// SPDX-License-Identifier: GPL-2.0
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#include <linux/kernel.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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