reloc(4)						     Kernel Interfaces Manual							  reloc(4)

NAME

       reloc - Relocation information for an object file

SYNOPSIS

       #include  <reloc.h>

DESCRIPTION

       Object  files  have one relocation entry for each relocatable reference in the text or data.  If relocation information is present, it will
       be in the following format.

       struct	 reloc {
	 long	    r_vaddr ;	   /* (virtual) address of
				       reference */
	 unsigned   r_symndx ;	   /* index into symbol table */
	 unsigned   r_type:8 ;	   /* relocation type */
	 unsigned   r_extern:1 ;   /* if 1 symndx is an index
				      into the external table
				      the external table, else
				      symndx is a section #  */
	 unsigned   r_offset;6 ;   /* for R_OP_STORE, quad
				      based LE bit offset */
	 unsigned   r_reserved;11; /* Must be zero */
	 unsigned   r_size;6 ;	   /* R_OP_STORE, bit size */ } ;

       /* Relocation types */ #define  R_ABS	    0 #define  R_REFLONG    1 #define  R_REFQUAD    2 #define  R_GPREL32    3  #define	 R_LITERAL
       4 #define  R_LITUSE     5 #define  R_GPDISP     6 #define  R_BRADDR     7 #define  R_HINT       8 #define  R_SREL16     9  /* self relative
       16 bit
				   offset */ #define  R_SREL32	   10 /* self relative 32 bit
				   offset */ #define  R_SREL64	   11 /* self relative 64-bit
				   offset */ #define  R_OP_PUSH    12 /* stack[++tos] =
				   relocate(vaddr) */ #define  R_OP_STORE   13 /* vaddr(r_offset:r_size =
				   stack[tos--] */ #define  R_OP_PSUB	 14 /* stack[tos] = stack[tos] -
				   relocate(vaddr) */ #define  R_OP_PRSHIFT 15 /* stack[tos] = stack[tos] >>
				   relocate(vaddr) */ #define  R_GPVALUE    16

       /* Section numbers */ #define  R_SN_NULL    0 #define  R_SN_TEXT    1 #define  R_SN_RDATA   2 #define  R_SN_DATA    3  #define	R_SN_SDATA
       4  #define   R_SN_SBSS	  5  #define   R_SN_BSS      6	#define   R_SN_INIT	7  #define  R_SN_LIT8	 8 #define  R_SN_LIT4	 9 #define
       R_SN_XDATA   10 #define	R_SN_PDATE   11 #define  R_SN_FINI    12 #define  R_SN_LITA    13 #define  R_SN_ABS	14

       The link editor (ld) reads each input section and performs relocation.  The relocation entries direct how references found within the input
       section are treated.

       If  r_extern  is  zero  then it is a local relocation entry and then r_symndx is a section number (R_SN_*).  For these entries the starting
       address for the section referenced by the section number is used in place of an external symbol table entry's value.

       For every external relocation (except R_ABS) a signed constant is added to the symbol's virtual address that the  relocation  entry  refers
       to.  This constant is assembled at the address being relocated.

       R_ABS		 A relocation has already been performed.

       R_REFLONG	 A 32-bit reference to the symbol's virtual address.

       R_REFQUAD	 A 64-bit reference to the symbol's virtual address.

       R_GPREL32	 A 32-bit displacement from the global pointer to the symbol's virtual address.

       R_LITERAL	 A  reference to a literal in the literal address pool as an offset from the global pointer.  R_LITUSE Identifies usage of
			 a lteral address previously loaded into a register.  The r_symndx field identifies the specific usage	of  the  register.
			 See the Assembly Language Programmer's Guide for more information.

       R_GPDISP 	 Identifies  an  lda/ldah  instruction pair that is used to initialize a procedure's global-pointer register. The r_symndx
			 contains a byte offset, which, when added to the r_vaddr field results in the address of the  other  instruction  of  the
			 pair.

       R_BRADDR 	 A 21-bit branch reference to the symbol's virtual address.

       R_HINT		 A 14-bit jsr hint reference to the symbol's virtual address.

       R_SREL16 	 A 16-bit self-relative reference to the symbol's virtual address.

       R_SREL32 	 A 32-bit self-relative reference to the symbols's virtual address.

       R_SREL64 	 A 64-bit self-relative reference to the symbol's virtual address.

       R_OP_PUSH	 Push symbol's virtual address on relocation expression stack.

       R_OP_STORE	 Pop value from the relocation expression stack and store at the symbol's virtual address. The r_size field determines the
			 number of bits stored. The r_offset field designates the bit offset from the symbol to the target.

       R_OP_PSUB	 Pop value from the relocation expression stack and subtract the symbol's virtual address. The result  is  pushed  on  the
			 relocation expression stack.

       R_OP_PRSHIFT	 Pop value from the relocation expression stack and shift right by the symbol's value. The result is pushed on the reloca-
			 tion stack.

       R_GPVALUE	 Specifies a new gp value is to be used starting with the address specified by the r_vaddr field. The gp value is the  sum
			 of the optional header's gp_value field and the r_symndx field.  The r_extern field must be zero.

RELATED INFORMATION

       as(1), ld(1), a.out(4), syms(4), scnhdr(4).

       Assembly Language Programmer's Guide delim off

																	  reloc(4)