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

Hi, Christophe.

On Wed, Jul 25, 2018 at 05:49:27PM +0200, LEROY Christophe wrote:

Murilo Opsfelder Araujo [off-list ref] a écrit :

quoted

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 <redacted>
---
 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