Re: [PATCH -next v5 1/8] arm64: extable: add new extable type EX_TYPE_KACCESS_ERR_ZERO support

Mark Rutland
2022-06-17T08:25:16Z

On Sat, May 28, 2022 at 06:50:49AM +0000, Tong Tiangen wrote:
> Currently, The extable type EX_TYPE_UACCESS_ERR_ZERO is used by
> __get/put_kernel_nofault(), but those helpers are not uaccess type, so we
> add a new extable type EX_TYPE_KACCESS_ERR_ZERO which can be used by
> __get/put_kernel_no_fault().
>
> This is also to prepare for distinguishing the two types in machine check
> safe process.
>
> Suggested-by: Mark Rutland <mark.rutland@arm.com>
> Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>

This looks good to me, so modulo one nit below:

Acked-by: Mark Rutland <mark.rutland@arm.com>

> ---
> arch/arm64/include/asm/asm-extable.h | 13 ++++
> arch/arm64/include/asm/uaccess.h | 94 ++++++++++++++--------------
> arch/arm64/mm/extable.c | 1 +
> 3 files changed, 61 insertions(+), 47 deletions(-)
>
> diff --git a/arch/arm64/include/asm/asm-extable.h b/arch/arm64/include/asm/asm-extable.h
> index c39f2437e08e..56ebe183e78b 100644
> --- a/arch/arm64/include/asm/asm-extable.h
> +++ b/arch/arm64/include/asm/asm-extable.h
> @@ -7,6 +7,7 @@
> #define EX_TYPE_BPF 2
> #define EX_TYPE_UACCESS_ERR_ZERO 3
> #define EX_TYPE_LOAD_UNALIGNED_ZEROPAD 4
> +#define EX_TYPE_KACCESS_ERR_ZERO 5

Could we please renumber this so the UACCESS and KACCESS definitions are next
to one another, i.e.

#define EX_TYPE_BPF 2
#define EX_TYPE_UACCESS_ERR_ZERO 3
#define EX_TYPE_KACCESS_ERR_ZERO 4
#define EX_TYPE_LOAD_UNALIGNED_ZEROPAD 5

Thanks,
Mark.

>
> #ifdef __ASSEMBLY__
>
> @@ -73,9 +74,21 @@
> EX_DATA_REG(ZERO, zero) \
> ")")
>
> +#define _ASM_EXTABLE_KACCESS_ERR_ZERO(insn, fixup, err, zero) \
> + __DEFINE_ASM_GPR_NUMS \
> + __ASM_EXTABLE_RAW(#insn, #fixup, \
> + __stringify(EX_TYPE_KACCESS_ERR_ZERO), \
> + "(" \
> + EX_DATA_REG(ERR, err) " | " \
> + EX_DATA_REG(ZERO, zero) \
> + ")")
> +
> #define _ASM_EXTABLE_UACCESS_ERR(insn, fixup, err) \
> _ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, err, wzr)
>
> +#define _ASM_EXTABLE_KACCESS_ERR(insn, fixup, err) \
> + _ASM_EXTABLE_KACCESS_ERR_ZERO(insn, fixup, err, wzr)
> +
> #define EX_DATA_REG_DATA_SHIFT 0
> #define EX_DATA_REG_DATA GENMASK(4, 0)
> #define EX_DATA_REG_ADDR_SHIFT 5
> diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
> index 63f9c828f1a7..2fc9f0861769 100644
> --- a/arch/arm64/include/asm/uaccess.h
> +++ b/arch/arm64/include/asm/uaccess.h
> @@ -232,34 +232,34 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
> * The "__xxx_error" versions set the third argument to -EFAULT if an error
> * occurs, and leave it unchanged on success.
> */
> -#define __get_mem_asm(load, reg, x, addr, err) \
> +#define __get_mem_asm(load, reg, x, addr, err, type) \
> asm volatile( \
> "1: " load " " reg "1, [%2]\n" \
> "2:\n" \
> - _ASM_EXTABLE_UACCESS_ERR_ZERO(1b, 2b, %w0, %w1) \
> + _ASM_EXTABLE_##type##ACCESS_ERR_ZERO(1b, 2b, %w0, %w1) \
> : "+r" (err), "=&r" (x) \
> : "r" (addr))
>
> -#define __raw_get_mem(ldr, x, ptr, err) \
> -do { \
> - unsigned long __gu_val; \
> - switch (sizeof(*(ptr))) { \
> - case 1: \
> - __get_mem_asm(ldr "b", "%w", __gu_val, (ptr), (err)); \
> - break; \
> - case 2: \
> - __get_mem_asm(ldr "h", "%w", __gu_val, (ptr), (err)); \
> - break; \
> - case 4: \
> - __get_mem_asm(ldr, "%w", __gu_val, (ptr), (err)); \
> - break; \
> - case 8: \
> - __get_mem_asm(ldr, "%x", __gu_val, (ptr), (err)); \
> - break; \
> - default: \
> - BUILD_BUG(); \
> - } \
> - (x) = (__force __typeof__(*(ptr)))__gu_val; \
> +#define __raw_get_mem(ldr, x, ptr, err, type) \
> +do { \
> + unsigned long __gu_val; \
> + switch (sizeof(*(ptr))) { \
> + case 1: \
> + __get_mem_asm(ldr "b", "%w", __gu_val, (ptr), (err), type); \
> + break; \
> + case 2: \
> + __get_mem_asm(ldr "h", "%w", __gu_val, (ptr), (err), type); \
> + break; \
> + case 4: \
> + __get_mem_asm(ldr, "%w", __gu_val, (ptr), (err), type); \
> + break; \
> + case 8: \
> + __get_mem_asm(ldr, "%x", __gu_val, (ptr), (err), type); \
> + break; \
> + default: \
> + BUILD_BUG(); \
> + } \
> + (x) = (__force __typeof__(*(ptr)))__gu_val; \
> } while (0)
>
> /*
> @@ -274,7 +274,7 @@ do { \
> __chk_user_ptr(ptr); \
> \
> uaccess_ttbr0_enable(); \
> - __raw_get_mem("ldtr", __rgu_val, __rgu_ptr, err); \
> + __raw_get_mem("ldtr", __rgu_val, __rgu_ptr, err, U); \
> uaccess_ttbr0_disable(); \
> \
> (x) = __rgu_val; \
> @@ -314,40 +314,40 @@ do { \
> \
> __uaccess_enable_tco_async(); \
> __raw_get_mem("ldr", *((type *)(__gkn_dst)), \
> - (__force type *)(__gkn_src), __gkn_err); \
> + (__force type *)(__gkn_src), __gkn_err, K); \
> __uaccess_disable_tco_async(); \
> \
> if (unlikely(__gkn_err)) \
> goto err_label; \
> } while (0)
>
> -#define __put_mem_asm(store, reg, x, addr, err) \
> +#define __put_mem_asm(store, reg, x, addr, err, type) \
> asm volatile( \
> "1: " store " " reg "1, [%2]\n" \
> "2:\n" \
> - _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0) \
> + _ASM_EXTABLE_##type##ACCESS_ERR(1b, 2b, %w0) \
> : "+r" (err) \
> : "r" (x), "r" (addr))
>
> -#define __raw_put_mem(str, x, ptr, err) \
> -do { \
> - __typeof__(*(ptr)) __pu_val = (x); \
> - switch (sizeof(*(ptr))) { \
> - case 1: \
> - __put_mem_asm(str "b", "%w", __pu_val, (ptr), (err)); \
> - break; \
> - case 2: \
> - __put_mem_asm(str "h", "%w", __pu_val, (ptr), (err)); \
> - break; \
> - case 4: \
> - __put_mem_asm(str, "%w", __pu_val, (ptr), (err)); \
> - break; \
> - case 8: \
> - __put_mem_asm(str, "%x", __pu_val, (ptr), (err)); \
> - break; \
> - default: \
> - BUILD_BUG(); \
> - } \
> +#define __raw_put_mem(str, x, ptr, err, type) \
> +do { \
> + __typeof__(*(ptr)) __pu_val = (x); \
> + switch (sizeof(*(ptr))) { \
> + case 1: \
> + __put_mem_asm(str "b", "%w", __pu_val, (ptr), (err), type); \
> + break; \
> + case 2: \
> + __put_mem_asm(str "h", "%w", __pu_val, (ptr), (err), type); \
> + break; \
> + case 4: \
> + __put_mem_asm(str, "%w", __pu_val, (ptr), (err), type); \
> + break; \
> + case 8: \
> + __put_mem_asm(str, "%x", __pu_val, (ptr), (err), type); \
> + break; \
> + default: \
> + BUILD_BUG(); \
> + } \
> } while (0)
>
> /*
> @@ -362,7 +362,7 @@ do { \
> __chk_user_ptr(__rpu_ptr); \
> \
> uaccess_ttbr0_enable(); \
> - __raw_put_mem("sttr", __rpu_val, __rpu_ptr, err); \
> + __raw_put_mem("sttr", __rpu_val, __rpu_ptr, err, U); \
> uaccess_ttbr0_disable(); \
> } while (0)
>
> @@ -400,7 +400,7 @@ do { \
> \
> __uaccess_enable_tco_async(); \
> __raw_put_mem("str", *((type *)(__pkn_src)), \
> - (__force type *)(__pkn_dst), __pkn_err); \
> + (__force type *)(__pkn_dst), __pkn_err, K); \
> __uaccess_disable_tco_async(); \
> \
> if (unlikely(__pkn_err)) \
> diff --git a/arch/arm64/mm/extable.c b/arch/arm64/mm/extable.c
> index 489455309695..056591e5ca80 100644
> --- a/arch/arm64/mm/extable.c
> +++ b/arch/arm64/mm/extable.c
> @@ -77,6 +77,7 @@ bool fixup_exception(struct pt_regs *regs)
> case EX_TYPE_BPF:
> return ex_handler_bpf(ex, regs);
> case EX_TYPE_UACCESS_ERR_ZERO:
> + case EX_TYPE_KACCESS_ERR_ZERO:
> return ex_handler_uaccess_err_zero(ex, regs);
> case EX_TYPE_LOAD_UNALIGNED_ZEROPAD:
> return ex_handler_load_unaligned_zeropad(ex, regs);
> --
> 2.25.1