lkml.org 
[lkml]   [2021]   [Jan]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [REGRESSION] x86/entry: TIF_SINGLESTEP handling is still broken
On Sun, Jan 31, 2021 at 3:35 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> I wonder if the simple solution is to just
>
> (a) always set one of the SYSCALL_WORK_EXIT bits on the child in
> ptrace (exactly to catch the child on system call exit)
>
> (b) basically revert 299155244770 ("entry: Drop usage of TIF flags in
> the generic syscall code") and have the syscall exit code check the
> TIF_SINGLESTEP flag

Actually, (b) looks unnecessary - as long as we get to
syscall_exit_work(), the current code will work fine.

So maybe just add a dummy SYSCALL_WORK_SYSCALL_EXIT_TRAP, and set that
flag whenever a singestep is requested for a process that is currently
in a system call?

IOW, make it a very explicit "do TF for system calls", rather than the
old code that was doing so implicitly and not very obviously. Hmm?

Linus

\
 
 \ /
  Last update: 2021-02-01 00:58    [W:0.077 / U:24.000 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site