diff options
Diffstat (limited to 'arch/arm/kernel/entry-armv.S')
| -rw-r--r-- | arch/arm/kernel/entry-armv.S | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index a3d050ce9b79..2d2ea3ca880c 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -557,9 +557,16 @@ ENTRY(__switch_to) ldmia r4, {r4 - sl, fp, ip, lr} @ Load all regs saved previously #ifdef CONFIG_VMAP_STACK @ - @ Do a dummy read from the new stack while running from the old one so - @ that we can rely on do_translation_fault() to fix up any stale PMD - @ entries covering the vmalloc region. + @ For a non-lazy mm switch, check_vmalloc_seq() has ensured that + @ that the active mm's page tables have mappings for the prev + @ task's stack and the next task's stack. + @ + @ For a lazy mm switch the active mm's page tables have mappings + @ for the prev task's stack but might not have mappings for the + @ new task's stack. Do a dummy read from the new stack while + @ running from the old stack so that we can rely on + @ do_translation_fault() to populate missing PMD entries covering the + @ new task's stack in the old task's page tables. @ ldr r2, [ip] #ifdef CONFIG_KASAN_VMALLOC |