linux-kernel - [PATCH v4 6/6] powerpc/traps: Show instructions on exceptions

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Message-Id: <20180801213320.11203-7-muriloo@linux.ibm.com>
Date:   Wed,  1 Aug 2018 18:33:20 -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 6/6] powerpc/traps: Show instructions on exceptions

Call show_user_instructions() in arch/powerpc/kernel/traps.c to dump
instructions at faulty location, useful to debugging.

Before this patch, an unhandled signal message looked like:

  pandafault[10524]: segfault (11) at 100007d0 nip 1000061c lr 7fffbd295100 code 2 in pandafault[10000000+10000]

After this patch, it looks like:

  pandafault[10524]: segfault (11) at 100007d0 nip 1000061c lr 7fffbd295100 code 2 in pandafault[10000000+10000]
  pandafault[10524]: code: 4bfffeec 4bfffee8 3c401002 38427f00 fbe1fff8 f821ffc1 7c3f0b78 3d22fffe
  pandafault[10524]: code: 392988d0 f93f0020 e93f0020 39400048 <99490000> 39200000 7d234b78 383f0040

Signed-off-by: Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>
---
 arch/powerpc/kernel/traps.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index bcefbb1ee771..8494b0ff4904 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -70,6 +70,7 @@
 #include <asm/hmi.h>
 #include <sysdev/fsl_pci.h>
 #include <asm/kprobes.h>
+#include <asm/stacktrace.h>
 
 #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC_CORE)
 int (*__debugger)(struct pt_regs *regs) __read_mostly;
@@ -337,6 +338,8 @@ static void show_signal_msg(int signr, struct pt_regs *regs, int code,
 	print_vma_addr(KERN_CONT " in ", regs->nip);
 
 	pr_cont("\n");
+
+	show_user_instructions(regs);
 }
 
 void _exception_pkey(int signr, struct pt_regs *regs, int code,
-- 
2.17.1