From: Dmitry Safonov <dima@xxxxxxxxxx> Subject: 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@xxxxxxxxxx/T/#u Link: http://lkml.kernel.org/r/20200418201944.482088-39-dima@xxxxxxxxxx Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx> Cc: Guan Xuetao <gxt@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/unicore32/kernel/setup.h | 2 +- arch/unicore32/kernel/traps.c | 2 +- arch/unicore32/lib/backtrace.S | 24 ++++++++++++++++-------- 3 files changed, 18 insertions(+), 10 deletions(-) --- a/arch/unicore32/kernel/setup.h~unicore32-add-loglvl-to-c_backtrace +++ a/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 *); --- a/arch/unicore32/kernel/traps.c~unicore32-add-loglvl-to-c_backtrace +++ a/arch/unicore32/kernel/traps.c @@ -163,7 +163,7 @@ static void dump_backtrace(struct pt_reg printk("\n"); if (ok) - c_backtrace(fp); + c_backtrace(fp, KERN_DEFAULT); } void show_stack(struct task_struct *tsk, unsigned long *sp) --- a/arch/unicore32/lib/backtrace.S~unicore32-add-loglvl-to-c_backtrace +++ a/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, () _
