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