[PATCH] powerpc/mm: Fix false detection of read faults

[Michael Ellerman]

On Fri, 10 Mar 2023 16:08:34 +1100, Russell Currey wrote:
> To support detection of read faults with Radix execute-only memory, the
> vma_is_accessible() check in access_error() (which checks for PROT_NONE)
> was replaced with a check to see if VM_READ was missing, and if so,
> returns true to assert the fault was caused by a bad read.
> 
> This is incorrect, as it ignores that both VM_WRITE and VM_EXEC imply
> read on powerpc, as defined in protection_map[].  This causes mappings
> containing VM_WRITE or VM_EXEC without VM_READ to misreport the cause of
> page faults, since the MMU is still allowing reads.
> 
> [...]

Applied to powerpc/fixes.

[1/1] powerpc/mm: Fix false detection of read faults
      https://git.kernel.org/powerpc/c/f2c7e3562b4c4f1699acc1538ebf3e75f5cced35

cheers