diff options
Diffstat (limited to 'arch/x86/lib/getuser.S')
| -rw-r--r-- | arch/x86/lib/getuser.S | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S new file mode 100644 index 000000000..9d5654b8a --- /dev/null +++ b/arch/x86/lib/getuser.S @@ -0,0 +1,172 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * __get_user functions. + * + * (C) Copyright 1998 Linus Torvalds + * (C) Copyright 2005 Andi Kleen + * (C) Copyright 2008 Glauber Costa + * + * These functions have a non-standard call interface + * to make them more efficient, especially as they + * return an error value in addition to the "real" + * return value. + */ + +/* + * __get_user_X + * + * Inputs: %[r|e]ax contains the address. + * + * Outputs: %[r|e]ax is error code (0 or -EFAULT) + * %[r|e]dx contains zero-extended value + * %ecx contains the high half for 32-bit __get_user_8 + * + * + * These functions should not modify any other registers, + * as they get called from within inline assembly. + */ + +#include <linux/export.h> +#include <linux/linkage.h> +#include <linux/objtool.h> +#include <asm/page_types.h> +#include <asm/errno.h> +#include <asm/asm-offsets.h> +#include <asm/thread_info.h> +#include <asm/asm.h> +#include <asm/smap.h> +#include <asm/runtime-const.h> + +#define ASM_BARRIER_NOSPEC ALTERNATIVE "", "lfence", X86_FEATURE_LFENCE_RDTSC + +.macro check_range size:req +.if IS_ENABLED(CONFIG_X86_64) + RUNTIME_CONST_PTR USER_PTR_MAX, rdx + cmp %rdx, %rax + cmova %rdx, %rax +.else + cmp $TASK_SIZE_MAX-\size+1, %eax + jae .Lbad_get_user + sbb %edx, %edx /* array_index_mask_nospec() */ + and %edx, %eax +.endif +.endm + +.macro UACCESS op src dst +1: \op \src,\dst + _ASM_EXTABLE_UA(1b, __get_user_handle_exception) +.endm + + + .text +SYM_FUNC_START(__get_user_1) + ANNOTATE_NOENDBR + check_range size=1 + ASM_STAC + UACCESS movzbl (%_ASM_AX),%edx + xor %eax,%eax + ASM_CLAC + RET +SYM_FUNC_END(__get_user_1) +EXPORT_SYMBOL(__get_user_1) + +SYM_FUNC_START(__get_user_2) + ANNOTATE_NOENDBR + check_range size=2 + ASM_STAC + UACCESS movzwl (%_ASM_AX),%edx + xor %eax,%eax + ASM_CLAC + RET +SYM_FUNC_END(__get_user_2) +EXPORT_SYMBOL(__get_user_2) + +SYM_FUNC_START(__get_user_4) + ANNOTATE_NOENDBR + check_range size=4 + ASM_STAC + UACCESS movl (%_ASM_AX),%edx + xor %eax,%eax + ASM_CLAC + RET +SYM_FUNC_END(__get_user_4) +EXPORT_SYMBOL(__get_user_4) + +SYM_FUNC_START(__get_user_8) + ANNOTATE_NOENDBR +#ifndef CONFIG_X86_64 + xor %ecx,%ecx +#endif + check_range size=8 + ASM_STAC +#ifdef CONFIG_X86_64 + UACCESS movq (%_ASM_AX),%rdx +#else + UACCESS movl (%_ASM_AX),%edx + UACCESS movl 4(%_ASM_AX),%ecx +#endif + xor %eax,%eax + ASM_CLAC + RET +SYM_FUNC_END(__get_user_8) +EXPORT_SYMBOL(__get_user_8) + +/* .. and the same for __get_user, just without the range checks */ +SYM_FUNC_START(__get_user_nocheck_1) + ANNOTATE_NOENDBR + ASM_STAC + ASM_BARRIER_NOSPEC + UACCESS movzbl (%_ASM_AX),%edx + xor %eax,%eax + ASM_CLAC + RET +SYM_FUNC_END(__get_user_nocheck_1) +EXPORT_SYMBOL(__get_user_nocheck_1) + +SYM_FUNC_START(__get_user_nocheck_2) + ANNOTATE_NOENDBR + ASM_STAC + ASM_BARRIER_NOSPEC + UACCESS movzwl (%_ASM_AX),%edx + xor %eax,%eax + ASM_CLAC + RET +SYM_FUNC_END(__get_user_nocheck_2) +EXPORT_SYMBOL(__get_user_nocheck_2) + +SYM_FUNC_START(__get_user_nocheck_4) + ANNOTATE_NOENDBR + ASM_STAC + ASM_BARRIER_NOSPEC + UACCESS movl (%_ASM_AX),%edx + xor %eax,%eax + ASM_CLAC + RET +SYM_FUNC_END(__get_user_nocheck_4) +EXPORT_SYMBOL(__get_user_nocheck_4) + +SYM_FUNC_START(__get_user_nocheck_8) + ANNOTATE_NOENDBR + ASM_STAC + ASM_BARRIER_NOSPEC +#ifdef CONFIG_X86_64 + UACCESS movq (%_ASM_AX),%rdx +#else + xor %ecx,%ecx + UACCESS movl (%_ASM_AX),%edx + UACCESS movl 4(%_ASM_AX),%ecx +#endif + xor %eax,%eax + ASM_CLAC + RET +SYM_FUNC_END(__get_user_nocheck_8) +EXPORT_SYMBOL(__get_user_nocheck_8) + + +SYM_CODE_START_LOCAL(__get_user_handle_exception) + ASM_CLAC +.Lbad_get_user: + xor %edx,%edx + mov $(-EFAULT),%_ASM_AX + RET +SYM_CODE_END(__get_user_handle_exception) |