Commit 4bf3286d authored by Will Deacon's avatar Will Deacon
Browse files

arm64: entry: Hook up entry trampoline to exception vectors 



Hook up the entry trampoline to our exception vectors so that all
exceptions from and returns to EL0 go via the trampoline, which swizzles
the vector base register accordingly. Transitioning to and from the
kernel clobbers x30, so we use tpidrro_el0 and far_el1 as scratch
registers for native tasks.

Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
Tested-by: default avatarLaura Abbott <labbott@redhat.com>
Tested-by: default avatarShanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 5b1f7fe4

arch/arm64/kernel/entry.S

+36 −3
Original line number Diff line number Diff line
@@ -73,6 +73,17 @@ 


	.macro kernel_ventry, el, label, regsize = 64

	.align 7

#ifdef CONFIG_UNMAP_KERNEL_AT_EL0

	.if	\el == 0

	.if	\regsize == 64

	mrs	x30, tpidrro_el0

	msr	tpidrro_el0, xzr

	.else

	mov	x30, xzr

	.endif

	.endif

#endif



	sub	sp, sp, #S_FRAME_SIZE

#ifdef CONFIG_VMAP_STACK

	/*
@@ -119,6 +130,11 @@ 
	b	el\()\el\()_\label

	.endm



	.macro tramp_alias, dst, sym

	mov_q	\dst, TRAMP_VALIAS

	add	\dst, \dst, #(\sym - .entry.tramp.text)

	.endm



	.macro	kernel_entry, el, regsize = 64

	.if	\regsize == 32

	mov	w0, w0				// zero upper 32 bits of x0
@@ -271,18 +287,20 @@ alternative_else_nop_endif 
	.if	\el == 0

	ldr	x23, [sp, #S_SP]		// load return stack pointer

	msr	sp_el0, x23

	tst	x22, #PSR_MODE32_BIT		// native task?

	b.eq	3f



#ifdef CONFIG_ARM64_ERRATUM_845719

alternative_if ARM64_WORKAROUND_845719

	tbz	x22, #4, 1f

#ifdef CONFIG_PID_IN_CONTEXTIDR

	mrs	x29, contextidr_el1

	msr	contextidr_el1, x29

#else

	msr contextidr_el1, xzr

#endif

1:

alternative_else_nop_endif

#endif

3:

	.endif



	msr	elr_el1, x21			// set up the return data
@@ -304,7 +322,22 @@ alternative_else_nop_endif 
	ldp	x28, x29, [sp, #16 * 14]

	ldr	lr, [sp, #S_LR]

	add	sp, sp, #S_FRAME_SIZE		// restore sp

	eret					// return to kernel



#ifndef CONFIG_UNMAP_KERNEL_AT_EL0

	eret

#else

	.if	\el == 0

	bne	4f

	msr	far_el1, x30

	tramp_alias	x30, tramp_exit_native

	br	x30

4:

	tramp_alias	x30, tramp_exit_compat

	br	x30

	.else

	eret

	.endif

#endif

	.endm



	.macro	irq_stack_entry

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