arc: 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().

As a good side-effect header "Stack Trace:" is now printed with the same
log level as the rest of backtrace.

[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: Vineet Gupta <vgupta@synopsys.com>
Link: http://lkml.kernel.org/r/20200418201944.482088-4-dima@arista.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/arc/include/asm/bug.h b/arch/arc/include/asm/bug.h
index 0be19fd1a4126ae42bcbd3dc4cd32a2f4e292748..4c453ba96c51956a0314eaa87d0a92959c725e9a 100644 (file)
--- a/arch/arc/include/asm/bug.h
+++ b/arch/arc/include/asm/bug.h
@@ -13,7 +13,8 @@
 struct task_struct;
 
 void show_regs(struct pt_regs *regs);
-void show_stacktrace(struct task_struct *tsk, struct pt_regs *regs);
+void show_stacktrace(struct task_struct *tsk, struct pt_regs *regs,
+                    const char *loglvl);
 void show_kernel_fault_diag(const char *str, struct pt_regs *regs,
                            unsigned long address);
 void die(const char *str, struct pt_regs *regs, unsigned long address);

diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c
index 1e440bbfa876ba2b26b667a29d4a8bdc577f9dcc..24f9cd8a12c94f0abc06cffc4149ee15396905b7 100644 (file)
--- a/arch/arc/kernel/stacktrace.c
+++ b/arch/arc/kernel/stacktrace.c
@@ -158,9 +158,11 @@ arc_unwind_core(struct task_struct *tsk, struct pt_regs *regs,
 /* Call-back which plugs into unwinding core to dump the stack in
  * case of panic/OOPs/BUG etc
  */
-static int __print_sym(unsigned int address, void *unused)
+static int __print_sym(unsigned int address, void *arg)
 {
-       printk("  %pS\n", (void *)address);
+       const char *loglvl = arg;
+
+       printk("%s  %pS\n", loglvl, (void *)address);
        return 0;
 }
 
@@ -217,17 +219,24 @@ static int __get_first_nonsched(unsigned int address, void *unused)
  *-------------------------------------------------------------------------
  */
 
-noinline void show_stacktrace(struct task_struct *tsk, struct pt_regs *regs)
+noinline void show_stacktrace(struct task_struct *tsk, struct pt_regs *regs,
+                             const char *loglvl)
 {
-       pr_info("\nStack Trace:\n");
-       arc_unwind_core(tsk, regs, __print_sym, NULL);
+       printk("%s\nStack Trace:\n", loglvl);
+       arc_unwind_core(tsk, regs, __print_sym, (void *)loglvl);
 }
 EXPORT_SYMBOL(show_stacktrace);
 
 /* Expected by sched Code */
+void show_stack_loglvl(struct task_struct *tsk, unsigned long *sp,
+                       const char *loglvl)
+{
+       show_stacktrace(tsk, NULL, loglvl);
+}
+
 void show_stack(struct task_struct *tsk, unsigned long *sp)
 {
-       show_stacktrace(tsk, NULL);
+       show_stack_loglvl(tsk, sp, KERN_DEFAULT);
 }
 
 /* Another API expected by schedular, shows up in "ps" as Wait Channel

diff --git a/arch/arc/kernel/troubleshoot.c b/arch/arc/kernel/troubleshoot.c
index 3393558876a9b154ef723b8c0e025ca1f96ab633..3044c8347b746e7d64943c7029d59bf039cd60df 100644 (file)
--- a/arch/arc/kernel/troubleshoot.c
+++ b/arch/arc/kernel/troubleshoot.c
@@ -240,5 +240,5 @@ void show_kernel_fault_diag(const char *str, struct pt_regs *regs,
 
        /* Show stack trace if this Fatality happened in kernel mode */
        if (!user_mode(regs))
-               show_stacktrace(current, regs);
+               show_stacktrace(current, regs, KERN_DEFAULT);
 }