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SubjectRe: [PATCH 01/11] Initialize the mapping of KASan shadow memory
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On 11/10/17 09:22, Abbott Liu wrote:
> From: Andrey Ryabinin <a.ryabinin@samsung.com>
>
> This patch initializes KASan shadow region's page table and memory.
> There are two stage for KASan initializing:
> 1. At early boot stage the whole shadow region is mapped to just
> one physical page (kasan_zero_page). It's finished by the function
> kasan_early_init which is called by __mmap_switched(arch/arm/kernel/
> head-common.S)
>
> 2. After the calling of paging_init, we use kasan_zero_page as zero
> shadow for some memory that KASan don't need to track, and we alloc
> new shadow space for the other memory that KASan need to track. These
> issues are finished by the function kasan_init which is call by setup_arch.
>
> Cc: Andrey Ryabinin <a.ryabinin@samsung.com>
> Signed-off-by: Abbott Liu <liuwenliang@huawei.com>
> ---
> arch/arm/include/asm/kasan.h | 20 +++
> arch/arm/include/asm/pgalloc.h | 5 +-
> arch/arm/include/asm/pgtable.h | 1 +
> arch/arm/include/asm/proc-fns.h | 33 +++++
> arch/arm/include/asm/thread_info.h | 4 +
> arch/arm/kernel/head-common.S | 4 +
> arch/arm/kernel/setup.c | 2 +
> arch/arm/mm/Makefile | 5 +
> arch/arm/mm/kasan_init.c | 257 +++++++++++++++++++++++++++++++++++++
> mm/kasan/kasan.c | 2 +-
> 10 files changed, 331 insertions(+), 2 deletions(-)
> create mode 100644 arch/arm/include/asm/kasan.h
> create mode 100644 arch/arm/mm/kasan_init.c
>
> diff --git a/arch/arm/include/asm/kasan.h b/arch/arm/include/asm/kasan.h
> new file mode 100644
> index 0000000..90ee60c
> --- /dev/null
> +++ b/arch/arm/include/asm/kasan.h
> @@ -0,0 +1,20 @@
> +#ifndef __ASM_KASAN_H
> +#define __ASM_KASAN_H
> +
> +#ifdef CONFIG_KASAN
> +
> +#include <asm/kasan_def.h>
> +/*
> + * Compiler uses shadow offset assuming that addresses start
> + * from 0. Kernel addresses don't start from 0, so shadow
> + * for kernel really starts from 'compiler's shadow offset' +
> + * ('kernel address space start' >> KASAN_SHADOW_SCALE_SHIFT)
> + */
> +
> +extern void kasan_init(void);
> +
> +#else
> +static inline void kasan_init(void) { }
> +#endif
> +
> +#endif
> diff --git a/arch/arm/include/asm/pgalloc.h b/arch/arm/include/asm/pgalloc.h
> index b2902a5..10cee6a 100644
> --- a/arch/arm/include/asm/pgalloc.h
> +++ b/arch/arm/include/asm/pgalloc.h
> @@ -50,8 +50,11 @@ static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
> */
> #define pmd_alloc_one(mm,addr) ({ BUG(); ((pmd_t *)2); })
> #define pmd_free(mm, pmd) do { } while (0)
> +#ifndef CONFIG_KASAN
> #define pud_populate(mm,pmd,pte) BUG()
> -
> +#else
> +#define pud_populate(mm,pmd,pte) do { } while (0)
> +#endif
> #endif /* CONFIG_ARM_LPAE */
>
> extern pgd_t *pgd_alloc(struct mm_struct *mm);
> diff --git a/arch/arm/include/asm/pgtable.h b/arch/arm/include/asm/pgtable.h
> index 1c46238..fdf343f 100644
> --- a/arch/arm/include/asm/pgtable.h
> +++ b/arch/arm/include/asm/pgtable.h
> @@ -97,6 +97,7 @@ extern pgprot_t pgprot_s2_device;
> #define PAGE_READONLY _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_RDONLY | L_PTE_XN)
> #define PAGE_READONLY_EXEC _MOD_PROT(pgprot_user, L_PTE_USER | L_PTE_RDONLY)
> #define PAGE_KERNEL _MOD_PROT(pgprot_kernel, L_PTE_XN)
> +#define PAGE_KERNEL_RO _MOD_PROT(pgprot_kernel, L_PTE_XN | L_PTE_RDONLY)
> #define PAGE_KERNEL_EXEC pgprot_kernel
> #define PAGE_HYP _MOD_PROT(pgprot_kernel, L_PTE_HYP | L_PTE_XN)
> #define PAGE_HYP_EXEC _MOD_PROT(pgprot_kernel, L_PTE_HYP | L_PTE_RDONLY)
> diff --git a/arch/arm/include/asm/proc-fns.h b/arch/arm/include/asm/proc-fns.h
> index f2e1af4..6e26714 100644
> --- a/arch/arm/include/asm/proc-fns.h
> +++ b/arch/arm/include/asm/proc-fns.h
> @@ -131,6 +131,15 @@ extern void cpu_resume(void);
> pg &= ~(PTRS_PER_PGD*sizeof(pgd_t)-1); \
> (pgd_t *)phys_to_virt(pg); \
> })
> +
> +#define cpu_set_ttbr0(val) \
> + do { \
> + u64 ttbr = val; \
> + __asm__("mcrr p15, 0, %Q0, %R0, c2" \
> + : : "r" (ttbr)); \
> + } while (0)
> +
> +
> #else
> #define cpu_get_pgd() \
> ({ \
> @@ -140,6 +149,30 @@ extern void cpu_resume(void);
> pg &= ~0x3fff; \
> (pgd_t *)phys_to_virt(pg); \
> })
> +
> +#define cpu_set_ttbr(nr, val) \
> + do { \
> + u64 ttbr = val; \
> + __asm__("mcr p15, 0, %0, c2, c0, 0" \
> + : : "r" (ttbr)); \
> + } while (0)
> +
> +#define cpu_get_ttbr(nr) \
> + ({ \
> + unsigned long ttbr; \
> + __asm__("mrc p15, 0, %0, c2, c0, 0" \
> + : "=r" (ttbr)); \
> + ttbr; \
> + })
> +
> +#define cpu_set_ttbr0(val) \
> + do { \
> + u64 ttbr = val; \
> + __asm__("mcr p15, 0, %0, c2, c0, 0" \
> + : : "r" (ttbr)); \
> + } while (0)
> +
> +

You could instead lift and extend the definitions provided in kvm_hyp.h,
and use the read_sysreg/write_sysreg helpers defined in cp15.h.

Thanks,

M.
--
Jazz is not dead. It just smells funny...

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