linux-kernel - [PATCHv3 20/50] microblaze: Add show_stack

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Message-Id: <20200418201944.482088-21-dima@arista.com>
Date:   Sat, 18 Apr 2020 21:19:14 +0100
From:   Dmitry Safonov <dima@...sta.com>
To:     linux-kernel@...r.kernel.org
Cc:     Dmitry Safonov <0x7f454c46@...il.com>,
        Dmitry Safonov <dima@...sta.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Ingo Molnar <mingo@...nel.org>, Jiri Slaby <jslaby@...e.com>,
        Petr Mladek <pmladek@...e.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        Michal Simek <monstr@...str.eu>
Subject: [PATCHv3 20/50] microblaze: Add show_stack_loglvl()

Currently, the log-level of show_stack() depends on a platform
realization. It creates situations where the headers are printed with
lower log level or higher than the stacktrace (depending on
a platform or user).

Furthermore, it forces the logic decision from user to an architecture
side. In result, some users as sysrq/kdb/etc are doing tricks with
temporary rising console_loglevel while printing their messages.
And in result it not only may print unwanted messages from other CPUs,
but also omit printing at all in the unlucky case where the printk()
was deferred.

Introducing log-level parameter and KERN_UNSUPPRESSED [1] seems
an easier approach than introducing more printk buffers.
Also, it will consolidate printings with headers.

Introduce show_stack_loglvl(), that eventually will substitute
show_stack().

Cc: Michal Simek <monstr@...str.eu>
[1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/T/#u
Signed-off-by: Dmitry Safonov <dima@...sta.com>
---
 arch/microblaze/kernel/traps.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/arch/microblaze/kernel/traps.c b/arch/microblaze/kernel/traps.c
index be726ee120fb..149ae534937e 100644
--- a/arch/microblaze/kernel/traps.c
+++ b/arch/microblaze/kernel/traps.c
@@ -31,7 +31,8 @@ static int __init kstack_setup(char *s)
 }
 __setup("kstack=", kstack_setup);
 
-void show_stack(struct task_struct *task, unsigned long *sp)
+void show_stack_loglvl(struct task_struct *task, unsigned long *sp,
+		       const char *loglvl)
 {
 	unsigned long words_to_show;
 	u32 fp = (u32) sp;
@@ -50,7 +51,7 @@ void show_stack(struct task_struct *task, unsigned long *sp)
 	if (kstack_depth_to_print && (words_to_show > kstack_depth_to_print))
 		words_to_show = kstack_depth_to_print;
 
-	pr_info("Kernel Stack:\n");
+	printk("%sKernel Stack:\n", loglvl);
 
 	/*
 	 * Make the first line an 'odd' size if necessary to get
@@ -65,14 +66,19 @@ void show_stack(struct task_struct *task, unsigned long *sp)
 			words_to_show -= line1_words;
 		}
 	}
-	print_hex_dump(KERN_INFO, "", DUMP_PREFIX_ADDRESS, 32, 4, (void *)fp,
+	print_hex_dump(loglvl, "", DUMP_PREFIX_ADDRESS, 32, 4, (void *)fp,
 		       words_to_show << 2, 0);
-	pr_info("\n\nCall Trace:\n");
-	microblaze_unwind(task, NULL, KERN_INFO);
-	pr_info("\n");
+	printk("%s\n\nCall Trace:\n", loglvl);
+	microblaze_unwind(task, NULL, loglvl);
+	printk("%s\n", loglvl);
 
 	if (!task)
 		task = current;
 
 	debug_show_held_locks(task);
 }
+
+void show_stack(struct task_struct *task, unsigned long *sp)
+{
+	show_stack_loglvl(task, sp, KERN_INFO);
+}
-- 
2.26.0