sh: add loglvl to printk_address()

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.

Add log level argument to printk_address() as a preparation to introduce
show_stack_loglvl().

As a good side-effect show_fault_oops() now prints the address with
KERN_EMREG as the rest of output, making sure there won't be situation
where "PC: " is printed without actual address.

[1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/T/#u

Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Rich Felker <dalias@libc.org>
Link: http://lkml.kernel.org/r/20200418201944.482088-32-dima@arista.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 6 insertions, 5 deletions

diff --git a/arch/sh/include/asm/kdebug.h b/arch/sh/include/asm/kdebug.h
index de8693fabb1d..960545306afa 100644
--- a/arch/sh/include/asm/kdebug.h
+++ b/arch/sh/include/asm/kdebug.h
@@ -12,7 +12,8 @@ enum die_val {
 };
 
 /* arch/sh/kernel/dumpstack.c */
-extern void printk_address(unsigned long address, int reliable);
+extern void printk_address(unsigned long address, int reliable,
+			   const char *loglvl);
 extern void dump_mem(const char *str, const char *loglvl,
 		     unsigned long bottom, unsigned long top);
 
diff --git a/arch/sh/kernel/dumpstack.c b/arch/sh/kernel/dumpstack.c
index 2c1a78e5776b..959064b90055 100644
--- a/arch/sh/kernel/dumpstack.c
+++ b/arch/sh/kernel/dumpstack.c
@@ -44,9 +44,9 @@ void dump_mem(const char *str, const char *loglvl,
 	}
 }
 
-void printk_address(unsigned long address, int reliable)
+void printk_address(unsigned long address, int reliable, const char *loglvl)
 {
-	printk(" [<%p>] %s%pS\n", (void *) address,
+	printk("%s [<%p>] %s%pS\n", loglvl, (void *) address,
 			reliable ? "" : "? ", (void *) address);
 }
 
@@ -118,7 +118,7 @@ static int print_trace_stack(void *data, char *name)
  */
 static void print_trace_address(void *data, unsigned long addr, int reliable)
 {
-	printk_address(addr, reliable);
+	printk_address(addr, reliable, (char *)data);
 }
 
 static const struct stacktrace_ops print_trace_ops = {
diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 7260a1a7fdca..67d0e739897c 100644
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -214,7 +214,7 @@ show_fault_oops(struct pt_regs *regs, unsigned long address)
 				     : "paging request",
 		 address);
 	pr_alert("PC:");
-	printk_address(regs->pc, 1);
+	printk_address(regs->pc, 1, KERN_ALERT);
 
 	show_pte(NULL, address);
 }