1#include <linux/kernel.h>
2#include <asm/system.h>
3
4typedef 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
40static 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
48static instr *
49display_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
67static instr *
68seek_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
77static long
78stack_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
90void
91stacktrace(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}
104