• Ard Biesheuvel's avatar
    ARM: 8662/1: module: split core and init PLT sections · b7ede5a1
    Ard Biesheuvel authored
    Since commit 35fa91ee ("ARM: kernel: merge core and init PLTs"),
    the ARM module PLT code allocates all PLT entries in a single core
    section, since the overhead of having a separate init PLT section is
    not justified by the small number of PLT entries usually required for
    init code.
    
    However, the core and init module regions are allocated independently,
    and there is a corner case where the core region may be allocated from
    the VMALLOC region if the dedicated module region is exhausted, but the
    init region, being much smaller, can still be allocated from the module
    region. This puts the PLT entries out of reach of the relocated branch
    instructions, defeating the whole purpose of PLTs.
    
    So split the core and init PLT regions, and name the latter ".init.plt"
    so it gets allocated along with (and sufficiently close to) the .init
    sections that it serves. Also, given that init PLT entries may need to
    be emitted for branches that target the core module, modify the logic
    that disregards defined symbols to only disregard symbols that are
    defined in the same section.
    
    Fixes: 35fa91ee ("ARM: kernel: merge core and init PLTs")
    Cc: <stable@vger.kernel.org> # v4.9+
    Reported-by: default avatarAngus Clark <angus@angusclark.org>
    Tested-by: default avatarAngus Clark <angus@angusclark.org>
    Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
    Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
    b7ede5a1
module-plts.c 7.46 KB