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    Subject[PATCH 5.15 043/530] riscv: Make VM_WRITE imply VM_READ
    Date
    From: Andrew Bresticker <abrestic@rivosinc.com>

    commit 7ab72c597356be1e7f0f3d856e54ce78527f43c8 upstream.

    RISC-V does not presently have write-only mappings as that PTE bit pattern
    is considered reserved in the privileged spec, so allow handling of read
    faults in VMAs that have VM_WRITE without VM_READ in order to be consistent
    with other architectures that have similar limitations.

    Fixes: 2139619bcad7 ("riscv: mmap with PROT_WRITE but no PROT_READ is invalid")
    Reviewed-by: Atish Patra <atishp@rivosinc.com>
    Signed-off-by: Andrew Bresticker <abrestic@rivosinc.com>
    Cc: stable@vger.kernel.org
    Link: https://lore.kernel.org/r/20220915193702.2201018-2-abrestic@rivosinc.com/
    Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/riscv/mm/fault.c | 3 ++-
    1 file changed, 2 insertions(+), 1 deletion(-)

    --- a/arch/riscv/mm/fault.c
    +++ b/arch/riscv/mm/fault.c
    @@ -188,7 +188,8 @@ static inline bool access_error(unsigned
    }
    break;
    case EXC_LOAD_PAGE_FAULT:
    - if (!(vma->vm_flags & VM_READ)) {
    + /* Write implies read */
    + if (!(vma->vm_flags & (VM_READ | VM_WRITE))) {
    return true;
    }
    break;

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