From 27600805e62f800bacf990354632eae4e487d34c Mon Sep 17 00:00:00 2001 From: Yazen Ghannam Date: Thu, 3 Sep 2026 10:43:25 -0500 Subject: x86/amd_node: Fix PCI device reference counting in amd_smn_init() The local "root" pointer is a temporary variable used during the device search. Therefore, refcount related to the search iterators should be cleaned up after the search is complete. Use the __free() cleanup macro to ensure the refcount is decremented when the temporary pointer goes out of scope. Additionally, increment the refcount when caching a root pointer. This ensures the in-use refcount is separate from the temporary search refcounting. Finally, drop the redundant "root = NULL" before the second search loop. The pci_get_class() iterator always decrements the refcount of its "from" argument, so the first loop can only fall through with "root" already NULL. Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching") Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com Reported-by: Sashiko Assisted-by: LLM Signed-off-by: Yazen Ghannam Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Mario Limonciello (AMD) Cc: Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com --- arch/x86/lib/getuser.S | 172 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 172 insertions(+) create mode 100644 arch/x86/lib/getuser.S (limited to 'arch/x86/lib/getuser.S') 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#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) -- cgit v1.3.1