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SubjectRe: [PATCH 1/8] riscv: add ARCH_HAS_SET_MEMORY support
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On Mon, 17 Feb 2020 00:32:16 PST (-0800), zong.li@sifive.com wrote:
> 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);

There are very few users of _novma, but I think it's correct here.

> +
> + 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));
> +}

Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>

Thanks!

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