On Oct 31, 2015 8:25 AM, "Stas Sergeev" <[email protected]> wrote:
>
> 26.10.2015 04:25, Andy Lutomirski пишет:
>
>> These fields have a strange history. This tries to document it.
>>
>> This borrows from 9a036b93a344 ("x86/signal/64: Remove 'fs' and 'gs'
>> from sigcontext"), which was reverted by ed596cde9425 ("Revert x86
>> sigcontext cleanups").
>>
>> Signed-off-by: Andy Lutomirski <[email protected]>
>
> Now the strategy about SS is to always save it to the sigcontext.
> This is good because the syscall can clobber it, so the app had
> to be very careful in the past trying to save it by hands.
> How about saving also fs and gs? (without restoring yet)
> If you do, you'll save dosemu a headache of doing any "pre-syscall"
> work. Pre-syscall work is very nasty.
> I haven't checked if the syscall clobber also these or only SS,
> but perhaps saving them by the kernel won't hurt?
There's a bunch of ongoing work about FS and GS. I want to wait and see.
08.12.2015 02:23, Andy Lutomirski пишет:
> On Oct 31, 2015 8:25 AM, "Stas Sergeev" <[email protected]> wrote:
>>
>> 26.10.2015 04:25, Andy Lutomirski пишет:
>>
>>> These fields have a strange history. This tries to document it.
>>>
>>> This borrows from 9a036b93a344 ("x86/signal/64: Remove 'fs' and 'gs'
>>> from sigcontext"), which was reverted by ed596cde9425 ("Revert x86
>>> sigcontext cleanups").
>>>
>>> Signed-off-by: Andy Lutomirski <[email protected]>
>>
>> Now the strategy about SS is to always save it to the sigcontext.
>> This is good because the syscall can clobber it, so the app had
>> to be very careful in the past trying to save it by hands.
>> How about saving also fs and gs? (without restoring yet)
>> If you do, you'll save dosemu a headache of doing any "pre-syscall"
>> work. Pre-syscall work is very nasty.
>> I haven't checked if the syscall clobber also these or only SS,
>> but perhaps saving them by the kernel won't hurt?
>
> There's a bunch of ongoing work about FS and GS. I want to wait and see.
Andy, have you postponed only this, or also the sigreturn patch?
Long time no news...
sigreturn patch would really be nice to have.
On Tue, Dec 29, 2015 at 4:24 AM, Stas Sergeev <[email protected]> wrote:
> 08.12.2015 02:23, Andy Lutomirski пишет:
>> On Oct 31, 2015 8:25 AM, "Stas Sergeev" <[email protected]> wrote:
>>>
>>> 26.10.2015 04:25, Andy Lutomirski пишет:
>>>
>>>> These fields have a strange history. This tries to document it.
>>>>
>>>> This borrows from 9a036b93a344 ("x86/signal/64: Remove 'fs' and 'gs'
>>>> from sigcontext"), which was reverted by ed596cde9425 ("Revert x86
>>>> sigcontext cleanups").
>>>>
>>>> Signed-off-by: Andy Lutomirski <[email protected]>
>>>
>>> Now the strategy about SS is to always save it to the sigcontext.
>>> This is good because the syscall can clobber it, so the app had
>>> to be very careful in the past trying to save it by hands.
>>> How about saving also fs and gs? (without restoring yet)
>>> If you do, you'll save dosemu a headache of doing any "pre-syscall"
>>> work. Pre-syscall work is very nasty.
>>> I haven't checked if the syscall clobber also these or only SS,
>>> but perhaps saving them by the kernel won't hurt?
>>
>> There's a bunch of ongoing work about FS and GS. I want to wait and see.
> Andy, have you postponed only this, or also the sigreturn patch?
> Long time no news...
> sigreturn patch would really be nice to have.
Sorry, I got caught up with a bunch of other stuff, and everyone being
slow with the holiday season. There's some slight chance we'll get it
in for 4.5, but 4.6 is more likely.
--Andy
--
Andy Lutomirski
AMA Capital Management, LLC