Re: port-hppa/56867: hppa: intermittent SIGSEGV reports in t_ptrace_wait's stepN and setstepN test cases

[Nick Hudson <nick.hudson%gmx.co.uk@localhost>]

The following reply was made to PR port-hppa/56867; it has been noted by GNATS.

From: Nick Hudson <nick.hudson%gmx.co.uk@localhost>
To: gnats-bugs%netbsd.org@localhost, port-hppa-maintainer%netbsd.org@localhost,
 gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, tgl%sss.pgh.pa.us@localhost
Cc: 
Subject: Re: port-hppa/56867: hppa: intermittent SIGSEGV reports in
 t_ptrace_wait's stepN and setstepN test cases
Date: Fri, 10 Jun 2022 11:23:24 +0100

 On 09/06/2022 06:40, Tom Lane wrote:
 > The following reply was made to PR port-hppa/56867; it has been noted by=
  GNATS.
 >
 > From: Tom Lane <tgl%sss.pgh.pa.us@localhost>
 > To: gnats-bugs%netbsd.org@localhost
 > Cc:
 > Subject: Re: port-hppa/56867: hppa: intermittent SIGSEGV reports in t_pt=
 race_wait's stepN and setstepN test cases
 > Date: Thu, 09 Jun 2022 01:39:23 -0400
 >
 >   I've managed to resurrect my NetBSD/hppa installation, and resumed
 >   investigating this issue.
 
 YAY. :)
 
 
 >   My theory that there's something wrong with
 >   ITLBMISS processing seems to be backwards: after adding some hacky
 >   instrumentation, I found that the test passes when an ITLBMISS trap
 >   occurs upon trying to execute the modified instruction stream, while
 >   it fails when one does not.  That led me to guess that what's missing
 >   is a TLB flush operation, and sure enough this quick-hack patch seems
 >   to fix it:
 >
 >   Index: sys/arch/hppa/hppa/pmap.c
 >   =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
 >   RCS file: /cvsroot/src/sys/arch/hppa/hppa/pmap.c,v
 >   retrieving revision 1.117
 >   diff -u -r1.117 pmap.c
 >   --- sys/arch/hppa/hppa/pmap.c   26 May 2022 05:34:04 -0000      1.117
 >   +++ sys/arch/hppa/hppa/pmap.c   9 Jun 2022 03:36:33 -0000
 >   @@ -1874,9 +1874,12 @@
 >    pmap_procwr(struct proc *p, vaddr_t va, size_t len)
 >    {
 >           pmap_t pmap =3D p->p_vmspace->vm_map.pmap;
 >   +       pa_space_t sp =3D pmap->pm_space;
 >
 >   -       fdcache(pmap->pm_space, va, len);
 >   -       ficache(pmap->pm_space, va, len);
 >   +       fdcache(sp, va, len);
 >   +       ficache(sp, va, len);
 >   +       pdtlb(sp, va);
 >   +       pitlb(sp, va);
 >    }
 >
 
 I dont this is right. The process mappings aren't changing. Will think
 about it some more.
 
 Thanks for poking at all of this.
 
 Nick