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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/alpha/lib/stacktrace.c
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#include <linux/kernel.h>

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#include <asm/system.h>

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typedef unsigned int instr;

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#define MAJOR_OP	0xfc000000

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#define LDA_OP		0x20000000

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#define STQ_OP		0xb4000000

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#define BR_OP		0xc0000000

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#define STK_ALLOC_1	0x23de8000 /* lda $30,-X($30) */

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#define STK_ALLOC_1M	0xffff8000

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#define STK_ALLOC_2	0x43c0153e /* subq $30,X,$30 */

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#define STK_ALLOC_2M	0xffe01fff

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#define MEM_REG		0x03e00000

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#define MEM_BASE	0x001f0000

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#define MEM_OFF		0x0000ffff

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#define MEM_OFF_SIGN	0x00008000

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#define	BASE_SP		0x001e0000

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#define STK_ALLOC_MATCH(INSTR)			\

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  (((INSTR) & STK_ALLOC_1M) == STK_ALLOC_1	\

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   || ((INSTR) & STK_ALLOC_2M) == STK_ALLOC_2)

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#define STK_PUSH_MATCH(INSTR) \

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  (((INSTR) & (MAJOR_OP | MEM_BASE | MEM_OFF_SIGN)) == (STQ_OP | BASE_SP))

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#define MEM_OP_OFFSET(INSTR) \

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  (((long)((INSTR) & MEM_OFF) << 48) >> 48)

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#define MEM_OP_REG(INSTR) \

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  (((INSTR) & MEM_REG) >> 22)

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/* Branches, jumps, PAL calls, and illegal opcodes end a basic block. */

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#define BB_END(INSTR)						\

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  (((instr)(INSTR) >= BR_OP) | ((instr)(INSTR) < LDA_OP) |	\

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   ((((instr)(INSTR) ^ 0x60000000) < 0x20000000) &		\

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    (((instr)(INSTR) & 0x0c000000) != 0)))

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

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static char reg_name[][4] = {

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	"v0 ", "t0 ", "t1 ", "t2 ", "t3 ", "t4 ", "t5 ", "t6 ", "t7 ",

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	"s0 ", "s1 ", "s2 ", "s3 ", "s4 ", "s5 ", "s6 ", "a0 ", "a1 ",

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	"a2 ", "a3 ", "a4 ", "a5 ", "t8 ", "t9 ", "t10", "t11", "ra ",

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	"pv ", "at ", "gp ", "sp ", "0"

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};

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static instr *

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display_stored_regs(instr * pro_pc, unsigned char * sp)

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{

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	instr * ret_pc = 0;

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	int reg;

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	unsigned long value;

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	printk("Prologue [<%p>], Frame %p:\n", pro_pc, sp);

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	while (!BB_END(*pro_pc))

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		if (STK_PUSH_MATCH(*pro_pc)) {

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			reg = (*pro_pc & MEM_REG) >> 21;

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			value = *(unsigned long *)(sp + (*pro_pc & MEM_OFF));

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			if (reg == 26)

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				ret_pc = (instr *)value;

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			printk("\t\t%s / 0x%016lx\n", reg_name[reg], value);

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		}

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	return ret_pc;

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}

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static instr *

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seek_prologue(instr * pc)

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{

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	while (!STK_ALLOC_MATCH(*pc))

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		--pc;

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	while (!BB_END(*(pc - 1)))

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		--pc;

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	return pc;

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}

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static long

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stack_increment(instr * prologue_pc)

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{

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	while (!STK_ALLOC_MATCH(*prologue_pc))

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		++prologue_pc;

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	/* Count the bytes allocated. */

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	if ((*prologue_pc & STK_ALLOC_1M) == STK_ALLOC_1M)

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		return -(((long)(*prologue_pc) << 48) >> 48);

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	else

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		return (*prologue_pc >> 13) & 0xff;

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}

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void

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stacktrace(void)

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{

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	instr * ret_pc;

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	instr * prologue = (instr *)stacktrace;

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	register unsigned char * sp __asm__ ("$30");

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	printk("\tstack trace:\n");

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	do {

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		ret_pc = display_stored_regs(prologue, sp);

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		sp += stack_increment(prologue);

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		prologue = seek_prologue(ret_pc);

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	} while (IS_KERNEL_TEXT(ret_pc));

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}

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