linux/arch/riscv/include/asm/tlbflush.h
Andrew Waterman 08f051eda3 RISC-V: Flush I$ when making a dirty page executable
The RISC-V ISA allows for instruction caches that are not coherent WRT
stores, even on a single hart.  As a result, we need to explicitly flush
the instruction cache whenever marking a dirty page as executable in
order to preserve the correct system behavior.

Local instruction caches aren't that scary (our implementations actually
flush the cache, but RISC-V is defined to allow higher-performance
implementations to exist), but RISC-V defines no way to perform an
instruction cache shootdown.  When explicitly asked to do so we can
shoot down remote instruction caches via an IPI, but this is a bit on
the slow side.

Instead of requiring an IPI to all harts whenever marking a page as
executable, we simply flush the currently running harts.  In order to
maintain correct behavior, we additionally mark every other hart as
needing a deferred instruction cache which will be taken before anything
runs on it.

Signed-off-by: Andrew Waterman <andrew@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2017-11-30 12:58:25 -08:00

67 lines
1.8 KiB
C

/*
* Copyright (C) 2009 Chen Liqin <liqin.chen@sunplusct.com>
* Copyright (C) 2012 Regents of the University of California
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#ifndef _ASM_RISCV_TLBFLUSH_H
#define _ASM_RISCV_TLBFLUSH_H
#ifdef CONFIG_MMU
#include <linux/mm_types.h>
/* Flush entire local TLB */
static inline void local_flush_tlb_all(void)
{
__asm__ __volatile__ ("sfence.vma" : : : "memory");
}
/* Flush one page from local TLB */
static inline void local_flush_tlb_page(unsigned long addr)
{
__asm__ __volatile__ ("sfence.vma %0" : : "r" (addr) : "memory");
}
#ifndef CONFIG_SMP
#define flush_tlb_all() local_flush_tlb_all()
#define flush_tlb_page(vma, addr) local_flush_tlb_page(addr)
#define flush_tlb_range(vma, start, end) local_flush_tlb_all()
#else /* CONFIG_SMP */
#include <asm/sbi.h>
#define flush_tlb_all() sbi_remote_sfence_vma(0, 0, -1)
#define flush_tlb_page(vma, addr) flush_tlb_range(vma, addr, 0)
#define flush_tlb_range(vma, start, end) \
sbi_remote_sfence_vma(0, start, (end) - (start))
#endif /* CONFIG_SMP */
/* Flush the TLB entries of the specified mm context */
static inline void flush_tlb_mm(struct mm_struct *mm)
{
flush_tlb_all();
}
/* Flush a range of kernel pages */
static inline void flush_tlb_kernel_range(unsigned long start,
unsigned long end)
{
flush_tlb_all();
}
#endif /* CONFIG_MMU */
#endif /* _ASM_RISCV_TLBFLUSH_H */