Hi,

在 2023/5/12 00:38, Mark Wielaard 写道:
>> diff --git a/backends/mips_regs.c b/backends/mips_regs.c
>>
>> +
>> +ssize_t
>> +mips_register_info (Ebl *ebl __attribute__ ((unused)),
>> +		      int regno, char *name, size_t namelen,
>> +		      const char **prefix, const char **setname,
>> +		      int *bits, int *type)
>> +{
>> +  if (name == NULL)
>> +    return 66;
>> +
>> +  if (regno < 0 || regno > 65 || namelen < 4)
>> +    return -1;
>> +
>> +  *prefix = "$";
>> +  
>> +  if (regno < 32)
>> +    {
>> +      *setname = "integer";
>> +      *type = DW_ATE_signed;
>> +      *bits = 32;
>> +      if (regno < 32 + 10)
>> +      {
>> +        name[0] = regno + '0';
>> +	namelen = 1;
>> +      }
>> +      else
>> +      {
>> +        name[0] = (regno / 10) + '0';
>> +	name[1] = (regno % 10) + '0';
>> +	namelen = 2;
>> +      }
>> +    }
>> +  else if (regno < 64)
>> +    {
>> +      *setname = "FPU";
>> +      *type = DW_ATE_float;
>> +      *bits = 32;
>> +      name[0] = 'f';
>> +      if (regno < 32 + 10)
>> +      {
>> +        name[1] = (regno - 32) + '0';
>> +	namelen = 2;
>> +      }
>> +      else
>> +      {
>> +        name[1] = (regno - 32) / 10 + '0';
>> +	name[2] = (regno - 32) % 10 + '0';
>> +	namelen = 3;
>> +      }
>>
> OK, but indentation seems slightly off. space vs tabs?


    Yes, those lines that not aligned are tabs, I would fix it. Thanks.


>
>> diff --git a/backends/mips_retval.c b/backends/mips_retval.c
>> new file mode 100644
>> index 00000000..fd9aaefa
>> --- /dev/null
>> +++ b/backends/mips_retval.c
>> @@ -0,0 +1,261 @@
>> +/* Function return value location for Linux/mips ABI.
>> +   Copyright (C) 2005 Red Hat, Inc.
>> +   Copyright (C) 2023 CIP United Inc.
>> +   This file is part of elfutils.
>> +
>> +   This file is free software; you can redistribute it and/or modify
>> +   it under the terms of either
>> +
>> +     * the GNU Lesser General Public License as published by the Free
>> +       Software Foundation; either version 3 of the License, or (at
>> +       your option) any later version
>> +
>> +   or
>> +
>> +     * the GNU General Public License as published by the Free
>> +       Software Foundation; either version 2 of the License, or (at
>> +       your option) any later version
>> +
>> +   or both in parallel, as here.
>> +
>> +   elfutils is distributed in the hope that it will be useful, but
>> +   WITHOUT ANY WARRANTY; without even the implied warranty of
>> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> +   General Public License for more details.
>> +
>> +   You should have received copies of the GNU General Public License and
>> +   the GNU Lesser General Public License along with this program.  If
>> +   not, see <http://www.gnu.org/licenses/>.  */
>> +
>> +#ifdef HAVE_CONFIG_H
>> +# include <config.h>
>> +#endif
>> +
>> +#include <assert.h>
>> +#include <dwarf.h>
>> +#include <string.h>
>> +#include <elf.h>
>> +#include <stdio.h>
>> +
>> +#define BACKEND mips_
>> +#include "libebl_CPU.h"
>> +#include "libdwP.h"
>> +
>> +/* All the possible MIPS ARCHs. */
>> +enum mips_arch
>> +  {
>> +    MIPS_ARCH_UNKNOWN = 0,
>> +    MIPS_ARCH_32,
>> +    MIPS_ARCH_64,
>> +    MIPS_ARCH_LAST
>> +  };
>> +
>> +/* Find the mips ARCH of the current file */
>> +enum mips_arch find_mips_arch(Elf *elf)
>> +{
>> +  GElf_Ehdr ehdr_mem;
>> +  GElf_Ehdr *ehdr = gelf_getehdr (elf, &ehdr_mem);
>> +
>> +  if (ehdr == NULL)
>> +    return MIPS_ARCH_LAST;
>> +
>> +  GElf_Word elf_flags = ehdr->e_flags;
>> +
>> +  /* Check elf_flags to see if it specifies the ARCH being used.  */
>> +  switch ((elf_flags & EF_MIPS_ARCH))
>> +    {
>> +    case E_MIPS_ARCH_32:
>> +    case EF_MIPS_ARCH_32R2:
>> +    case E_MIPS_ARCH_32R6:
>> +      return MIPS_ARCH_32;
>> +    case E_MIPS_ARCH_64:
>> +    case EF_MIPS_ARCH_64R2:
>> +    case E_MIPS_ARCH_64R6:
>> +      return MIPS_ARCH_64;
>> +    default:
>> +      return MIPS_ARCH_32;
>> +    }
>> +
>> +  return MIPS_ARCH_UNKNOWN;
>> +}
>>
>> +unsigned int
>> +mips_arch_regsize (enum mips_arch arch)
>> +{
>> +  switch (arch)
>> +    {
>> +    case MIPS_ARCH_32:
>> +      return 4;
>> +    case MIPS_ARCH_64:
>> +      return 8;
>> +    case MIPS_ARCH_UNKNOWN:
>> +    case MIPS_ARCH_LAST:
>> +    default:
>> +      return 0;
>> +    }
>> +}
> So this is different from checking ELFCLASS32/64?

    OK, I would change to use ELFCLASS32/64:

>
>> +/* $v0 or pair $v0, $v1 */
>> +static const Dwarf_Op loc_intreg_o32[] =
>> +  {
>> +    { .atom = DW_OP_reg2 }, { .atom = DW_OP_piece, .number = 4 },
>> +    { .atom = DW_OP_reg3 }, { .atom = DW_OP_piece, .number = 4 },
>> +  };
>> +
>> +static const Dwarf_Op loc_intreg[] =
>> +  {
>> +    { .atom = DW_OP_reg2 }, { .atom = DW_OP_piece, .number = 8 },
>> +    { .atom = DW_OP_reg3 }, { .atom = DW_OP_piece, .number = 8 },
>> +  };
>> +#define nloc_intreg	1
>> +#define nloc_intregpair	4
>> +
>> +/* $f0 (float), or pair $f0, $f1 (double).
>> + * f2/f3 are used for COMPLEX (= 2 doubles) returns in Fortran */
>> +static const Dwarf_Op loc_fpreg_o32[] =
>> +  {
>> +    { .atom = DW_OP_regx, .number = 32 }, { .atom = DW_OP_piece, .number = 4 },
>> +    { .atom = DW_OP_regx, .number = 33 }, { .atom = DW_OP_piece, .number = 4 },
>> +    { .atom = DW_OP_regx, .number = 34 }, { .atom = DW_OP_piece, .number = 4 },
>> +    { .atom = DW_OP_regx, .number = 35 }, { .atom = DW_OP_piece, .number = 4 },
>> +  };
>> +
>> +/* $f0, or pair $f0, $f2.  */
>> +static const Dwarf_Op loc_fpreg[] =
>> +  {
>> +    { .atom = DW_OP_regx, .number = 32 }, { .atom = DW_OP_piece, .number = 8 },
>> +    { .atom = DW_OP_regx, .number = 34 }, { .atom = DW_OP_piece, .number = 8 },
>> +  };
>> +#define nloc_fpreg  1
>> +#define nloc_fpregpair 4
>> +#define nloc_fpregquad 8
>> +
>> +/* The return value is a structure and is actually stored in stack space
>> +   passed in a hidden argument by the caller.  But, the compiler
>> +   helpfully returns the address of that space in $v0.  */
>> +static const Dwarf_Op loc_aggregate[] =
>> +  {
>> +    { .atom = DW_OP_breg2, .number = 0 }
>> +  };
>> +#define nloc_aggregate 1
>> +
>> +int
>> +mips_return_value_location (Dwarf_Die *functypedie, const Dwarf_Op **locp)
>> +{
>> +  /* First find the ARCH used by the elf object */
>> +  enum mips_arch arch = find_mips_arch(functypedie->cu->dbg->elf);
>> +  /* Something went seriously wrong while trying to figure out the ARCH */
>> +  if (arch == MIPS_ARCH_LAST)
>> +    return -1;
>> +
>> +  /* We couldn't identify the ARCH, but the file seems valid */
>> +  if (arch == MIPS_ARCH_UNKNOWN)
>> +    return -3;
>> +
>> +  unsigned int regsize = mips_arch_regsize (arch);
>> +  if (!regsize)
>> +    return -2;
>> +
>> +  /* Start with the function's type, and get the DW_AT_type attribute,
>> +     which is the type of the return value.  */
>> +  
>> +  Dwarf_Attribute attr_mem;
>> +  Dwarf_Attribute *attr = dwarf_attr_integrate (functypedie, DW_AT_type, &attr_mem);
>> +  if (attr == NULL)
>> +    /* The function has no return value, like a `void' function in C.  */
>> +    return 0;
>> +
>> +  Dwarf_Die die_mem;
>> +  Dwarf_Die *typedie = dwarf_formref_die (attr, &die_mem);
>> +  int tag = dwarf_tag (typedie);
>> +
>> +  /* Follow typedefs and qualifiers to get to the actual type.  */
>> +  while (tag == DW_TAG_typedef
>> +	 || tag == DW_TAG_const_type || tag == DW_TAG_volatile_type
>> +	 || tag == DW_TAG_restrict_type)
>> +    {
>> +      attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
>> +      typedie = dwarf_formref_die (attr, &die_mem);
>> +      tag = dwarf_tag (typedie);
>> +    }
>> +
>> +  switch (tag)
>> +    {
>> +    case -1:
>> +      return -1;
>> +
>> +    case DW_TAG_subrange_type:
>> +      if (! dwarf_hasattr_integrate (typedie, DW_AT_byte_size))
>> +	{
>> +	  attr = dwarf_attr_integrate (typedie, DW_AT_type, &attr_mem);
>> +	  typedie = dwarf_formref_die (attr, &die_mem);
>> +	  tag = dwarf_tag (typedie);
>> +	}
>> +      /* Fall through.  */
>> +      FALLTHROUGH;
>> +
>> +    case DW_TAG_base_type:
>> +    case DW_TAG_enumeration_type:
>> +    CASE_POINTER:
>> +      {
>> +        Dwarf_Word size;
>> +	if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_byte_size,
>> +					 &attr_mem), &size) != 0)
>> +	  {
>> +	    if (dwarf_is_pointer (tag))
>> +	      size = regsize;
>> +	    else
>> +	      return -1;
>> +	  }
>> +	if (tag == DW_TAG_base_type)
>> +	  {
>> +	    Dwarf_Word encoding;
>> +	    if (dwarf_formudata (dwarf_attr_integrate (typedie, DW_AT_encoding,
>> +					     &attr_mem), &encoding) != 0)
>> +	      return -1;
>> +
>> +#define ARCH_LOC(loc, regsize) ((regsize) == 4 ? (loc ## _o32) : (loc))
>> +
>> +	    if (encoding == DW_ATE_float)
>> +	      {
>> +		*locp = ARCH_LOC(loc_fpreg, regsize);
>> +		if (size <= regsize)
>> +		  return nloc_fpreg;
>> +
>> +		if (size <= 2*regsize)
>> +                  return nloc_fpregpair;
>> +
>> +		if (size <= 4*regsize && arch == MIPS_ARCH_32)
>> +                  return nloc_fpregquad;
>> +
>> +		goto aggregate;
>> +	      }
>> +	  }
>> +	*locp = ARCH_LOC(loc_intreg, regsize);
>> +	if (size <= regsize)
>> +	  return nloc_intreg;
>> +	if (size <= 2*regsize)
>> +	  return nloc_intregpair;
>> +
>> +	/* Else fall through. Shouldn't happen though (at least with gcc) */
>> +      }
>> +      FALLTHROUGH;
>> +
>> +    case DW_TAG_structure_type:
>> +    case DW_TAG_class_type:
>> +    case DW_TAG_union_type:
>> +    case DW_TAG_array_type:
>> +    aggregate:
>> +      /* XXX TODO: Can't handle structure return with other ABI's yet :-/ */
>> +      if ((arch != MIPS_ARCH_32) && (arch != MIPS_ARCH_64))
>> +        return -2;
>> +
>> +      *locp = loc_aggregate;
>> +      return nloc_aggregate;
>> +    }
>> +
>> +  /* XXX We don't have a good way to return specific errors from ebl calls.
>> +     This value means we do not understand the type, but it is well-formed
>> +     DWARF and might be valid.  */
>> +  return -2;
>> +}
> OK. This looks plausible. Would be good to have a reference to the
> actual calling convention.
>
> Thanks,
>
> Mark


Thanks,

YIng