powerpc/32s: Prepare Kernel Userspace Access Protection
This patch prepares Kernel Userspace Access Protection for book3s/32. Due to limitations of the processor page protection capabilities, the protection is only against writing. read protection cannot be achieved using page protection. book3s/32 provides the following values for PP bits: PP00 provides RW for Key 0 and NA for Key 1 PP01 provides RW for Key 0 and RO for Key 1 PP10 provides RW for all PP11 provides RO for all Today PP10 is used for RW pages and PP11 for RO pages, and user segment register's Kp and Ks are set to 1. This patch modifies page protection to use PP01 for RW pages and sets user segment registers to Kp 0 and Ks 0. This will allow to setup Userspace write access protection by settng Ks to 1 in the following patch. Kernel space segment registers remain unchanged. Signed-off-by:Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au>
parent
31ed2b13
Please register or sign in to comment