root/arch/alpha/lib/stacktrace.c

DEFINITIONS

1. display_stored_regs
2. seek_prologue
3. stack_increment
4. stacktrace

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/kernel.h>
   3 
   4 typedef unsigned int instr;
   5 
   6 #define MAJOR_OP        0xfc000000
   7 #define LDA_OP          0x20000000
   8 #define STQ_OP          0xb4000000
   9 #define BR_OP           0xc0000000
  10 
  11 #define STK_ALLOC_1     0x23de8000 /* lda $30,-X($30) */
  12 #define STK_ALLOC_1M    0xffff8000
  13 #define STK_ALLOC_2     0x43c0153e /* subq $30,X,$30 */
  14 #define STK_ALLOC_2M    0xffe01fff
  15 
  16 #define MEM_REG         0x03e00000
  17 #define MEM_BASE        0x001f0000
  18 #define MEM_OFF         0x0000ffff
  19 #define MEM_OFF_SIGN    0x00008000
  20 #define BASE_SP         0x001e0000
  21 
  22 #define STK_ALLOC_MATCH(INSTR)                  \
  23   (((INSTR) & STK_ALLOC_1M) == STK_ALLOC_1      \
  24    || ((INSTR) & STK_ALLOC_2M) == STK_ALLOC_2)
  25 #define STK_PUSH_MATCH(INSTR) \
  26   (((INSTR) & (MAJOR_OP | MEM_BASE | MEM_OFF_SIGN)) == (STQ_OP | BASE_SP))
  27 #define MEM_OP_OFFSET(INSTR) \
  28   (((long)((INSTR) & MEM_OFF) << 48) >> 48)
  29 #define MEM_OP_REG(INSTR) \
  30   (((INSTR) & MEM_REG) >> 22)
  31 
  32 /* Branches, jumps, PAL calls, and illegal opcodes end a basic block. */
  33 #define BB_END(INSTR)                                           \
  34   (((instr)(INSTR) >= BR_OP) | ((instr)(INSTR) < LDA_OP) |      \
  35    ((((instr)(INSTR) ^ 0x60000000) < 0x20000000) &              \
  36     (((instr)(INSTR) & 0x0c000000) != 0)))
  37 
  38 #define IS_KERNEL_TEXT(PC) ((unsigned long)(PC) > START_ADDR)
  39 
  40 static char reg_name[][4] = {
  41         "v0 ", "t0 ", "t1 ", "t2 ", "t3 ", "t4 ", "t5 ", "t6 ", "t7 ",
  42         "s0 ", "s1 ", "s2 ", "s3 ", "s4 ", "s5 ", "s6 ", "a0 ", "a1 ",
  43         "a2 ", "a3 ", "a4 ", "a5 ", "t8 ", "t9 ", "t10", "t11", "ra ",
  44         "pv ", "at ", "gp ", "sp ", "0"
  45 };
  46 
  47 
  48 static instr *
  49 display_stored_regs(instr * pro_pc, unsigned char * sp)
  50 {
  51         instr * ret_pc = 0;
  52         int reg;
  53         unsigned long value;
  54 
  55         printk("Prologue [<%p>], Frame %p:\n", pro_pc, sp);
  56         while (!BB_END(*pro_pc))
  57                 if (STK_PUSH_MATCH(*pro_pc)) {
  58                         reg = (*pro_pc & MEM_REG) >> 21;
  59                         value = *(unsigned long *)(sp + (*pro_pc & MEM_OFF));
  60                         if (reg == 26)
  61                                 ret_pc = (instr *)value;
  62                         printk("\t\t%s / 0x%016lx\n", reg_name[reg], value);
  63                 }
  64         return ret_pc;
  65 }
  66 
  67 static instr *
  68 seek_prologue(instr * pc)
  69 {
  70         while (!STK_ALLOC_MATCH(*pc))
  71                 --pc;
  72         while (!BB_END(*(pc - 1)))
  73                 --pc;
  74         return pc;
  75 }
  76 
  77 static long
  78 stack_increment(instr * prologue_pc)
  79 {
  80         while (!STK_ALLOC_MATCH(*prologue_pc))
  81                 ++prologue_pc;
  82 
  83         /* Count the bytes allocated. */
  84         if ((*prologue_pc & STK_ALLOC_1M) == STK_ALLOC_1M)
  85                 return -(((long)(*prologue_pc) << 48) >> 48);
  86         else
  87                 return (*prologue_pc >> 13) & 0xff;
  88 }
  89 
  90 void
  91 stacktrace(void)
  92 {
  93         instr * ret_pc;
  94         instr * prologue = (instr *)stacktrace;
  95         register unsigned char * sp __asm__ ("$30");
  96 
  97         printk("\tstack trace:\n");
  98         do {
  99                 ret_pc = display_stored_regs(prologue, sp);
 100                 sp += stack_increment(prologue);
 101                 prologue = seek_prologue(ret_pc);
 102         } while (IS_KERNEL_TEXT(ret_pc));
 103 }