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 *
display_stored_regs(instr * pro_pc,unsigned char * sp)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 *
seek_prologue(instr * pc)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
stack_increment(instr * prologue_pc)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
stacktrace(void)91 stacktrace(void)
92 {
93 instr * ret_pc;
94 instr * prologue = (instr *)stacktrace;
95 unsigned char *sp = (unsigned char *)current_stack_pointer;
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 }
104