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authorAndrew Waterman <andrew@sifive.com>2017-10-25 14:30:32 -0700
committerPalmer Dabbelt <palmer@sifive.com>2017-11-30 12:58:25 -0800
commit08f051eda33b51e8ee0f45f05bcfe49d0f0caf6b (patch)
tree46a1e3577de686377e859c7f346299e9ea726260 /arch/riscv/mm
parent28dfbe6ed483e8a589cce88095d7787d61bf9c16 (diff)
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>
Diffstat (limited to 'arch/riscv/mm')
-rw-r--r--arch/riscv/mm/Makefile1
-rw-r--r--arch/riscv/mm/cacheflush.c23
2 files changed, 24 insertions, 0 deletions
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 <asm/pgtable.h>
+#include <asm/cacheflush.h>
+
+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();
+}