Hi, On Mon, Nov 20, 2017 at 10:57 AM, Palmer Dabbelt <pal...@sifive.com> wrote: > From: Andrew Waterman <and...@sifive.com> > > 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 <and...@sifive.com> > Signed-off-by: Palmer Dabbelt <pal...@sifive.com> > --- > arch/riscv/include/asm/cacheflush.h | 24 ++++++++++++--- > arch/riscv/include/asm/mmu.h | 4 +++ > arch/riscv/include/asm/mmu_context.h | 44 +++++++++++++++++++++++++++ > arch/riscv/include/asm/pgtable.h | 58 > ++++++++++++++++++++---------------- > arch/riscv/include/asm/tlbflush.h | 2 ++ > arch/riscv/kernel/smp.c | 48 +++++++++++++++++++++++++++++ > arch/riscv/mm/Makefile | 2 ++ > arch/riscv/mm/cacheflush.c | 23 ++++++++++++++ > 8 files changed, 175 insertions(+), 30 deletions(-) > create mode 100644 arch/riscv/mm/cacheflush.c
[...] > diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile > index 81f7d9ce6d88..786b5fdec0fd 100644 > --- a/arch/riscv/mm/Makefile > +++ b/arch/riscv/mm/Makefile > @@ -2,3 +2,5 @@ obj-y += init.o > obj-y += fault.o > obj-y += extable.o > obj-y += ioremap.o > +obj-y += dma.o > +obj-y += cacheflush.o Looks like dma.c didn't make it into this patch (and didn't already exist), so builds fail with: make[3]: *** No rule to make target 'arch/riscv/mm/dma.o', needed by 'arch/riscv/mm/built-in.o'. -Olof
