The patch titled
Subject: arm64: mte: add in-kernel MTE helpers
has been added to the -mm tree. Its filename is
arm64-mte-add-in-kernel-mte-helpers.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/arm64-mte-add-in-kernel-mte-helpers.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/arm64-mte-add-in-kernel-mte-helpers.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Subject: arm64: mte: add in-kernel MTE helpers
Provide helper functions to manipulate allocation and pointer tags for
kernel addresses.
Low-level helper functions (mte_assign_*, written in assembly) operate tag
values from the [0x0, 0xF] range. High-level helper functions
(mte_get/set_*) use the [0xF0, 0xFF] range to preserve compatibility with
normal kernel pointers that have 0xFF in their top byte.
MTE_GRANULE_SIZE and related definitions are moved to mte-def.h header
that doesn't have any dependencies and is safe to include into any
low-level header.
Link: https://lkml.kernel.org/r/c31bf759b4411b2d98cdd801eb928e241584fd1f.1606161801.git.andreyknvl@xxxxxxxxxx
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Co-developed-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Tested-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Branislav Rankov <Branislav.Rankov@xxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx>
Cc: Kevin Brodsky <kevin.brodsky@xxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/esr.h | 1
arch/arm64/include/asm/mte-def.h | 15 +++++++
arch/arm64/include/asm/mte-kasan.h | 56 +++++++++++++++++++++++++++
arch/arm64/include/asm/mte.h | 20 ++++++---
arch/arm64/kernel/mte.c | 48 +++++++++++++++++++++++
arch/arm64/lib/mte.S | 16 +++++++
6 files changed, 150 insertions(+), 6 deletions(-)
--- a/arch/arm64/include/asm/esr.h~arm64-mte-add-in-kernel-mte-helpers
+++ a/arch/arm64/include/asm/esr.h
@@ -105,6 +105,7 @@
#define ESR_ELx_FSC (0x3F)
#define ESR_ELx_FSC_TYPE (0x3C)
#define ESR_ELx_FSC_EXTABT (0x10)
+#define ESR_ELx_FSC_MTE (0x11)
#define ESR_ELx_FSC_SERROR (0x11)
#define ESR_ELx_FSC_ACCESS (0x08)
#define ESR_ELx_FSC_FAULT (0x04)
--- /dev/null
+++ a/arch/arm64/include/asm/mte-def.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 ARM Ltd.
+ */
+#ifndef __ASM_MTE_DEF_H
+#define __ASM_MTE_DEF_H
+
+#define MTE_GRANULE_SIZE UL(16)
+#define MTE_GRANULE_MASK (~(MTE_GRANULE_SIZE - 1))
+#define MTE_TAG_SHIFT 56
+#define MTE_TAG_SIZE 4
+#define MTE_TAG_MASK GENMASK((MTE_TAG_SHIFT + (MTE_TAG_SIZE - 1)), MTE_TAG_SHIFT)
+#define MTE_TAG_MAX (MTE_TAG_MASK >> MTE_TAG_SHIFT)
+
+#endif /* __ASM_MTE_DEF_H */
--- a/arch/arm64/include/asm/mte.h~arm64-mte-add-in-kernel-mte-helpers
+++ a/arch/arm64/include/asm/mte.h
@@ -5,14 +5,16 @@
#ifndef __ASM_MTE_H
#define __ASM_MTE_H
-#define MTE_GRANULE_SIZE UL(16)
-#define MTE_GRANULE_MASK (~(MTE_GRANULE_SIZE - 1))
-#define MTE_TAG_SHIFT 56
-#define MTE_TAG_SIZE 4
+#include <asm/compiler.h>
+#include <asm/mte-def.h>
+
+#define __MTE_PREAMBLE ARM64_ASM_PREAMBLE ".arch_extension memtag\n"
#ifndef __ASSEMBLY__
+#include <linux/bitfield.h>
#include <linux/page-flags.h>
+#include <linux/types.h>
#include <asm/pgtable-types.h>
@@ -45,7 +47,9 @@ long get_mte_ctrl(struct task_struct *ta
int mte_ptrace_copy_tags(struct task_struct *child, long request,
unsigned long addr, unsigned long data);
-#else
+void mte_assign_mem_tag_range(void *addr, size_t size);
+
+#else /* CONFIG_ARM64_MTE */
/* unused if !CONFIG_ARM64_MTE, silence the compiler */
#define PG_mte_tagged 0
@@ -80,7 +84,11 @@ static inline int mte_ptrace_copy_tags(s
return -EIO;
}
-#endif
+static inline void mte_assign_mem_tag_range(void *addr, size_t size)
+{
+}
+
+#endif /* CONFIG_ARM64_MTE */
#endif /* __ASSEMBLY__ */
#endif /* __ASM_MTE_H */
--- /dev/null
+++ a/arch/arm64/include/asm/mte-kasan.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 ARM Ltd.
+ */
+#ifndef __ASM_MTE_KASAN_H
+#define __ASM_MTE_KASAN_H
+
+#include <asm/mte-def.h>
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+
+/*
+ * The functions below are meant to be used only for the
+ * KASAN_HW_TAGS interface defined in asm/memory.h.
+ */
+#ifdef CONFIG_ARM64_MTE
+
+static inline u8 mte_get_ptr_tag(void *ptr)
+{
+ /* Note: The format of KASAN tags is 0xF<x> */
+ u8 tag = 0xF0 | (u8)(((u64)(ptr)) >> MTE_TAG_SHIFT);
+
+ return tag;
+}
+
+u8 mte_get_mem_tag(void *addr);
+u8 mte_get_random_tag(void);
+void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag);
+
+#else /* CONFIG_ARM64_MTE */
+
+static inline u8 mte_get_ptr_tag(void *ptr)
+{
+ return 0xFF;
+}
+
+static inline u8 mte_get_mem_tag(void *addr)
+{
+ return 0xFF;
+}
+static inline u8 mte_get_random_tag(void)
+{
+ return 0xFF;
+}
+static inline void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
+{
+ return addr;
+}
+
+#endif /* CONFIG_ARM64_MTE */
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __ASM_MTE_KASAN_H */
--- a/arch/arm64/kernel/mte.c~arm64-mte-add-in-kernel-mte-helpers
+++ a/arch/arm64/kernel/mte.c
@@ -13,10 +13,13 @@
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/thread_info.h>
+#include <linux/types.h>
#include <linux/uio.h>
+#include <asm/barrier.h>
#include <asm/cpufeature.h>
#include <asm/mte.h>
+#include <asm/mte-kasan.h>
#include <asm/ptrace.h>
#include <asm/sysreg.h>
@@ -72,6 +75,51 @@ int memcmp_pages(struct page *page1, str
return ret;
}
+u8 mte_get_mem_tag(void *addr)
+{
+ if (!system_supports_mte())
+ return 0xFF;
+
+ asm(__MTE_PREAMBLE "ldg %0, [%0]"
+ : "+r" (addr));
+
+ return mte_get_ptr_tag(addr);
+}
+
+u8 mte_get_random_tag(void)
+{
+ void *addr;
+
+ if (!system_supports_mte())
+ return 0xFF;
+
+ asm(__MTE_PREAMBLE "irg %0, %0"
+ : "+r" (addr));
+
+ return mte_get_ptr_tag(addr);
+}
+
+void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag)
+{
+ void *ptr = addr;
+
+ if ((!system_supports_mte()) || (size == 0))
+ return addr;
+
+ /* Make sure that size is MTE granule aligned. */
+ WARN_ON(size & (MTE_GRANULE_SIZE - 1));
+
+ /* Make sure that the address is MTE granule aligned. */
+ WARN_ON((u64)addr & (MTE_GRANULE_SIZE - 1));
+
+ tag = 0xF0 | tag;
+ ptr = (void *)__tag_set(ptr, tag);
+
+ mte_assign_mem_tag_range(ptr, size);
+
+ return ptr;
+}
+
static void update_sctlr_el1_tcf0(u64 tcf0)
{
/* ISB required for the kernel uaccess routines */
--- a/arch/arm64/lib/mte.S~arm64-mte-add-in-kernel-mte-helpers
+++ a/arch/arm64/lib/mte.S
@@ -149,3 +149,19 @@ SYM_FUNC_START(mte_restore_page_tags)
ret
SYM_FUNC_END(mte_restore_page_tags)
+
+/*
+ * Assign allocation tags for a region of memory based on the pointer tag
+ * x0 - source pointer
+ * x1 - size
+ *
+ * Note: The address must be non-NULL and MTE_GRANULE_SIZE aligned and
+ * size must be non-zero and MTE_GRANULE_SIZE aligned.
+ */
+SYM_FUNC_START(mte_assign_mem_tag_range)
+1: stg x0, [x0]
+ add x0, x0, #MTE_GRANULE_SIZE
+ subs x1, x1, #MTE_GRANULE_SIZE
+ b.gt 1b
+ ret
+SYM_FUNC_END(mte_assign_mem_tag_range)
_
Patches currently in -mm which might be from vincenzo.frascino@xxxxxxx are
mm-vmalloc-fix-kasan-shadow-poisoning-size.patch
arm64-enable-armv85-a-asm-arch-option.patch
arm64-mte-add-in-kernel-mte-helpers.patch
arm64-mte-reset-the-page-tag-in-page-flags.patch
arm64-mte-add-in-kernel-tag-fault-handler.patch
arm64-kasan-allow-enabling-in-kernel-mte.patch
arm64-mte-convert-gcr_user-into-an-exclude-mask.patch
arm64-mte-switch-gcr_el1-in-kernel-entry-and-exit.patch
kasan-mm-untag-page-address-in-free_reserved_area.patch
kselftest-arm64-check-gcr_el1-after-context-switch.patch
