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htejuntorvalds
htejun
authored and
torvalds
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dump_stack: consolidate dump_stack() implementations and unify their behaviors
Both dump_stack() and show_stack() are currently implemented by each architecture. show_stack(NULL, NULL) dumps the backtrace for the current task as does dump_stack(). On some archs, dump_stack() prints extra information - pid, utsname and so on - in addition to the backtrace while the two are identical on other archs. The usages in arch-independent code of the two functions indicate show_stack(NULL, NULL) should print out bare backtrace while dump_stack() is used for debugging purposes when something went wrong, so it does make sense to print additional information on the task which triggered dump_stack(). There's no reason to require archs to implement two separate but mostly identical functions. It leads to unnecessary subtle information. This patch expands the dummy fallback dump_stack() implementation in lib/dump_stack.c such that it prints out debug information (taken from x86) and invokes show_stack(NULL, NULL) and drops arch-specific dump_stack() implementations in all archs except blackfin. Blackfin's dump_stack() does something wonky that I don't understand. Debug information can be printed separately by calling dump_stack_print_info() so that arch-specific dump_stack() implementation can still emit the same debug information. This is used in blackfin. This patch brings the following behavior changes. * On some archs, an extra level in backtrace for show_stack() could be printed. This is because the top frame was determined in dump_stack() on those archs while generic dump_stack() can't do that reliably. It can be compensated by inlining dump_stack() but not sure whether that'd be necessary. * Most archs didn't use to print debug info on dump_stack(). They do now. An example WARN dump follows. WARNING: at kernel/workqueue.c:4841 init_workqueues+0x35/0x505() Hardware name: empty Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.9.0-rc1-work+ hardkernel#9 0000000000000009 ffff88007c861e08 ffffffff81c614dc ffff88007c861e48 ffffffff8108f50f ffffffff82228240 0000000000000040 ffffffff8234a03c 0000000000000000 0000000000000000 0000000000000000 ffff88007c861e58 Call Trace: [<ffffffff81c614dc>] dump_stack+0x19/0x1b [<ffffffff8108f50f>] warn_slowpath_common+0x7f/0xc0 [<ffffffff8108f56a>] warn_slowpath_null+0x1a/0x20 [<ffffffff8234a071>] init_workqueues+0x35/0x505 ... v2: CPU number added to the generic debug info as requested by s390 folks and dropped the s390 specific dump_stack(). This loses %ksp from the debug message which the maintainers think isn't important enough to keep the s390-specific dump_stack() implementation. dump_stack_print_info() is moved to kernel/printk.c from lib/dump_stack.c. Because linkage is per objecct file, dump_stack_print_info() living in the same lib file as generic dump_stack() means that archs which implement custom dump_stack() - at this point, only blackfin - can't use dump_stack_print_info() as that will bring in the generic version of dump_stack() too. v1 The v1 patch broke build on blackfin due to this issue. The build breakage was reported by Fengguang Wu. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Vineet Gupta <vgupta@synopsys.com> Acked-by: Jesper Nilsson <jesper.nilsson@axis.com> Acked-by: Vineet Gupta <vgupta@synopsys.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> [s390 bits] Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Mike Frysinger <vapier@gentoo.org> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Sam Ravnborg <sam@ravnborg.org> Acked-by: Richard Kuo <rkuo@codeaurora.org> [hexagon bits] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 89e3f23 commit 196779b

33 files changed

Lines changed: 32 additions & 262 deletions

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‎arch/alpha/kernel/traps.c‎

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@@ -169,13 +169,6 @@ void show_stack(struct task_struct *task, unsigned long *sp)
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dik_show_trace(sp);
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}
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void dump_stack(void)
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{
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show_stack(NULL, NULL);
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}
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EXPORT_SYMBOL(dump_stack);
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void
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die_if_kernel(char * str, struct pt_regs *regs, long err, unsigned long *r9_15)
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{

‎arch/arc/kernel/stacktrace.c‎

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@@ -220,13 +220,6 @@ void show_stack(struct task_struct *tsk, unsigned long *sp)
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show_stacktrace(tsk, NULL);
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}
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/* Expected by Rest of kernel code */
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void dump_stack(void)
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{
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show_stacktrace(NULL, NULL);
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}
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EXPORT_SYMBOL(dump_stack);
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/* Another API expected by schedular, shows up in "ps" as Wait Channel
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* Ofcourse just returning schedule( ) would be pointless so unwind until
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* the function is not in schedular code

‎arch/arm/kernel/traps.c‎

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@@ -204,13 +204,6 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
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}
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#endif
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void dump_stack(void)
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{
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dump_backtrace(NULL, NULL);
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}
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EXPORT_SYMBOL(dump_stack);
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void show_stack(struct task_struct *tsk, unsigned long *sp)
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{
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dump_backtrace(NULL, tsk);

‎arch/arm64/kernel/traps.c‎

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@@ -167,13 +167,6 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
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}
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}
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void dump_stack(void)
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{
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dump_backtrace(NULL, NULL);
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}
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EXPORT_SYMBOL(dump_stack);
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void show_stack(struct task_struct *tsk, unsigned long *sp)
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{
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dump_backtrace(NULL, tsk);

‎arch/avr32/kernel/process.c‎

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@@ -204,14 +204,6 @@ void show_stack(struct task_struct *tsk, unsigned long *stack)
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show_stack_log_lvl(tsk, (unsigned long)stack, NULL, "");
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}
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void dump_stack(void)
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{
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unsigned long stack;
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show_trace_log_lvl(current, &stack, NULL, "");
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}
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EXPORT_SYMBOL(dump_stack);
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static const char *cpu_modes[] = {
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"Application", "Supervisor", "Interrupt level 0", "Interrupt level 1",
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"Interrupt level 2", "Interrupt level 3", "Exception", "NMI"

‎arch/blackfin/kernel/dumpstack.c‎

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@@ -168,6 +168,7 @@ void dump_stack(void)
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#endif
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trace_buffer_save(tflags);
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dump_bfin_trace_buffer();
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dump_stack_print_info(KERN_DEFAULT);
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show_stack(current, &stack);
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trace_buffer_restore(tflags);
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}

‎arch/c6x/kernel/traps.c‎

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@@ -67,15 +67,6 @@ void show_regs(struct pt_regs *regs)
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pr_err("A31: %08lx B31: %08lx\n", regs->a31, regs->b31);
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}
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void dump_stack(void)
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{
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unsigned long stack;
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show_stack(current, &stack);
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}
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EXPORT_SYMBOL(dump_stack);
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void die(char *str, struct pt_regs *fp, int nr)
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{
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console_verbose();

‎arch/cris/kernel/traps.c‎

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@@ -146,13 +146,6 @@ show_stack(void)
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}
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#endif
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void
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dump_stack(void)
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{
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show_stack(NULL, NULL);
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}
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EXPORT_SYMBOL(dump_stack);
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void
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set_nmi_handler(void (*handler)(struct pt_regs *))
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{

‎arch/frv/kernel/traps.c‎

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@@ -466,17 +466,6 @@ asmlinkage void compound_exception(unsigned long esfr1,
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BUG();
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} /* end compound_exception() */
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/*****************************************************************************/
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/*
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* The architecture-independent backtrace generator
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*/
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void dump_stack(void)
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{
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show_stack(NULL, NULL);
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}
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EXPORT_SYMBOL(dump_stack);
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void show_stack(struct task_struct *task, unsigned long *sp)
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{
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}

‎arch/h8300/kernel/traps.c‎

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@@ -164,10 +164,3 @@ void show_trace_task(struct task_struct *tsk)
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{
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show_stack(tsk,(unsigned long *)tsk->thread.esp0);
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}
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void dump_stack(void)
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{
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show_stack(NULL,NULL);
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}
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EXPORT_SYMBOL(dump_stack);

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