[PATCH 4.15 02/64] arm64: mm: dont write garbage into TTBR1_EL1 register

[Greg Kroah-Hartman]

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>

Stable backport commit 173358a49173 ("arm64: kpti: Add ->enable callback
to remap swapper using nG mappings") of upstream commit f992b4dfd58b did
not survive the backporting process unscathed, and ends up writing garbage
into the TTBR1_EL1 register, rather than pointing it to the zero page to
disable translations. Fix that.

Cc: <stable@xxxxxxxxxxxxxxx> #v4.14
Reported-by: Nicolas Dechesne <nicolas.dechesne@xxxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Acked-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/arm64/mm/proc.S |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -155,7 +155,7 @@ ENDPROC(cpu_do_switch_mm)
 
 .macro	__idmap_cpu_set_reserved_ttbr1, tmp1, tmp2
 	adrp	\tmp1, empty_zero_page
-	msr	ttbr1_el1, \tmp2
+	msr	ttbr1_el1, \tmp1
 	isb
 	tlbi	vmalle1
 	dsb	nsh