reloc(5) [ultrix man page]
reloc(5) File Formats Manual reloc(5) Name reloc - relocation information for a MIPS object file Syntax #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 */ long r_symndx ; /* index into symbol table */ ushort r_type ; /* relocation type */ unsigned r_symndx:24, /* index into symbol table */ r_reserved:3, r_type:4, /* relocation type */ r_extern:1; /* if 1 symndx is an index into the external symbol table, else symndx is a section # */ } ; /* Relocation types */ #define R_ABS 0 #define R_REFHALF 1 #define R_REFWORD 2 #define R_JMPADDR 3 #define R_REFHI 4 #define R_REFLO 5 #define R_GPREL 6 #define R_LITERAL 7 /* 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 The link editor reads each input section and performs relocation. The relocation entries direct how references found within the input sec- tion are treated. If is zero, it is a local relocation entry and then 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. The assembler and loader always use local relocation entries if the item to be relocated is defined in the object file. 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 The reference is absolute and no relocation is necessary. The entry will be ignored. R_REFHALF A 16-bit reference to the symbol's virtual address. R_REFWORD A 32-bit reference to the symbol's virtual address. R_JMPADDR A 26-bit jump instruction reference to the symbol's virtual address. R_REFHI A reference to the high 16 bits of the symbol's virtual address. The next relocation entry must be the corresponding R_REFLO entry, so the proper value of the constant to be added to the symbol's virtual address can be reconstructed. R_REFLO A reference to low 16 bits to the symbol's virtual address. R_GPREL A 16-bit offset to the symbol's virtual address from the global pointer register. R_LITERAL A 16-bit offset to the literal's virtual address from the global pointer register. Relocation entries are generated automatically by the assembler and automatically used by the link editor. Link editor options exist for both preserving and removing the relocation entries from object files. The number of relocation entries for a section is found in the field of the section header. This field is a C language short and can over- flow with large objects. If this field overflows, the section header field has the S_NRELOC_OVFL bit set. In this case, the true number of relocation entries is found in the field of the first relocation entry for that section. That relocation entry has a type of R_ABS, so it is ignored when the relocation takes place. See Also as(1), ld(1), a.out(5), syms(5), scnhdr(5) RISC reloc(5)
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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)