x86/smpboot: Remove stale TLB flush invocations

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 era 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_debug()s which come from the same 2.1
change.

Reported-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linuxfoundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20171230211829.586548655@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 33d6000265aa75e6f4d41ed55d4a9ac13a1b6ba2..c3402fc30865cae73f19f828959629f6e91dbb96 100644 (file)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -128,25 +128,16 @@ static inline void smpboot_setup_warm_reset_vector(unsigned long start_eip)
        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)
 {
        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.