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Date: Thu, 30 Mar 2023 14:50:51 +0800
From: Youling Tang <tangyouling@...ngson.cn>
To: Qing Zhang <zhangqing@...ngson.cn>
Cc: Andrey Ryabinin <ryabinin.a.a@...il.com>,
Jonathan Corbet <corbet@....net>,
Huacai Chen <chenhuacai@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Alexander Potapenko <glider@...gle.com>,
Andrey Konovalov <andreyknvl@...il.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Vincenzo Frascino <vincenzo.frascino@....com>,
WANG Xuerui <kernel@...0n.name>,
Jiaxun Yang <jiaxun.yang@...goat.com>,
kasan-dev@...glegroups.com, linux-doc@...r.kernel.org,
linux-mm@...ck.org, loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] LoongArch: Add kernel address sanitizer support
Hi, Qing
On 03/28/2023 07:17 PM, Qing Zhang wrote:
> 1/8 of kernel addresses reserved for shadow memory. But for LoongArch,
> There are a lot of holes between different segments and valid address
> space(256T available) is insufficient to map all these segments to kasan
> shadow memory with the common formula provided by kasan core, saying
> addr >> KASAN_SHADOW_SCALE_SHIFT) + KASAN_SHADOW_OFFSET
>
> So Loongarch has a ARCH specific mapping formula,different segments
> are mapped individually, and only limited length of space of that
> specific segment is mapped to shadow.
>
> At early boot stage the whole shadow region populated with just
> one physical page (kasan_early_shadow_page). Later, this page is
> reused as readonly zero shadow for some memory that Kasan currently
> don't track.
> After mapping the physical memory, pages for shadow memory are
> allocated and mapped.
>
> Functions like memset/memmove/memcpy do a lot of memory accesses.
> If bad pointer passed to one of these function it is important
> to catch this. Compiler's instrumentation cannot do this since
> these functions are written in assembly.
> KASan replaces memory functions with manually instrumented variants.
> Original functions declared as weak symbols so strong definitions
> in mm/kasan/kasan.c could replace them. Original functions have aliases
> with '__' prefix in name, so we could call non-instrumented variant
> if needed.
>
> Signed-off-by: Qing Zhang <zhangqing@...ngson.cn>
> ---
> Documentation/dev-tools/kasan.rst | 4 +-
> .../features/debug/KASAN/arch-support.txt | 2 +-
> arch/loongarch/Kconfig | 7 +
> arch/loongarch/include/asm/kasan.h | 120 +++++++++
> arch/loongarch/include/asm/pgtable.h | 7 +
> arch/loongarch/include/asm/setup.h | 2 +-
> arch/loongarch/include/asm/string.h | 20 ++
> arch/loongarch/kernel/Makefile | 3 +
> arch/loongarch/kernel/head.S | 14 +-
> arch/loongarch/kernel/relocate.c | 8 +-
> arch/loongarch/kernel/setup.c | 4 +
> arch/loongarch/lib/memcpy.S | 4 +-
> arch/loongarch/lib/memmove.S | 13 +-
> arch/loongarch/lib/memset.S | 4 +-
> arch/loongarch/mm/Makefile | 2 +
> arch/loongarch/mm/kasan_init.c | 255 ++++++++++++++++++
> arch/loongarch/vdso/Makefile | 4 +
> include/linux/kasan.h | 2 +
> mm/kasan/generic.c | 5 +
> mm/kasan/init.c | 10 +-
> mm/kasan/kasan.h | 6 +
> 21 files changed, 470 insertions(+), 26 deletions(-)
> create mode 100644 arch/loongarch/include/asm/kasan.h
> create mode 100644 arch/loongarch/mm/kasan_init.c
>
> diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
> index e66916a483cd..ee91f2872767 100644
> --- a/Documentation/dev-tools/kasan.rst
> +++ b/Documentation/dev-tools/kasan.rst
> @@ -41,8 +41,8 @@ Support
> Architectures
> ~~~~~~~~~~~~~
>
> -Generic KASAN is supported on x86_64, arm, arm64, powerpc, riscv, s390, and
> -xtensa, and the tag-based KASAN modes are supported only on arm64.
> +Generic KASAN is supported on x86_64, arm, arm64, powerpc, riscv, s390, xtensa,
> +and loongarch, and the tag-based KASAN modes are supported only on arm64.
>
> Compilers
> ~~~~~~~~~
> diff --git a/Documentation/features/debug/KASAN/arch-support.txt b/Documentation/features/debug/KASAN/arch-support.txt
> index bf0124fae643..c4581c2edb28 100644
> --- a/Documentation/features/debug/KASAN/arch-support.txt
> +++ b/Documentation/features/debug/KASAN/arch-support.txt
> @@ -13,7 +13,7 @@
> | csky: | TODO |
> | hexagon: | TODO |
> | ia64: | TODO |
> - | loongarch: | TODO |
> + | loongarch: | ok |
> | m68k: | TODO |
> | microblaze: | TODO |
> | mips: | TODO |
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index 72dd00f48b8c..61f883c51045 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -7,6 +7,7 @@ config LOONGARCH
> select ACPI_MCFG if ACPI
> select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI
> select ARCH_BINFMT_ELF_STATE
> + select ARCH_DISABLE_KASAN_INLINE
> select ARCH_ENABLE_MEMORY_HOTPLUG
> select ARCH_ENABLE_MEMORY_HOTREMOVE
> select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
> @@ -83,6 +84,7 @@ config LOONGARCH
> select HAVE_ARCH_AUDITSYSCALL
> select HAVE_ARCH_MMAP_RND_BITS if MMU
> select HAVE_ARCH_SECCOMP_FILTER
> + select HAVE_ARCH_KASAN if 64BIT
> select HAVE_ARCH_TRACEHOOK
> select HAVE_ARCH_TRANSPARENT_HUGEPAGE
> select HAVE_ASM_MODVERSIONS
> @@ -626,6 +628,11 @@ config ARCH_MMAP_RND_BITS_MIN
> config ARCH_MMAP_RND_BITS_MAX
> default 18
>
> +config KASAN_SHADOW_OFFSET
> + hex
> + default 0x0
> + depends on KASAN
> +
> menu "Power management options"
>
> config ARCH_SUSPEND_POSSIBLE
> diff --git a/arch/loongarch/include/asm/kasan.h b/arch/loongarch/include/asm/kasan.h
> new file mode 100644
> index 000000000000..582bcded311e
> --- /dev/null
> +++ b/arch/loongarch/include/asm/kasan.h
> @@ -0,0 +1,120 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __ASM_KASAN_H
> +#define __ASM_KASAN_H
> +
> +#ifndef __ASSEMBLY__
> +
> +#include <linux/linkage.h>
> +#include <linux/mmzone.h>
> +#include <asm/addrspace.h>
> +#include <asm/io.h>
> +#include <asm/pgtable.h>
> +
> +#define __HAVE_ARCH_SHADOW_MAP
> +
> +#define KASAN_SHADOW_SCALE_SHIFT 3
> +#define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
> +
> +#define XRANGE_SHIFT (48)
> +
> +/* Valid address length */
> +#define XRANGE_SHADOW_SHIFT (PGDIR_SHIFT + PAGE_SHIFT - 3)
> +/* Used for taking out the valid address */
> +#define XRANGE_SHADOW_MASK GENMASK_ULL(XRANGE_SHADOW_SHIFT - 1, 0)
> +/* One segment whole address space size */
> +#define XRANGE_SIZE (XRANGE_SHADOW_MASK + 1)
> +
> +/* 64-bit segment value. */
> +#define XKPRANGE_UC_SEG (0x8000)
> +#define XKPRANGE_CC_SEG (0x9000)
> +#define XKVRANGE_VC_SEG (0xffff)
> +
> +/* Cached */
> +#define XKPRANGE_CC_START CACHE_BASE
> +#define XKPRANGE_CC_SIZE XRANGE_SIZE
> +#define XKPRANGE_CC_KASAN_OFFSET (0)
> +#define XKPRANGE_CC_SHADOW_SIZE (XKPRANGE_CC_SIZE >> KASAN_SHADOW_SCALE_SHIFT)
> +#define XKPRANGE_CC_SHADOW_END (XKPRANGE_CC_KASAN_OFFSET + XKPRANGE_CC_SHADOW_SIZE)
> +
> +/* UnCached */
> +#define XKPRANGE_UC_START UNCACHE_BASE
> +#define XKPRANGE_UC_SIZE XRANGE_SIZE
> +#define XKPRANGE_UC_KASAN_OFFSET XKPRANGE_CC_SHADOW_END
> +#define XKPRANGE_UC_SHADOW_SIZE (XKPRANGE_UC_SIZE >> KASAN_SHADOW_SCALE_SHIFT)
> +#define XKPRANGE_UC_SHADOW_END (XKPRANGE_UC_KASAN_OFFSET + XKPRANGE_UC_SHADOW_SIZE)
> +
> +/* VMALLOC (Cached or UnCached) */
> +#define XKVRANGE_VC_START MODULES_VADDR
> +#define XKVRANGE_VC_SIZE round_up(VMEMMAP_END - MODULES_VADDR + 1, PGDIR_SIZE)
> +#define XKVRANGE_VC_KASAN_OFFSET XKPRANGE_UC_SHADOW_END
> +#define XKVRANGE_VC_SHADOW_SIZE (XKVRANGE_VC_SIZE >> KASAN_SHADOW_SCALE_SHIFT)
> +#define XKVRANGE_VC_SHADOW_END (XKVRANGE_VC_KASAN_OFFSET + XKVRANGE_VC_SHADOW_SIZE)
> +
> +/* Kasan shadow memory start right after vmalloc. */
> +#define KASAN_SHADOW_START round_up(VMEMMAP_END, PGDIR_SIZE)
> +#define KASAN_SHADOW_SIZE (XKVRANGE_VC_SHADOW_END - XKPRANGE_CC_KASAN_OFFSET)
> +#define KASAN_SHADOW_END round_up(KASAN_SHADOW_START + KASAN_SHADOW_SIZE, PGDIR_SIZE)
> +
> +#define XKPRANGE_CC_SHADOW_OFFSET (KASAN_SHADOW_START + XKPRANGE_CC_KASAN_OFFSET)
> +#define XKPRANGE_UC_SHADOW_OFFSET (KASAN_SHADOW_START + XKPRANGE_UC_KASAN_OFFSET)
> +#define XKVRANGE_VC_SHADOW_OFFSET (KASAN_SHADOW_START + XKVRANGE_VC_KASAN_OFFSET)
> +
> +extern bool kasan_early_stage;
> +extern unsigned char kasan_early_shadow_page[PAGE_SIZE];
> +
> +static inline void *kasan_mem_to_shadow(const void *addr)
> +{
> + if (kasan_early_stage) {
> + return (void *)(kasan_early_shadow_page);
> + } else {
> + unsigned long maddr = (unsigned long)addr;
> + unsigned long xrange = (maddr >> XRANGE_SHIFT) & 0xffff;
> + unsigned long offset = 0;
> +
> + maddr &= XRANGE_SHADOW_MASK;
> + switch (xrange) {
> + case XKPRANGE_CC_SEG:
> + offset = XKPRANGE_CC_SHADOW_OFFSET;
> + break;
> + case XKPRANGE_UC_SEG:
> + offset = XKPRANGE_UC_SHADOW_OFFSET;
> + break;
> + case XKVRANGE_VC_SEG:
> + offset = XKVRANGE_VC_SHADOW_OFFSET;
> + break;
> + default:
> + WARN_ON(1);
> + return NULL;
> + }
> +
> + return (void *)((maddr >> KASAN_SHADOW_SCALE_SHIFT) + offset);
> + }
> +}
> +
> +static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
> +{
> + unsigned long addr = (unsigned long)shadow_addr;
> +
> + if (unlikely(addr > KASAN_SHADOW_END) ||
> + unlikely(addr < KASAN_SHADOW_START)) {
> + WARN_ON(1);
> + return NULL;
> + }
> +
> + if (addr >= XKVRANGE_VC_SHADOW_OFFSET)
> + return (void *)(((addr - XKVRANGE_VC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKVRANGE_VC_START);
> + else if (addr >= XKPRANGE_UC_SHADOW_OFFSET)
> + return (void *)(((addr - XKPRANGE_UC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_UC_START);
> + else if (addr >= XKPRANGE_CC_SHADOW_OFFSET)
> + return (void *)(((addr - XKPRANGE_CC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_CC_START);
> + else {
> + WARN_ON(1);
> + return NULL;
> + }
> +}
> +
> +void kasan_init(void);
> +asmlinkage void kasan_early_init(void);
> +
> +#endif
> +#endif
> diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h
> index d28fb9dbec59..5cfdf79b287e 100644
> --- a/arch/loongarch/include/asm/pgtable.h
> +++ b/arch/loongarch/include/asm/pgtable.h
> @@ -86,9 +86,16 @@ extern unsigned long zero_page_mask;
> #define MODULES_END (MODULES_VADDR + SZ_256M)
>
> #define VMALLOC_START MODULES_END
> +
> +#ifndef CONFIG_KASAN
> #define VMALLOC_END \
> (vm_map_base + \
> min(PTRS_PER_PGD * PTRS_PER_PUD * PTRS_PER_PMD * PTRS_PER_PTE * PAGE_SIZE, (1UL << cpu_vabits)) - PMD_SIZE - VMEMMAP_SIZE)
> +#else
> +#define VMALLOC_END \
> + (vm_map_base + \
> + min(PTRS_PER_PGD * PTRS_PER_PUD * PTRS_PER_PMD * PTRS_PER_PTE * PAGE_SIZE, (1UL << cpu_vabits) / 2) - PMD_SIZE - VMEMMAP_SIZE)
> +#endif
>
> #define vmemmap ((struct page *)((VMALLOC_END + PMD_SIZE) & PMD_MASK))
> #define VMEMMAP_END ((unsigned long)vmemmap + VMEMMAP_SIZE - 1)
> diff --git a/arch/loongarch/include/asm/setup.h b/arch/loongarch/include/asm/setup.h
> index be05c0e706a2..2dca0d1dd90a 100644
> --- a/arch/loongarch/include/asm/setup.h
> +++ b/arch/loongarch/include/asm/setup.h
> @@ -33,7 +33,7 @@ extern long __la_abs_end;
> extern long __rela_dyn_begin;
> extern long __rela_dyn_end;
>
> -extern void * __init relocate_kernel(void);
> +extern unsigned long __init relocate_kernel(void);
>
> #endif
>
> diff --git a/arch/loongarch/include/asm/string.h b/arch/loongarch/include/asm/string.h
> index 7b29cc9c70aa..5bb5a90d2681 100644
> --- a/arch/loongarch/include/asm/string.h
> +++ b/arch/loongarch/include/asm/string.h
> @@ -7,11 +7,31 @@
>
> #define __HAVE_ARCH_MEMSET
> extern void *memset(void *__s, int __c, size_t __count);
> +extern void *__memset(void *__s, int __c, size_t __count);
>
> #define __HAVE_ARCH_MEMCPY
> extern void *memcpy(void *__to, __const__ void *__from, size_t __n);
> +extern void *__memcpy(void *__to, __const__ void *__from, size_t __n);
>
> #define __HAVE_ARCH_MEMMOVE
> extern void *memmove(void *__dest, __const__ void *__src, size_t __n);
> +extern void *__memmove(void *__dest, __const__ void *__src, size_t __n);
> +
> +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
> +
> +/*
> + * For files that are not instrumented (e.g. mm/slub.c) we
> + * should use not instrumented version of mem* functions.
> + */
> +
> +#define memset(s, c, n) __memset(s, c, n)
> +#define memcpy(dst, src, len) __memcpy(dst, src, len)
> +#define memmove(dst, src, len) __memmove(dst, src, len)
> +
> +#ifndef __NO_FORTIFY
> +#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
If we need to add __NO_FORTIFY processing, please add
ARCH_HAS_FORTIFY_SOURCE in Kconfig, and submit a separate patch like
9530141455c9 ("riscv: Add ARCH_HAS_FORTIFY_SOURCE").
Youling.
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