x86/dumpstack: Use uniform "Oops: " prefix for die() messages

panic() prints a uniform prompt: "Kernel panic - not syncing:",
but die() messages don't have any of that, the message is the
raw user-defined message with no prefix.

There's companies that collect thousands of die() messages per week,
but w/o a prompt in dmesg, it's hard to write scripts to collect and
analize the reasons.

Add a uniform "Oops:" prefix like other architectures.

[ mingo: Rewrote changelog. ]
Signed-off-by: Alex Shi <alexs@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240327024419.471433-1-alexs@kernel.org

arch/x86/kernel/dumpstack.c

@@ -405,8 +405,8 @@ static void __die_header(const char *str, struct pt_regs *regs, long err)
 		pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
 
 	printk(KERN_DEFAULT
-	       "%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter,
-	       pr,
+	       "Oops: %s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff,
+	       ++die_counter, pr,
 	       IS_ENABLED(CONFIG_SMP)     ? " SMP"             : "",
 	       debug_pagealloc_enabled()  ? " DEBUG_PAGEALLOC" : "",
 	       IS_ENABLED(CONFIG_KASAN)   ? " KASAN"           : "",