In order to avoid having to touch memory with the MMU and caches disabled, and therefore having to invalidate it from the caches explicitly, just defer storing the boot mode until after the MMU has been turned on. Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> --- arch/arm64/kernel/head.S | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index db315129f15d..ec57a29f3f43 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -81,7 +81,8 @@ * The following callee saved general purpose registers are used on the * primary lowlevel boot path: * - * Register Scope Purpose + * Register Scope Purpose + * x20 primary_entry() .. __primary_switch() CPU boot mode * x21 primary_entry() .. start_kernel() FDT pointer passed at boot in x0 * x22 primary_entry() .. start_kernel() whether we entered with the MMU on * x23 __primary_switch() .. relocate_kernel() physical misalignment/KASLR offset @@ -91,7 +92,7 @@ SYM_CODE_START(primary_entry) bl preserve_boot_args bl create_idmap bl init_kernel_el // w0=cpu_boot_mode - bl set_cpu_boot_mode_flag + mov x20, x0 /* * The following calls CPU setup code, see arch/arm64/mm/proc.S for @@ -576,8 +577,6 @@ SYM_FUNC_START_LOCAL(set_cpu_boot_mode_flag) b.ne 1f add x1, x1, #4 1: str w0, [x1] // Save CPU boot mode - dmb sy - dc ivac, x1 // Invalidate potentially stale cache line ret SYM_FUNC_END(set_cpu_boot_mode_flag) @@ -615,7 +614,7 @@ SYM_DATA_END(__early_cpu_boot_status) */ SYM_FUNC_START(secondary_holding_pen) bl init_kernel_el // w0=cpu_boot_mode - bl set_cpu_boot_mode_flag + mov x20, x0 mrs x0, mpidr_el1 mov_q x1, MPIDR_HWID_BITMASK and x0, x0, x1 @@ -633,7 +632,7 @@ SYM_FUNC_END(secondary_holding_pen) */ SYM_FUNC_START(secondary_entry) bl init_kernel_el // w0=cpu_boot_mode - bl set_cpu_boot_mode_flag + mov x20, x0 b secondary_startup SYM_FUNC_END(secondary_entry) @@ -646,6 +645,8 @@ SYM_FUNC_START_LOCAL(secondary_startup) bl __cpu_setup // initialise processor adrp x1, swapper_pg_dir bl __enable_mmu + mov x0, x20 + bl set_cpu_boot_mode_flag ldr x8, =__secondary_switched br x8 SYM_FUNC_END(secondary_startup) @@ -861,6 +862,9 @@ SYM_FUNC_START_LOCAL(__primary_switch) bl __enable_mmu bl clear_page_tables + mov x0, x20 + bl set_cpu_boot_mode_flag + #ifdef CONFIG_RELOCATABLE adrp x23, __PHYS_OFFSET and x23, x23, MIN_KIMG_ALIGN - 1 -- 2.30.2
