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/include/asm/mmu.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/riscv/include/asm/mmu.h') diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h index 66805cba9a27..5df2dccdba12 100644 --- a/arch/riscv/include/asm/mmu.h +++ b/arch/riscv/include/asm/mmu.h @@ -19,6 +19,10 @@ typedef struct { void *vdso; +#ifdef CONFIG_SMP + /* A local icache flush is needed before user execution can resume. */ + cpumask_t icache_stale_mask; +#endif } mm_context_t; #endif /* __ASSEMBLY__ */ -- cgit v1.2.3-70-g09d2