riscv: mmap with PROT_WRITE but no PROT_READ is invalid

As mentioned in Table 4.5 in RISC-V spec Volume 2 Section 4.3, write
but not read is "Reserved for future use.". For now, they are not valid.
In the current code, -wx is marked as invalid, but -w- is not marked
as invalid.
This patch refines that judgment.

Reported-by: xctan <xc-tan@outlook.com>
Co-developed-by: dram <dramforever@live.com>
Signed-off-by: dram <dramforever@live.com>
Co-developed-by: Ruizhe Pan <c141028@gmail.com>
Signed-off-by: Ruizhe Pan <c141028@gmail.com>
Signed-off-by: Celeste Liu <coelacanthus@outlook.com>
Link: https://lore.kernel.org/r/PH7PR14MB559464DBDD310E755F5B21E8CEDC9@PH7PR14MB5594.namprd14.prod.outlook.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/kernel/sys_riscv.c b/arch/riscv/kernel/sys_riscv.c
index 9c0194f176fc09e556a28fb250c2440ada28dbf4..571556bb9261a9686f57f4336dbbe8447031e04b 100644 (file)
--- a/arch/riscv/kernel/sys_riscv.c
+++ b/arch/riscv/kernel/sys_riscv.c
@@ -18,9 +18,8 @@ static long riscv_sys_mmap(unsigned long addr, unsigned long len,
        if (unlikely(offset & (~PAGE_MASK >> page_shift_offset)))
                return -EINVAL;
 
-       if ((prot & PROT_WRITE) && (prot & PROT_EXEC))
-               if (unlikely(!(prot & PROT_READ)))
-                       return -EINVAL;
+       if (unlikely((prot & PROT_WRITE) && !(prot & PROT_READ)))
+               return -EINVAL;
 
        return ksys_mmap_pgoff(addr, len, prot, flags, fd,
                               offset >> (PAGE_SHIFT - page_shift_offset));