linux-kernel - [PATCH v6 1/3] x86/mm/tlb: Make enter_lazy

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20260124171546.43398-2-qq570070308@gmail.com>
Date: Sun, 25 Jan 2026 01:15:44 +0800
From: Xie Yuanbin <qq570070308@...il.com>
To: peterz@...radead.org,
	tglx@...nel.org,
	riel@...riel.com,
	segher@...nel.crashing.org,
	david@...nel.org,
	hpa@...or.com,
	arnd@...db.de,
	mingo@...hat.com,
	juri.lelli@...hat.com,
	vincent.guittot@...aro.org,
	dietmar.eggemann@....com,
	rostedt@...dmis.org,
	bsegall@...gle.com,
	mgorman@...e.de,
	vschneid@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	luto@...nel.org,
	houwenlong.hwl@...group.com
Cc: linux-kernel@...r.kernel.org,
	x86@...nel.org,
	Xie Yuanbin <qq570070308@...il.com>
Subject: [PATCH v6 1/3] x86/mm/tlb: Make enter_lazy_tlb() always inline on x86

enter_lazy_tlb() on x86 is short enough, and is called in context
switching, which is the hot code path.

Make enter_lazy_tlb() always inline on x86 to optimize performance.

Signed-off-by: Xie Yuanbin <qq570070308@...il.com>
Reviewed-by: Rik van Riel <riel@...riel.com>
Cc: Thomas Gleixner <tglx@...nel.org>
Cc: David Hildenbrand (Red Hat) <david@...nel.org>
---
 arch/x86/include/asm/mmu_context.h | 23 ++++++++++++++++++++++-
 arch/x86/mm/tlb.c                  | 21 ---------------------
 2 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 1acafb1c6a93..ec3f9bebcf7b 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -136,8 +136,29 @@ static inline void mm_reset_untag_mask(struct mm_struct *mm)
 }
 #endif
 
+/*
+ * Please ignore the name of this function.  It should be called
+ * switch_to_kernel_thread().
+ *
+ * enter_lazy_tlb() is a hint from the scheduler that we are entering a
+ * kernel thread or other context without an mm.  Acceptable implementations
+ * include doing nothing whatsoever, switching to init_mm, or various clever
+ * lazy tricks to try to minimize TLB flushes.
+ *
+ * The scheduler reserves the right to call enter_lazy_tlb() several times
+ * in a row.  It will notify us that we're going back to a real mm by
+ * calling switch_mm_irqs_off().
+ */
+#ifndef MODULE
+static __always_inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
+{
+	if (this_cpu_read(cpu_tlbstate.loaded_mm) == &init_mm)
+		return;
+
+	this_cpu_write(cpu_tlbstate_shared.is_lazy, true);
+}
+#endif
 #define enter_lazy_tlb enter_lazy_tlb
-extern void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk);
 
 extern void mm_init_global_asid(struct mm_struct *mm);
 extern void mm_free_global_asid(struct mm_struct *mm);
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 621e09d049cb..af43d177087e 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -971,27 +971,6 @@ void switch_mm_irqs_off(struct mm_struct *unused, struct mm_struct *next,
 	}
 }
 
-/*
- * Please ignore the name of this function.  It should be called
- * switch_to_kernel_thread().
- *
- * enter_lazy_tlb() is a hint from the scheduler that we are entering a
- * kernel thread or other context without an mm.  Acceptable implementations
- * include doing nothing whatsoever, switching to init_mm, or various clever
- * lazy tricks to try to minimize TLB flushes.
- *
- * The scheduler reserves the right to call enter_lazy_tlb() several times
- * in a row.  It will notify us that we're going back to a real mm by
- * calling switch_mm_irqs_off().
- */
-void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
-{
-	if (this_cpu_read(cpu_tlbstate.loaded_mm) == &init_mm)
-		return;
-
-	this_cpu_write(cpu_tlbstate_shared.is_lazy, true);
-}
-
 /*
  * Using a temporary mm allows to set temporary mappings that are not accessible
  * by other CPUs. Such mappings are needed to perform sensitive memory writes
-- 
2.51.0