Commit d9be0325 authored Jul 11, 2018 by Mark Rutland Committed by Will Deacon Jul 12, 2018

arm64: don't restore GPRs when context tracking



Now that syscalls are invoked with pt_regs, we no longer need to ensure
that the argument regsiters are live in the entry assembly, and it's
fine to not restore them after context_tracking_user_exit() has
corrupted them.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

parent 3b714275

arch/arm64/kernel/entry.S

+1 −11

Original line number	Diff line number	Diff line
		@@ -41,19 +41,9 @@
		* Context tracking subsystem. Used to instrument transitions
		* between user and kernel mode.
		*/
		.macro ct_user_exit, syscall = 0
		.macro ct_user_exit
		#ifdef CONFIG_CONTEXT_TRACKING
		bl context_tracking_user_exit
		.if \syscall == 1
		/*
		* Save/restore needed during syscalls. Restore syscall arguments from
		* the values already saved on stack during kernel_entry.
		*/
		ldp x0, x1, [sp]
		ldp x2, x3, [sp, #S_X2]
		ldp x4, x5, [sp, #S_X4]
		ldp x6, x7, [sp, #S_X6]
		.endif
		#endif
		.endm