linux-kernel - [PATCH v4 4/6] powerpc/traps: Print VMA for unhandled signals

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Date:   Wed,  1 Aug 2018 18:33:18 -0300
From:   Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     "Alastair D'Silva" <alastair@...ilva.org>,
        Andrew Donnellan <andrew.donnellan@....ibm.com>,
        Balbir Singh <bsingharora@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Christophe Leroy <christophe.leroy@....fr>,
        Cyril Bur <cyrilbur@...il.com>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Joe Perches <joe@...ches.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Michael Neuling <mikey@...ling.org>,
        Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Paul Mackerras <paulus@...ba.org>,
        Simon Guo <wei.guo.simon@...il.com>,
        Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>,
        "Tobin C . Harding" <me@...in.cc>, linuxppc-dev@...ts.ozlabs.org,
        Segher Boessenkool <segher@...nel.crashing.org>
Subject: [PATCH v4 4/6] powerpc/traps: Print VMA for unhandled signals

This adds VMA address in the message printed for unhandled signals,
similarly to what other architectures, like x86, print.

Before this patch, a page fault looked like:

  pandafault[61470]: unhandled signal 11 at 100007d0 nip 1000061c lr 7fff8d185100 code 2

After this patch, a page fault looks like:

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

Signed-off-by: Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>
---
 arch/powerpc/kernel/traps.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 4503e22f6ba5..bcefbb1ee771 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -96,6 +96,19 @@ EXPORT_SYMBOL(__debugger_fault_handler);
 #define TM_DEBUG(x...) do { } while(0)
 #endif
 
+static const char *signame(int signr)
+{
+	switch (signr) {
+	case SIGBUS:	return "bus error";
+	case SIGFPE:	return "floating point exception";
+	case SIGILL:	return "illegal instruction";
+	case SIGSEGV:	return "segfault";
+	case SIGTRAP:	return "unhandled trap";
+	}
+
+	return "unknown signal";
+}
+
 /*
  * Trap & Exception support
  */
@@ -317,9 +330,13 @@ static void show_signal_msg(int signr, struct pt_regs *regs, int code,
 	if (!show_unhandled_signals_ratelimited())
 		return;
 
-	pr_info("%s[%d]: unhandled signal %d at %lx nip %lx lr %lx code %x\n",
-		current->comm, current->pid, signr,
+	pr_info("%s[%d]: %s (%d) at %lx nip %lx lr %lx code %x",
+		current->comm, current->pid, signame(signr), signr,
 		addr, regs->nip, regs->link, code);
+
+	print_vma_addr(KERN_CONT " in ", regs->nip);
+
+	pr_cont("\n");
 }
 
 void _exception_pkey(int signr, struct pt_regs *regs, int code,
-- 
2.17.1