52e7c52d2d
GCC allows users to hint to the register allocation that a variable should be
placed in a register by using a syntax along the lines of
function(...) {
register long in_REG __asm__("REG");
}
We've abused this a bit throughout the RISC-V port to access fixed registers
directly as C variables. In practice it's never going to blow up because GCC
isn't going to allocate these registers, but it's not a well defined syntax so
we really shouldn't be relying upon this. Luckily there is a very similar but
well defined syntax that allows us to still access these registers directly as
C variables, which is to simply declare the register variables globally. For
fixed variables this doesn't change the ABI.
LLVM disallows this ambiguous syntax, so this isn't just strictly a formatting
change.
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
39 lines
940 B
C
39 lines
940 B
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Based on arm/arm64/include/asm/current.h
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*
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* Copyright (C) 2016 ARM
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* Copyright (C) 2017 SiFive
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*/
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#ifndef _ASM_RISCV_CURRENT_H
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#define _ASM_RISCV_CURRENT_H
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#include <linux/bug.h>
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#include <linux/compiler.h>
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#ifndef __ASSEMBLY__
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struct task_struct;
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register struct task_struct *riscv_current_is_tp __asm__("tp");
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/*
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* This only works because "struct thread_info" is at offset 0 from "struct
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* task_struct". This constraint seems to be necessary on other architectures
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* as well, but __switch_to enforces it. We can't check TASK_TI here because
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* <asm/asm-offsets.h> includes this, and I can't get the definition of "struct
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* task_struct" here due to some header ordering problems.
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*/
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static __always_inline struct task_struct *get_current(void)
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{
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return riscv_current_is_tp;
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}
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#define current get_current()
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#endif /* __ASSEMBLY__ */
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#endif /* _ASM_RISCV_CURRENT_H */
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