel #elif defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP) 369c46929eSArd Biesheuvel asm("0: mrc p15, 0, %0, c13, c0, 3 \n\t" 379c46929eSArd Biesheuvel #ifdef CONFIG_CPU_V6 389c46929eSArd Biesheuvel "1: \n\t" 399c46929eSArd Biesheuvel " .subsection 1 \n\t" 40*5fe41793SArd Biesheuvel #if !(defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS)) && \ 41*5fe41793SArd Biesheuvel !(defined(CONFIG_LD_IS_LLD) && CONFIG_LLD_VERSION < 140000) 429c46929eSArd Biesheuvel "2: " LOAD_SYM_ARMV6(%0, __current) " \n\t" 439c46929eSArd Biesheuvel " b 1b \n\t" 44*5fe41793SArd Biesheuvel #else 45*5fe41793SArd Biesheuvel "2: ldr %0, 3f \n\t" 46*5fe41793SArd Biesheuvel " ldr %0, [%0] \n\t" 47*5fe41793SArd Biesheuvel " b 1b \n\t" 48*5fe41793SArd Biesheuvel "3: .long __current \n\t" 49*5fe41793SArd Biesheuvel #endif 509c46929eSArd Biesheuvel " .previous \n\t" 519c46929eSArd Biesheuvel " .pushsection \".alt.smp.init\", \"a\" \n\t" 529c46929eSArd Biesheuvel " .long 0b - . \n\t" 539c46929eSArd Biesheuvel " b . + (2b - 0b) \n\t" 549c46929eSArd Biesheuvel " .popsection \n\t" 559c46929eSArd Biesheuvel #endif 569c46929eSArd Biesheuvel : "=r"(cur)); 579c46929eSArd Biesheuvel #elif __LINUX_ARM_ARCH__>= 7 || \ 58*5fe41793SArd Biesheuvel (defined(MODULE) && defined(CONFIG_ARM_MODULE_PLTS)) || \ 59*5fe41793SArd Biesheuvel (defined(CONFIG_LD_IS_LLD) && CONFIG_LLD_VERSION < 140000) 609c46929eSArd Biesheuvel cur = __current; 6150596b75SArd Biesheuvel #else 629c46929eSArd Biesheuvel asm(LOAD_SYM_ARMV6(%0, __current) : "=r"(cur)); 6350596b75SArd Biesheuvel #endif 6450596b75SArd Biesheuvel return cur; 6550596b75SArd Biesheuvel } 6650596b75SArd Biesheuvel 6750596b75SArd Biesheuvel #define current get_current() 6850596b75SArd Biesheuvel 6950596b75SArd Biesheuvel #endif /* __ASSEMBLY__ */ 7050596b75SArd Biesheuvel 7150596b75SArd Biesheuvel #endif /* _ASM_ARM_CURRENT_H */ 72