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Wed, 25 Feb 2026 08:34:39 -0800 (PST) Date: Wed, 25 Feb 2026 16:34:28 +0000 In-Reply-To: <20260225-page_alloc-unmapped-v1-0-e8808a03cd66@google.com> Mime-Version: 1.0 References: <20260225-page_alloc-unmapped-v1-0-e8808a03cd66@google.com> X-Mailer: b4 0.14.3 Message-ID: <20260225-page_alloc-unmapped-v1-3-e8808a03cd66@google.com> Subject: [PATCH RFC 03/19] x86/tlb: Expose some flush function declarations to modules From: Brendan Jackman To: Borislav Petkov , Dave Hansen , Peter Zijlstra , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , Vlastimil Babka , Wei Xu , Johannes Weiner , Zi Yan Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, rppt@kernel.org, Sumit Garg , derkling@google.com, reijiw@google.com, Will Deacon , rientjes@google.com, "Kalyazin, Nikita" , patrick.roy@linux.dev, "Itazuri, Takahiro" , Andy Lutomirski , David Kaplan , Thomas Gleixner , Brendan Jackman , Yosry Ahmed Content-Type: text/plain; charset="utf-8" X-Rspam-User: X-Rspamd-Queue-Id: 3F0B6A000C X-Rspamd-Server: rspam02 X-Stat-Signature: gd3bthysotpt7jpgzisnb3uh8mbfmiho X-HE-Tag: 1772037280-923280 X-HE-Meta: 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 7cMUmZvZ 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: In commit bfe3d8f6313d ("x86/tlb: Restrict access to tlbstate") some low-level logic (the important detail here is flush_tlb_info) was hidden from modules, along with functions associated with that data. Later, the set of functions defined here changed and there are now a bunch of flush_tlb_*() functions that do not depend on x86 internals like flush_tlb_info. This leads to some build fragility: KVM (which can be a module) cares about TLB flushing and includes {linux->asm}/mmu_context.h which includes asm/tlb.h and asm/tlbflush.h. This x86 TLB code expects these helpers to be defined (e.g. tlb_flush() calls flush_tlb_mm_range()). Modules probably shouldn't call these helpers - luckily this is already enforced by the lack of EXPORT_SYMBOL(). Therefore keep things simple and just expose the declarations anyway to prevent build failures. Signed-off-by: Brendan Jackman --- arch/x86/include/asm/tlbflush.h | 43 +++++++++++++++++++++-------------------- 1 file changed, 22 insertions(+), 21 deletions(-) diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 5a3cdc439e38d..ee49724403ef9 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -229,7 +229,6 @@ struct flush_tlb_info { u8 trim_cpumask; }; -void flush_tlb_local(void); void flush_tlb_one_user(unsigned long addr); void flush_tlb_one_kernel(unsigned long addr); void flush_tlb_multi(const struct cpumask *cpumask, @@ -303,26 +302,6 @@ static inline void mm_clear_asid_transition(struct mm_struct *mm) { } static inline bool mm_in_asid_transition(struct mm_struct *mm) { return false; } #endif /* CONFIG_BROADCAST_TLB_FLUSH */ -#define flush_tlb_mm(mm) \ - flush_tlb_mm_range(mm, 0UL, TLB_FLUSH_ALL, 0UL, true) - -#define flush_tlb_range(vma, start, end) \ - flush_tlb_mm_range((vma)->vm_mm, start, end, \ - ((vma)->vm_flags & VM_HUGETLB) \ - ? huge_page_shift(hstate_vma(vma)) \ - : PAGE_SHIFT, true) - -extern void flush_tlb_all(void); -extern void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start, - unsigned long end, unsigned int stride_shift, - bool freed_tables); -extern void flush_tlb_kernel_range(unsigned long start, unsigned long end); - -static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned long a) -{ - flush_tlb_mm_range(vma->vm_mm, a, a + PAGE_SIZE, PAGE_SHIFT, false); -} - static inline bool arch_tlbbatch_should_defer(struct mm_struct *mm) { bool should_defer = false; @@ -487,4 +466,26 @@ static inline void __native_tlb_flush_global(unsigned long cr4) native_write_cr4(cr4 ^ X86_CR4_PGE); native_write_cr4(cr4); } + +#define flush_tlb_mm(mm) \ + flush_tlb_mm_range(mm, 0UL, TLB_FLUSH_ALL, 0UL, true) + +#define flush_tlb_range(vma, start, end) \ + flush_tlb_mm_range((vma)->vm_mm, start, end, \ + ((vma)->vm_flags & VM_HUGETLB) \ + ? huge_page_shift(hstate_vma(vma)) \ + : PAGE_SHIFT, true) + +void flush_tlb_local(void); +extern void flush_tlb_all(void); +extern void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start, + unsigned long end, unsigned int stride_shift, + bool freed_tables); +extern void flush_tlb_kernel_range(unsigned long start, unsigned long end); + +static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned long a) +{ + flush_tlb_mm_range(vma->vm_mm, a, a + PAGE_SIZE, PAGE_SHIFT, false); +} + #endif /* _ASM_X86_TLBFLUSH_H */ -- 2.51.2