Commit de985dd5 authored by Dmitry Safonov's avatar Dmitry Safonov Committed by Linus Torvalds
Browse files

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: default avatarDmitry Safonov <dima@arista.com>
Signed-off-by: default avatarAndrew 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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ee1e9900

arch/unicore32/kernel/setup.h

+1 −1
Original line number Diff line number Diff line
@@ -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 *);

arch/unicore32/kernel/traps.c

+1 −1
Original line number Diff line number Diff line
@@ -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)

arch/unicore32/lib/backtrace.S

+16 −8
Original line number Diff line number Diff line
@@ -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, ()