| From 565630d503ef24e44c252bed55571b3a0d68455f Mon Sep 17 00:00:00 2001 |
| From: Catalin Marinas <catalin.marinas@arm.com> |
| Date: Fri, 12 Jun 2015 11:24:41 +0100 |
| Subject: arm64: Do not attempt to use init_mm in reset_context() |
| |
| From: Catalin Marinas <catalin.marinas@arm.com> |
| |
| commit 565630d503ef24e44c252bed55571b3a0d68455f upstream. |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/arm64/mm/context.c | 8 ++++++++ |
| 1 file changed, 8 insertions(+) |
| |
| --- a/arch/arm64/mm/context.c |
| +++ b/arch/arm64/mm/context.c |
| @@ -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; |
| |