linux-kernel - [PATCH v2 28/37] arm64: kasan: Enable TBI EL1

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Message-Id: <9ecc27d43a01ca32bcacf44b393a9a100e0dfdb2.1600204505.git.andreyknvl@google.com>
Date:   Tue, 15 Sep 2020 23:16:10 +0200
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Dmitry Vyukov <dvyukov@...gle.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        kasan-dev@...glegroups.com
Cc:     Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Marco Elver <elver@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Elena Petrova <lenaptr@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        Will Deacon <will.deacon@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-arm-kernel@...ts.infradead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH v2 28/37] arm64: kasan: Enable TBI EL1

From: Vincenzo Frascino <vincenzo.frascino@....com>

Hardware tag-based KASAN relies on Memory Tagging Extension (MTE) that is
built on top of the Top Byte Ignore (TBI) feature.

Enable in-kernel TBI when CONFIG_KASAN_HW_TAGS is turned on by enabling
the TCR_TBI1 bit in proc.S.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@....com>
Co-developed-by: Andrey Konovalov <andreyknvl@...gle.com>
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
Change-Id: I91944903bc9c9c9044f0d50e74bcd6b9971d21ff
---
 arch/arm64/mm/proc.S | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 5ba7ac5e9c77..1687447dee7a 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -40,9 +40,13 @@
 #define TCR_CACHE_FLAGS	TCR_IRGN_WBWA | TCR_ORGN_WBWA
 
 #ifdef CONFIG_KASAN_SW_TAGS
-#define TCR_KASAN_FLAGS TCR_TBI1
+#define TCR_KASAN_SW_FLAGS TCR_TBI1
 #else
-#define TCR_KASAN_FLAGS 0
+#define TCR_KASAN_SW_FLAGS 0
+#endif
+
+#ifdef CONFIG_KASAN_HW_TAGS
+#define TCR_KASAN_HW_FLAGS TCR_TBI1
 #endif
 
 /*
@@ -462,7 +466,7 @@ SYM_FUNC_START(__cpu_setup)
 	 */
 	mov_q	x10, TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
 			TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \
-			TCR_TBI0 | TCR_A1 | TCR_KASAN_FLAGS
+			TCR_TBI0 | TCR_A1 | TCR_KASAN_SW_FLAGS
 	tcr_clear_errata_bits x10, x9, x5
 
 #ifdef CONFIG_ARM64_VA_BITS_52
@@ -495,6 +499,9 @@ SYM_FUNC_START(__cpu_setup)
 	/* Update TCR_EL1 if MTE is supported (ID_AA64PFR1_EL1[11:8] > 1) */
 	cbz	mte_present, 1f
 	orr	x10, x10, #SYS_TCR_EL1_TCMA1
+#ifdef CONFIG_KASAN_HW_TAGS
+	orr	x10, x10, #TCR_KASAN_HW_FLAGS
+#endif
 1:
 	.unreq	mte_present
 #endif
-- 
2.28.0.618.gf4bc123cb7-goog