[v2,1/2] ARM: module: split core and init PLT sections

[Ard Biesheuvel]

On 25 April 2017 at 23:30, Florian Fainelli <f.fainelli at gmail.com> wrote:
> On 02/21/2017 02:12 PM, Ard Biesheuvel wrote:
>> Since commit 35fa91eed817 ("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: 35fa91eed817 ("ARM: kernel: merge core and init PLTs")
>> Reported-by: Angus Clark <angus at angusclark.org>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
>
> Ard, has this been submitted to Russell's patch tracker? If not, can you
> do it?
>

It's already queued for v4.12:

b7ede5a1f5905ac394cc8e61712a13e3c5cb7b8f
ARM: 8662/1: module: split core and init PLT sections

Regards,
Ard.