Re: [PATCH v3 5/9] powerpc/traps: Print signal name for unhandled signals

From: Christophe LEROY
Date: Wed Aug 01 2018 - 02:37:23 EST




Le 31/07/2018 Ã 16:50, Murilo Opsfelder Araujo a ÃcritÂ:
This adds a human-readable name in the unhandled signal message.

Before this patch, a page fault looked like:

pandafault[6303]: unhandled signal 11 at 100007d0 nip 1000061c lr 7fff93c55100 code 2 in pandafault[10000000+10000]

After this patch, a page fault looks like:

pandafault[6352]: segfault (11) at 13a2a09f8 nip 13a2a086c lr 7fffb63e5100 code 2 in pandafault[13a2a0000+10000]

Signed-off-by: Murilo Opsfelder Araujo <muriloo@xxxxxxxxxxxxx>
---
arch/powerpc/kernel/traps.c | 39 +++++++++++++++++++++++++++++++++++--
1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 1c4f06fca370..e71f12bca146 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
+};

I don't think is is worth having that full table when we only use a few of them. (As discussed in v1 https://patchwork.ozlabs.org/patch/948802/)

I would suggest to instead use a function like this:

static const char *signame(int signr)
{
if (signr == SIGBUS)
return "bus error";
if (signr == SIGFPE)
return "floating point exception";
if (signr == SIGILL)
return "illegal instruction";
if (signr == SIGILL)
return "segfault";
if (signr == SIGTRAP)
return "unhandled trap";
return "unknown signal";
}

Christophe

+
/*
* Trap & Exception support
*/
@@ -314,8 +349,8 @@ 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 %lx nip %lx lr %lx code %x",
- current->comm, current->pid, signr,
+ pr_info("%s[%d]: %s (%d) at %lx nip %lx lr %lx code %x",
+ current->comm, current->pid, signames[signr], signr,
addr, regs->nip, regs->link, code);
print_vma_addr(KERN_CONT " in ", regs->nip);