Commit 565630d5 authored Jun 12, 2015 by Catalin Marinas

arm64: Do not attempt to use init_mm in reset_context()



After secondary CPU boot or hotplug, the active_mm of the idle thread is
&init_mm. The init_mm.pgd (swapper_pg_dir) is only meant for TTBR1_EL1
and must not be set in TTBR0_EL1. Since when active_mm == &init_mm the
TTBR0_EL1 is already set to the reserved value, there is no need to
perform any context reset.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: <stable@vger.kernel.org>

parent 8a14849b

arch/arm64/mm/context.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -92,6 +92,14 @@ static void reset_context(void *info)
		unsigned int cpu = smp_processor_id();
		struct mm_struct *mm = current->active_mm;

		/*
		* current->active_mm could be init_mm for the idle thread immediately
		* after secondary CPU boot or hotplug. TTBR0_EL1 is already set to
		* the reserved value, so no need to reset any context.
		*/
		if (mm == &init_mm)
		return;

		smp_rmb();
		asid = cpu_last_asid + cpu;