svn commit: r313772 - head/sys/arm64/arm64

[Mark Millard]

On 2017-Feb-15, at 1:39 PM, Oliver Pinter <oliver.pinter at hardenedbsd.org> wrote:

> On 2/15/17, Mark Millard <markmi at dsl-only.net> wrote:
>>> Author: andrew
>>> Date: Wed Feb 15 14:56:47 2017
>>> New Revision: 313772
>>> URL:
>>> https://svnweb.freebsd.org/changeset/base/313772
>>> 
>>> Log:
>>>  Load the new sp_el0 with interrupts disabled in fork_trampoline. If an
>>>  interrupt arrives in fork_trampoline after sp_el0 was written we may
>>> then
>>>  switch to a new thread, enter userland so change this stack pointer,
>>> then
>>>  return to this code with the wrong value. This fixes this case by
>>> moving
>>>  the load of sp_el0 until after interrupts have been disabled.
>> 
>> https://svnweb.freebsd.org/base/stable/11/sys/arm64/arm64/swtch.S?revision=302408&view=markup
>> 
>> shows stable/11 has the same issue.
>> 
>> Is this to be MFC'd at some point?
>> 
>> 
>> stable/10 seems to have a different code structure:
>> 
>> https://svnweb.freebsd.org/base/stable/10/sys/amd64/amd64/
> 
> This is x86-64 aka amd64 in FreeBSD, in 10-STABLE only 32 bit ARM
> support exists, so there isn't arm64.

Clearly I was somewhat distracted and careless when I looked at
stable/10. Sorry for the noise in that part.

Still the stable/11 part does apply: at least I got something
right.

>> 
>> . . .

===
Mark Millard
markmi at dsl-only.net