linux/arch/blackfin/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

176 lines
4.3 KiB
C

/* Provide basic stack dumping functions
*
* Copyright 2004-2009 Analog Devices Inc.
*
* Licensed under the GPL-2 or later
*/
#include <linux/kernel.h>
#include <linux/thread_info.h>
#include <linux/mm.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <asm/trace.h>
/*
* Checks to see if the address pointed to is either a
* 16-bit CALL instruction, or a 32-bit CALL instruction
*/
static bool is_bfin_call(unsigned short *addr)
{
unsigned int opcode;
if (!get_instruction(&opcode, addr))
return false;
if ((opcode >= 0x0060 && opcode <= 0x0067) ||
(opcode >= 0x0070 && opcode <= 0x0077) ||
(opcode >= 0xE3000000 && opcode <= 0xE3FFFFFF))
return true;
return false;
}
void show_stack(struct task_struct *task, unsigned long *stack)
{
#ifdef CONFIG_PRINTK
unsigned int *addr, *endstack, *fp = 0, *frame;
unsigned short *ins_addr;
char buf[150];
unsigned int i, j, ret_addr, frame_no = 0;
/*
* If we have been passed a specific stack, use that one otherwise
* if we have been passed a task structure, use that, otherwise
* use the stack of where the variable "stack" exists
*/
if (stack == NULL) {
if (task) {
/* We know this is a kernel stack, so this is the start/end */
stack = (unsigned long *)task->thread.ksp;
endstack = (unsigned int *)(((unsigned int)(stack) & ~(THREAD_SIZE - 1)) + THREAD_SIZE);
} else {
/* print out the existing stack info */
stack = (unsigned long *)&stack;
endstack = (unsigned int *)PAGE_ALIGN((unsigned int)stack);
}
} else
endstack = (unsigned int *)PAGE_ALIGN((unsigned int)stack);
printk(KERN_NOTICE "Stack info:\n");
decode_address(buf, (unsigned int)stack);
printk(KERN_NOTICE " SP: [0x%p] %s\n", stack, buf);
if (!access_ok(VERIFY_READ, stack, (unsigned int)endstack - (unsigned int)stack)) {
printk(KERN_NOTICE "Invalid stack pointer\n");
return;
}
/* First thing is to look for a frame pointer */
for (addr = (unsigned int *)((unsigned int)stack & ~0xF); addr < endstack; addr++) {
if (*addr & 0x1)
continue;
ins_addr = (unsigned short *)*addr;
ins_addr--;
if (is_bfin_call(ins_addr))
fp = addr - 1;
if (fp) {
/* Let's check to see if it is a frame pointer */
while (fp >= (addr - 1) && fp < endstack
&& fp && ((unsigned int) fp & 0x3) == 0)
fp = (unsigned int *)*fp;
if (fp == 0 || fp == endstack) {
fp = addr - 1;
break;
}
fp = 0;
}
}
if (fp) {
frame = fp;
printk(KERN_NOTICE " FP: (0x%p)\n", fp);
} else
frame = 0;
/*
* Now that we think we know where things are, we
* walk the stack again, this time printing things out
* incase there is no frame pointer, we still look for
* valid return addresses
*/
/* First time print out data, next time, print out symbols */
for (j = 0; j <= 1; j++) {
if (j)
printk(KERN_NOTICE "Return addresses in stack:\n");
else
printk(KERN_NOTICE " Memory from 0x%08lx to %p", ((long unsigned int)stack & ~0xF), endstack);
fp = frame;
frame_no = 0;
for (addr = (unsigned int *)((unsigned int)stack & ~0xF), i = 0;
addr < endstack; addr++, i++) {
ret_addr = 0;
if (!j && i % 8 == 0)
printk(KERN_NOTICE "%p:", addr);
/* if it is an odd address, or zero, just skip it */
if (*addr & 0x1 || !*addr)
goto print;
ins_addr = (unsigned short *)*addr;
/* Go back one instruction, and see if it is a CALL */
ins_addr--;
ret_addr = is_bfin_call(ins_addr);
print:
if (!j && stack == (unsigned long *)addr)
printk("[%08x]", *addr);
else if (ret_addr)
if (j) {
decode_address(buf, (unsigned int)*addr);
if (frame == addr) {
printk(KERN_NOTICE " frame %2i : %s\n", frame_no, buf);
continue;
}
printk(KERN_NOTICE " address : %s\n", buf);
} else
printk("<%08x>", *addr);
else if (fp == addr) {
if (j)
frame = addr+1;
else
printk("(%08x)", *addr);
fp = (unsigned int *)*addr;
frame_no++;
} else if (!j)
printk(" %08x ", *addr);
}
if (!j)
printk("\n");
}
#endif
}
EXPORT_SYMBOL(show_stack);
void dump_stack(void)
{
unsigned long stack;
#ifdef CONFIG_DEBUG_BFIN_HWTRACE_ON
int tflags;
#endif
trace_buffer_save(tflags);
dump_bfin_trace_buffer();
dump_stack_print_info(KERN_DEFAULT);
show_stack(current, &stack);
trace_buffer_restore(tflags);
}
EXPORT_SYMBOL(dump_stack);