Commit f481bb32 authored by Will Deacon's avatar Will Deacon
Browse files

Reapply "arm64: fpsimd: Implement lazy restore for kernel mode FPSIMD" 



This reverts commit b8995a18.

Ard managed to reproduce the dm-crypt corruption problem and got to the
bottom of it, so re-apply the problematic patch in preparation for
fixing things properly.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent ffbf4fb9

arch/arm64/include/asm/processor.h

+1 −0
Original line number Diff line number Diff line
@@ -171,6 +171,7 @@ struct thread_struct { 
	struct debug_info	debug;		/* debugging */



	struct user_fpsimd_state	kernel_fpsimd_state;

	unsigned int			kernel_fpsimd_cpu;

#ifdef CONFIG_ARM64_PTR_AUTH

	struct ptrauth_keys_user	keys_user;

#ifdef CONFIG_ARM64_PTR_AUTH_KERNEL

arch/arm64/kernel/fpsimd.c

+18 −0
Original line number Diff line number Diff line
@@ -1509,12 +1509,30 @@ void do_fpsimd_exc(unsigned long esr, struct pt_regs *regs) 


static void fpsimd_load_kernel_state(struct task_struct *task)

{

	struct cpu_fp_state *last = this_cpu_ptr(&fpsimd_last_state);



	/*

	 * Elide the load if this CPU holds the most recent kernel mode

	 * FPSIMD context of the current task.

	 */

	if (last->st == &task->thread.kernel_fpsimd_state &&

	    task->thread.kernel_fpsimd_cpu == smp_processor_id())

		return;



	fpsimd_load_state(&task->thread.kernel_fpsimd_state);

}



static void fpsimd_save_kernel_state(struct task_struct *task)

{

	struct cpu_fp_state cpu_fp_state = {

		.st		= &task->thread.kernel_fpsimd_state,

		.to_save	= FP_STATE_FPSIMD,

	};



	fpsimd_save_state(&task->thread.kernel_fpsimd_state);

	fpsimd_bind_state_to_cpu(&cpu_fp_state);



	task->thread.kernel_fpsimd_cpu = smp_processor_id();

}



void fpsimd_thread_switch(struct task_struct *next)