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    Subject[PATCH v5 4/9] riscv: add ARCH_HAS_SET_MEMORY support
    Date
    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>
    Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
    ---
    arch/riscv/Kconfig | 1 +
    arch/riscv/include/asm/set_memory.h | 24 +++++
    arch/riscv/mm/Makefile | 2 +-
    arch/riscv/mm/pageattr.c | 150 ++++++++++++++++++++++++++++
    4 files changed, 176 insertions(+), 1 deletion(-)
    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 39c93ddff0cb..9044e0dd95ea 100644
    --- a/arch/riscv/Kconfig
    +++ b/arch/riscv/Kconfig
    @@ -59,6 +59,7 @@ 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..79a810f0f38b
    --- /dev/null
    +++ b/arch/riscv/include/asm/set_memory.h
    @@ -0,0 +1,24 @@
    +/* 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.
    + */
    +#ifdef CONFIG_MMU
    +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);
    +#else
    +static inline int set_memory_ro(unsigned long addr, int numpages) { return 0; }
    +static inline int set_memory_rw(unsigned long addr, int numpages) { return 0; }
    +static inline int set_memory_x(unsigned long addr, int numpages) { return 0; }
    +static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
    +#endif
    +
    +#endif /* _ASM_RISCV_SET_MEMORY_H */
    diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile
    index 814e16a8d68a..363ef01c30b1 100644
    --- a/arch/riscv/mm/Makefile
    +++ b/arch/riscv/mm/Makefile
    @@ -7,7 +7,7 @@ endif

    obj-y += init.o
    obj-y += extable.o
    -obj-$(CONFIG_MMU) += fault.o
    +obj-$(CONFIG_MMU) += fault.o pageattr.o
    obj-y += cacheflush.o
    obj-y += context.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));
    +}
    --
    2.26.0
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