• Chintan Pandya's avatar
    ioremap: Update pgtable free interfaces with addr · 785a19f9
    Chintan Pandya authored
    The following kernel panic was observed on ARM64 platform due to a stale
    TLB entry.
    
     1. ioremap with 4K size, a valid pte page table is set.
     2. iounmap it, its pte entry is set to 0.
     3. ioremap the same address with 2M size, update its pmd entry with
        a new value.
     4. CPU may hit an exception because the old pmd entry is still in TLB,
        which leads to a kernel panic.
    
    Commit b6bdb751 ("mm/vmalloc: add interfaces to free unmapped page
    table") has addressed this panic by falling to pte mappings in the above
    case on ARM64.
    
    To support pmd mappings in all cases, TLB purge needs to be performed
    in this case on ARM64.
    
    Add a new arg, 'addr', to pud_free_pmd_page() and pmd_free_pte_page()
    so that TLB purge can be added later in seprate patches.
    
    [toshi.kani@hpe.com: merge changes, rewrite patch description]
    Fixes: 28ee90fe ("x86/mm: implement free pmd/pte page interfaces")
    Signed-off-by: 's avatarChintan Pandya <cpandya@codeaurora.org>
    Signed-off-by: 's avatarToshi Kani <toshi.kani@hpe.com>
    Signed-off-by: 's avatarThomas Gleixner <tglx@linutronix.de>
    Cc: mhocko@suse.com
    Cc: akpm@linux-foundation.org
    Cc: hpa@zytor.com
    Cc: linux-mm@kvack.org
    Cc: linux-arm-kernel@lists.infradead.org
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: Joerg Roedel <joro@8bytes.org>
    Cc: stable@vger.kernel.org
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Michal Hocko <mhocko@suse.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: <stable@vger.kernel.org>
    Link: https://lkml.kernel.org/r/20180627141348.21777-3-toshi.kani@hpe.com
    785a19f9
ioremap.c 4.22 KB