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x86/smpboot: Remove stale TLB flush invocations
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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 <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
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KAGA-KOKO authored and Ingo Molnar committed Dec 31, 2017
1 parent 9f5cb6b commit 322f8b8
Showing 1 changed file with 0 additions and 9 deletions.
9 changes: 0 additions & 9 deletions arch/x86/kernel/smpboot.c
Original file line number Diff line number Diff line change
Expand Up @@ -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.
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