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196779b9b4
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>
78 lines
1.9 KiB
C
78 lines
1.9 KiB
C
/*
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* Copyright (C) 2007-2009 Michal Simek <monstr@monstr.eu>
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* Copyright (C) 2007-2009 PetaLogix
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* Copyright (C) 2006 Atmark Techno, Inc.
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/export.h>
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#include <linux/kernel.h>
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#include <linux/kallsyms.h>
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#include <linux/sched.h>
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#include <linux/debug_locks.h>
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#include <asm/exceptions.h>
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#include <asm/unwind.h>
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void trap_init(void)
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{
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__enable_hw_exceptions();
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}
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static unsigned long kstack_depth_to_print; /* 0 == entire stack */
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static int __init kstack_setup(char *s)
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{
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return !kstrtoul(s, 0, &kstack_depth_to_print);
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}
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__setup("kstack=", kstack_setup);
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void show_stack(struct task_struct *task, unsigned long *sp)
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{
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unsigned long words_to_show;
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u32 fp = (u32) sp;
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if (fp == 0) {
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if (task) {
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fp = ((struct thread_info *)
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(task->stack))->cpu_context.r1;
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} else {
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/* Pick up caller of dump_stack() */
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fp = (u32)&sp - 8;
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}
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}
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words_to_show = (THREAD_SIZE - (fp & (THREAD_SIZE - 1))) >> 2;
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if (kstack_depth_to_print && (words_to_show > kstack_depth_to_print))
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words_to_show = kstack_depth_to_print;
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pr_info("Kernel Stack:\n");
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/*
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* Make the first line an 'odd' size if necessary to get
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* remaining lines to start at an address multiple of 0x10
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*/
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if (fp & 0xF) {
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unsigned long line1_words = (0x10 - (fp & 0xF)) >> 2;
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if (line1_words < words_to_show) {
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print_hex_dump(KERN_INFO, "", DUMP_PREFIX_ADDRESS, 32,
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4, (void *)fp, line1_words << 2, 0);
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fp += line1_words << 2;
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words_to_show -= line1_words;
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}
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}
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print_hex_dump(KERN_INFO, "", DUMP_PREFIX_ADDRESS, 32, 4, (void *)fp,
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words_to_show << 2, 0);
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pr_info("\n\nCall Trace:\n");
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microblaze_unwind(task, NULL);
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pr_info("\n");
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if (!task)
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task = current;
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debug_show_held_locks(task);
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}
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