Hi,
On Mon, Nov 20, 2017 at 10:57 AM, Palmer Dabbelt <[email protected]> wrote:
> From: Andrew Waterman <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Palmer Dabbelt <[email protected]>
> ---
> 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
From 1584794155897187380@xxx Wed Nov 22 19:04:43 +0000 2017
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