On 18 February 2016 at 14:28, Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> wrote:
> On Thu, 18 Feb, at 01:16:05PM, Ard Biesheuvel wrote:
>> On 18 February 2016 at 11:44, Matt Fleming <matt@xxxxxxxxxxxxxxxxxxx> wrote:
>> > On Mon, 15 Feb, at 12:32:32PM, Ard Biesheuvel wrote:
>> >> On ARM and arm64, ioremap() and memremap() are not interchangeable like
>> >> on x86, and the use of ioremap() on ordinary RAM is typically flagged
>> >> as an error if the memory region being mapped is also covered by the
>> >> linear mapping, since that would lead to aliases with conflicting
>> >> cacheability attributes.
>> >>
>> >> Since what we are dealing with is not an I/O region with side effects,
>> >> using ioremap() here is arguably incorrect anyway, so let's replace
>> >> it with memremap instead. Also add a missing unmap on the success path,
>> >> and drop a memblock_remove() call which does not belong here, this far
>> >> into the boot sequence.
>> >>
>> >> Cc: Peter Jones <pjones@xxxxxxxxxx>
>> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
>> >> ---
>> >> drivers/firmware/efi/esrt.c | 16 ++++++++--------
>> >> 1 file changed, 8 insertions(+), 8 deletions(-)
>> >>
>> >
>> > [...]
>> >
>> >> @@ -432,8 +434,6 @@ static int __init esrt_sysfs_init(void)
>> >> if (error)
>> >> goto err_cleanup_list;
>> >>
>> >> - memblock_remove(esrt_data, esrt_data_size);
>> >> -
>> >> pr_debug("esrt-sysfs: loaded.\n");
>> >>
>> >> return 0;
>> >
>> > Shouldn't we be replacing memblock_remove() with free_bootmem_late()?
>> > The original ESRT region is still reserved at this point, so we should
>> > do our best to release it to the page allocator.
>>
>> I'd rather we keep it reserved. That way, the config table entry still
>> points to something valid, which could be useful for kexec(), I think?
>> At least, that is how I intended to handle config tables on ARM ...
>
> If we're going to reserve it why do we need to copy the data out at
> all in esrt_sysfs_init()?
Excellent question. I don't think there is any point to doing that.
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