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Date:   Fri, 25 Sep 2020 00:50:37 +0200
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Subject: [PATCH v3 30/39] arm64: kasan: Enable TBI EL1
From:   Andrey Konovalov <andreyknvl@google.com>
To:     Dmitry Vyukov <dvyukov@google.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        kasan-dev@googlegroups.com
Cc:     Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Alexander Potapenko <glider@google.com>,
        Marco Elver <elver@google.com>,
        Evgenii Stepanov <eugenis@google.com>,
        Elena Petrova <lenaptr@google.com>,
        Branislav Rankov <Branislav.Rankov@arm.com>,
        Kevin Brodsky <kevin.brodsky@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Andrey Konovalov <andreyknvl@google.com>
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From: Vincenzo Frascino <vincenzo.frascino@arm.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@arm.com>
Co-developed-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.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 12ba98bc3b3f..dce06e553c7c 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
 
 /*
@@ -454,6 +458,9 @@ SYM_FUNC_START(__cpu_setup)
 
 	/* set the TCR_EL1 bits */
 	orr	mte_tcr, mte_tcr, #SYS_TCR_EL1_TCMA1
+#ifdef CONFIG_KASAN_HW_TAGS
+	orr	mte_tcr, mte_tcr, #TCR_KASAN_HW_FLAGS
+#endif
 1:
 #endif
 	msr	mair_el1, x5
@@ -463,7 +470,7 @@ 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
 #ifdef CONFIG_ARM64_MTE
 	orr	x10, x10, mte_tcr
 	.unreq	mte_tcr
-- 
2.28.0.681.g6f77f65b4e-goog