On Thu, Dec 06, 2018 at 11:50:12AM +0000, Catalin Marinas wrote: > On Wed, Dec 05, 2018 at 04:41:43PM +0000, Steve Capper wrote: > > diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h > > index 4128bec033f6..cd361dd16b12 100644 > > --- a/arch/arm64/include/asm/asm-uaccess.h > > +++ b/arch/arm64/include/asm/asm-uaccess.h > > @@ -14,11 +14,13 @@ > > #ifdef CONFIG_ARM64_SW_TTBR0_PAN > > .macro __uaccess_ttbr0_disable, tmp1 > > mrs \tmp1, ttbr1_el1 // swapper_pg_dir > > + restore_ttbr1 \tmp1 > > bic \tmp1, \tmp1, #TTBR_ASID_MASK > > sub \tmp1, \tmp1, #RESERVED_TTBR0_SIZE // reserved_ttbr0 just before swapper_pg_dir > > msr ttbr0_el1, \tmp1 // set reserved TTBR0_EL1 > > isb > > add \tmp1, \tmp1, #RESERVED_TTBR0_SIZE > > + offset_ttbr1 \tmp1 > > msr ttbr1_el1, \tmp1 // set reserved ASID > > isb > > .endm > > @@ -27,8 +29,10 @@ > > get_thread_info \tmp1 > > ldr \tmp1, [\tmp1, #TSK_TI_TTBR0] // load saved TTBR0_EL1 > > mrs \tmp2, ttbr1_el1 > > + restore_ttbr1 \tmp2 > > extr \tmp2, \tmp2, \tmp1, #48 > > ror \tmp2, \tmp2, #16 > > + offset_ttbr1 \tmp2 > > msr ttbr1_el1, \tmp2 // set the active ASID > > isb > > msr ttbr0_el1, \tmp1 // set the non-PAN TTBR0_EL1 > > The patch looks alright but I think we can simplify it further if we add: > > depends on ARM64_PAN || !ARM64_SW_TTBR0_PAN > > to the 52-bit Kconfig entry. Ahh, thank you okay, I didn't make the connection that Privileged access never was a mandatory feature in ARMv8.1. Cheers, -- Steve
