kdump on ARM

[M. Warner Losh]

In message: <6c36ec371002171047m13544419sf8ca5ad283cdc65 at mail.gmail.com>
            batcilla itself <batcilla at gmail.com> writes:
: 2010/2/17 M. Warner Losh <imp at bsdimp.com>:
: > In message: <6c36ec371002170654n5e441c6eib9a8c9aad61c1e87 at mail.gmail.com>
: >            batcilla itself <batcilla at gmail.com> writes:
: > : 2010/2/17 Hans Petter Selasky <hselasky at c2i.net>
: > : >
: > : > On Wednesday 17 February 2010 15:18:12 Grzegorz Bernacki wrote:
: > : > > Hi,
: > : > >
: > : > > I've noticed that kdump on ARM doesn't work properly, it generates bus
: > : > >  error. The problem is that structures dumped into ktrace.out are not
: > : > >  aligned. Processing such a structure causes Aligment Fault. One solution
: > : > >  is to copy structure into local variable and then process it, please see
: > : > >  patch below. But I am not sure if this is the best solution and maybe
: > : > >  someone has a better idea.
: > : > >
: > : > > grzesiek
: > : > >
: > : > >
: > : > > diff --git a/usr.bin/kdump/kdump.c b/usr.bin/kdump/kdump.c
: > : > > index 386221e..5a15886 100644
: > : > > --- a/usr.bin/kdump/kdump.c
: > : > > +++ b/usr.bin/kdump/kdump.c
: > : > > @@ -1325,6 +1325,10 @@ ktrstat(struct stat *statp)
: > : > >   void
: > : > >   ktrstruct(char *buf, size_t buflen)
: > : > >   {
: > : > > +#if defined(__arm__)
: > : > > +       struct stat stat;
: > : > > +       struct sockaddr sockaddr;
: > : > > +#endif
: > : > >          char *name, *data;
: > : > >          size_t namelen, datalen;
: > : > >          int i;
: > : > > @@ -1348,12 +1352,22 @@ ktrstruct(char *buf, size_t buflen)
: > : > >          if (strcmp(name, "stat") == 0) {
: > : > >                  if (datalen != sizeof(struct stat))
: > : > >                          goto invalid;
: > : > > +#if defined(__arm__)
: > : > > +               memcpy(&stat, data, sizeof(struct stat));
: > : > > +               ktrstat(&stat);
: > : > > +#else
: > : > >                  ktrstat((struct stat *)data);
: > : > > +#endif
: > : > >          } else if (strcmp(name, "sockaddr") == 0) {
: > : > >                  if (datalen < sizeof(struct sockaddr) ||
: > : > >                      datalen != ((struct sockaddr *)(data))->sa_len)
: > : > >                          goto invalid;
: > : > > +#if defined(__arm__)
: > : > > +               memcpy(&sockaddr, data, sizeof(struct sockaddr));
: > : > > +               ktrsockaddr(&sockaddr);
: > : > > +#else
: > : > >                  ktrsockaddr((struct sockaddr *)data);
: > : > > +#endif
: > : > >          } else {
: > : > >                  printf("unknown structure\n");
: > : > >          }
: > : >
: > : > I think more than ARM is affected by this.
: > : >
: > : > --HPS
: > : ARM affected definitely, just today had that Align error with -current
: > : while tried to use ng_bridge with wlan0
: >
: > Where exactly was the error?  Do you have a traceback?
: It was ARM/Xcale avila custom nanobsd build, error was caused adding
: wlan0 into ng_bridge, while wlan0 was in tdma master (slot 0) mode,
: with slot 1 there was no errors. Exact message here:
: 
: Fatal kernel mode data abort: 'Alignment Fault 3'
: trapframe: 0xc5e38cac
: FSR=00000003, FAR=c10fd1fe, spsr=00000013
: r0 =c0e15080, r1 =c0508288, r2 =c10fd1fe, r3 =00000001
: r4 =0000003c, r5 =c0e15080, r6 =c0e15500, r7 =c111a600
: r8 =c1182a00, r9 =c116dc00, r10=c0e15d80, r11=00000001
: r12=c0e15080, ssp=c5e38cf8, slr=c041cb58, pc =c041ec98
: 
: panic: Fatal abort
: Uptime: 3h26m17s
: Cannot dump. Device not defined or unavailable.
: Automatic reboot in 15 seconds - press a key on the console to abort
: 
: uname: avila ... FreeBSD 9.0-CURRENT #1: Wed Feb 17 12:08:37 UTC 2010 ... arm
: 
: Not really sure, if this alignment error come from kdump, there is
: really no dump device in this unit and other debugging facilities was
: turned off to save space.

I'd wager that it wasn't caused by kdump, but something in the kernel.

Warner