diff options
Diffstat (limited to '')
| -rw-r--r-- | arch/arm/include/asm/current.h | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/arch/arm/include/asm/current.h b/arch/arm/include/asm/current.h new file mode 100644 index 0000000000..1e1178bf17 --- /dev/null +++ b/arch/arm/include/asm/current.h @@ -0,0 +1,71 @@ +/* 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) && \ + !(defined(CONFIG_THUMB2_KERNEL) && \ + defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 130001) + /* + * 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. + * + * Clang < 13.0.1 gets this wrong for Thumb2 builds: + * https://github.com/ClangBuiltLinux/linux/issues/1485 + */ + 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 */ |