On Mon, Mar 5, 2018 at 3:36 PM, Mark Rutland <mark.rutland@xxxxxxx> wrote: > On Fri, Mar 02, 2018 at 08:44:25PM +0100, Andrey Konovalov wrote: >> KHWASAN uses the Top Byte Ignore feature of arm64 CPUs to store a pointer >> tag in the top byte of each pointer. This commit enables the TCR_TBI1 bit, >> which enables Top Byte Ignore for the kernel, when KHWASAN is used. >> --- >> arch/arm64/include/asm/pgtable-hwdef.h | 1 + >> arch/arm64/mm/proc.S | 8 +++++++- >> 2 files changed, 8 insertions(+), 1 deletion(-) > > Before it's safe to do this, I also think you'll need to fix up at > least: > > * virt_to_phys() I've already got some issues with it (the jbd2 patch), so I'll look into this. > > * access_ok() This is used for accessing user addresses, and they are not tagged. Am I missing something? > > ... and potentially others which assume that bits [63:56] of kernel > addresses are 0xff. For example, bits of the fault handling logic might > need fixups. I'll look into this as well. > > Thanks, > Mark.
