arch/powerpc/xmon/ppc-dis.c

Source file repositories/reference/linux-study-clean/arch/powerpc/xmon/ppc-dis.c

File Facts

System
Linux kernel
Corpus path
arch/powerpc/xmon/ppc-dis.c
Extension
.c
Size
7655 bytes
Lines
275
Domain
Architecture Layer
Bucket
arch/powerpc
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0-or-later
/* ppc-dis.c -- Disassemble PowerPC instructions
   Copyright (C) 1994-2016 Free Software Foundation, Inc.
   Written by Ian Lance Taylor, Cygnus Support

This file is part of GDB, GAS, and the GNU binutils.

 */

#include <asm/cputable.h>
#include <asm/cpu_has_feature.h>
#include "nonstdio.h"
#include "ansidecl.h"
#include "ppc.h"
#include "dis-asm.h"

/* This file provides several disassembler functions, all of which use
   the disassembler interface defined in dis-asm.h.  Several functions
   are provided because this file handles disassembly for the PowerPC
   in both big and little endian mode and also for the POWER (RS/6000)
   chip.  */

/* Extract the operand value from the PowerPC or POWER instruction.  */

static long
operand_value_powerpc (const struct powerpc_operand *operand,
		       unsigned long insn, ppc_cpu_t dialect)
{
  long value;
  int invalid;
  /* Extract the value from the instruction.  */
  if (operand->extract)
    value = (*operand->extract) (insn, dialect, &invalid);
  else
    {
      if (operand->shift >= 0)
	value = (insn >> operand->shift) & operand->bitm;
      else
	value = (insn << -operand->shift) & operand->bitm;
      if ((operand->flags & PPC_OPERAND_SIGNED) != 0)
	{
	  /* BITM is always some number of zeros followed by some
	     number of ones, followed by some number of zeros.  */
	  unsigned long top = operand->bitm;
	  /* top & -top gives the rightmost 1 bit, so this
	     fills in any trailing zeros.  */
	  top |= (top & -top) - 1;
	  top &= ~(top >> 1);
	  value = (value ^ top) - top;
	}
    }

  return value;
}

/* Determine whether the optional operand(s) should be printed.  */

static int
skip_optional_operands (const unsigned char *opindex,
			unsigned long insn, ppc_cpu_t dialect)
{
  const struct powerpc_operand *operand;

  for (; *opindex != 0; opindex++)
    {
      operand = &powerpc_operands[*opindex];
      if ((operand->flags & PPC_OPERAND_NEXT) != 0
	  || ((operand->flags & PPC_OPERAND_OPTIONAL) != 0
	      && operand_value_powerpc (operand, insn, dialect) !=
		 ppc_optional_operand_value (operand)))
	return 0;
    }

  return 1;
}

/* Find a match for INSN in the opcode table, given machine DIALECT.
   A DIALECT of -1 is special, matching all machine opcode variations.  */

static const struct powerpc_opcode *
lookup_powerpc (unsigned long insn, ppc_cpu_t dialect)
{
  const struct powerpc_opcode *opcode;
  const struct powerpc_opcode *opcode_end;

  opcode_end = powerpc_opcodes + powerpc_num_opcodes;
  /* Find the first match in the opcode table for this major opcode.  */
  for (opcode = powerpc_opcodes; opcode < opcode_end; ++opcode)
    {
      const unsigned char *opindex;

Annotation

Implementation Notes