Re: [PATCH] x86: make PTRACE_GETREGSET return 32-bit regs if 64-bit process entered kernel with int 80

Oleg Nesterov
2013-02-15T15:11:03Z

On 02/15, Cyrill Gorcunov wrote:
>
> > strace needs to get that data on every syscall entry in the traced process.
> > Doing open/read/close on every syscall entry is going to slow it down a lot.
>
> Don't you need to read it only once when strace is attached? Compat flag can't
> be arbitrary dropped when program executes, no?

TS_COMPAT is set/cleared every time a 64bit task does int80.

I guess you need TIF_IA32, not TS_COMPAT, for c/r.

Oleg.