diff options
| -rw-r--r-- | arch/powerpc/include/asm/task_size_32.h | 6 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/uaccess.h | 76 |
2 files changed, 79 insertions, 3 deletions
diff --git a/arch/powerpc/include/asm/task_size_32.h b/arch/powerpc/include/asm/task_size_32.h index 42a64bbd1964..725ddbf06217 100644 --- a/arch/powerpc/include/asm/task_size_32.h +++ b/arch/powerpc/include/asm/task_size_32.h @@ -13,7 +13,7 @@ #define MODULES_SIZE (CONFIG_MODULES_SIZE * SZ_1M) #define MODULES_VADDR (MODULES_END - MODULES_SIZE) #define MODULES_BASE (MODULES_VADDR & ~(UL(SZ_4M) - 1)) -#define USER_TOP MODULES_BASE +#define USER_TOP (MODULES_BASE - SZ_4M) #endif #ifdef CONFIG_PPC_BOOK3S_32 @@ -21,11 +21,11 @@ #define MODULES_SIZE (CONFIG_MODULES_SIZE * SZ_1M) #define MODULES_VADDR (MODULES_END - MODULES_SIZE) #define MODULES_BASE (MODULES_VADDR & ~(UL(SZ_256M) - 1)) -#define USER_TOP MODULES_BASE +#define USER_TOP (MODULES_BASE - SZ_4M) #endif #ifndef USER_TOP -#define USER_TOP ASM_CONST(CONFIG_PAGE_OFFSET) +#define USER_TOP ((ASM_CONST(CONFIG_PAGE_OFFSET) - SZ_128K) & ~(UL(SZ_128K) - 1)) #endif #if CONFIG_TASK_SIZE < USER_TOP diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h index 721d65dbbb2e..ba1d878c3f40 100644 --- a/arch/powerpc/include/asm/uaccess.h +++ b/arch/powerpc/include/asm/uaccess.h @@ -2,6 +2,8 @@ #ifndef _ARCH_POWERPC_UACCESS_H #define _ARCH_POWERPC_UACCESS_H +#include <linux/sizes.h> + #include <asm/processor.h> #include <asm/page.h> #include <asm/extable.h> @@ -435,6 +437,80 @@ static __must_check __always_inline bool __user_access_begin(const void __user * #define user_access_save prevent_user_access_return #define user_access_restore restore_user_access +/* + * Masking the user address is an alternative to a conditional + * user_access_begin that can avoid the fencing. This only works + * for dense accesses starting at the address. + */ +static inline void __user *mask_user_address_simple(const void __user *ptr) +{ + unsigned long addr = (unsigned long)ptr; + unsigned long mask = (unsigned long)(((long)addr >> (BITS_PER_LONG - 1)) & LONG_MAX); + + return (void __user *)(addr & ~mask); +} + +static inline void __user *mask_user_address_isel(const void __user *ptr) +{ + unsigned long addr; + + asm("cmplw %1, %2; iselgt %0, %2, %1" : "=r"(addr) : "r"(ptr), "r"(TASK_SIZE) : "cr0"); + + return (void __user *)addr; +} + +/* TASK_SIZE is a multiple of 128K for shifting by 17 to the right */ +static inline void __user *mask_user_address_32(const void __user *ptr) +{ + unsigned long addr = (unsigned long)ptr; + unsigned long mask = (unsigned long)((long)((TASK_SIZE >> 17) - 1 - (addr >> 17)) >> 31); + + addr = (addr & ~mask) | (TASK_SIZE & mask); + + return (void __user *)addr; +} + +static inline void __user *mask_user_address_fallback(const void __user *ptr) +{ + unsigned long addr = (unsigned long)ptr; + + return (void __user *)(likely(addr < TASK_SIZE) ? addr : TASK_SIZE); +} + +static inline void __user *mask_user_address(const void __user *ptr) +{ +#ifdef MODULES_VADDR + const unsigned long border = MODULES_VADDR; +#else + const unsigned long border = PAGE_OFFSET; +#endif + + if (IS_ENABLED(CONFIG_PPC64)) + return mask_user_address_simple(ptr); + if (IS_ENABLED(CONFIG_E500)) + return mask_user_address_isel(ptr); + if (TASK_SIZE <= UL(SZ_2G) && border >= UL(SZ_2G)) + return mask_user_address_simple(ptr); + if (IS_ENABLED(CONFIG_PPC_BARRIER_NOSPEC)) + return mask_user_address_32(ptr); + return mask_user_address_fallback(ptr); +} + +static __always_inline void __user *__masked_user_access_begin(const void __user *p, + unsigned long dir) +{ + void __user *ptr = mask_user_address(p); + + might_fault(); + allow_user_access(ptr, dir); + + return ptr; +} + +#define masked_user_access_begin(p) __masked_user_access_begin(p, KUAP_READ_WRITE) +#define masked_user_read_access_begin(p) __masked_user_access_begin(p, KUAP_READ) +#define masked_user_write_access_begin(p) __masked_user_access_begin(p, KUAP_WRITE) + #define arch_unsafe_get_user(x, p, e) do { \ __long_type(*(p)) __gu_val; \ __typeof__(*(p)) __user *__gu_addr = (p); \ |