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Sourcecode: linux-2.6 version File versions

stacktrace.c

#include <linux/kernel.h>
#include <asm/system.h>

typedef unsigned int instr;

#define MAJOR_OP  0xfc000000
#define LDA_OP          0x20000000
#define STQ_OP          0xb4000000
#define BR_OP           0xc0000000

#define STK_ALLOC_1     0x23de8000 /* lda $30,-X($30) */
#define STK_ALLOC_1M    0xffff8000
#define STK_ALLOC_2     0x43c0153e /* subq $30,X,$30 */
#define STK_ALLOC_2M    0xffe01fff

#define MEM_REG         0x03e00000
#define MEM_BASE  0x001f0000
#define MEM_OFF         0x0000ffff
#define MEM_OFF_SIGN    0x00008000
#define     BASE_SP           0x001e0000

#define STK_ALLOC_MATCH(INSTR)                  \
  (((INSTR) & STK_ALLOC_1M) == STK_ALLOC_1      \
   || ((INSTR) & STK_ALLOC_2M) == STK_ALLOC_2)
#define STK_PUSH_MATCH(INSTR) \
  (((INSTR) & (MAJOR_OP | MEM_BASE | MEM_OFF_SIGN)) == (STQ_OP | BASE_SP))
#define MEM_OP_OFFSET(INSTR) \
  (((long)((INSTR) & MEM_OFF) << 48) >> 48)
#define MEM_OP_REG(INSTR) \
  (((INSTR) & MEM_REG) >> 22)

/* Branches, jumps, PAL calls, and illegal opcodes end a basic block. */
#define BB_END(INSTR)                                 \
  (((instr)(INSTR) >= BR_OP) | ((instr)(INSTR) < LDA_OP) |  \
   ((((instr)(INSTR) ^ 0x60000000) < 0x20000000) &          \
    (((instr)(INSTR) & 0x0c000000) != 0)))

#define IS_KERNEL_TEXT(PC) ((unsigned long)(PC) > START_ADDR)

static char reg_name[][4] = {
      "v0 ", "t0 ", "t1 ", "t2 ", "t3 ", "t4 ", "t5 ", "t6 ", "t7 ",
      "s0 ", "s1 ", "s2 ", "s3 ", "s4 ", "s5 ", "s6 ", "a0 ", "a1 ",
      "a2 ", "a3 ", "a4 ", "a5 ", "t8 ", "t9 ", "t10", "t11", "ra ",
      "pv ", "at ", "gp ", "sp ", "0"
};


static instr *
display_stored_regs(instr * pro_pc, unsigned char * sp)
{
      instr * ret_pc = 0;
      int reg;
      unsigned long value;

      printk("Prologue [<%p>], Frame %p:\n", pro_pc, sp);
      while (!BB_END(*pro_pc))
            if (STK_PUSH_MATCH(*pro_pc)) {
                  reg = (*pro_pc & MEM_REG) >> 21;
                  value = *(unsigned long *)(sp + (*pro_pc & MEM_OFF));
                  if (reg == 26)
                        ret_pc = (instr *)value;
                  printk("\t\t%s / 0x%016lx\n", reg_name[reg], value);
            }
      return ret_pc;
}

static instr *
seek_prologue(instr * pc)
{
      while (!STK_ALLOC_MATCH(*pc))
            --pc;
      while (!BB_END(*(pc - 1)))
            --pc;
      return pc;
}

static long
stack_increment(instr * prologue_pc)
{
      while (!STK_ALLOC_MATCH(*prologue_pc))
            ++prologue_pc;

      /* Count the bytes allocated. */
      if ((*prologue_pc & STK_ALLOC_1M) == STK_ALLOC_1M)
            return -(((long)(*prologue_pc) << 48) >> 48);
      else
            return (*prologue_pc >> 13) & 0xff;
}

void
stacktrace(void)
{
      instr * ret_pc;
      instr * prologue = (instr *)stacktrace;
      register unsigned char * sp __asm__ ("$30");

      printk("\tstack trace:\n");
      do {
            ret_pc = display_stored_regs(prologue, sp);
            sp += stack_increment(prologue);
            prologue = seek_prologue(ret_pc);
      } while (IS_KERNEL_TEXT(ret_pc));
}

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