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Subject[PATCH v3 30/39] arm64: kasan: Enable TBI EL1
From
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
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