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Date: Tue, 28 Mar 2023 20:08:34 +0800
From: Youling Tang <tangyouling@...ngson.cn>
To: Qing Zhang <zhangqing@...ngson.cn>,
Andrey Ryabinin <ryabinin.a.a@...il.com>,
Jonathan Corbet <corbet@....net>,
Huacai Chen <chenhuacai@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: 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
If you can provide a virtual memory layout (similar to
Documentation/riscv/vm-layout.rst), it will be convenient for everyone
to review the relevant code, and it will also better explain why
LoongArch needs to implement kasan_mem_to_shadow() separately.
Thanks,
Youling.
>
> 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. */
> +#endif
> +
> +#endif
>
> #endif /* _ASM_STRING_H */
> diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
> index 9a72d91cd104..0055e7582e15 100644
> --- a/arch/loongarch/kernel/Makefile
> +++ b/arch/loongarch/kernel/Makefile
> @@ -30,6 +30,9 @@ ifdef CONFIG_FUNCTION_TRACER
> CFLAGS_REMOVE_perf_event.o = $(CC_FLAGS_FTRACE)
> endif
>
> +KASAN_SANITIZE_vdso.o := n
> +KASAN_SANITIZE_efi.o := n
> +
> obj-$(CONFIG_MODULES) += module.o module-sections.o
> obj-$(CONFIG_STACKTRACE) += stacktrace.o
>
> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
> index aa64b179744f..19d4be5c8381 100644
> --- a/arch/loongarch/kernel/head.S
> +++ b/arch/loongarch/kernel/head.S
> @@ -95,13 +95,17 @@ SYM_CODE_START(kernel_entry) # kernel entry point
> PTR_LI sp, (_THREAD_SIZE - PT_SIZE)
> PTR_ADD sp, sp, tp
> set_saved_sp sp, t0, t1
> -#endif
> -
> - /* relocate_kernel() returns the new kernel entry point */
> - jr a0
> - ASM_BUG()
>
> + /* Jump to new kernel: new_pc = current_pc + random_offset */
> + pcaddi t0, 0
> + add.d t0, t0, a0
> + jirl zero, t0, 0xc
> #endif
> +#endif
> +
> + #ifdef CONFIG_KASAN
> + bl kasan_early_init
> + #endif
>
> bl start_kernel
> ASM_BUG()
> diff --git a/arch/loongarch/kernel/relocate.c b/arch/loongarch/kernel/relocate.c
> index 01f94d1e3edf..6c3eff9af9fb 100644
> --- a/arch/loongarch/kernel/relocate.c
> +++ b/arch/loongarch/kernel/relocate.c
> @@ -157,12 +157,11 @@ static inline void __init update_reloc_offset(unsigned long *addr, long random_o
> *new_addr = (unsigned long)reloc_offset;
> }
>
> -void * __init relocate_kernel(void)
> +unsigned long __init relocate_kernel(void)
> {
> unsigned long kernel_length;
> unsigned long random_offset = 0;
> void *location_new = _text; /* Default to original kernel start */
> - void *kernel_entry = start_kernel; /* Default to original kernel entry point */
> char *cmdline = early_ioremap(fw_arg1, COMMAND_LINE_SIZE); /* Boot command line is passed in fw_arg1 */
>
> strscpy(boot_command_line, cmdline, COMMAND_LINE_SIZE);
> @@ -190,9 +189,6 @@ void * __init relocate_kernel(void)
>
> reloc_offset += random_offset;
>
> - /* Return the new kernel's entry point */
> - kernel_entry = RELOCATED_KASLR(start_kernel);
> -
> /* The current thread is now within the relocated kernel */
> __current_thread_info = RELOCATED_KASLR(__current_thread_info);
>
> @@ -204,7 +200,7 @@ void * __init relocate_kernel(void)
>
> relocate_absolute(random_offset);
>
> - return kernel_entry;
> + return random_offset;
> }
>
> /*
> diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
> index 27f71f9531e1..18453f8cb9e8 100644
> --- a/arch/loongarch/kernel/setup.c
> +++ b/arch/loongarch/kernel/setup.c
> @@ -610,4 +610,8 @@ void __init setup_arch(char **cmdline_p)
> #endif
>
> paging_init();
> +
> +#if defined(CONFIG_KASAN)
> + kasan_init();
> +#endif
> }
> diff --git a/arch/loongarch/lib/memcpy.S b/arch/loongarch/lib/memcpy.S
> index 3b7e1dec7109..db92ef7bef3a 100644
> --- a/arch/loongarch/lib/memcpy.S
> +++ b/arch/loongarch/lib/memcpy.S
> @@ -10,16 +10,18 @@
> #include <asm/export.h>
> #include <asm/regdef.h>
>
> -SYM_FUNC_START(memcpy)
> +SYM_FUNC_START_WEAK(memcpy)
> /*
> * Some CPUs support hardware unaligned access
> */
> ALTERNATIVE "b __memcpy_generic", \
> "b __memcpy_fast", CPU_FEATURE_UAL
> SYM_FUNC_END(memcpy)
> +SYM_FUNC_ALIAS(__memcpy, memcpy)
> _ASM_NOKPROBE(memcpy)
>
> EXPORT_SYMBOL(memcpy)
> +EXPORT_SYMBOL(__memcpy)
>
> /*
> * void *__memcpy_generic(void *dst, const void *src, size_t n)
> diff --git a/arch/loongarch/lib/memmove.S b/arch/loongarch/lib/memmove.S
> index b796c3d6da05..a2dec5899f5c 100644
> --- a/arch/loongarch/lib/memmove.S
> +++ b/arch/loongarch/lib/memmove.S
> @@ -10,7 +10,7 @@
> #include <asm/export.h>
> #include <asm/regdef.h>
>
> -SYM_FUNC_START(memmove)
> +SYM_FUNC_START_WEAK(memmove)
> blt a0, a1, 1f /* dst < src, memcpy */
> blt a1, a0, 3f /* src < dst, rmemcpy */
> jr ra /* dst == src, return */
> @@ -19,27 +19,30 @@ SYM_FUNC_START(memmove)
> 1: ori a3, zero, 64
> sub.d t0, a1, a0
> blt t0, a3, 2f
> - b memcpy
> + b __memcpy
> 2: b __memcpy_generic
>
> /* if (dst - src) < 64, copy 1 byte at a time */
> 3: ori a3, zero, 64
> sub.d t0, a0, a1
> blt t0, a3, 4f
> - b rmemcpy
> + b __rmemcpy
> 4: b __rmemcpy_generic
> SYM_FUNC_END(memmove)
> +SYM_FUNC_ALIAS(__memmove, memmove)
> _ASM_NOKPROBE(memmove)
>
> EXPORT_SYMBOL(memmove)
> +EXPORT_SYMBOL(__memmove)
> +
> +SYM_FUNC_START(__rmemcpy)
>
> -SYM_FUNC_START(rmemcpy)
> /*
> * Some CPUs support hardware unaligned access
> */
> ALTERNATIVE "b __rmemcpy_generic", \
> "b __rmemcpy_fast", CPU_FEATURE_UAL
> -SYM_FUNC_END(rmemcpy)
> +SYM_FUNC_END(__rmemcpy)
> _ASM_NOKPROBE(rmemcpy)
>
> /*
> diff --git a/arch/loongarch/lib/memset.S b/arch/loongarch/lib/memset.S
> index a9eb732ab2ad..b5cdbecba8ef 100644
> --- a/arch/loongarch/lib/memset.S
> +++ b/arch/loongarch/lib/memset.S
> @@ -16,16 +16,18 @@
> bstrins.d \r0, \r0, 63, 32
> .endm
>
> -SYM_FUNC_START(memset)
> +SYM_FUNC_START_WEAK(memset)
> /*
> * Some CPUs support hardware unaligned access
> */
> ALTERNATIVE "b __memset_generic", \
> "b __memset_fast", CPU_FEATURE_UAL
> SYM_FUNC_END(memset)
> +SYM_FUNC_ALIAS(__memset, memset)
> _ASM_NOKPROBE(memset)
>
> EXPORT_SYMBOL(memset)
> +EXPORT_SYMBOL(__memset)
>
> /*
> * void *__memset_generic(void *s, int c, size_t n)
> diff --git a/arch/loongarch/mm/Makefile b/arch/loongarch/mm/Makefile
> index 8ffc6383f836..6e50cf6cf733 100644
> --- a/arch/loongarch/mm/Makefile
> +++ b/arch/loongarch/mm/Makefile
> @@ -7,3 +7,5 @@ obj-y += init.o cache.o tlb.o tlbex.o extable.o \
> fault.o ioremap.o maccess.o mmap.o pgtable.o page.o
>
> obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o
> +obj-$(CONFIG_KASAN) += kasan_init.o
> +KASAN_SANITIZE_kasan_init.o := n
> diff --git a/arch/loongarch/mm/kasan_init.c b/arch/loongarch/mm/kasan_init.c
> new file mode 100644
> index 000000000000..fb3077f8d508
> --- /dev/null
> +++ b/arch/loongarch/mm/kasan_init.c
> @@ -0,0 +1,255 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2023 Loongson Technology Corporation Limited
> + */
> +#define pr_fmt(fmt) "kasan: " fmt
> +#include <linux/kasan.h>
> +#include <linux/memblock.h>
> +#include <linux/sched/task.h>
> +
> +#include <asm/tlbflush.h>
> +#include <asm/pgalloc.h>
> +#include <asm-generic/sections.h>
> +
> +static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
> +
> +static inline int __p4d_none(int early, p4d_t p4d) {return 0; }
> +
> +#ifndef __PAGETABLE_PUD_FOLDED
> +#define __p4d_none(early, p4d) (early ? (p4d_val(p4d) == 0) : \
> +(__pa(p4d_val(p4d)) == (unsigned long)__pa(kasan_early_shadow_pud)))
> +#endif
> +
> +#define __pud_none(early, pud) (early ? (pud_val(pud) == 0) : \
> +(__pa(pud_val(pud)) == (unsigned long)__pa(kasan_early_shadow_pmd)))
> +
> +#define __pmd_none(early, pmd) (early ? (pmd_val(pmd) == 0) : \
> +(__pa(pmd_val(pmd)) == (unsigned long)__pa(kasan_early_shadow_pte)))
> +
> +#define __pte_none(early, pte) (early ? pte_none(pte) : \
> +((pte_val(pte) & _PFN_MASK) == (unsigned long)__pa(kasan_early_shadow_page)))
> +
> +bool kasan_early_stage = true;
> +
> +/*
> + * Alloc memory for shadow memory page table.
> + */
> +static phys_addr_t __init kasan_alloc_zeroed_page(int node)
> +{
> + void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
> + __pa(MAX_DMA_ADDRESS),
> + MEMBLOCK_ALLOC_ACCESSIBLE, node);
> + if (!p)
> + panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
> + __func__, PAGE_SIZE, PAGE_SIZE, node, __pa(MAX_DMA_ADDRESS));
> + return __pa(p);
> +}
> +
> +static pte_t *kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node,
> + bool early)
> +{
> + if (__pmd_none(early, READ_ONCE(*pmdp))) {
> + phys_addr_t pte_phys = early ?
> + __pa_symbol(kasan_early_shadow_pte)
> + : kasan_alloc_zeroed_page(node);
> + if (!early)
> + memcpy(__va(pte_phys), kasan_early_shadow_pte,
> + sizeof(kasan_early_shadow_pte));
> + pmd_populate_kernel(NULL, pmdp, (pte_t *)__va(pte_phys));
> + }
> +
> + return pte_offset_kernel(pmdp, addr);
> +}
> +
> +static inline void kasan_set_pgd(pgd_t *pgdp, pgd_t pgdval)
> +{
> + WRITE_ONCE(*pgdp, pgdval);
> +}
> +
> +static pmd_t *kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node,
> + bool early)
> +{
> + if (__pud_none(early, READ_ONCE(*pudp))) {
> + phys_addr_t pmd_phys = early ?
> + __pa_symbol(kasan_early_shadow_pmd)
> + : kasan_alloc_zeroed_page(node);
> + if (!early)
> + memcpy(__va(pmd_phys), kasan_early_shadow_pmd,
> + sizeof(kasan_early_shadow_pmd));
> + pud_populate(&init_mm, pudp, (pmd_t *)__va(pmd_phys));
> + }
> +
> + return pmd_offset(pudp, addr);
> +}
> +
> +static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node,
> + bool early)
> +{
> + if (__p4d_none(early, READ_ONCE(*p4dp))) {
> + phys_addr_t pud_phys = early ?
> + __pa_symbol(kasan_early_shadow_pud)
> + : kasan_alloc_zeroed_page(node);
> + if (!early)
> + memcpy(__va(pud_phys), kasan_early_shadow_pud,
> + sizeof(kasan_early_shadow_pud));
> + p4d_populate(&init_mm, p4dp, (pud_t *)__va(pud_phys));
> + }
> +
> + return pud_offset(p4dp, addr);
> +}
> +
> +static void kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
> + unsigned long end, int node, bool early)
> +{
> + unsigned long next;
> + pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
> +
> + do {
> + phys_addr_t page_phys = early ?
> + __pa_symbol(kasan_early_shadow_page)
> + : kasan_alloc_zeroed_page(node);
> + next = addr + PAGE_SIZE;
> + set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
> + } while (ptep++, addr = next, addr != end && __pte_none(early, READ_ONCE(*ptep)));
> +}
> +
> +static void kasan_pmd_populate(pud_t *pudp, unsigned long addr,
> + unsigned long end, int node, bool early)
> +{
> + unsigned long next;
> + pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
> +
> + do {
> + next = pmd_addr_end(addr, end);
> + kasan_pte_populate(pmdp, addr, next, node, early);
> + } while (pmdp++, addr = next, addr != end && __pmd_none(early, READ_ONCE(*pmdp)));
> +}
> +
> +static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
> + unsigned long end, int node, bool early)
> +{
> + unsigned long next;
> + pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
> +
> + do {
> + next = pud_addr_end(addr, end);
> + kasan_pmd_populate(pudp, addr, next, node, early);
> + } while (pudp++, addr = next, addr != end);
> +}
> +
> +static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
> + unsigned long end, int node, bool early)
> +{
> + unsigned long next;
> + p4d_t *p4dp = p4d_offset(pgdp, addr);
> +
> + do {
> + next = p4d_addr_end(addr, end);
> + kasan_pud_populate(p4dp, addr, next, node, early);
> + } while (p4dp++, addr = next, addr != end);
> +}
> +
> +static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
> + int node, bool early)
> +{
> + unsigned long next;
> + pgd_t *pgdp;
> +
> + pgdp = pgd_offset_k(addr);
> +
> + do {
> + next = pgd_addr_end(addr, end);
> + kasan_p4d_populate(pgdp, addr, next, node, early);
> + } while (pgdp++, addr = next, addr != end);
> +
> +}
> +
> +asmlinkage void __init kasan_early_init(void)
> +{
> + BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
> + BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
> +}
> +
> +/* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
> +static void __init kasan_map_populate(unsigned long start, unsigned long end,
> + int node)
> +{
> + kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
> +}
> +
> +static void __init clear_pgds(unsigned long start, unsigned long end)
> +{
> + /*
> + * Remove references to kasan page tables from
> + * swapper_pg_dir. pgd_clear() can't be used
> + * here because it's nop on 2,3-level pagetable setups
> + */
> + for (; start < end; start += PGDIR_SIZE)
> + kasan_set_pgd((pgd_t *)pgd_offset_k(start), __pgd(0));
> +}
> +
> +void __init kasan_init(void)
> +{
> + u64 i;
> + phys_addr_t pa_start, pa_end;
> + /*
> + * PGD was populated as invalid_pmd_table or invalid_pud_table
> + * in pagetable_init() which depends on how many levels of page
> + * table you are using, but we had to clean the gpd of kasan
> + * shadow memory, as the pgd value is none-zero.
> + * The assertion pgd_none is going to be false and the formal populate
> + * afterwards is not going to create any new pgd at all.
> + */
> + memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir));
> + __sync();
> + csr_write64(__pa_symbol(tmp_pg_dir), LOONGARCH_CSR_PGDH);
> + local_flush_tlb_all();
> +
> + clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
> +
> + /* Maps everything to a single page of zeroes */
> + kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END,
> + NUMA_NO_NODE, true);
> +
> + kasan_populate_early_shadow(kasan_mem_to_shadow((void *)MODULES_END),
> + kasan_mem_to_shadow((void *)VMEMMAP_END));
> +
> + if (!IS_ENABLED(CONFIG_KASAN_VMALLOC))
> + kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
> + kasan_mem_to_shadow((void *)VMALLOC_END));
> +
> + kasan_early_stage = false;
> +
> + /* Populate the linear mapping */
> + for_each_mem_range(i, &pa_start, &pa_end) {
> + void *start = (void *)phys_to_virt(pa_start);
> + void *end = (void *)phys_to_virt(pa_end);
> +
> + if (start >= end)
> + break;
> +
> + kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
> + (unsigned long)kasan_mem_to_shadow(end), NUMA_NO_NODE);
> + }
> +
> + /* Populate modules mapping */
> + kasan_map_populate((unsigned long)kasan_mem_to_shadow((void *)MODULES_VADDR),
> + (unsigned long)kasan_mem_to_shadow((void *)MODULES_END), NUMA_NO_NODE);
> + /*
> + * Kasan may reuse the contents of kasan_early_shadow_pte directly, so we
> + * should make sure that it maps the zero page read-only.
> + */
> + for (i = 0; i < PTRS_PER_PTE; i++)
> + set_pte(&kasan_early_shadow_pte[i],
> + pfn_pte(__phys_to_pfn(__pa_symbol(kasan_early_shadow_page)),
> + PAGE_KERNEL_RO));
> +
> + memset(kasan_early_shadow_page, 0, PAGE_SIZE);
> + __sync();
> + csr_write64(__pa_symbol(swapper_pg_dir), LOONGARCH_CSR_PGDH);
> + local_flush_tlb_all();
> +
> + /* At this point kasan is fully initialized. Enable error messages */
> + init_task.kasan_depth = 0;
> + pr_info("KernelAddressSanitizer initialized.\n");
> +}
> diff --git a/arch/loongarch/vdso/Makefile b/arch/loongarch/vdso/Makefile
> index d89e2ac75f7b..df328cd92875 100644
> --- a/arch/loongarch/vdso/Makefile
> +++ b/arch/loongarch/vdso/Makefile
> @@ -1,6 +1,10 @@
> # SPDX-License-Identifier: GPL-2.0
> # Objects to go into the VDSO.
>
> +ifdef CONFIG_KASAN
> +KASAN_SANITIZE := n
> +endif
> +
> # Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before
> # the inclusion of generic Makefile.
> ARCH_REL_TYPE_ABS := R_LARCH_32|R_LARCH_64|R_LARCH_MARK_LA|R_LARCH_JUMP_SLOT
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index f7ef70661ce2..3b91b941873d 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -54,11 +54,13 @@ extern p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D];
> int kasan_populate_early_shadow(const void *shadow_start,
> const void *shadow_end);
>
> +#ifndef __HAVE_ARCH_SHADOW_MAP
> static inline void *kasan_mem_to_shadow(const void *addr)
> {
> return (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)
> + KASAN_SHADOW_OFFSET;
> }
> +#endif
>
> int kasan_add_zero_shadow(void *start, unsigned long size);
> void kasan_remove_zero_shadow(void *start, unsigned long size);
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index e5eef670735e..f86194750df5 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -175,6 +175,11 @@ static __always_inline bool check_region_inline(unsigned long addr,
> if (unlikely(!addr_has_metadata((void *)addr)))
> return !kasan_report(addr, size, write, ret_ip);
>
> +#ifndef __HAVE_ARCH_SHADOW_MAP
> + if (unlikely(kasan_mem_to_shadow((unsigned long *)addr) == NULL))
> + return !kasan_report(addr, size, write, ret_ip);
> +#endif
> +
> if (likely(!memory_is_poisoned(addr, size)))
> return true;
>
> diff --git a/mm/kasan/init.c b/mm/kasan/init.c
> index cc64ed6858c6..860061a22ca9 100644
> --- a/mm/kasan/init.c
> +++ b/mm/kasan/init.c
> @@ -166,8 +166,9 @@ static int __ref zero_pud_populate(p4d_t *p4d, unsigned long addr,
> if (!p)
> return -ENOMEM;
> } else {
> - pud_populate(&init_mm, pud,
> - early_alloc(PAGE_SIZE, NUMA_NO_NODE));
> + p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
> + pmd_init(p);
> + pud_populate(&init_mm, pud, p);
> }
> }
> zero_pmd_populate(pud, addr, next);
> @@ -207,8 +208,9 @@ static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr,
> if (!p)
> return -ENOMEM;
> } else {
> - p4d_populate(&init_mm, p4d,
> - early_alloc(PAGE_SIZE, NUMA_NO_NODE));
> + p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
> + pud_init(p);
> + p4d_populate(&init_mm, p4d, p);
> }
> }
> zero_pud_populate(p4d, addr, next);
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index a61eeee3095a..033335c13b25 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -291,16 +291,22 @@ struct kasan_stack_ring {
>
> #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
>
> +#ifndef __HAVE_ARCH_SHADOW_MAP
> static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
> {
> return (void *)(((unsigned long)shadow_addr - KASAN_SHADOW_OFFSET)
> << KASAN_SHADOW_SCALE_SHIFT);
> }
> +#endif
>
> static __always_inline bool addr_has_metadata(const void *addr)
> {
> +#ifdef __HAVE_ARCH_SHADOW_MAP
> + return (kasan_mem_to_shadow((void *)addr) != NULL);
> +#else
> return (kasan_reset_tag(addr) >=
> kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
> +#endif
> }
>
> /**
>
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