Re: [PATCH] S390: Sync ptrace.h with kernel. [BZ #21539]

[Stefan Liebler <stli at linux dot vnet dot ibm dot com>]

On 06/19/2017 03:26 PM, Dmitry V. Levin wrote:
> On Mon, Jun 19, 2017 at 03:10:57PM +0200, Stefan Liebler wrote:
> > On 06/13/2017 10:05 PM, Dmitry V. Levin wrote:
> > > On Tue, Jun 06, 2017 at 12:17:33PM +0200, Stefan Liebler wrote:
> > > [...]
> > > > diff --git a/sysdeps/unix/sysv/linux/s390/tst-ptrace-singleblock.c b/sysdeps/unix/sysv/linux/s390/tst-ptrace-singleblock.c
> > > > new file mode 100644
> >   >> [...]
> > > > +      /* Get information about tracee: gprs, last breaking address.  */
> > > > +      parea.len = sizeof (regs);
> > > > +      parea.process_addr = (unsigned long) &regs;
> > > > +      parea.kernel_addr = 0;
> > > > +      ptrace (PTRACE_PEEKUSR_AREA, pid, &parea);
> > >
> > > Note that you can verify whether PTRACE_PEEKUSR_AREA has returned
> > > the expected result by comparing registers with those returned
> > > by PTRACE_GETREGSET.  The latter is implemented on s390 since
> > > linux 2.6.27 so its use in glibc is safe.
> > Okay. Now the gprs are obtained by PTRACE_PEEKUSR_AREA and
> > PTRACE_GETREGSET. Afterwards I use memcmp to check whether the values
> > are the same.
> > > > +      ptrace (PTRACE_GET_LAST_BREAK, pid, NULL, &last_break);
> > >
> > > As these ptrace calls are expected to succeed,
> > > you might want to check their return code.
> > Done with several usages of TEST_VERIFY_EXIT.
> >
> > > > +
> > > > +      printf ("child IA: %p last_break: %p\n",
> > > > +	      (void *) regs[1], (void *) last_break);
> > > > +
> > > > +      /* Execute tracee until next taken branch.
> > > > +
> > > > +	 Note:
> > > > +	 Before the commit which introduced this testcase,
> > > > +	 <glibc>/sysdeps/unix/sysv/linux/s390/sys/ptrace.h
> > > > +	 uses ptrace-request 12 for PTRACE_GETREGS,
> > > > +	 but <kernel>/include/uapi/linux/ptrace.h
> > > > +	 uses 12 for PTRACE_SINGLEBLOCK.
> > > > +
> > > > +	 The s390 kernel has no support for PTRACE_GETREGS!
> > > > +	 Thus glibc ptrace.h is adjusted to match kernel ptrace.h.
> > > > +
> > > > +	 This test ensures, that PTRACE_SINGLEBLOCK defined in glibc
> > > > +	 works as expected.  If the kernel would interpret it as
> > > > +	 PTRACE_GETREGS, then the tracee will not make any progress
> > > > +	 and this testcase will time out.  */
> > > > +      ptrace (req_singleblock, pid, NULL, NULL);
> > >
> > > Likewise.
> >
> > I've attached the patch with the mentioned changes and the NEWS entry
> > requested by Andreas.
> >
> > Is this okay?
>
> Looks fine, thanks.
Committed.

Thanks.
Stefan