linux/arch/sh/kernel/dumpstack.c
Tejun Heo 196779b9b4 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+ #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>
2013-04-30 17:04:02 -07:00

161 lines
3.4 KiB
C

/*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
* Copyright (C) 2009 Matt Fleming
* Copyright (C) 2002 - 2012 Paul Mundt
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/kallsyms.h>
#include <linux/ftrace.h>
#include <linux/debug_locks.h>
#include <linux/kdebug.h>
#include <linux/export.h>
#include <linux/uaccess.h>
#include <asm/unwinder.h>
#include <asm/stacktrace.h>
void dump_mem(const char *str, unsigned long bottom, unsigned long top)
{
unsigned long p;
int i;
printk("%s(0x%08lx to 0x%08lx)\n", str, bottom, top);
for (p = bottom & ~31; p < top; ) {
printk("%04lx: ", p & 0xffff);
for (i = 0; i < 8; i++, p += 4) {
unsigned int val;
if (p < bottom || p >= top)
printk(" ");
else {
if (__get_user(val, (unsigned int __user *)p)) {
printk("\n");
return;
}
printk("%08x ", val);
}
}
printk("\n");
}
}
void printk_address(unsigned long address, int reliable)
{
printk(" [<%p>] %s%pS\n", (void *) address,
reliable ? "" : "? ", (void *) address);
}
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
static void
print_ftrace_graph_addr(unsigned long addr, void *data,
const struct stacktrace_ops *ops,
struct thread_info *tinfo, int *graph)
{
struct task_struct *task = tinfo->task;
unsigned long ret_addr;
int index = task->curr_ret_stack;
if (addr != (unsigned long)return_to_handler)
return;
if (!task->ret_stack || index < *graph)
return;
index -= *graph;
ret_addr = task->ret_stack[index].ret;
ops->address(data, ret_addr, 1);
(*graph)++;
}
#else
static inline void
print_ftrace_graph_addr(unsigned long addr, void *data,
const struct stacktrace_ops *ops,
struct thread_info *tinfo, int *graph)
{ }
#endif
void
stack_reader_dump(struct task_struct *task, struct pt_regs *regs,
unsigned long *sp, const struct stacktrace_ops *ops,
void *data)
{
struct thread_info *context;
int graph = 0;
context = (struct thread_info *)
((unsigned long)sp & (~(THREAD_SIZE - 1)));
while (!kstack_end(sp)) {
unsigned long addr = *sp++;
if (__kernel_text_address(addr)) {
ops->address(data, addr, 1);
print_ftrace_graph_addr(addr, data, ops,
context, &graph);
}
}
}
static int print_trace_stack(void *data, char *name)
{
printk("%s <%s> ", (char *)data, name);
return 0;
}
/*
* Print one address/symbol entries per line.
*/
static void print_trace_address(void *data, unsigned long addr, int reliable)
{
printk(data);
printk_address(addr, reliable);
}
static const struct stacktrace_ops print_trace_ops = {
.stack = print_trace_stack,
.address = print_trace_address,
};
void show_trace(struct task_struct *tsk, unsigned long *sp,
struct pt_regs *regs)
{
if (regs && user_mode(regs))
return;
printk("\nCall trace:\n");
unwind_stack(tsk, regs, sp, &print_trace_ops, "");
printk("\n");
if (!tsk)
tsk = current;
debug_show_held_locks(tsk);
}
void show_stack(struct task_struct *tsk, unsigned long *sp)
{
unsigned long stack;
if (!tsk)
tsk = current;
if (tsk == current)
sp = (unsigned long *)current_stack_pointer;
else
sp = (unsigned long *)tsk->thread.sp;
stack = (unsigned long)sp;
dump_mem("Stack: ", stack, THREAD_SIZE +
(unsigned long)task_stack_page(tsk));
show_trace(tsk, sp, NULL);
}