Hi Jun, On 22/08/18 10:54, Jun Yao wrote: > The kernel sets up the initial page table in the init_pg_dir.
(Nit: 'will set up', it doesn't until patch 3.) > However, it will create the final page table in the swapper_pg_dir > during the initialization process. We need to let __enable_mmu() > know which page table to use. > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S > index 2c83a8c47e3f..c3e4b1886cde 100644 > --- a/arch/arm64/kernel/head.S > +++ b/arch/arm64/kernel/head.S > @@ -756,6 +757,7 @@ ENDPROC(__secondary_switched) > * Enable the MMU. > * > * x0 = SCTLR_EL1 value for turning on the MMU. > + * x1 = TTBR1_EL1 value for turning on the MMU. > * > * Returns to the caller via x30/lr. This requires the caller to be covered > * by the .idmap.text section. > @@ -764,15 +766,15 @@ ENDPROC(__secondary_switched) > * If it isn't, park the CPU > */ > ENTRY(__enable_mmu) > - mrs x1, ID_AA64MMFR0_EL1 > - ubfx x2, x1, #ID_AA64MMFR0_TGRAN_SHIFT, 4 > - cmp x2, #ID_AA64MMFR0_TGRAN_SUPPORTED > + mrs x5, ID_AA64MMFR0_EL1 > + ubfx x6, x5, #ID_AA64MMFR0_TGRAN_SHIFT, 4 > + cmp x6, #ID_AA64MMFR0_TGRAN_SUPPORTED > b.ne __no_granule_support > - update_early_cpu_boot_status 0, x1, x2 > - adrp x1, idmap_pg_dir > - adrp x2, swapper_pg_dir > - phys_to_ttbr x3, x1 > - phys_to_ttbr x4, x2 > + update_early_cpu_boot_status 0, x5, x6 > + adrp x5, idmap_pg_dir > + mov x6, x1 > + phys_to_ttbr x3, x5 > + phys_to_ttbr x4, x6 > msr ttbr0_el1, x3 // load TTBR0 > msr ttbr1_el1, x4 // load TTBR1 > isb > @@ -791,7 +793,7 @@ ENDPROC(__enable_mmu) > > __no_granule_support: > /* Indicate that this CPU can't boot and is stuck in the kernel */ > - update_early_cpu_boot_status CPU_STUCK_IN_KERNEL, x1, x2 > + update_early_cpu_boot_status CPU_STUCK_IN_KERNEL, x5, x6 (You don't need to change these as they are both temporary registers.) Reviewed-by: James Morse <james.mo...@arm.com> Thanks, James
