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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>,
	x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Borislav Petkov <bp@alien8.de>,
	Dominik Brodowski <linux@dominikbrodowski.net>
Subject: [patch 2/3] x86/smpboot: Remove stale tlb flush invocations
Date: Sat, 30 Dec 2017 22:13:53 +0100
Message-ID: <20171230211829.586548655@linutronix.de> (raw)
In-Reply-To: <20171230211351.980176980@linutronix.de>


[-- Attachment #0: x86-smpboot--Remove-stale-tlb-flush-invocations.patch --]
[-- Type: text/plain, Size: 1504 bytes --]

smpboot_setup_warm_reset_vector() and smpboot_restore_warm_reset_vector()
invoke local_flush_tlb() for no obvious reason.

Digging in history revealed that the original code in the 2.1 aera added
those because the code manipulated a swapper_pg_dir pagetable entry. The
pagetable manipulation was removed long ago in the 2.3 timeframe, but the
tlb flush invocations stayed around forever.

Remove them along with the pointless pr_debugs which come from the same 2.1
change.

Reported-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/smpboot.c |    9 ---------
 1 file changed, 9 deletions(-)

--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -128,14 +128,10 @@ static inline void smpboot_setup_warm_re
 	spin_lock_irqsave(&rtc_lock, flags);
 	CMOS_WRITE(0xa, 0xf);
 	spin_unlock_irqrestore(&rtc_lock, flags);
-	local_flush_tlb();
-	pr_debug("1.\n");
 	*((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_HIGH)) =
 							start_eip >> 4;
-	pr_debug("2.\n");
 	*((volatile unsigned short *)phys_to_virt(TRAMPOLINE_PHYS_LOW)) =
 							start_eip & 0xf;
-	pr_debug("3.\n");
 }
 
 static inline void smpboot_restore_warm_reset_vector(void)
@@ -143,11 +139,6 @@ static inline void smpboot_restore_warm_
 	unsigned long flags;
 
 	/*
-	 * Install writable page 0 entry to set BIOS data area.
-	 */
-	local_flush_tlb();
-
-	/*
 	 * Paranoid:  Set warm reset code and vector here back
 	 * to default values.
 	 */

  parent reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-30 21:13 [patch 0/3] x86/pti: Fix various fallout Thomas Gleixner
2017-12-30 21:13 ` [patch 1/3] x86/ldt: Free the right LDT memory in write_ldt() error path Thomas Gleixner
2017-12-30 21:33   ` Ingo Molnar
2017-12-31 10:24   ` [patch V2 1/3] x86/ldt: Plug memory leak in " Thomas Gleixner
2017-12-31 15:23     ` Andy Lutomirski
2017-12-30 21:13 ` Thomas Gleixner [this message]
2017-12-30 21:32   ` [patch 2/3] x86/smpboot: Remove stale tlb flush invocations Ingo Molnar
2017-12-30 21:13 ` [patch 3/3] x86/mm: Remove preempt_disable/enable() from __native_flush_tlb() Thomas Gleixner
2017-12-30 21:31   ` Ingo Molnar
2017-12-30 21:35 ` [patch 0/3] x86/pti: Fix various fallout Ingo Molnar
2017-12-30 22:06   ` Linus Torvalds
2017-12-31  2:23     ` Andy Lutomirski

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