arch/alpha/lib/stacktrace.c

   1 #include <linux/kernel.h>
   2
   3 typedef unsigned int instr;
   4
   5 #define MAJOR_OP        0xfc000000
   6 #define LDA_OP          0x20000000
   7 #define STQ_OP          0xb4000000
   8 #define BR_OP           0xc0000000
   9
  10 #define STK_ALLOC_1     0x23de8000 /* lda $30,-X($30) */
  11 #define STK_ALLOC_1M    0xffff8000
  12 #define STK_ALLOC_2     0x43c0153e /* subq $30,X,$30 */
  13 #define STK_ALLOC_2M    0xffe01fff
  14
  15 #define MEM_REG         0x03e00000
  16 #define MEM_BASE        0x001f0000
  17 #define MEM_OFF         0x0000ffff
  18 #define MEM_OFF_SIGN    0x00008000
  19 #define BASE_SP         0x001e0000
  20
  21 #define STK_ALLOC_MATCH(INSTR)                  \
  22   (((INSTR) & STK_ALLOC_1M) == STK_ALLOC_1      \
  23    || ((INSTR) & STK_ALLOC_2M) == STK_ALLOC_2)
  24 #define STK_PUSH_MATCH(INSTR) \
  25   (((INSTR) & (MAJOR_OP | MEM_BASE | MEM_OFF_SIGN)) == (STQ_OP | BASE_SP))
  26 #define MEM_OP_OFFSET(INSTR) \
  27   (((long)((INSTR) & MEM_OFF) << 48) >> 48)
  28 #define MEM_OP_REG(INSTR) \
  29   (((INSTR) & MEM_REG) >> 22)
  30
  31 /* Branches, jumps, PAL calls, and illegal opcodes end a basic block. */
  32 #define BB_END(INSTR)                                           \
  33   (((instr)(INSTR) >= BR_OP) | ((instr)(INSTR) < LDA_OP) |      \
  34    ((((instr)(INSTR) ^ 0x60000000) < 0x20000000) &              \
  35     (((instr)(INSTR) & 0x0c000000) != 0)))
  36
  37 #define IS_KERNEL_TEXT(PC) ((unsigned long)(PC) > START_ADDR)
  38
  39 static char reg_name[][4] = {
  40         "v0 ", "t0 ", "t1 ", "t2 ", "t3 ", "t4 ", "t5 ", "t6 ", "t7 ",
  41         "s0 ", "s1 ", "s2 ", "s3 ", "s4 ", "s5 ", "s6 ", "a0 ", "a1 ",
  42         "a2 ", "a3 ", "a4 ", "a5 ", "t8 ", "t9 ", "t10", "t11", "ra ",
  43         "pv ", "at ", "gp ", "sp ", "0"
  44 };
  45
  46
  47 static instr *
  48 display_stored_regs(instr * pro_pc, unsigned char * sp)
  49 {
  50         instr * ret_pc = 0;
  51         int reg;
  52         unsigned long value;
  53
  54         printk("Prologue [<%p>], Frame %p:\n", pro_pc, sp);
  55         while (!BB_END(*pro_pc))
  56                 if (STK_PUSH_MATCH(*pro_pc)) {
  57                         reg = (*pro_pc & MEM_REG) >> 21;
  58                         value = *(unsigned long *)(sp + (*pro_pc & MEM_OFF));
  59                         if (reg == 26)
  60                                 ret_pc = (instr *)value;
  61                         printk("\t\t%s / 0x%016lx\n", reg_name[reg], value);
  62                 }
  63         return ret_pc;
  64 }
  65
  66 static instr *
  67 seek_prologue(instr * pc)
  68 {
  69         while (!STK_ALLOC_MATCH(*pc))
  70                 --pc;
  71         while (!BB_END(*(pc - 1)))
  72                 --pc;
  73         return pc;
  74 }
  75
  76 static long
  77 stack_increment(instr * prologue_pc)
  78 {
  79         while (!STK_ALLOC_MATCH(*prologue_pc))
  80                 ++prologue_pc;
  81
  82         /* Count the bytes allocated. */
  83         if ((*prologue_pc & STK_ALLOC_1M) == STK_ALLOC_1M)
  84                 return -(((long)(*prologue_pc) << 48) >> 48);
  85         else
  86                 return (*prologue_pc >> 13) & 0xff;
  87 }
  88
  89 void
  90 stacktrace(void)
  91 {
  92         instr * ret_pc;
  93         instr * prologue = (instr *)stacktrace;
  94         register unsigned char * sp __asm__ ("$30");
  95
  96         printk("\tstack trace:\n");
  97         do {
  98                 ret_pc = display_stored_regs(prologue, sp);
  99                 sp += stack_increment(prologue);
 100                 prologue = seek_prologue(ret_pc);
 101         } while (IS_KERNEL_TEXT(ret_pc));
 102 }