From da75c6afba6229c52cd3a5e81b60d883848b5686 Mon Sep 17 00:00:00 2001
From: Tao Huang <huangtao@rock-chips.com>
Date: Wed, 13 Dec 2017 15:19:04 +0800
Subject: [PATCH] printk: add support show process information on printks

Change-Id: I34cf76388ceb2e1f6b6417638c82bf774641ebac
Signed-off-by: Tao Huang <huangtao@rock-chips.com>
---
 kernel/printk/printk.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 lib/Kconfig.debug      |  7 +++++++
 2 files changed, 49 insertions(+)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 06045abd1887..0d28734cda22 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -364,6 +364,12 @@ struct printk_log {
 	u8 facility;		/* syslog facility */
 	u8 flags:5;		/* internal record flags */
 	u8 level:3;		/* syslog level */
+#ifdef CONFIG_PRINTK_PROCESS
+	char process[16];	/* process name */
+	pid_t pid;		/* process id */
+	u8 cpu;			/* cpu id */
+	u8 in_interrupt;	/* interrupt context */
+#endif
 }
 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 __packed __aligned(4)
@@ -428,7 +434,11 @@ static u32 console_idx;
 static u64 clear_seq;
 static u32 clear_idx;
 
+#ifdef CONFIG_PRINTK_PROCESS
+#define PREFIX_MAX		48
+#else
 #define PREFIX_MAX		32
+#endif
 #define LOG_LINE_MAX		(1024 - PREFIX_MAX)
 
 #define LOG_LEVEL(v)		((v) & 0x07)
@@ -497,6 +507,25 @@ static u32 log_next(u32 idx)
 	return idx + msg->len;
 }
 
+#ifdef CONFIG_PRINTK_PROCESS
+static bool printk_process = true;
+static size_t print_process(const struct printk_log *msg, char *buf)
+{
+	if (!printk_process)
+		return 0;
+
+	if (!buf)
+		return snprintf(NULL, 0, "%c[%1d:%15s:%5d] ", ' ', 0, " ", 0);
+
+	return sprintf(buf, "%c[%1d:%15s:%5d] ",
+			msg->in_interrupt ? 'I' : ' ',
+			msg->cpu,
+			msg->process,
+			msg->pid);
+}
+module_param_named(process, printk_process, bool, 0644);
+#endif
+
 /*
  * Check whether there is enough free space for the given message.
  *
@@ -633,6 +662,16 @@ static int log_store(int facility, int level,
 	memset(log_dict(msg) + dict_len, 0, pad_len);
 	msg->len = size;
 
+#ifdef CONFIG_PRINTK_PROCESS
+	if (printk_process) {
+		strncpy(msg->process, current->comm, sizeof(msg->process) - 1);
+		msg->process[sizeof(msg->process) - 1] = '\0';
+		msg->pid = task_pid_nr(current);
+		msg->cpu = raw_smp_processor_id();
+		msg->in_interrupt = in_interrupt() ? 1 : 0;
+	}
+#endif
+
 	/* insert message */
 	log_next_idx += msg->len;
 	log_next_seq++;
@@ -1250,6 +1289,9 @@ static size_t print_prefix(const struct printk_log *msg, bool syslog, char *buf)
 	}
 
 	len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
+#ifdef CONFIG_PRINTK_PROCESS
+	len += print_process(msg, buf ? buf + len : NULL);
+#endif
 	return len;
 }
 
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 4966c4fbe7f7..de11ea9e1ee8 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -17,6 +17,13 @@ config PRINTK_TIME
 	  The behavior is also controlled by the kernel command line
 	  parameter printk.time=1. See Documentation/admin-guide/kernel-parameters.rst
 
+config PRINTK_PROCESS
+	bool "Show process information on printks"
+	depends on PRINTK
+	help
+	  Selecting this option causes process to be
+	  included in printk output. Or add printk.process=1 at boot-time.
+
 config CONSOLE_LOGLEVEL_DEFAULT
 	int "Default console loglevel (1-15)"
 	range 1 15