Christophe Leroy <christophe.le...@csgroup.eu> writes:
> In the old days, when we didn't have kernel userspace access
> protection and had set_fs(), it was wise to use __get_user()
> and friends to read kernel memory.
>
> Nowadays, get_user() is granting userspace access and is exclusively
> for userspace access.
>
> In alignment exception handler, use probe_kernel_read_inst()
> instead of __get_user_instr() for reading instructions in kernel.
>
> This will allow to remove the is_kernel_addr() check in
> __get/put_user() in a following patch.
>
Looks good to me!
Reviewed-by: Daniel Axtens <d...@axtens.net>
Kind regards,
Daniel
> Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
> ---
> arch/powerpc/kernel/align.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kernel/align.c b/arch/powerpc/kernel/align.c
> index c4d7b445b459..8d4c7af262e2 100644
> --- a/arch/powerpc/kernel/align.c
> +++ b/arch/powerpc/kernel/align.c
> @@ -310,7 +310,11 @@ int fix_alignment(struct pt_regs *regs)
> */
> CHECK_FULL_REGS(regs);
>
> - if (unlikely(__get_user_instr(instr, (void __user *)regs->nip)))
> + if (is_kernel_addr(regs->nip))
> + r = probe_kernel_read_inst(&instr, (void *)regs->nip);
> + else
> + r = __get_user_instr(instr, (void __user *)regs->nip);
> + if (unlikely(r))
> return -EFAULT;
> if ((regs->msr & MSR_LE) != (MSR_KERNEL & MSR_LE)) {
> /* We don't handle PPC little-endian any more... */
> --
> 2.25.0
