1#include <linux/kernel.h>
2
3typedef 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
39static 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
47static instr *
48display_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
66static instr *
67seek_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
76static long
77stack_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
89void
90stacktrace(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}
103