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Mon, 21 Oct 2019 02:34:08 -0700 (PDT) MIME-Version: 1.0 References: <8d86d53e904bece0623cb8969cdc70f782fa2bae.1570514544.git.nickhu@andestech.com> In-Reply-To: <8d86d53e904bece0623cb8969cdc70f782fa2bae.1570514544.git.nickhu@andestech.com> From: Greentime Hu Date: Mon, 21 Oct 2019 17:33:31 +0800 Message-ID: Subject: Re: [PATCH v3 2/3] riscv: Add KASAN support To: Nick Hu , Greentime Hu Cc: alankao@andestech.com, Paul Walmsley , Palmer Dabbelt , Albert Ou , aryabinin@virtuozzo.com, glider@google.com, dvyukov@google.com, corbet@lwn.net, alexios.zavras@intel.com, allison@lohutok.net, Anup.Patel@wdc.com, Thomas Gleixner , gregkh@linuxfoundation.org, atish.patra@wdc.com, Kate Stewart , linux-doc@vger.kernel.org, linux-riscv@lists.infradead.org, Linux Kernel Mailing List , kasan-dev@googlegroups.com, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Nick Hu =E6=96=BC 2019=E5=B9=B410=E6=9C=888=E6=97=A5= =E9=80=B1=E4=BA=8C =E4=B8=8B=E5=8D=882:17=E5=AF=AB=E9=81=93=EF=BC=9A > > This patch ports the feature Kernel Address SANitizer (KASAN). > > Note: The start address of shadow memory is at the beginning of kernel > space, which is 2^64 - (2^39 / 2) in SV39. The size of the kernel space i= s > 2^38 bytes so the size of shadow memory should be 2^38 / 8. Thus, the > shadow memory would not overlap with the fixmap area. > > There are currently two limitations in this port, > > 1. RV64 only: KASAN need large address space for extra shadow memory > region. > > 2. KASAN can't debug the modules since the modules are allocated in VMALL= OC > area. We mapped the shadow memory, which corresponding to VMALLOC area, t= o > the kasan_early_shadow_page because we don't have enough physical space f= or > all the shadow memory corresponding to VMALLOC area. > > Signed-off-by: Nick Hu > --- > arch/riscv/Kconfig | 1 + > arch/riscv/include/asm/kasan.h | 27 ++++++++ > arch/riscv/include/asm/pgtable-64.h | 5 ++ > arch/riscv/include/asm/string.h | 9 +++ > arch/riscv/kernel/head.S | 3 + > arch/riscv/kernel/riscv_ksyms.c | 2 + > arch/riscv/kernel/setup.c | 5 ++ > arch/riscv/kernel/vmlinux.lds.S | 1 + > arch/riscv/lib/memcpy.S | 5 +- > arch/riscv/lib/memset.S | 5 +- > arch/riscv/mm/Makefile | 6 ++ > arch/riscv/mm/kasan_init.c | 104 ++++++++++++++++++++++++++++ > 12 files changed, 169 insertions(+), 4 deletions(-) > create mode 100644 arch/riscv/include/asm/kasan.h > create mode 100644 arch/riscv/mm/kasan_init.c > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index 8eebbc8860bb..ca2fc8ba8550 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -61,6 +61,7 @@ config RISCV > select SPARSEMEM_STATIC if 32BIT > select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU > select HAVE_ARCH_MMAP_RND_BITS > + select HAVE_ARCH_KASAN if MMU && 64BIT > > config ARCH_MMAP_RND_BITS_MIN > default 18 if 64BIT > diff --git a/arch/riscv/include/asm/kasan.h b/arch/riscv/include/asm/kasa= n.h > new file mode 100644 > index 000000000000..eb9b1a2f641c > --- /dev/null > +++ b/arch/riscv/include/asm/kasan.h > @@ -0,0 +1,27 @@ > +/* SPDX-License-Identifier: GPL-2.0 */ > +/* Copyright (C) 2019 Andes Technology Corporation */ > + > +#ifndef __ASM_KASAN_H > +#define __ASM_KASAN_H > + > +#ifndef __ASSEMBLY__ > + > +#ifdef CONFIG_KASAN > + > +#include > + > +#define KASAN_SHADOW_SCALE_SHIFT 3 > + > +#define KASAN_SHADOW_SIZE (UL(1) << (38 - KASAN_SHADOW_SCALE_SHIFT)= ) > +#define KASAN_SHADOW_START 0xffffffc000000000 // 2^64 - 2^38 > +#define KASAN_SHADOW_END (KASAN_SHADOW_START + KASAN_SHADOW_SIZE) > + > +#define KASAN_SHADOW_OFFSET (KASAN_SHADOW_END - (1ULL << \ > + (64 - KASAN_SHADOW_SCALE_SHIFT))) > + > +void kasan_init(void); > +asmlinkage void kasan_early_init(void); > + > +#endif > +#endif > +#endif /* __ASM_KASAN_H */ > diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm= /pgtable-64.h > index 7df8daa66cc8..777a1dddb3df 100644 > --- a/arch/riscv/include/asm/pgtable-64.h > +++ b/arch/riscv/include/asm/pgtable-64.h > @@ -59,6 +59,11 @@ static inline unsigned long pud_page_vaddr(pud_t pud) > return (unsigned long)pfn_to_virt(pud_val(pud) >> _PAGE_PFN_SHIFT= ); > } > > +static inline struct page *pud_page(pud_t pud) > +{ > + return pfn_to_page(pud_val(pud) >> _PAGE_PFN_SHIFT); > +} > + > #define pmd_index(addr) (((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1)) > > static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr) > diff --git a/arch/riscv/include/asm/string.h b/arch/riscv/include/asm/str= ing.h > index 1b5d44585962..a4451f768826 100644 > --- a/arch/riscv/include/asm/string.h > +++ b/arch/riscv/include/asm/string.h > @@ -11,8 +11,17 @@ > > #define __HAVE_ARCH_MEMSET > extern asmlinkage void *memset(void *, int, size_t); > +extern asmlinkage void *__memset(void *, int, size_t); > > #define __HAVE_ARCH_MEMCPY > extern asmlinkage void *memcpy(void *, const void *, size_t); > +extern asmlinkage void *__memcpy(void *, const void *, size_t); > > +// For those files which don't want to check by kasan. > +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__) > + > +#define memcpy(dst, src, len) __memcpy(dst, src, len) > +#define memset(s, c, n) __memset(s, c, n) > + > +#endif > #endif /* _ASM_RISCV_STRING_H */ > diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S > index 72f89b7590dd..95eca23cd811 100644 > --- a/arch/riscv/kernel/head.S > +++ b/arch/riscv/kernel/head.S > @@ -102,6 +102,9 @@ clear_bss_done: > sw zero, TASK_TI_CPU(tp) > la sp, init_thread_union + THREAD_SIZE > > +#ifdef CONFIG_KASAN > + call kasan_early_init > +#endif > /* Start the kernel */ > call parse_dtb > tail start_kernel > diff --git a/arch/riscv/kernel/riscv_ksyms.c b/arch/riscv/kernel/riscv_ks= yms.c > index 4800cf703186..376bba7f65ce 100644 > --- a/arch/riscv/kernel/riscv_ksyms.c > +++ b/arch/riscv/kernel/riscv_ksyms.c > @@ -14,3 +14,5 @@ EXPORT_SYMBOL(__asm_copy_to_user); > EXPORT_SYMBOL(__asm_copy_from_user); > EXPORT_SYMBOL(memset); > EXPORT_SYMBOL(memcpy); > +EXPORT_SYMBOL(__memset); > +EXPORT_SYMBOL(__memcpy); > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c > index a990a6cb184f..41f7eae9bc4d 100644 > --- a/arch/riscv/kernel/setup.c > +++ b/arch/riscv/kernel/setup.c > @@ -23,6 +23,7 @@ > #include > #include > #include > +#include > > #ifdef CONFIG_DUMMY_CONSOLE > struct screen_info screen_info =3D { > @@ -70,6 +71,10 @@ void __init setup_arch(char **cmdline_p) > swiotlb_init(1); > #endif > > +#ifdef CONFIG_KASAN > + kasan_init(); > +#endif > + > #ifdef CONFIG_SMP > setup_smp(); > #endif > diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.= lds.S > index 23cd1a9e52a1..97009803ba9f 100644 > --- a/arch/riscv/kernel/vmlinux.lds.S > +++ b/arch/riscv/kernel/vmlinux.lds.S > @@ -46,6 +46,7 @@ SECTIONS > KPROBES_TEXT > ENTRY_TEXT > IRQENTRY_TEXT > + SOFTIRQENTRY_TEXT > *(.fixup) > _etext =3D .; > } > diff --git a/arch/riscv/lib/memcpy.S b/arch/riscv/lib/memcpy.S > index b4c477846e91..51ab716253fa 100644 > --- a/arch/riscv/lib/memcpy.S > +++ b/arch/riscv/lib/memcpy.S > @@ -7,7 +7,8 @@ > #include > > /* void *memcpy(void *, const void *, size_t) */ > -ENTRY(memcpy) > +ENTRY(__memcpy) > +WEAK(memcpy) > move t6, a0 /* Preserve return value */ > > /* Defer to byte-oriented copy for small sizes */ > @@ -104,4 +105,4 @@ ENTRY(memcpy) > bltu a1, a3, 5b > 6: > ret > -END(memcpy) > +END(__memcpy) > diff --git a/arch/riscv/lib/memset.S b/arch/riscv/lib/memset.S > index 5a7386b47175..34c5360c6705 100644 > --- a/arch/riscv/lib/memset.S > +++ b/arch/riscv/lib/memset.S > @@ -8,7 +8,8 @@ > #include > > /* void *memset(void *, int, size_t) */ > -ENTRY(memset) > +ENTRY(__memset) > +WEAK(memset) > move t0, a0 /* Preserve return value */ > > /* Defer to byte-oriented fill for small sizes */ > @@ -109,4 +110,4 @@ ENTRY(memset) > bltu t0, a3, 5b > 6: > ret > -END(memset) > +END(__memset) > diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile > index 9d9a17335686..b8a8ca71f86e 100644 > --- a/arch/riscv/mm/Makefile > +++ b/arch/riscv/mm/Makefile > @@ -17,3 +17,9 @@ ifeq ($(CONFIG_MMU),y) > obj-$(CONFIG_SMP) +=3D tlbflush.o > endif > obj-$(CONFIG_HUGETLB_PAGE) +=3D hugetlbpage.o > +obj-$(CONFIG_KASAN) +=3D kasan_init.o > + > +ifdef CONFIG_KASAN > +KASAN_SANITIZE_kasan_init.o :=3D n > +KASAN_SANITIZE_init.o :=3D n > +endif > diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c > new file mode 100644 > index 000000000000..c3152768cdbe > --- /dev/null > +++ b/arch/riscv/mm/kasan_init.c > @@ -0,0 +1,104 @@ > +// SPDX-License-Identifier: GPL-2.0 > +// Copyright (C) 2019 Andes Technology Corporation > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +extern pgd_t early_pg_dir[PTRS_PER_PGD]; > +asmlinkage void __init kasan_early_init(void) > +{ > + uintptr_t i; > + pgd_t *pgd =3D early_pg_dir + pgd_index(KASAN_SHADOW_START); > + > + for (i =3D 0; i < PTRS_PER_PTE; ++i) > + set_pte(kasan_early_shadow_pte + i, > + mk_pte(virt_to_page(kasan_early_shadow_page), > + PAGE_KERNEL)); > + > + for (i =3D 0; i < PTRS_PER_PMD; ++i) > + set_pmd(kasan_early_shadow_pmd + i, > + pfn_pmd(PFN_DOWN(__pa((uintptr_t)kasan_early_shadow_pte)= ), > + __pgprot(_PAGE_TABLE))); > + > + for (i =3D KASAN_SHADOW_START; i < KASAN_SHADOW_END; > + i +=3D PGDIR_SIZE, ++pgd) > + set_pgd(pgd, > + pfn_pgd(PFN_DOWN(__pa(((uintptr_t)kasan_early_shadow_pmd= ))), > + __pgprot(_PAGE_TABLE))); > + > + // init for swapper_pg_dir > + pgd =3D pgd_offset_k(KASAN_SHADOW_START); > + > + for (i =3D KASAN_SHADOW_START; i < KASAN_SHADOW_END; > + i +=3D PGDIR_SIZE, ++pgd) > + set_pgd(pgd, > + pfn_pgd(PFN_DOWN(__pa(((uintptr_t)kasan_early_shadow_pmd= ))), > + __pgprot(_PAGE_TABLE))); > + > + flush_tlb_all(); > +} > + > +static void __init populate(void *start, void *end) > +{ > + unsigned long i; > + unsigned long vaddr =3D (unsigned long)start & PAGE_MASK; > + unsigned long vend =3D PAGE_ALIGN((unsigned long)end); > + unsigned long n_pages =3D (vend - vaddr) / PAGE_SIZE; > + unsigned long n_pmds =3D > + (n_pages % PTRS_PER_PTE) ? n_pages / PTRS_PER_PTE + 1 : > + n_pages / PTRS_PER_PTE; > + pgd_t *pgd =3D pgd_offset_k(vaddr); > + pmd_t *pmd =3D memblock_alloc(n_pmds * sizeof(pmd_t), PAGE_SIZE); > + pte_t *pte =3D memblock_alloc(n_pages * sizeof(pte_t), PAGE_SIZE)= ; > + > + for (i =3D 0; i < n_pages; i++) { > + phys_addr_t phys =3D memblock_phys_alloc(PAGE_SIZE, PAGE_= SIZE); > + > + set_pte(pte + i, pfn_pte(PHYS_PFN(phys), PAGE_KERNEL)); > + } > + > + for (i =3D 0; i < n_pages; ++pmd, i +=3D PTRS_PER_PTE) > + set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa((uintptr_t)(pte + i)))= , > + __pgprot(_PAGE_TABLE))); > + > + for (i =3D vaddr; i < vend; i +=3D PGDIR_SIZE, ++pgd) > + set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(((uintptr_t)pmd))), ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > + __pgprot(_PAGE_TABLE))); > + Hi Nick, I verify this patch in Qemu and Unleashed board. I found it works well if DRAM size is less than 4GB. It will get an access fault if the DRAM size is larger than 4GB. I spend some time to debug this case and I found it hang in the following memset(). It is because the mapping is not created correctly. I check the page table creating logic again and I found it always sets the last pmd here.