From 08f051eda33b51e8ee0f45f05bcfe49d0f0caf6b Mon Sep 17 00:00:00 2001 From: Andrew Waterman Date: Wed, 25 Oct 2017 14:30:32 -0700 Subject: 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 Signed-off-by: Palmer Dabbelt --- arch/riscv/mm/Makefile | 1 + arch/riscv/mm/cacheflush.c | 23 +++++++++++++++++++++++ 2 files changed, 24 insertions(+) create mode 100644 arch/riscv/mm/cacheflush.c (limited to 'arch/riscv/mm') diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile index 81f7d9ce6d88..eb22ab49b3e0 100644 --- a/arch/riscv/mm/Makefile +++ b/arch/riscv/mm/Makefile @@ -2,3 +2,4 @@ obj-y += init.o obj-y += fault.o obj-y += extable.o obj-y += ioremap.o +obj-y += cacheflush.o diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c new file mode 100644 index 000000000000..498c0a0814fe --- /dev/null +++ b/arch/riscv/mm/cacheflush.c @@ -0,0 +1,23 @@ +/* + * Copyright (C) 2017 SiFive + * + * 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. + */ + +#include +#include + +void flush_icache_pte(pte_t pte) +{ + struct page *page = pte_page(pte); + + if (!test_and_set_bit(PG_dcache_clean, &page->flags)) + flush_icache_all(); +} -- cgit v1.2.3