Commit 5dad87cd authored by Vincenzo Frascino's avatar Vincenzo Frascino Committed by Stephen Rothwell
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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@google.com

Signed-off-by: Vincenzo Frascino's avatarVincenzo Frascino <vincenzo.frascino@arm.com>
Co-developed-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Signed-off-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: Catalin Marinas's avatarCatalin Marinas <catalin.marinas@arm.com>
Tested-by: Vincenzo Frascino's avatarVincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
parent 264edd81
......@@ -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)
......
/* 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 */
/* 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 */
......@@ -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 *task);
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(struct task_struct *child,
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 */
......@@ -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, struct page *page2)
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 */
......
......@@ -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)
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