Re: [PATCH 6/7] powerpc/traps: Print signal name for unhandled signals

Murilo Opsfelder Araujo
2018-07-25T20:06:45Z

Hi, Christophe.

On Wed, Jul 25, 2018 at 05:49:27PM +0200, LEROY Christophe wrote:
> Murilo Opsfelder Araujo <muriloo@linux.ibm.com> a écrit :
>
> > This adds a human-readable name in the unhandled signal message.
> >
> > Before this patch, a page fault looked like:
> >
> > Jul 11 16:04:11 localhost kernel: pandafault[6303]: unhandled signal
> > 11 at 00000000100007d0 nip 000000001000061c lr 00007fff93c55100 code 2
> > in pandafault[10000000+10000]
> >
> > After this patch, a page fault looks like:
> >
> > Jul 11 18:14:48 localhost kernel: pandafault[6352]: segfault (11) at
> > 000000013a2a09f8 nip 000000013a2a086c lr 00007fffb63e5100 code 2 in
> > pandafault[13a2a0000+10000]
> >
> > Signed-off-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
> > ---
> > arch/powerpc/kernel/traps.c | 43 +++++++++++++++++++++++++++++++++----
> > 1 file changed, 39 insertions(+), 4 deletions(-)
> >
> > diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
> > index e6c43ef9fb50..e55ee639d010 100644
> > --- a/arch/powerpc/kernel/traps.c
> > +++ b/arch/powerpc/kernel/traps.c
> > @@ -96,6 +96,41 @@ EXPORT_SYMBOL(__debugger_fault_handler);
> > #define TM_DEBUG(x...) do { } while(0)
> > #endif
> >
> > +static const char *signames[SIGRTMIN + 1] = {
> > + "UNKNOWN",
> > + "SIGHUP", // 1
> > + "SIGINT", // 2
> > + "SIGQUIT", // 3
> > + "SIGILL", // 4
> > + "unhandled trap", // 5 = SIGTRAP
> > + "SIGABRT", // 6 = SIGIOT
> > + "bus error", // 7 = SIGBUS
> > + "floating point exception", // 8 = SIGFPE
> > + "illegal instruction", // 9 = SIGILL
> > + "SIGUSR1", // 10
> > + "segfault", // 11 = SIGSEGV
> > + "SIGUSR2", // 12
> > + "SIGPIPE", // 13
> > + "SIGALRM", // 14
> > + "SIGTERM", // 15
> > + "SIGSTKFLT", // 16
> > + "SIGCHLD", // 17
> > + "SIGCONT", // 18
> > + "SIGSTOP", // 19
> > + "SIGTSTP", // 20
> > + "SIGTTIN", // 21
> > + "SIGTTOU", // 22
> > + "SIGURG", // 23
> > + "SIGXCPU", // 24
> > + "SIGXFSZ", // 25
> > + "SIGVTALRM", // 26
> > + "SIGPROF", // 27
> > + "SIGWINCH", // 28
> > + "SIGIO", // 29 = SIGPOLL = SIGLOST
> > + "SIGPWR", // 30
> > + "SIGSYS", // 31 = SIGUNUSED
> > +};
> > +
> > /*
> > * Trap & Exception support
> > */
> > @@ -314,10 +349,10 @@ static void show_signal_msg(int signr, struct
> > pt_regs *regs, int code,
> > if (!unhandled_signal(current, signr))
> > return;
> >
> > - pr_info("%s[%d]: unhandled signal %d at "REG_FMT \
> > - " nip "REG_FMT" lr "REG_FMT" code %x",
> > - current->comm, current->pid, signr, addr,
> > - regs->nip, regs->link, code);
> > + pr_info("%s[%d]: %s (%d) at "REG_FMT" nip "REG_FMT \
> > + " lr "REG_FMT" code %x",
> > + current->comm, current->pid, signames[signr],
> > + signr, addr, regs->nip, regs->link, code);
>
> Are we sure that signr is always within the limits of the table ?

Looking at the code, we only pass the following signals:

SIGBUS
SIGFPE
SIGILL
SIGSEGV
SIGTRAP

All of them are within the limits of the table. We've added other
signals for completeness.

Cheers
Murilo