linux-kernel - [PATCH v2 10/10] powerpc/traps: Add line prefix in show

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Date:   Fri, 27 Jul 2018 11:58:11 -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>,
        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
Subject: [PATCH v2 10/10] powerpc/traps: Add line prefix in show_instructions()

Remove "Instruction dump:" line by adding a prefix to display current->comm
and current->pid, along with the instructions dump.

The prefix can serve as a glue that links the instructions dump to its
originator, allowing messages to be interleaved in the logs.

Before this patch, a page fault looked like:

    pandafault[10524]: segfault (11) at 00000000100007d0 nip 000000001000061c lr 00007fffbd295100 code 2 in pandafault[10000000+10000]
    Instruction dump:
    4bfffeec 4bfffee8 3c401002 38427f00 fbe1fff8 f821ffc1 7c3f0b78 3d22fffe
    392988d0 f93f0020 e93f0020 39400048 <99490000> 39200000 7d234b78 383f0040

After this patch, it looks like:

    pandafault[10850]: segfault (11) at 00000000100007d0 nip 000000001000061c lr 00007fff9f3e5100 code 2 in pandafault[10000000+10000]
    pandafault[10850]: code: 4bfffeec 4bfffee8 3c401002 38427f00 fbe1fff8 f821ffc1 7c3f0b78 3d22fffe
    pandafault[10850]: code: 392988d0 f93f0020 e93f0020 39400048 <99490000> 39200000 7d234b78 383f0040

Signed-off-by: Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>
---
 arch/powerpc/kernel/process.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 709bfb524b84..25b6dfc8dd81 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1265,16 +1265,19 @@ static int instructions_to_print = 16;
 void show_instructions(struct pt_regs *regs)
 {
 	int i;
+	const char *prefix = KERN_INFO "%s[%d]: code: ";
 	unsigned long pc = regs->nip - (instructions_to_print * 3 / 4 *
 			sizeof(int));
 
-	printk("Instruction dump:");
+	printk(prefix, current->comm, current->pid);
 
 	for (i = 0; i < instructions_to_print; i++) {
 		int instr;
 
-		if (!(i % 8))
+		if (!(i % 8) && (i > 0)) {
 			pr_cont("\n");
+			printk(prefix, current->comm, current->pid);
+		}
 
 #if !defined(CONFIG_BOOKE)
 		/* If executing with the IMMU off, adjust pc rather
-- 
2.17.1