Commit 8e334d72 authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon
Browse files

arm64: smp: unify task and sp setup 



Once we enable the MMU, we have to initialize:

* SP_EL0 to point at the active task
* SP to point at the active task's stack
* SCS_SP to point at the active task's shadow stack

For all tasks (including init_task), this information can be derived
from the task's task_struct.

Let's unify __primary_switched and __secondary_switched to consistently
acquire this information from the relevant task_struct. At the same
time, let's fold this together with initializing a task's final frame.

There should be no functional change as a result of this patch.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Suzuki Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: default avatarArd Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20210520115031.18509-6-mark.rutland@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 3305e7f7

arch/arm64/kernel/head.S

+15 −18
Original line number Diff line number Diff line
@@ -395,15 +395,24 @@ SYM_FUNC_START_LOCAL(__create_page_tables) 
SYM_FUNC_END(__create_page_tables)



	/*

	 * Initialize CPU registers with task-specific and cpu-specific context.

	 *

	 * Create a final frame record at task_pt_regs(current)->stackframe, so

	 * that the unwinder can identify the final frame record of any task by

	 * its location in the task stack. We reserve the entire pt_regs space

	 * for consistency with user tasks and kthreads.

	 */

	.macro setup_final_frame

	.macro	init_cpu_task tsk, tmp

	msr	sp_el0, \tsk



	ldr	\tmp, [\tsk, #TSK_STACK]

	add	sp, \tmp, #THREAD_SIZE

	sub	sp, sp, #PT_REGS_SIZE



	stp	xzr, xzr, [sp, #S_STACKFRAME]

	add	x29, sp, #S_STACKFRAME



	scs_load \tsk, \tmp

	.endm



/*
@@ -412,22 +421,16 @@ SYM_FUNC_END(__create_page_tables) 
 *   x0 = __PHYS_OFFSET

 */

SYM_FUNC_START_LOCAL(__primary_switched)

	adrp	x4, init_thread_union

	add	sp, x4, #THREAD_SIZE

	adr_l	x5, init_task

	msr	sp_el0, x5			// Save thread_info

	adr_l	x4, init_task

	init_cpu_task x4, x5



	adr_l	x8, vectors			// load VBAR_EL1 with virtual

	msr	vbar_el1, x8			// vector table address

	isb



	stp	xzr, x30, [sp, #-16]!

	stp	x29, x30, [sp, #-16]!

	mov	x29, sp



#ifdef CONFIG_SHADOW_CALL_STACK

	adr_l	scs_sp, init_shadow_call_stack	// Set shadow call stack

#endif



	str_l	x21, __fdt_pointer, x5		// Save FDT pointer



	ldr_l	x4, kimage_vaddr		// Save the offset between
@@ -459,8 +462,7 @@ SYM_FUNC_START_LOCAL(__primary_switched) 
0:

#endif

	bl	switch_to_vhe			// Prefer VHE if possible

	add	sp, sp, #16

	setup_final_frame

	ldp	x29, x30, [sp], #16

	bl	start_kernel

	ASM_BUG()

SYM_FUNC_END(__primary_switched)
@@ -648,12 +650,7 @@ SYM_FUNC_START_LOCAL(__secondary_switched) 
	ldr	x2, [x0, #CPU_BOOT_TASK]

	cbz	x2, __secondary_too_slow



	ldr	x1, [x2, #TSK_STACK]

	add	sp, x1, #THREAD_SIZE



	msr	sp_el0, x2

	scs_load x2, x3

	setup_final_frame

	init_cpu_task x2, x1



#ifdef CONFIG_ARM64_PTR_AUTH

	ptrauth_keys_init_cpu x2, x3, x4, x5