• Colin Cross's avatar
    ARM: 7414/1: SMP: prevent use of the console when using idmap_pgd · fde165b2
    Colin Cross authored
    Commit 4e8ee7de (ARM: SMP: use
    idmap_pgd for mapping MMU enable during secondary booting)
    switched secondary boot to use idmap_pgd, which is initialized
    during early_initcall, instead of a page table initialized during
    __cpu_up.  This causes idmap_pgd to contain the static mappings
    but be missing all dynamic mappings.
    
    If a console is registered that creates a dynamic mapping, the
    printk in secondary_start_kernel will trigger a data abort on
    the missing mapping before the exception handlers have been
    initialized, leading to a hang.  Initial boot is not affected
    because no consoles have been registered, and resume is usually
    not affected because the offending console is suspended.
    Onlining a cpu with hotplug triggers the problem.
    
    A workaround is to the printk in secondary_start_kernel until
    after the page tables have been switched back to init_mm.
    
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarColin Cross <ccross@android.com>
    Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
    fde165b2
smp.c 13.2 KB