diff options
| -rw-r--r-- | arch/metag/include/asm/uaccess.h | 40 |
1 files changed, 24 insertions, 16 deletions
diff --git a/arch/metag/include/asm/uaccess.h b/arch/metag/include/asm/uaccess.h index 469a2f1393d3..1e5f26d2dce8 100644 --- a/arch/metag/include/asm/uaccess.h +++ b/arch/metag/include/asm/uaccess.h @@ -28,24 +28,32 @@ #define segment_eq(a, b) ((a).seg == (b).seg) -#define __kernel_ok (segment_eq(get_fs(), KERNEL_DS)) -/* - * Explicitly allow NULL pointers here. Parts of the kernel such - * as readv/writev use access_ok to validate pointers, but want - * to allow NULL pointers for various reasons. NULL pointers are - * safe to allow through because the first page is not mappable on - * Meta. - * - * We also wish to avoid letting user code access the system area - * and the kernel half of the address space. - */ -#define __user_bad(addr, size) (((addr) > 0 && (addr) < META_MEMORY_BASE) || \ - ((addr) > PAGE_OFFSET && \ - (addr) < LINCORE_BASE)) - static inline int __access_ok(unsigned long addr, unsigned long size) { - return __kernel_ok || !__user_bad(addr, size); + /* + * Allow access to the user mapped memory area, but not the system area + * before it. The check extends to the top of the address space when + * kernel access is allowed (there's no real reason to user copy to the + * system area in any case). + */ + if (likely(addr >= META_MEMORY_BASE && addr < get_fs().seg && + size <= get_fs().seg - addr)) + return true; + /* + * Explicitly allow NULL pointers here. Parts of the kernel such + * as readv/writev use access_ok to validate pointers, but want + * to allow NULL pointers for various reasons. NULL pointers are + * safe to allow through because the first page is not mappable on + * Meta. + */ + if (!addr) + return true; + /* Allow access to core code memory area... */ + if (addr >= LINCORE_CODE_BASE && addr <= LINCORE_CODE_LIMIT && + size <= LINCORE_CODE_LIMIT + 1 - addr) + return true; + /* ... but no other areas. */ + return false; } #define access_ok(type, addr, size) __access_ok((unsigned long)(addr), \ |