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SubjectRe: [PATCH] ptrace/x86: introduce TS_COMPAT_RESTART to fix get_nr_restart_syscall()
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> On Nov 29, 2019, at 9:32 AM, Oleg Nesterov <oleg@redhat.com> wrote:
>
> On 11/28, Andy Lutomirski wrote:
>>
>> I think this doesn’t work for x32.
>
> Why? get_nr_restart_syscall() can still rely on the "orig_ax & __X32_SYSCALL_BIT"
> check, debugger should restore regs->orig_ax correctly.

Right. Although relying on this is IMO a ridiculous bit of ABI.

>
>> Let’s either save the result of syscall_get_arch()
>
> We can save the result of syscall_get_arch(), but it doesn't distinguish
> x32/x86_64 tasks, so it doesn't really differ from TS_COMPAT.

Duh. Never mind.

>
>> or just actually calculate and save the restart_syscall nr here.
>
> sure, we we can do this.

I like this the best unless we can renumber the syscalls.

>
>> Before we commit to this, Kees, do you think we can manage to just renumber
>> restart_syscall()? That’s a much better solution if we can pull it off.
>
> Agreed.
>
> Oleg.
>

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