Re: mips64 elf64 reloc data structures

[Alexandre Oliva <aoliva at redhat dot com>]

On Mar 14, 2003, Roland McGrath <roland at redhat dot com> wrote:

>> I don't know how cleaner this, but here's what I'm working with now.

> You have some "ytpe" comment typos.

Thanks, fixed.

> The union casts and struct/union constants are GCC extensions and if
> used in an exported header should use __extension__.

Even though I'm moving to a private header, I put the __extension__s
in, just we can we eventually move it back into elf/elf.h.

>> You mean, a private elf.h?  That would probably work just as well.

> I suppose putting it in include/elf.h would be alright.

Here's the patch that implements this change.  Ok to install?

Index: ChangeLog
2003-03-14  Alexandre Oliva  <aoliva at redhat dot com>

	* include/elf.h: Add structures and macros to support MIPS ELF64
	relocations.  Override ELF64_R_ macros with mips-specific
	definitions on mips.

Index: include/elf.h
===================================================================
RCS file: /cvs/glibc/libc/include/elf.h,v
retrieving revision 1.2
diff -u -p -r1.2 elf.h
--- include/elf.h 8 Jun 2000 04:45:24 -0000 1.2
+++ include/elf.h 14 Mar 2003 10:59:18 -0000
@@ -3,4 +3,87 @@
 /* Some information which is not meant for the public and therefore not
    in <elf.h>.  */
 # include <dl-dtprocnum.h>
+
+/* The 64-bit MIPS ELF ABI uses an unusual reloc format.  Each
+   relocation entry specifies up to three actual relocations, all at
+   the same address.  The first relocation which required a symbol
+   uses the symbol in the r_sym field.  The second relocation which
+   requires a symbol uses the symbol in the r_ssym field.  If all
+   three relocations require a symbol, the third one uses a zero
+   value.
+
+   We define these structures in internal headers because we're not
+   sure we want to make them part of the ABI yet.  Eventually, some of
+   this may move into elf/elf.h.  */
+
+/* An entry in a 64 bit SHT_REL section.  */
+
+typedef struct
+{
+  Elf32_Word    r_sym;		/* Symbol index */
+  unsigned char r_ssym;		/* Special symbol for 2nd relocation */
+  unsigned char r_type3;	/* 3rd relocation type */
+  unsigned char r_type2;	/* 2nd relocation type */
+  unsigned char r_type1;	/* 1st relocation type */
+} _Elf64_Mips_R_Info;
+
+typedef union
+{
+  Elf64_Xword	r_info_number;
+  _Elf64_Mips_R_Info r_info_fields;
+} _Elf64_Mips_R_Info_union;
+
+typedef struct
+{
+  Elf64_Addr	r_offset;		/* Address */
+  _Elf64_Mips_R_Info_union r_info;	/* Relocation type and symbol index */
+} Elf64_Mips_Rel;
+
+typedef struct
+{
+  Elf64_Addr	r_offset;		/* Address */
+  _Elf64_Mips_R_Info_union r_info;	/* Relocation type and symbol index */
+  Elf64_Sxword	r_addend;		/* Addend */
+} Elf64_Mips_Rela;
+
+#define ELF64_MIPS_R_SYM(i) \
+  ((__extension__ (_Elf64_Mips_R_Info_union)(i)).r_info_fields.r_sym)
+#define ELF64_MIPS_R_TYPE(i) \
+  (((_Elf64_Mips_R_Info_union)(i)).r_info_fields.r_type1 \
+   | ((Elf32_Word)(__extension__ (_Elf64_Mips_R_Info_union)(i) \
+		   ).r_info_fields.r_type2 << 8) \
+   | ((Elf32_Word)(__extension__ (_Elf64_Mips_R_Info_union)(i) \
+		   ).r_info_fields.r_type3 << 16) \
+   | ((Elf32_Word)(__extension__ (_Elf64_Mips_R_Info_union)(i) \
+		   ).r_info_fields.r_ssym << 24))
+#define ELF64_MIPS_R_INFO(sym, type) \
+  (__extension__ (_Elf64_Mips_R_Info_union) \
+   (__extension__ (_Elf64_Mips_R_Info) \
+   { (sym), ELF64_MIPS_R_SSYM (type), \
+       ELF64_MIPS_R_TYPE3 (type), \
+       ELF64_MIPS_R_TYPE2 (type), \
+       ELF64_MIPS_R_TYPE1 (type) \
+   }).r_info_number)
+/* These macros decompose the value returned by ELF64_MIPS_R_TYPE, and
+   compose it back into a value that it can be used as an argument to
+   ELF64_MIPS_R_INFO.  */
+#define ELF64_MIPS_R_SSYM(i) (((i) >> 24) & 0xff)
+#define ELF64_MIPS_R_TYPE3(i) (((i) >> 16) & 0xff)
+#define ELF64_MIPS_R_TYPE2(i) (((i) >> 8) & 0xff)
+#define ELF64_MIPS_R_TYPE1(i) ((i) & 0xff)
+#define ELF64_MIPS_R_TYPEENC(type1, type2, type3, ssym) \
+  ((type1) \
+   | ((Elf32_Word)(type2) << 8) \
+   | ((Elf32_Word)(type3) << 16) \
+   | ((Elf32_Word)(ssym) << 24))
+
+#ifdef __mips
+# undef ELF64_R_SYM
+# define ELF64_R_SYM(i) ELF64_MIPS_R_SYM (i)
+# undef ELF64_R_TYPE
+# define ELF64_R_TYPE(i) ELF64_MIPS_R_TYPE (i)
+# undef ELF64_R_INFO
+# define ELF64_R_INFO(sym, type) ELF64_MIPS_R_INFO ((sym), (type))
+#endif
+
 #endif

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                 aoliva at {redhat dot com, gcc.gnu.org}
CS PhD student at IC-Unicamp        oliva at {lsd dot ic dot unicamp dot br, gnu.org}
Free Software Evangelist                Professional serial bug killer