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x86/mm: Avoid redundant interrupt disable in load_mm_cr4()

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load_mm_cr4() is always called with interrupts disabled from:

 - switch_mm_irqs_off()
 - refresh_pce(), which is a on_each_cpu() callback

Thus, disabling interrupts in cr4_set/clear_bits() is redundant.

Implement cr4_set/clear_bits_irqsoff() helpers, rename load_mm_cr4() to
load_mm_cr4_irqsoff() and use the new helpers. The new helpers do not need
a lockdep assert as __cr4_set() has one already.

The renaming in combination with the checks in __cr4_set() ensure that any
changes in the boundary conditions at the call sites will be detected.

[ tglx: Massaged change log ]

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/0fbbcb64-5f26-4ffb-1bb9-4f5f48426893@siemens.com
This commit is contained in:
Jan Kiszka
2019-06-18 09:32:11 +02:00
committed by Thomas Gleixner
parent 5f9e832c13
commit 21e450d21c
4 changed files with 29 additions and 13 deletions
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2
arch/x86/events/core.c
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@@ -2087,7 +2087,7 @@ static int x86_pmu_event_init(struct perf_event *event)
static void refresh_pce(void *ignored)
{
load_mm_cr4(this_cpu_read(cpu_tlbstate.loaded_mm));
load_mm_cr4_irqsoff(this_cpu_read(cpu_tlbstate.loaded_mm));
}
static void x86_pmu_event_mapped(struct perf_event *event, struct mm_struct *mm)