Re: [PATCH v12 06/28] riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE

[Arnd Bergmann]

On Thu, Apr 24, 2025, at 14:23, Radim Krčmář wrote:
> 2025-04-23T17:45:53-07:00, Deepak Gupta <debug@xxxxxxxxxxxx>:
>> On Thu, Apr 10, 2025 at 12:03:44PM +0200, Radim Krčmář wrote:
>>>2025-03-14T14:39:25-07:00, Deepak Gupta <debug@xxxxxxxxxxxx>:
>>>Why isn't the previous hunk be enough?  (Or why don't we do just this?)
>>>
>>>riscv_sys_mmap() eventually calls arch_calc_vm_prot_bits(), so I'd
>>>rather fix each code path just once.
>>
>> You're right. Above hunk (arch/riscv/include/asm/mman.h) alone should be enough.
>> I did this change in `sys_riscv.c` out of caution. If it feels like un-necessary,
>> I'll remove it. No hard feelings either way.
>
> I think it makes the code harder to reason about.  Here it is not clear
> why this caller of ksys_mmap_pgoff() has to do this, while others don't.

Right, I've been meaning to clean this up for years: there should
really not be anything architecture specific in the sys_mmap() or
sys_mmap2() syscalls, but we never managed to have a global definition
for those and instead leave them up to the architectures and over
the years they have diverged.

See below for my earlier prototype of this.

       Arnd