linux-kernel - [PATCH 4.15 02/64] arm64: mm: dont write garbage into TTBR1

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Message-Id: <20180226202153.550888076@linuxfoundation.org>
Date:   Mon, 26 Feb 2018 21:21:39 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Nicolas Dechesne <nicolas.dechesne@...aro.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Will Deacon <will.deacon@....com>
Subject: [PATCH 4.15 02/64] arm64: mm: dont write garbage into TTBR1_EL1 register

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

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

From: Ard Biesheuvel <ard.biesheuvel@...aro.org>

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@...r.kernel.org> #v4.14
Reported-by: Nicolas Dechesne <nicolas.dechesne@...aro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Acked-by: Will Deacon <will.deacon@....com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 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