Balbir Singh <bsinghar...@gmail.com> writes:
> ISA 3 allows for prevention of instruction fetch and execution
> of user mode pages. If such an error occurs, SRR1 bit 35
> reports the error. We catch and report the error in do_page_fault()
>
> Signed-off-by: Balbir Singh <bsinghar...@gmail.com>
> ---
> arch/powerpc/mm/fault.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
> index d0b137d..d498e40 100644
> --- a/arch/powerpc/mm/fault.c
> +++ b/arch/powerpc/mm/fault.c
> @@ -390,6 +390,13 @@ int do_page_fault(struct pt_regs *regs, unsigned long
> address,
> #endif /* CONFIG_8xx */
>
> if (is_exec) {
> +
> + /*
> + * An execution fault + no execute ?
> + */
> + if (regs->msr & SRR1_ISI_N_OR_G)
> + goto bad_area;
> +
Can we get that SRR1 value on cpu with CPU_FTR_NOEXECUTE cleared ?
The comment below says, we should look at at VM_READ and VM_WRITE.
Also don't we need to look at user_mode(regs) here if we are moving this
above the vma check.
> /*
> * Allow execution from readable areas if the MMU does not
> * provide separate controls over reading and executing.
> @@ -404,6 +411,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long
> address,
> (cpu_has_feature(CPU_FTR_NOEXECUTE) ||
> !(vma->vm_flags & (VM_READ | VM_WRITE))))
> goto bad_area;
> +
> #ifdef CONFIG_PPC_STD_MMU
> /*
> * protfault should only happen due to us
> --
> 2.5.5
