On 2/27/23 01:41, Φώτης Βαλασιάδης wrote:
> Ah yes sorry for the confusion.
>
> First name is Φώτιος, surname Βαλασιάδης,
> just call me Fotis!
Hi Fotis, :)
>
> we use both formats in Greece, confusing i know . :D
>
> It's fine by me, you know best! But if I have to point something it's
> that Dmitry didn't like the word "Fixed" and we in fact agreed to replace:
>
> Fixed incomplete doc. PTRACE_GET_SYSCALL_INFO's description wouldn't
> inform the user that they need to enable PTRACE_O_TRACESYSGOOD to get
> detailed information from said operation.
>
> with:
>
> Document the role of PTRACE_O_TRACESYSGOOD option in connection with
> PTRACE_GET_SYSCALL_INFO.
>
> So perhaps you'd want to look into that? Can probably communicate on
> this with Dmitry so we can all agree to something.
>
> I repeat though, from me it's all good, you know best!
Ahh, sorry, I forgot about that. I reworded it to the following:
ptrace.2: Add details about usage of PTRACE_GET_SYSCALL_INFO
Document the role of PTRACE_O_TRACESYSGOOD option in connection with
PTRACE_GET_SYSCALL_INFO.
Came upon this after writing a test program using PTRACE_O_TRACESYSGOOD.
After failing to find what's wrong I posted a StackOverflow question
which you can find right here:
<https://stackoverflow.com/questions/72410182/ptrace-get-syscall-info-always-returns-info-op-as-ptrace-syscall-info-none>
Nate Eldredge found out what happens by looking into the kernel's source
code, here is a link to the relevant part
<https://github.com/torvalds/linux/blob/8291eaafed36f575f23951f3ce18407f480e9ecf/kernel/ptrace.c#L1018>
In the code it can be seen that the union is filled if and only if the
signal matches "SIGTRAP | 0x80", a signal which is only sent if the
PTRACE_O_TRACESYSGOOD option is set. You can read about that in the
PTRACE_O_TRACESYSGOOD section of ptrace(2)'s manual.
Complements: fc91449cb "ptrace.2: Document PTRACE_GET_SYSCALL_INFO"
Cowritten-by: Dmitry V. Levin <ldv@xxxxxxxxx>
Signed-off-by: Dmitry V. Levin <ldv@xxxxxxxxx>
Signed-off-by: Fotios Valasiadis <fvalasiad@xxxxxxxxx>
Acked-by: Nate Eldredge <nate@xxxxxxxxxxxxxxxxxxxx>
Cc: Elvira Khabirova <lineprinter0@xxxxxxxxx>
Signed-off-by: Alejandro Colomar <alx@xxxxxxxxxx>
Cheers!
Alex
--
<http://www.alejandro-colomar.es/>
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