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Commit 6ab6463a authored by Larry Bassel's avatar Larry Bassel Committed by Catalin Marinas
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arm64: adjust el0_sync so that a function can be called 



To implement the context tracker properly on arm64,
a function call needs to be made after debugging and
interrupts are turned on, but before the lr is changed
to point to ret_to_user(). If the function call
is made after the lr is changed the function will not
return to the correct place.

For similar reasons, defer the setting of x0 so that
it doesn't need to be saved around the function call
(save far_el1 in x26 temporarily instead).

Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Reviewed-by: default avatarKevin Hilman <khilman@linaro.org>
Tested-by: default avatarKevin Hilman <khilman@linaro.org>
Signed-off-by: default avatarLarry Bassel <larry.bassel@linaro.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent c0c264ae

arch/arm64/kernel/entry.S

+13 −6
Original line number Diff line number Diff line
@@ -353,7 +353,6 @@ el0_sync: 
	lsr	x24, x25, #ESR_EL1_EC_SHIFT	// exception class

	cmp	x24, #ESR_EL1_EC_SVC64		// SVC in 64-bit state

	b.eq	el0_svc

	adr	lr, ret_to_user

	cmp	x24, #ESR_EL1_EC_DABT_EL0	// data abort in EL0

	b.eq	el0_da

	cmp	x24, #ESR_EL1_EC_IABT_EL0	// instruction abort in EL0
@@ -382,7 +381,6 @@ el0_sync_compat: 
	lsr	x24, x25, #ESR_EL1_EC_SHIFT	// exception class

	cmp	x24, #ESR_EL1_EC_SVC32		// SVC in 32-bit state

	b.eq	el0_svc_compat

	adr	lr, ret_to_user

	cmp	x24, #ESR_EL1_EC_DABT_EL0	// data abort in EL0

	b.eq	el0_da

	cmp	x24, #ESR_EL1_EC_IABT_EL0	// instruction abort in EL0
@@ -425,22 +423,25 @@ el0_da: 
	/*

	 * Data abort handling

	 */

	mrs	x0, far_el1

	bic	x0, x0, #(0xff << 56)

	mrs	x26, far_el1

	// enable interrupts before calling the main handler

	enable_dbg_and_irq

	bic	x0, x26, #(0xff << 56)

	mov	x1, x25

	mov	x2, sp

	adr	lr, ret_to_user

	b	do_mem_abort

el0_ia:

	/*

	 * Instruction abort handling

	 */

	mrs	x0, far_el1

	mrs	x26, far_el1

	// enable interrupts before calling the main handler

	enable_dbg_and_irq

	mov	x0, x26

	orr	x1, x25, #1 << 24		// use reserved ISS bit for instruction aborts

	mov	x2, sp

	adr	lr, ret_to_user

	b	do_mem_abort

el0_fpsimd_acc:

	/*
@@ -449,6 +450,7 @@ el0_fpsimd_acc: 
	enable_dbg

	mov	x0, x25

	mov	x1, sp

	adr	lr, ret_to_user

	b	do_fpsimd_acc

el0_fpsimd_exc:

	/*
@@ -457,16 +459,19 @@ el0_fpsimd_exc: 
	enable_dbg

	mov	x0, x25

	mov	x1, sp

	adr	lr, ret_to_user

	b	do_fpsimd_exc

el0_sp_pc:

	/*

	 * Stack or PC alignment exception handling

	 */

	mrs	x0, far_el1

	mrs	x26, far_el1

	// enable interrupts before calling the main handler

	enable_dbg_and_irq

	mov	x0, x26

	mov	x1, x25

	mov	x2, sp

	adr	lr, ret_to_user

	b	do_sp_pc_abort

el0_undef:

	/*
@@ -475,6 +480,7 @@ el0_undef: 
	// enable interrupts before calling the main handler

	enable_dbg_and_irq

	mov	x0, sp

	adr	lr, ret_to_user

	b	do_undefinstr

el0_dbg:

	/*
@@ -492,6 +498,7 @@ el0_inv: 
	mov	x0, sp

	mov	x1, #BAD_SYNC

	mrs	x2, esr_el1

	adr	lr, ret_to_user

	b	bad_mode

ENDPROC(el0_sync)