linux-kernel - [PATCH 1/7] x86/mm: Add mm argument to unuse_temporary

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Message-Id: <20241119163035.322525475@infradead.org>
Date: Tue, 19 Nov 2024 17:25:28 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: x86@...nel.org, "To:riel"@surriel.com
Cc: linux-kernel@...r.kernel.org,
 peterz@...radead.org
Subject: [PATCH 1/7] x86/mm: Add mm argument to unuse_temporary_mm()

In commit 209954cbc7d0 ("x86/mm/tlb: Update mm_cpumask lazily")
unuse_temporary_mm() grew the assumption that it gets used on
poking_nn exclusively. While this is currently true, lets not hard
code this assumption.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/kernel/alternative.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -1828,14 +1828,14 @@ static inline temp_mm_state_t use_tempor
 __ro_after_init struct mm_struct *poking_mm;
 __ro_after_init unsigned long poking_addr;
 
-static inline void unuse_temporary_mm(temp_mm_state_t prev_state)
+static inline void unuse_temporary_mm(struct mm_struct *mm, temp_mm_state_t prev_state)
 {
 	lockdep_assert_irqs_disabled();
 
 	switch_mm_irqs_off(NULL, prev_state.mm, current);
 
 	/* Clear the cpumask, to indicate no TLB flushing is needed anywhere */
-	cpumask_clear_cpu(raw_smp_processor_id(), mm_cpumask(poking_mm));
+	cpumask_clear_cpu(raw_smp_processor_id(), mm_cpumask(mm));
 
 	/*
 	 * Restore the breakpoints if they were disabled before the temporary mm
@@ -1942,7 +1942,7 @@ static void *__text_poke(text_poke_f fun
 	 * instruction that already allows the core to see the updated version.
 	 * Xen-PV is assumed to serialize execution in a similar manner.
 	 */
-	unuse_temporary_mm(prev);
+	unuse_temporary_mm(poking_mm, prev);
 
 	/*
 	 * Flushing the TLB might involve IPIs, which would require enabled