Commit 3305e7f7 authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon
Browse files

arm64: smp: remove stack from secondary_data 



When we boot a secondary CPU, we pass it a task and a stack to use. As
the stack is always the task's stack, which can be derived from the
task, let's have the secondary CPU derive this itself and avoid passing
redundant information.

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/20210520115031.18509-5-mark.rutland@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 98c7a166

arch/arm64/include/asm/smp.h

+0 −2
Original line number Diff line number Diff line
@@ -73,12 +73,10 @@ asmlinkage void secondary_start_kernel(void); 


/*

 * Initial data for bringing up a secondary CPU.

 * @stack  - sp for the secondary CPU

 * @status - Result passed back from the secondary CPU to

 *           indicate failure.

 */

struct secondary_data {

	void *stack;

	struct task_struct *task;

	long status;

};

arch/arm64/kernel/asm-offsets.c

+0 −1
Original line number Diff line number Diff line
@@ -99,7 +99,6 @@ int main(void) 
  DEFINE(SOFTIRQ_SHIFT, SOFTIRQ_SHIFT);

  DEFINE(IRQ_CPUSTAT_SOFTIRQ_PENDING, offsetof(irq_cpustat_t, __softirq_pending));

  BLANK();

  DEFINE(CPU_BOOT_STACK,	offsetof(struct secondary_data, stack));

  DEFINE(CPU_BOOT_TASK,		offsetof(struct secondary_data, task));

  BLANK();

  DEFINE(FTR_OVR_VAL_OFFSET,	offsetof(struct arm64_ftr_override, val));

arch/arm64/kernel/head.S

+4 −3
Original line number Diff line number Diff line
@@ -645,11 +645,12 @@ SYM_FUNC_START_LOCAL(__secondary_switched) 
	isb



	adr_l	x0, secondary_data

	ldr	x1, [x0, #CPU_BOOT_STACK]	// get secondary_data.stack

	cbz	x1, __secondary_too_slow

	mov	sp, x1

	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

arch/arm64/kernel/smp.c

+0 −2
Original line number Diff line number Diff line
@@ -120,7 +120,6 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) 
	 * page tables.

	 */

	secondary_data.task = idle;

	secondary_data.stack = task_stack_page(idle) + THREAD_SIZE;

	update_cpu_boot_status(CPU_MMU_OFF);



	/* Now bring the CPU into our world */
@@ -141,7 +140,6 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) 


	pr_crit("CPU%u: failed to come online\n", cpu);

	secondary_data.task = NULL;

	secondary_data.stack = NULL;

	status = READ_ONCE(secondary_data.status);

	if (status == CPU_MMU_OFF)

		status = READ_ONCE(__early_cpu_boot_status);