unicore32: add loglvl to c_backtrace()

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 parameter to c_backtrace() as a preparation for introducing
show_stack_loglvl()

[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: Guan Xuetao <gxt@pku.edu.cn>
Link: http://lkml.kernel.org/r/20200418201944.482088-39-dima@arista.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/unicore32/kernel/setup.h b/arch/unicore32/kernel/setup.h
index 03e70e3..9673523 100644 (file)
--- a/arch/unicore32/kernel/setup.h
+++ b/arch/unicore32/kernel/setup.h
@@ -29,7 +29,7 @@ extern void kernel_thread_helper(void);
 extern void __init early_signal_init(void);
 
 extern asmlinkage void __backtrace(void);
-extern asmlinkage void c_backtrace(unsigned long fp);
+extern asmlinkage void c_backtrace(unsigned long fp, const char *loglvl);
 
 extern void __show_regs(struct pt_regs *);
 

diff --git a/arch/unicore32/kernel/traps.c b/arch/unicore32/kernel/traps.c
index 3682a4c..2b7d734 100644 (file)
--- a/arch/unicore32/kernel/traps.c
+++ b/arch/unicore32/kernel/traps.c
@@ -163,7 +163,7 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
        printk("\n");
 
        if (ok)
-               c_backtrace(fp);
+               c_backtrace(fp, KERN_DEFAULT);
 }
 
 void show_stack(struct task_struct *tsk, unsigned long *sp)

diff --git a/arch/unicore32/lib/backtrace.S b/arch/unicore32/lib/backtrace.S
index f303671..6221944 100644 (file)
--- a/arch/unicore32/lib/backtrace.S
+++ b/arch/unicore32/lib/backtrace.S
@@ -16,6 +16,7 @@
 #define sv_fp  v5
 #define sv_pc  v6
 #define offset v8
+#define loglvl v9
 
 ENTRY(__backtrace)
                mov     r0, fp
@@ -27,10 +28,11 @@ ENTRY(c_backtrace)
 ENDPROC(__backtrace)
 ENDPROC(c_backtrace)
 #else
-               stm.w   (v4 - v8, lr), [sp-]    @ Save an extra register
+               stm.w   (v4 - v10, lr), [sp-]   @ Save an extra register
                                                @ so we have a location...
                mov.a   frame, r0               @ if frame pointer is zero
                beq     no_frame                @ we have no stack frames
+               mov     loglvl, r1
 
 1:             stm.w   (pc), [sp-]             @ calculate offset of PC stored
                ldw.w   r0, [sp]+, #4           @ by stmfd for this CPU
@@ -95,9 +97,10 @@ for_each_frame:
                bua     for_each_frame
 
 1006:          adr     r0, .Lbad
-               mov     r1, frame
+               mov     r1, loglvl
+               mov     r2, frame
                b.l     printk
-no_frame:      ldm.w   (v4 - v8, pc), [sp]+
+no_frame:      ldm.w   (v4 - v10, pc), [sp]+
 ENDPROC(__backtrace)
 ENDPROC(c_backtrace)
 
@@ -128,8 +131,11 @@ ENDPROC(c_backtrace)
                add     v7, v7, #1
                cxor.a  v7, #6
                cmoveq  v7, #1
-               cmoveq  r1, #'\n'
-               cmovne  r1, #' '
+               bne     201f
+               adr     r0, .Lcr
+               mov     r1, loglvl
+               b.l     printk
+201:
                ldw.w   r3, [stack]+, #-4
                mov     r2, reg
                csub.a  r2, #8
@@ -141,18 +147,20 @@ ENDPROC(c_backtrace)
                add     r2, r2, #0x10           @ so r2 need add 16
 201:
                adr     r0, .Lfp
+               mov     r1, loglvl
                b.l     printk
 2:             sub.a   reg, reg, #1
                bns     1b
                cxor.a  v7, #0
                beq     201f
                adr     r0, .Lcr
+               mov     r1, loglvl
                b.l     printk
 201:           ldm.w   (instr, reg, stack, v7, pc), [sp]+
 
-.Lfp:          .asciz  "%cr%d:%08x"
-.Lcr:          .asciz  "\n"
-.Lbad:         .asciz  "Backtrace aborted due to bad frame pointer <%p>\n"
+.Lfp:          .asciz  "%sr%d:%08x "
+.Lcr:          .asciz  "%s\n"
+.Lbad:         .asciz  "%sBacktrace aborted due to bad frame pointer <%p>\n"
                .align
 .Ldsi:         .word   0x92eec000 >> 14        @ stm.w sp, (... fp, ip, lr, pc)
                .word   0x92e10000 >> 14        @ stm.w sp, ()