simplify the stacktrace code
[linux-2.6.git] / arch / s390 / kernel / stacktrace.c
1 /*
2  * arch/s390/kernel/stacktrace.c
3  *
4  * Stack trace management functions
5  *
6  *  Copyright (C) IBM Corp. 2006
7  *  Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
8  */
9
10 #include <linux/sched.h>
11 #include <linux/stacktrace.h>
12 #include <linux/kallsyms.h>
13
14 static unsigned long save_context_stack(struct stack_trace *trace,
15                                         unsigned int *skip,
16                                         unsigned long sp,
17                                         unsigned long low,
18                                         unsigned long high)
19 {
20         struct stack_frame *sf;
21         struct pt_regs *regs;
22         unsigned long addr;
23
24         while(1) {
25                 sp &= PSW_ADDR_INSN;
26                 if (sp < low || sp > high)
27                         return sp;
28                 sf = (struct stack_frame *)sp;
29                 while(1) {
30                         addr = sf->gprs[8] & PSW_ADDR_INSN;
31                         if (!(*skip))
32                                 trace->entries[trace->nr_entries++] = addr;
33                         else
34                                 (*skip)--;
35                         if (trace->nr_entries >= trace->max_entries)
36                                 return sp;
37                         low = sp;
38                         sp = sf->back_chain & PSW_ADDR_INSN;
39                         if (!sp)
40                                 break;
41                         if (sp <= low || sp > high - sizeof(*sf))
42                                 return sp;
43                         sf = (struct stack_frame *)sp;
44                 }
45                 /* Zero backchain detected, check for interrupt frame. */
46                 sp = (unsigned long)(sf + 1);
47                 if (sp <= low || sp > high - sizeof(*regs))
48                         return sp;
49                 regs = (struct pt_regs *)sp;
50                 addr = regs->psw.addr & PSW_ADDR_INSN;
51                 if (!(*skip))
52                         trace->entries[trace->nr_entries++] = addr;
53                 else
54                         (*skip)--;
55                 if (trace->nr_entries >= trace->max_entries)
56                         return sp;
57                 low = sp;
58                 sp = regs->gprs[15];
59         }
60 }
61
62 void save_stack_trace(struct stack_trace *trace)
63 {
64         register unsigned long sp asm ("15");
65         unsigned long orig_sp, new_sp;
66
67         orig_sp = sp & PSW_ADDR_INSN;
68
69         new_sp = save_context_stack(trace, &trace->skip, orig_sp,
70                                 S390_lowcore.panic_stack - PAGE_SIZE,
71                                 S390_lowcore.panic_stack);
72         if (new_sp != orig_sp)
73                 return;
74         new_sp = save_context_stack(trace, &trace->skip, new_sp,
75                                 S390_lowcore.async_stack - ASYNC_SIZE,
76                                 S390_lowcore.async_stack);
77         if (new_sp != orig_sp)
78                 return;
79
80         save_context_stack(trace, &trace->skip, new_sp,
81                            S390_lowcore.thread_info,
82                            S390_lowcore.thread_info + THREAD_SIZE);
83         return;
84 }