diff options
Diffstat (limited to 'arch/x86/lib/getuser.S')
| -rw-r--r-- | arch/x86/lib/getuser.S | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S new file mode 100644 index 0000000000..9c63713477 --- /dev/null +++ b/arch/x86/lib/getuser.S @@ -0,0 +1,185 @@ +/* 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/linkage.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/export.h> + +#define ASM_BARRIER_NOSPEC ALTERNATIVE "", "lfence", X86_FEATURE_LFENCE_RDTSC + +.macro check_range size:req +.if IS_ENABLED(CONFIG_X86_64) + mov %rax, %rdx + sar $63, %rdx + or %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 + + .text +SYM_FUNC_START(__get_user_1) + check_range size=1 + ASM_STAC +1: 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) + check_range size=2 + ASM_STAC +2: 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) + check_range size=4 + ASM_STAC +3: 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) + check_range size=8 + ASM_STAC +#ifdef CONFIG_X86_64 +4: movq (%_ASM_AX),%rdx +#else +4: movl (%_ASM_AX),%edx +5: 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) + ASM_STAC + ASM_BARRIER_NOSPEC +6: 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) + ASM_STAC + ASM_BARRIER_NOSPEC +7: 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) + ASM_STAC + ASM_BARRIER_NOSPEC +8: 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) + ASM_STAC + ASM_BARRIER_NOSPEC +#ifdef CONFIG_X86_64 +9: movq (%_ASM_AX),%rdx +#else +9: movl (%_ASM_AX),%edx +10: 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) + +#ifdef CONFIG_X86_32 +SYM_CODE_START_LOCAL(__get_user_8_handle_exception) + ASM_CLAC +bad_get_user_8: + xor %edx,%edx + xor %ecx,%ecx + mov $(-EFAULT),%_ASM_AX + RET +SYM_CODE_END(__get_user_8_handle_exception) +#endif + +/* get_user */ + _ASM_EXTABLE(1b, __get_user_handle_exception) + _ASM_EXTABLE(2b, __get_user_handle_exception) + _ASM_EXTABLE(3b, __get_user_handle_exception) +#ifdef CONFIG_X86_64 + _ASM_EXTABLE(4b, __get_user_handle_exception) +#else + _ASM_EXTABLE(4b, __get_user_8_handle_exception) + _ASM_EXTABLE(5b, __get_user_8_handle_exception) +#endif + +/* __get_user */ + _ASM_EXTABLE(6b, __get_user_handle_exception) + _ASM_EXTABLE(7b, __get_user_handle_exception) + _ASM_EXTABLE(8b, __get_user_handle_exception) +#ifdef CONFIG_X86_64 + _ASM_EXTABLE(9b, __get_user_handle_exception) +#else + _ASM_EXTABLE(9b, __get_user_8_handle_exception) + _ASM_EXTABLE(10b, __get_user_8_handle_exception) +#endif |