Re: [PATCH 5/5] backends: Fix run-native-test.sh and run-funcretval++11.sh run fail on mips

[Mark Wielaard <mark@klomp.org>]

Hi,

On Tue, 2023-04-11 at 16:12 +0800, Ying Huang wrote:
> From: Ying Huang <ying.huang@oss.cipunited.com>
> 
> add register_info, return_value_location function on mips
> ---
>  backends/Makefile.am   |   2 +-
>  backends/mips_init.c   |   2 +
>  backends/mips_regs.c   | 109 +++++++++++++++++
>  backends/mips_retval.c | 261 +++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 373 insertions(+), 1 deletion(-)
>  create mode 100644 backends/mips_regs.c
>  create mode 100644 backends/mips_retval.c
> 
> diff --git a/backends/Makefile.am b/backends/Makefile.am
> index ddc31c9d..5453f787 100644
> --- a/backends/Makefile.am
> +++ b/backends/Makefile.am
> @@ -101,7 +101,7 @@ loongarch_SRCS = loongarch_init.c loongarch_symbol.c
>  arc_SRCS = arc_init.c arc_symbol.c
>  
>  mips_SRCS = mips_init.c mips_symbol.c mips_attrs.c mips_initreg.c \
> -	    mips_cfi.c mips_unwind.c
> +	    mips_cfi.c mips_unwind.c mips_regs.c mips_retval.c

OK.
 
>  libebl_backends_a_SOURCES = $(i386_SRCS) $(sh_SRCS) $(x86_64_SRCS) \
>  			    $(ia64_SRCS) $(alpha_SRCS) $(arm_SRCS) \
> diff --git a/backends/mips_init.c b/backends/mips_init.c
> index 3caa9fee..7ca93314 100644
> --- a/backends/mips_init.c
> +++ b/backends/mips_init.c
> @@ -58,6 +58,8 @@ mips_init (Elf *elf __attribute__ ((unused)),
>    HOOK (eh, set_initial_registers_tid);
>    HOOK (eh, abi_cfi);
>    HOOK (eh, unwind);
> +  HOOK (eh, register_info);
> +  HOOK (eh, return_value_location);
>    eh->frame_nregs = 32;
>    return eh;
>  }

OK

> diff --git a/backends/mips_regs.c b/backends/mips_regs.c
> new file mode 100644
> index 00000000..733caeee
> --- /dev/null
> +++ b/backends/mips_regs.c
> @@ -0,0 +1,109 @@
> +/* Register names and numbers for mips DWARF.
> +   Copyright (C) 2006 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>
> +
> +#define BACKEND mips_
> +#include "libebl_CPU.h"
> +
> +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;
> +      }
> +    }
> +  else if (regno == 64)
> +    {
> +      *type = DW_ATE_signed;
> +      *bits = 32;
> +      name[0] = 'h';
> +      name[1] = 'i';
> +      namelen = 2;
> +    }
> +  else
> +    {
> +      *type = DW_ATE_signed;
> +      *bits = 32;
> +      name[0] = 'l';
> +      name[1] = 'o';
> +      namelen = 2;
> +    }
> +
> +  name[namelen++] = '\0';
> +  return namelen;
> +}

OK, but indentation seems slightly off. space vs tabs?

> 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?

> +/* $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