Hi Al,
Am 21.06.2021 um 14:27 schrieb Al Viro:
On Mon, Jun 21, 2021 at 02:01:18PM +1200, Michael Schmitz wrote:
Hi Eric,
instrumenting get_reg on m68k and using a similar patch to yours to warn
when unsaved registers are accessed on the switch stack, I get a hit from
getegid and getegid32, just by running a simple ptrace on ls.
Going to wack those two moles now ...
Explain, please. get_reg() is called by tracer; whose state are you checking?
The check is only triggered when syscall tracing (I set a flag on trace
entry, and clear that on trace exit)... From the WARN_ONCE stack dump,
it appears that I get the warning from inside the syscall, not
syscall_trace().
Because you are *not* accessing the switch stack of the caller of get_reg().
And tracee should be in something like syscall_trace() or do_notify_resume();
both have SAVE_SWITCH_STACK done by the glue...
And that's where my problem may be - I stupidly forgot to set the 'all
registers saved' flag before calling syscall_trace() ...
I'll fix that and try again. Sorry for the noise!
Cheers,
Michael
