Commit 5aa4ac64 authored by Qing Zhang's avatar Qing Zhang Committed by Huacai Chen
Browse files

LoongArch: Add KASAN (Kernel Address Sanitizer) support 



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 space lengths of these specific
segments are 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()/memcpy()/memmove() do a lot of memory accesses.
If bad pointer passed to one of these function it is important to be
caught. 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 names, so we could call non-instrumented variant
if needed.

Signed-off-by: default avatarQing Zhang <zhangqing@loongson.cn>
Signed-off-by: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent 9fbcc076

Documentation/dev-tools/kasan.rst

+2 −2
Original line number Diff line number Diff line
@@ -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

~~~~~~~~~

Documentation/features/debug/KASAN/arch-support.txt

+1 −1
Original line number Diff line number Diff line
@@ -13,7 +13,7 @@ 
    |        csky: | TODO |

    |     hexagon: | TODO |

    |        ia64: | TODO |

    |   loongarch: | TODO |

    |   loongarch: |  ok  |

    |        m68k: | TODO |

    |  microblaze: | TODO |

    |        mips: | TODO |

Documentation/translations/zh_CN/dev-tools/kasan.rst

+1 −1
Original line number Diff line number Diff line
@@ -42,7 +42,7 @@ KASAN有三种模式: 
体系架构

~~~~~~~~



在x86_64、arm、arm64、powerpc、riscv、s390和xtensa上支持通用KASAN，

在x86_64、arm、arm64、powerpc、riscv、s390、xtensa和loongarch上支持通用KASAN，

而基于标签的KASAN模式只在arm64上支持。



编译器

arch/loongarch/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ config LOONGARCH 
	select ACPI_PPTT 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
@@ -92,6 +93,7 @@ config LOONGARCH 
	select HAVE_ARCH_AUDITSYSCALL

	select HAVE_ARCH_JUMP_LABEL

	select HAVE_ARCH_JUMP_LABEL_RELATIVE

	select HAVE_ARCH_KASAN

	select HAVE_ARCH_KFENCE

	select HAVE_ARCH_KGDB if PERF_EVENTS

	select HAVE_ARCH_MMAP_RND_BITS if MMU
@@ -669,6 +671,11 @@ config ARCH_MMAP_RND_BITS_MAX 
config ARCH_SUPPORTS_UPROBES

	def_bool y



config KASAN_SHADOW_OFFSET

	hex

	default 0x0

	depends on KASAN



menu "Power management options"



config ARCH_SUSPEND_POSSIBLE

arch/loongarch/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -84,7 +84,10 @@ LDFLAGS_vmlinux += -static -pie --no-dynamic-linker -z notext 
endif



cflags-y += $(call cc-option, -mno-check-zero-division)



ifndef CONFIG_KASAN

cflags-y += -fno-builtin-memcpy -fno-builtin-memmove -fno-builtin-memset

endif



load-y		= 0x9000000000200000

bootvars-y	= VMLINUX_LOAD_ADDRESS=$(load-y)