cregit-Linux how code gets into the kernel

Release 4.14 arch/alpha/lib/stacktrace.c

Directory: arch/alpha/lib
// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>


typedef unsigned int instr;


#define MAJOR_OP	0xfc000000

#define LDA_OP		0x20000000

#define STQ_OP		0xb4000000

#define BR_OP		0xc0000000


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

#define STK_ALLOC_1M	0xffff8000

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

#define STK_ALLOC_2M	0xffe01fff


#define MEM_REG		0x03e00000

#define MEM_BASE	0x001f0000

#define MEM_OFF		0x0000ffff

#define MEM_OFF_SIGN	0x00008000

#define	BASE_SP		0x001e0000


#define STK_ALLOC_MATCH(INSTR)			\
  (((INSTR) & STK_ALLOC_1M) == STK_ALLOC_1        \
   || ((INSTR) & STK_ALLOC_2M) == STK_ALLOC_2)

#define STK_PUSH_MATCH(INSTR) \
  (((INSTR) & (MAJOR_OP | MEM_BASE | MEM_OFF_SIGN)) == (STQ_OP | BASE_SP))

#define MEM_OP_OFFSET(INSTR) \
  (((long)((INSTR) & MEM_OFF) << 48) >> 48)

#define MEM_OP_REG(INSTR) \
  (((INSTR) & MEM_REG) >> 22)

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

#define BB_END(INSTR)						\
  (((instr)(INSTR) >= BR_OP) | ((instr)(INSTR) < LDA_OP) |        \
   ((((instr)(INSTR) ^ 0x60000000) < 0x20000000) &              \
    (((instr)(INSTR) & 0x0c000000) != 0)))


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


static char reg_name[][4] = {
	"v0 ", "t0 ", "t1 ", "t2 ", "t3 ", "t4 ", "t5 ", "t6 ", "t7 ",
	"s0 ", "s1 ", "s2 ", "s3 ", "s4 ", "s5 ", "s6 ", "a0 ", "a1 ",
	"a2 ", "a3 ", "a4 ", "a5 ", "t8 ", "t9 ", "t10", "t11", "ra ",
	"pv ", "at ", "gp ", "sp ", "0"
};



static instr * display_stored_regs(instr * pro_pc, unsigned char * sp) { instr * ret_pc = 0; int reg; unsigned long value; printk("Prologue [<%p>], Frame %p:\n", pro_pc, sp); while (!BB_END(*pro_pc)) if (STK_PUSH_MATCH(*pro_pc)) { reg = (*pro_pc & MEM_REG) >> 21; value = *(unsigned long *)(sp + (*pro_pc & MEM_OFF)); if (reg == 26) ret_pc = (instr *)value; printk("\t\t%s / 0x%016lx\n", reg_name[reg], value); } return ret_pc; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)116100.00%1100.00%
Total116100.00%1100.00%


static instr * seek_prologue(instr * pc) { while (!STK_ALLOC_MATCH(*pc)) --pc; while (!BB_END(*(pc - 1))) --pc; return pc; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)42100.00%1100.00%
Total42100.00%1100.00%


static long stack_increment(instr * prologue_pc) { while (!STK_ALLOC_MATCH(*prologue_pc)) ++prologue_pc; /* Count the bytes allocated. */ if ((*prologue_pc & STK_ALLOC_1M) == STK_ALLOC_1M) return -(((long)(*prologue_pc) << 48) >> 48); else return (*prologue_pc >> 13) & 0xff; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)63100.00%1100.00%
Total63100.00%1100.00%


void stacktrace(void) { instr * ret_pc; instr * prologue = (instr *)stacktrace; register unsigned char * sp __asm__ ("$30"); printk("\tstack trace:\n"); do { ret_pc = display_stored_regs(prologue, sp); sp += stack_increment(prologue); prologue = seek_prologue(ret_pc); } while (IS_KERNEL_TEXT(ret_pc)); }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)70100.00%1100.00%
Total70100.00%1100.00%


Overall Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)47599.79%150.00%
Greg Kroah-Hartman10.21%150.00%
Total476100.00%2100.00%
Directory: arch/alpha/lib
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