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Re: [PATCH v2] Suport for bi-endianess in elf file

From: Paulo Flabiano Smorigo
Subject: Re: [PATCH v2] Suport for bi-endianess in elf file
Date: Sun, 26 Jul 2015 22:34:26 -0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 
On 2015-07-24 16:00, Vladimir 'phcoder' Serbinenko wrote:


Le 23 juil. 2015 16:11, "Paulo Flabiano Smorigo"
<address@hidden <mailto:address@hidden>> a
écrit :
 >
 > Updated version with the suggestions from Andrei Borzenkov.
 >
 > * grub-core/kern/elf.c: check and switch endianess with grub_{be,le}_to
 > cpu functions.
 > * grub-core/kern/elfXX.c: Likewise.
 >
 > Also-by: Tomohiro B Berry <address@hidden
<mailto:address@hidden>>
 > ---
 >  grub-core/kern/elf.c   | 51 ++++++++++++++++++++++++++++++---
 >  grub-core/kern/elfXX.c | 76
++++++++++++++++++++++++++++++++++++++++++++++++++
 >  2 files changed, 123 insertions(+), 4 deletions(-)
 >
 > diff --git a/grub-core/kern/elf.c b/grub-core/kern/elf.c
 > index 5f99c43..1be9c1c 100644
 > --- a/grub-core/kern/elf.c
 > +++ b/grub-core/kern/elf.c
 > @@ -28,6 +28,11 @@
 >
 >  GRUB_MOD_LICENSE ("GPLv3+");
 >
 > +#if defined(__powerpc__) && defined(GRUB_MACHINE_IEEE1275)
 > +void grub_elf32_check_endianess (grub_elf_t elf);
 > +void grub_elf64_check_endianess (grub_elf_t elf);
 > +#endif /* defined(__powerpc__) && defined(GRUB_MACHINE_IEEE1275) */
 > +
 >  /* Check if EHDR is a valid ELF header.  */
 >  static grub_err_t
 >  grub_elf_check_header (grub_elf_t elf)
 > @@ -38,8 +43,19 @@ grub_elf_check_header (grub_elf_t elf)
 >        || e->e_ident[EI_MAG1] != ELFMAG1
 >        || e->e_ident[EI_MAG2] != ELFMAG2
 >        || e->e_ident[EI_MAG3] != ELFMAG3
 > -      || e->e_ident[EI_VERSION] != EV_CURRENT
 > -      || e->e_version != EV_CURRENT)
 > +      || e->e_ident[EI_VERSION] != EV_CURRENT)
 > +    return grub_error (GRUB_ERR_BAD_OS, N_("invalid arch-independent
ELF magic"));
 > +
 > +#if defined(__powerpc__) && defined(GRUB_MACHINE_IEEE1275)
 > +  if (grub_elf_is_elf32 (elf))
 > +      grub_elf32_check_endianess (elf);
 > +  else if (grub_elf_is_elf64 (elf))
 > +      grub_elf64_check_endianess (elf);
 > +  else
 > +    return grub_error (GRUB_ERR_BAD_OS, N_("Uknown ELF class"));
 > +#endif /* defined(__powerpc__) && defined(GRUB_MACHINE_IEEE1275) */
 > +
 > +  if (e->e_version != EV_CURRENT)
 >      return grub_error (GRUB_ERR_BAD_OS, N_("invalid arch-independent
ELF magic"));
 >
 >    return GRUB_ERR_NONE;
 > @@ -116,7 +132,11 @@ grub_elf_open (const char *name)
 >    return elf;
 >  }
 >
 > -
 > +#define grub_be_to_halfXX grub_be_to_cpu16
 > +#define grub_le_to_halfXX grub_le_to_cpu16
 > +#define grub_be_to_wordXX grub_be_to_cpu32
 > +#define grub_le_to_wordXX grub_le_to_cpu32
 > +
 >  /* 32-bit */
 >  #define ehdrXX ehdr32
 >  #define ELFCLASSXX ELFCLASS32
 > @@ -127,7 +147,15 @@ grub_elf_open (const char *name)
 >  #define grub_elf_is_elfXX grub_elf_is_elf32
 >  #define grub_elfXX_load_phdrs grub_elf32_load_phdrs
 >  #define ElfXX_Phdr Elf32_Phdr
 > +#define ElfXX_Ehdr Elf32_Ehdr
 >  #define grub_uintXX_t grub_uint32_t
 > +#define grub_be_to_addrXX grub_be_to_cpu32
 > +#define grub_le_to_addrXX grub_le_to_cpu32
 > +#define grub_be_to_offXX grub_be_to_cpu32
 > +#define grub_le_to_offXX grub_le_to_cpu32
 > +#define grub_be_to_XwordXX grub_be_to_cpu32
 > +#define grub_le_to_XwordXX grub_le_to_cpu32
 > +#define grub_elfXX_check_endianess grub_elf32_check_endianess
 >
 >  #include "elfXX.c"
 >
 > @@ -140,9 +168,16 @@ grub_elf_open (const char *name)
 >  #undef grub_elf_is_elfXX
 >  #undef grub_elfXX_load_phdrs
 >  #undef ElfXX_Phdr
 > +#undef ElfXX_Ehdr
 >  #undef grub_uintXX_t
 > +#undef grub_be_to_addrXX
 > +#undef grub_le_to_addrXX
 > +#undef grub_be_to_offXX
 > +#undef grub_le_to_offXX
 > +#undef grub_be_to_XwordXX
 > +#undef grub_le_to_XwordXX
 > +#undef grub_elfXX_check_endianess
 >
 > -
 >  /* 64-bit */
 >  #define ehdrXX ehdr64
 >  #define ELFCLASSXX ELFCLASS64
 > @@ -153,6 +188,14 @@ grub_elf_open (const char *name)
 >  #define grub_elf_is_elfXX grub_elf_is_elf64
 >  #define grub_elfXX_load_phdrs grub_elf64_load_phdrs
 >  #define ElfXX_Phdr Elf64_Phdr
 > +#define ElfXX_Ehdr Elf64_Ehdr
 >  #define grub_uintXX_t grub_uint64_t
 > +#define grub_be_to_addrXX grub_be_to_cpu64
 > +#define grub_le_to_addrXX grub_le_to_cpu64
 > +#define grub_be_to_offXX grub_be_to_cpu64
 > +#define grub_le_to_offXX grub_le_to_cpu64
 > +#define grub_be_to_XwordXX grub_be_to_cpu64
 > +#define grub_le_to_XwordXX grub_le_to_cpu64
 > +#define grub_elfXX_check_endianess grub_elf64_check_endianess
 >
 >  #include "elfXX.c"
 > diff --git a/grub-core/kern/elfXX.c b/grub-core/kern/elfXX.c
 > index 1d09971..c14e071 100644
 > --- a/grub-core/kern/elfXX.c
 > +++ b/grub-core/kern/elfXX.c
 > @@ -31,6 +31,39 @@ grub_elfXX_load_phdrs (grub_elf_t elf)
 >        return grub_errno;
 >      }
 >
 > +#if defined(__powerpc__) && defined(GRUB_MACHINE_IEEE1275)
 > +  ElfXX_Phdr *phdr;
 > +  for (phdr = elf->phdrs;
 > +       phdr && phdr < (ElfXX_Phdr *) elf->phdrs +
elf->ehdr.ehdrXX.e_phnum;
 > +       phdr++)
 > +    {
 > +      if (elf->ehdr.ehdrXX.e_ident[EI_DATA] == ELFDATA2LSB)
 > +        {
 > +          phdr->p_type = grub_le_to_wordXX (phdr->p_type);
 > +          phdr->p_flags = grub_le_to_wordXX (phdr->p_flags);
 > +          phdr->p_offset = grub_le_to_offXX (phdr->p_offset);
 > +          phdr->p_vaddr = grub_le_to_addrXX (phdr->p_vaddr);
 > +          phdr->p_paddr = grub_le_to_addrXX (phdr->p_paddr);
 > +          phdr->p_filesz = grub_le_to_XwordXX (phdr->p_filesz);
 > +          phdr->p_memsz = grub_le_to_XwordXX (phdr->p_memsz);
 > +          phdr->p_align = grub_le_to_XwordXX (phdr->p_align);
 > +        }
 > +#if !defined(GRUB_CPU_WORDS_BIGENDIAN) && 0
&&0. Really. AFAICT this breaks bigendian elf support. Please test your
patch with be kernel
I built and tested in both endianess. No problem found. Will double check it. 


 > +      else if (elf->ehdr.ehdrXX.e_ident[EI_DATA] == ELFDATA2MSB)
 > +        {
 > +          phdr->p_type = grub_be_to_wordXX (phdr->p_type);
 > +          phdr->p_flags = grub_be_to_wordXX (phdr->p_flags);
 > +          phdr->p_offset = grub_be_to_offXX (phdr->p_offset);
 > +          phdr->p_vaddr = grub_be_to_addrXX (phdr->p_vaddr);
 > +          phdr->p_paddr = grub_be_to_addrXX (phdr->p_paddr);
 > +          phdr->p_filesz = grub_be_to_XwordXX (phdr->p_filesz);
 > +          phdr->p_memsz = grub_be_to_XwordXX (phdr->p_memsz);
 > +          phdr->p_align = grub_be_to_XwordXX (phdr->p_align);
 > +        }
 > +#endif /* !defined(GRUB_CPU_WORDS_BIGENDIAN) && 0 */
 > +    }
 > +#endif /* defined(__powerpc__) && defined(GRUB_MACHINE_IEEE1275) */
 > +
 >    return GRUB_ERR_NONE;
 >  }
 >
 > @@ -154,3 +187,46 @@ grub_elfXX_load (grub_elf_t elf, const char
*filename,
 >
 >    return grub_errno;
 >  }
 > +
 > +#if defined(__powerpc__) && defined(GRUB_MACHINE_IEEE1275)
 > +void
 > +grub_elfXX_check_endianess (grub_elf_t elf)
 > +{
 > +  ElfXX_Ehdr *e = &(elf->ehdr.ehdrXX);
 > +
 > +  if (e->e_ident[EI_DATA] == ELFDATA2LSB)
 > +    {
 > +      e->e_type = grub_le_to_halfXX (e->e_type);
This is more than just check. Please reflect it in function name for
code readability.


Agree. Maybe grub_check_convert_endianess?


 > +      e->e_machine = grub_le_to_halfXX (e->e_machine);
 > +      e->e_version = grub_le_to_wordXX (e->e_version);
 > +      e->e_entry = grub_le_to_addrXX (e->e_entry);
 > +      e->e_phoff = grub_le_to_offXX (e->e_phoff);
 > +      e->e_shoff = grub_le_to_offXX (e->e_shoff);
 > +      e->e_flags = grub_le_to_wordXX (e->e_flags);
 > +      e->e_ehsize = grub_le_to_halfXX (e->e_ehsize);
 > +      e->e_phentsize = grub_le_to_halfXX (e->e_phentsize);
 > +      e->e_phnum = grub_le_to_halfXX (e->e_phnum);
 > +      e->e_shentsize = grub_le_to_halfXX (e->e_shentsize);
 > +      e->e_shnum = grub_le_to_halfXX (e->e_shnum);
 > +      e->e_shstrndx = grub_le_to_halfXX (e->e_shstrndx);
 > +    }
 > +#if !defined(GRUB_CPU_WORDS_BIGENDIAN) && 0
 > +  else if (e->e_ident[EI_DATA] == ELFDATA2MSB)
 > +    {
 > +      e->e_type = grub_be_to_halfXX (e->e_type);
 > +      e->e_machine = grub_be_to_halfXX (e->e_machine);
 > +      e->e_version = grub_be_to_wordXX (e->e_version);
 > +      e->e_entry = grub_be_to_addrXX (e->e_entry);
 > +      e->e_phoff = grub_be_to_offXX (e->e_phoff);
 > +      e->e_shoff = grub_be_to_offXX (e->e_shoff);
 > +      e->e_flags = grub_be_to_wordXX (e->e_flags);
 > +      e->e_ehsize = grub_be_to_halfXX (e->e_ehsize);
 > +      e->e_phentsize = grub_be_to_halfXX (e->e_phentsize);
 > +      e->e_phnum = grub_be_to_halfXX (e->e_phnum);
 > +      e->e_shentsize = grub_be_to_halfXX (e->e_shentsize);
 > +      e->e_shnum = grub_be_to_halfXX (e->e_shnum);
 > +      e->e_shstrndx = grub_be_to_halfXX (e->e_shstrndx);
 > +    }
 > +#endif /* !defined(GRUB_CPU_WORDS_BIGENDIAN) && 0 */
 > +}
 > +#endif /* defined(__powerpc__) && defined(GRUB_MACHINE_IEEE1275) */
 > --
 > 2.1.0
 >
 >
 > _______________________________________________
 > Grub-devel mailing list
 > address@hidden <mailto:address@hidden>
 > https://lists.gnu.org/mailman/listinfo/grub-devel



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Paulo Flabiano Smorigo
IBM Linux Technology Center
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