arch/metag/kernel/stacktrace.c

   1 #include <linux/export.h>
   2 #include <linux/sched.h>
   3 #include <linux/stacktrace.h>
   4
   5 #include <asm/stacktrace.h>
   6
   7 #if defined(CONFIG_FRAME_POINTER)
   8
   9 #ifdef CONFIG_KALLSYMS
  10 #include <linux/kallsyms.h>
  11 #include <linux/module.h>
  12
  13 static unsigned long tbi_boing_addr;
  14 static unsigned long tbi_boing_size;
  15
  16 static void tbi_boing_init(void)
  17 {
  18         /* We need to know where TBIBoingVec is and it's size */
  19         unsigned long size;
  20         unsigned long offset;
  21         char modname[MODULE_NAME_LEN];
  22         char name[KSYM_NAME_LEN];
  23         tbi_boing_addr = kallsyms_lookup_name("___TBIBoingVec");
  24         if (!tbi_boing_addr)
  25                 tbi_boing_addr = 1;
  26         else if (!lookup_symbol_attrs(tbi_boing_addr, &size,
  27                                       &offset, modname, name))
  28                 tbi_boing_size = size;
  29 }
  30 #endif
  31
  32 #define ALIGN_DOWN(addr, size)  ((addr)&(~((size)-1)))
  33
  34 /*
  35  * Unwind the current stack frame and store the new register values in the
  36  * structure passed as argument. Unwinding is equivalent to a function return,
  37  * hence the new PC value rather than LR should be used for backtrace.
  38  */
  39 int notrace unwind_frame(struct stackframe *frame)
  40 {
  41         struct metag_frame *fp = (struct metag_frame *)frame->fp;
  42         unsigned long lr;
  43         unsigned long fpnew;
  44
  45         if (frame->fp & 0x7)
  46                 return -EINVAL;
  47
  48         fpnew = fp->fp;
  49         lr = fp->lr - 4;
  50
  51 #ifdef CONFIG_KALLSYMS
  52         /* If we've reached TBIBoingVec then we're at an interrupt
  53          * entry point or a syscall entry point. The frame pointer
  54          * points to a pt_regs which can be used to continue tracing on
  55          * the other side of the boing.
  56          */
  57         if (!tbi_boing_addr)
  58                 tbi_boing_init();
  59         if (tbi_boing_size && lr >= tbi_boing_addr &&
  60             lr < tbi_boing_addr + tbi_boing_size) {
  61                 struct pt_regs *regs = (struct pt_regs *)fpnew;
  62                 if (user_mode(regs))
  63                         return -EINVAL;
  64                 fpnew = regs->ctx.AX[1].U0;
  65                 lr = regs->ctx.DX[4].U1;
  66         }
  67 #endif
  68
  69         /* stack grows up, so frame pointers must decrease */
  70         if (fpnew < (ALIGN_DOWN((unsigned long)fp, THREAD_SIZE) +
  71                      sizeof(struct thread_info)) || fpnew >= (unsigned long)fp)
  72                 return -EINVAL;
  73
  74         /* restore the registers from the stack frame */
  75         frame->fp = fpnew;
  76         frame->pc = lr;
  77
  78         return 0;
  79 }
  80 #else
  81 int notrace unwind_frame(struct stackframe *frame)
  82 {
  83         struct metag_frame *sp = (struct metag_frame *)frame->sp;
  84
  85         if (frame->sp & 0x7)
  86                 return -EINVAL;
  87
  88         while (!kstack_end(sp)) {
  89                 unsigned long addr = sp->lr - 4;
  90                 sp--;
  91
  92                 if (__kernel_text_address(addr)) {
  93                         frame->sp = (unsigned long)sp;
  94                         frame->pc = addr;
  95                         return 0;
  96                 }
  97         }
  98         return -EINVAL;
  99 }
 100 #endif
 101
 102 void notrace walk_stackframe(struct stackframe *frame,
 103                      int (*fn)(struct stackframe *, void *), void *data)
 104 {
 105         while (1) {
 106                 int ret;
 107
 108                 if (fn(frame, data))
 109                         break;
 110                 ret = unwind_frame(frame);
 111                 if (ret < 0)
 112                         break;
 113         }
 114 }
 115 EXPORT_SYMBOL(walk_stackframe);
 116
 117 #ifdef CONFIG_STACKTRACE
 118 struct stack_trace_data {
 119         struct stack_trace *trace;
 120         unsigned int no_sched_functions;
 121         unsigned int skip;
 122 };
 123
 124 static int save_trace(struct stackframe *frame, void *d)
 125 {
 126         struct stack_trace_data *data = d;
 127         struct stack_trace *trace = data->trace;
 128         unsigned long addr = frame->pc;
 129
 130         if (data->no_sched_functions && in_sched_functions(addr))
 131                 return 0;
 132         if (data->skip) {
 133                 data->skip--;
 134                 return 0;
 135         }
 136
 137         trace->entries[trace->nr_entries++] = addr;
 138
 139         return trace->nr_entries >= trace->max_entries;
 140 }
 141
 142 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
 143 {
 144         struct stack_trace_data data;
 145         struct stackframe frame;
 146
 147         data.trace = trace;
 148         data.skip = trace->skip;
 149
 150         if (tsk != current) {
 151 #ifdef CONFIG_SMP
 152                 /*
 153                  * What guarantees do we have here that 'tsk' is not
 154                  * running on another CPU?  For now, ignore it as we
 155                  * can't guarantee we won't explode.
 156                  */
 157                 if (trace->nr_entries < trace->max_entries)
 158                         trace->entries[trace->nr_entries++] = ULONG_MAX;
 159                 return;
 160 #else
 161                 data.no_sched_functions = 1;
 162                 frame.fp = thread_saved_fp(tsk);
 163                 frame.sp = thread_saved_sp(tsk);
 164                 frame.lr = 0;           /* recovered from the stack */
 165                 frame.pc = thread_saved_pc(tsk);
 166 #endif
 167         } else {
 168                 register unsigned long current_sp asm ("A0StP");
 169
 170                 data.no_sched_functions = 0;
 171                 frame.fp = (unsigned long)__builtin_frame_address(0);
 172                 frame.sp = current_sp;
 173                 frame.lr = (unsigned long)__builtin_return_address(0);
 174                 frame.pc = (unsigned long)save_stack_trace_tsk;
 175         }
 176
 177         walk_stackframe(&frame, save_trace, &data);
 178         if (trace->nr_entries < trace->max_entries)
 179                 trace->entries[trace->nr_entries++] = ULONG_MAX;
 180 }
 181
 182 void save_stack_trace(struct stack_trace *trace)
 183 {
 184         save_stack_trace_tsk(current, trace);
 185 }
 186 EXPORT_SYMBOL_GPL(save_stack_trace);
 187 #endif