[PATCH v2 1/9] riscv: add ARCH_HAS_SET_MEMORY support

Zong Li
2020-03-09T08:22:44Z

Add set_memory_ro/rw/x/nx architecture hooks to change the page
attribution.

Use own set_memory.h rather than generic set_memory.h
(i.e. include/asm-generic/set_memory.h), because we want to add other
function prototypes here.

Signed-off-by: Zong Li <zong.li@sifive.com>
---
arch/riscv/Kconfig | 1 +
arch/riscv/include/asm/set_memory.h | 17 ++++
arch/riscv/mm/Makefile | 1 +
arch/riscv/mm/pageattr.c | 150 ++++++++++++++++++++++++++++
4 files changed, 169 insertions(+)
create mode 100644 arch/riscv/include/asm/set_memory.h
create mode 100644 arch/riscv/mm/pageattr.c

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 6e81da55b5e4..76ed36543b3a 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -60,6 +60,7 @@ config RISCV
select HAVE_EBPF_JIT if 64BIT
select EDAC_SUPPORT
select ARCH_HAS_GIGANTIC_PAGE
+ select ARCH_HAS_SET_MEMORY
select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
select SPARSEMEM_STATIC if 32BIT
select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/set_memory.h
new file mode 100644
index 000000000000..936f08063566
--- /dev/null
+++ b/arch/riscv/include/asm/set_memory.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2019 SiFive
+ */
+
+#ifndef _ASM_RISCV_SET_MEMORY_H
+#define _ASM_RISCV_SET_MEMORY_H
+
+/*
+ * Functions to change memory attributes.
+ */
+int set_memory_ro(unsigned long addr, int numpages);
+int set_memory_rw(unsigned long addr, int numpages);
+int set_memory_x(unsigned long addr, int numpages);
+int set_memory_nx(unsigned long addr, int numpages);
+
+#endif /* _ASM_RISCV_SET_MEMORY_H */
diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile
index 814e16a8d68a..b94643aee84c 100644
--- a/arch/riscv/mm/Makefile
+++ b/arch/riscv/mm/Makefile
@@ -10,6 +10,7 @@ obj-y += extable.o
obj-$(CONFIG_MMU) += fault.o
obj-y += cacheflush.o
obj-y += context.o
+obj-y += pageattr.o

ifeq ($(CONFIG_MMU),y)
obj-$(CONFIG_SMP) += tlbflush.o
diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
new file mode 100644
index 000000000000..fcd59ef2835b
--- /dev/null
+++ b/arch/riscv/mm/pageattr.c
@@ -0,0 +1,150 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2019 SiFive
+ */
+
+#include <linux/pagewalk.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include <asm/bitops.h>
+
+struct pageattr_masks {
+ pgprot_t set_mask;
+ pgprot_t clear_mask;
+};
+
+static unsigned long set_pageattr_masks(unsigned long val, struct mm_walk *walk)
+{
+ struct pageattr_masks *masks = walk->private;
+ unsigned long new_val = val;
+
+ new_val &= ~(pgprot_val(masks->clear_mask));
+ new_val |= (pgprot_val(masks->set_mask));
+
+ return new_val;
+}
+
+static int pageattr_pgd_entry(pgd_t *pgd, unsigned long addr,
+ unsigned long next, struct mm_walk *walk)
+{
+ pgd_t val = READ_ONCE(*pgd);
+
+ if (pgd_leaf(val)) {
+ val = __pgd(set_pageattr_masks(pgd_val(val), walk));
+ set_pgd(pgd, val);
+ }
+
+ return 0;
+}
+
+static int pageattr_p4d_entry(p4d_t *p4d, unsigned long addr,
+ unsigned long next, struct mm_walk *walk)
+{
+ p4d_t val = READ_ONCE(*p4d);
+
+ if (p4d_leaf(val)) {
+ val = __p4d(set_pageattr_masks(p4d_val(val), walk));
+ set_p4d(p4d, val);
+ }
+
+ return 0;
+}
+
+static int pageattr_pud_entry(pud_t *pud, unsigned long addr,
+ unsigned long next, struct mm_walk *walk)
+{
+ pud_t val = READ_ONCE(*pud);
+
+ if (pud_leaf(val)) {
+ val = __pud(set_pageattr_masks(pud_val(val), walk));
+ set_pud(pud, val);
+ }
+
+ return 0;
+}
+
+static int pageattr_pmd_entry(pmd_t *pmd, unsigned long addr,
+ unsigned long next, struct mm_walk *walk)
+{
+ pmd_t val = READ_ONCE(*pmd);
+
+ if (pmd_leaf(val)) {
+ val = __pmd(set_pageattr_masks(pmd_val(val), walk));
+ set_pmd(pmd, val);
+ }
+
+ return 0;
+}
+
+static int pageattr_pte_entry(pte_t *pte, unsigned long addr,
+ unsigned long next, struct mm_walk *walk)
+{
+ pte_t val = READ_ONCE(*pte);
+
+ val = __pte(set_pageattr_masks(pte_val(val), walk));
+ set_pte(pte, val);
+
+ return 0;
+}
+
+static int pageattr_pte_hole(unsigned long addr, unsigned long next,
+ int depth, struct mm_walk *walk)
+{
+ /* Nothing to do here */
+ return 0;
+}
+
+const static struct mm_walk_ops pageattr_ops = {
+ .pgd_entry = pageattr_pgd_entry,
+ .p4d_entry = pageattr_p4d_entry,
+ .pud_entry = pageattr_pud_entry,
+ .pmd_entry = pageattr_pmd_entry,
+ .pte_entry = pageattr_pte_entry,
+ .pte_hole = pageattr_pte_hole,
+};
+
+static int __set_memory(unsigned long addr, int numpages, pgprot_t set_mask,
+ pgprot_t clear_mask)
+{
+ int ret;
+ unsigned long start = addr;
+ unsigned long end = start + PAGE_SIZE * numpages;
+ struct pageattr_masks masks = {
+ .set_mask = set_mask,
+ .clear_mask = clear_mask
+ };
+
+ if (!numpages)
+ return 0;
+
+ down_read(&init_mm.mmap_sem);
+ ret = walk_page_range_novma(&init_mm, start, end, &pageattr_ops, NULL,
+ &masks);
+ up_read(&init_mm.mmap_sem);
+
+ flush_tlb_kernel_range(start, end);
+
+ return ret;
+}
+
+int set_memory_ro(unsigned long addr, int numpages)
+{
+ return __set_memory(addr, numpages, __pgprot(_PAGE_READ),
+ __pgprot(_PAGE_WRITE));
+}
+
+int set_memory_rw(unsigned long addr, int numpages)
+{
+ return __set_memory(addr, numpages, __pgprot(_PAGE_READ | _PAGE_WRITE),
+ __pgprot(0));
+}
+
+int set_memory_x(unsigned long addr, int numpages)
+{
+ return __set_memory(addr, numpages, __pgprot(_PAGE_EXEC), __pgprot(0));
+}
+
+int set_memory_nx(unsigned long addr, int numpages)
+{
+ return __set_memory(addr, numpages, __pgprot(0), __pgprot(_PAGE_EXEC));
+}
--
2.25.1