diff options
Diffstat (limited to '')
| -rw-r--r-- | arch/x86/lib/getuser.S | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/arch/x86/lib/getuser.S b/arch/x86/lib/getuser.S new file mode 100644 index 000000000..49b167f73 --- /dev/null +++ b/arch/x86/lib/getuser.S @@ -0,0 +1,143 @@ +/* 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> + + .text +ENTRY(__get_user_1) + mov PER_CPU_VAR(current_task), %_ASM_DX + cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX + jae bad_get_user + sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */ + and %_ASM_DX, %_ASM_AX + ASM_STAC +1: movzbl (%_ASM_AX),%edx + xor %eax,%eax + ASM_CLAC + ret +ENDPROC(__get_user_1) +EXPORT_SYMBOL(__get_user_1) + +ENTRY(__get_user_2) + add $1,%_ASM_AX + jc bad_get_user + mov PER_CPU_VAR(current_task), %_ASM_DX + cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX + jae bad_get_user + sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */ + and %_ASM_DX, %_ASM_AX + ASM_STAC +2: movzwl -1(%_ASM_AX),%edx + xor %eax,%eax + ASM_CLAC + ret +ENDPROC(__get_user_2) +EXPORT_SYMBOL(__get_user_2) + +ENTRY(__get_user_4) + add $3,%_ASM_AX + jc bad_get_user + mov PER_CPU_VAR(current_task), %_ASM_DX + cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX + jae bad_get_user + sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */ + and %_ASM_DX, %_ASM_AX + ASM_STAC +3: movl -3(%_ASM_AX),%edx + xor %eax,%eax + ASM_CLAC + ret +ENDPROC(__get_user_4) +EXPORT_SYMBOL(__get_user_4) + +ENTRY(__get_user_8) +#ifdef CONFIG_X86_64 + add $7,%_ASM_AX + jc bad_get_user + mov PER_CPU_VAR(current_task), %_ASM_DX + cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX + jae bad_get_user + sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */ + and %_ASM_DX, %_ASM_AX + ASM_STAC +4: movq -7(%_ASM_AX),%rdx + xor %eax,%eax + ASM_CLAC + ret +#else + add $7,%_ASM_AX + jc bad_get_user_8 + mov PER_CPU_VAR(current_task), %_ASM_DX + cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX + jae bad_get_user_8 + sbb %_ASM_DX, %_ASM_DX /* array_index_mask_nospec() */ + and %_ASM_DX, %_ASM_AX + ASM_STAC +4: movl -7(%_ASM_AX),%edx +5: movl -3(%_ASM_AX),%ecx + xor %eax,%eax + ASM_CLAC + ret +#endif +ENDPROC(__get_user_8) +EXPORT_SYMBOL(__get_user_8) + + +bad_get_user: + xor %edx,%edx + mov $(-EFAULT),%_ASM_AX + ASM_CLAC + ret +END(bad_get_user) + +#ifdef CONFIG_X86_32 +bad_get_user_8: + xor %edx,%edx + xor %ecx,%ecx + mov $(-EFAULT),%_ASM_AX + ASM_CLAC + ret +END(bad_get_user_8) +#endif + + _ASM_EXTABLE(1b,bad_get_user) + _ASM_EXTABLE(2b,bad_get_user) + _ASM_EXTABLE(3b,bad_get_user) +#ifdef CONFIG_X86_64 + _ASM_EXTABLE(4b,bad_get_user) +#else + _ASM_EXTABLE(4b,bad_get_user_8) + _ASM_EXTABLE(5b,bad_get_user_8) +#endif |