From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- arch/x86/lib/putuser.S | 156 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 156 insertions(+) create mode 100644 arch/x86/lib/putuser.S (limited to 'arch/x86/lib/putuser.S') diff --git a/arch/x86/lib/putuser.S b/arch/x86/lib/putuser.S new file mode 100644 index 000000000..46d9e9b98 --- /dev/null +++ b/arch/x86/lib/putuser.S @@ -0,0 +1,156 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * __put_user functions. + * + * (C) Copyright 2005 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. + */ +#include +#include +#include +#include +#include +#include +#include + +/* + * __put_user_X + * + * Inputs: %eax[:%edx] contains the data + * %ecx contains the address + * + * Outputs: %ecx is error code (0 or -EFAULT) + * + * Clobbers: %ebx needed for task pointer + * + * These functions should not modify any other registers, + * as they get called from within inline assembly. + */ + +.macro check_range size:req +.if IS_ENABLED(CONFIG_X86_64) + mov %rcx, %rbx + sar $63, %rbx + or %rbx, %rcx +.else + cmp $TASK_SIZE_MAX-\size+1, %ecx + jae .Lbad_put_user +.endif +.endm + +.text +SYM_FUNC_START(__put_user_1) + ANNOTATE_NOENDBR + check_range size=1 + ASM_STAC +1: movb %al,(%_ASM_CX) + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_1) +EXPORT_SYMBOL(__put_user_1) + +SYM_FUNC_START(__put_user_nocheck_1) + ANNOTATE_NOENDBR + ASM_STAC +2: movb %al,(%_ASM_CX) + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_nocheck_1) +EXPORT_SYMBOL(__put_user_nocheck_1) + +SYM_FUNC_START(__put_user_2) + ANNOTATE_NOENDBR + check_range size=2 + ASM_STAC +3: movw %ax,(%_ASM_CX) + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_2) +EXPORT_SYMBOL(__put_user_2) + +SYM_FUNC_START(__put_user_nocheck_2) + ANNOTATE_NOENDBR + ASM_STAC +4: movw %ax,(%_ASM_CX) + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_nocheck_2) +EXPORT_SYMBOL(__put_user_nocheck_2) + +SYM_FUNC_START(__put_user_4) + ANNOTATE_NOENDBR + check_range size=4 + ASM_STAC +5: movl %eax,(%_ASM_CX) + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_4) +EXPORT_SYMBOL(__put_user_4) + +SYM_FUNC_START(__put_user_nocheck_4) + ANNOTATE_NOENDBR + ASM_STAC +6: movl %eax,(%_ASM_CX) + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_nocheck_4) +EXPORT_SYMBOL(__put_user_nocheck_4) + +SYM_FUNC_START(__put_user_8) + ANNOTATE_NOENDBR + check_range size=8 + ASM_STAC +7: mov %_ASM_AX,(%_ASM_CX) +#ifdef CONFIG_X86_32 +8: movl %edx,4(%_ASM_CX) +#endif + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_8) +EXPORT_SYMBOL(__put_user_8) + +SYM_FUNC_START(__put_user_nocheck_8) + ANNOTATE_NOENDBR + ASM_STAC +9: mov %_ASM_AX,(%_ASM_CX) +#ifdef CONFIG_X86_32 +10: movl %edx,4(%_ASM_CX) +#endif + xor %ecx,%ecx + ASM_CLAC + RET +SYM_FUNC_END(__put_user_nocheck_8) +EXPORT_SYMBOL(__put_user_nocheck_8) + +SYM_CODE_START_LOCAL(__put_user_handle_exception) + ASM_CLAC +.Lbad_put_user: + movl $-EFAULT,%ecx + RET +SYM_CODE_END(__put_user_handle_exception) + + _ASM_EXTABLE_UA(1b, __put_user_handle_exception) + _ASM_EXTABLE_UA(2b, __put_user_handle_exception) + _ASM_EXTABLE_UA(3b, __put_user_handle_exception) + _ASM_EXTABLE_UA(4b, __put_user_handle_exception) + _ASM_EXTABLE_UA(5b, __put_user_handle_exception) + _ASM_EXTABLE_UA(6b, __put_user_handle_exception) + _ASM_EXTABLE_UA(7b, __put_user_handle_exception) + _ASM_EXTABLE_UA(9b, __put_user_handle_exception) +#ifdef CONFIG_X86_32 + _ASM_EXTABLE_UA(8b, __put_user_handle_exception) + _ASM_EXTABLE_UA(10b, __put_user_handle_exception) +#endif -- cgit v1.3.1