Module goblin::elf::reloc [−][src]
Expand description
Relocation computations
The following notation is used to describe relocation computations specific to x86_64 ELF.
- A: The addend used to compute the value of the relocatable field.
- B: The base address at which a shared object is loaded into memory during execution. Generally, a shared object file is built with a base virtual address of 0. However, the execution address of the shared object is different.
- G: The offset into the global offset table at which the address of the relocation entry’s symbol resides during execution.
- GOT: The address of the global offset table.
- L: The section offset or address of the procedure linkage table entry for a symbol.
- P: The section offset or address of the storage unit being relocated, computed using r_offset.
- S: The value of the symbol whose index resides in the relocation entry.
- Z: The size of the symbol whose index resides in the relocation entry.
Below are some common x86_64 relocation computations you might find useful:
| Relocation | Value | Size | Formula |
|---|---|---|---|
R_X86_64_NONE | 0 | NONE | NONE |
R_X86_64_64 | 1 | 64 | S + A |
R_X86_64_PC32 | 2 | 32 | S + A - P |
R_X86_64_GOT32 | 3 | 32 | G + A |
R_X86_64_PLT32 | 4 | 32 | L + A - P |
R_X86_64_COPY | 5 | NONE | NONE |
R_X86_64_GLOB_DAT | 6 | 64 | S |
R_X86_64_JUMP_SLOT | 7 | 64 | S |
R_X86_64_RELATIVE | 8 | 64 | B + A |
R_X86_64_GOTPCREL | 9 | 32 | G + GOT + A - P |
R_X86_64_32 | 10 | 32 | S + A |
R_X86_64_32S | 11 | 32 | S + A |
R_X86_64_16 | 12 | 16 | S + A |
R_X86_64_PC16 | 13 | 16 | S + A - P |
R_X86_64_8 | 14 | 8 | S + A |
R_X86_64_PC8 | 15 | 8 | S + A - P |
R_X86_64_DTPMOD64 | 16 | 64 | |
R_X86_64_DTPOFF64 | 17 | 64 | |
R_X86_64_TPOFF64 | 18 | 64 | |
R_X86_64_TLSGD | 19 | 32 | |
R_X86_64_TLSLD | 20 | 32 | |
R_X86_64_DTPOFF32 | 21 | 32 | |
R_X86_64_GOTTPOFF | 22 | 32 | |
R_X86_64_TPOFF32 | 23 | 32 | |
R_X86_64_PC64 | 24 | 64 | S + A - P |
R_X86_64_GOTOFF64 | 25 | 64 | S + A - GOT |
R_X86_64_GOTPC32 | 26 | 32 | GOT + A - P |
R_X86_64_SIZE32 | 32 | 32 | Z + A |
R_X86_64_SIZE64 | 33 | 64 | Z + A |
R_X86_64_GOTPC32_TLSDESC 34 | 32 | ||
R_X86_64_TLSDESC_CALL | 35 | NONE | |
R_X86_64_TLSDESC | 36 | 64 × 2 | |
R_X86_64_IRELATIVE | 37 | 64 | indirect (B + A) |
TLS information is at http://people.redhat.com/aoliva/writeups/TLS/RFC-TLSDESC-x86.txt
R_X86_64_IRELATIVE is similar to R_X86_64_RELATIVE except that
the value used in this relocation is the program address returned by the function,
which takes no arguments, at the address of the result of the corresponding
R_X86_64_RELATIVE relocation.
Read more https://docs.oracle.com/cd/E23824_01/html/819-0690/chapter6-54839.html
Modules
Structs
A unified ELF relocation structure
An ELF section containing relocations, allowing lazy iteration over symbols.
Constants
Direct 32 bit
Copy symbol at runtime
Create GOT entry
32 bit GOT entry
Load from 32 bit GOT entry, relaxable
32 bit offset to GOT
32 bit PC relative offset to GOT
Adjust indirectly by program base
Create PLT entry
No reloc
Keep this the last entry
PC relative 32 bit
32 bit PLT address
Adjust by program base
32-bit symbol size
TLS descriptor containing pointer to code and to argument, returning the TLS offset for the symbol
Marker of call through TLS descriptor for relaxation
ID of module containing symbol
Offset in TLS block
Direct 32 bit for GNU version of general dynamic thread local data
Direct 32 bit for general dynamic thread local data
Relocation for call to __tls_get_addr()
Tag for popl in GD TLS code
Tag for pushl in GD TLS code
GOT offset for TLS descriptor.
GOT entry for static TLS block offset
Address of GOT entry for static TLS block offset
GOT entry for negated static TLS block offset
Direct 32 bit for GNU version of local dynamic thread local data in LE code
Direct 32 bit for local dynamic thread local data in LE code
Relocation for call to __tls_get_addr() in LDM code
Tag for popl in LDM TLS code
Tag for pushl in LDM TLS code
Offset relative to TLS block
Offset relative to static TLS block
Negated offset relative to static TLS block
Offset in static TLS block
Negated offset in static TLS block
Direct 16-bit
Direct 32 bit
Direct 64 bit
Dir. ADD imm. from bits 11:0
P-page-rel. GOT off. ADRP 32:12
PC-rel. ADR imm. from bits 20:0
Page-rel. ADRP imm. from 32:12
Likewise; no overflow check
Likewise for CALL
PC-rel. cond. br. imm. from 20:2.
Copy symbol at runtime
Create GOT entry
GOT-relative 32-bit
GOT-relative 64-bit
PC-rel. GOT off. load imm. 20:2
STT_GNU_IFUNC relocation
PC-rel. B imm. from bits 27:2
Create PLT entry
GOT-rel. off. LD/ST imm. 14:3
GOT-page-rel. GOT off. LD/ST 14:3
Dir. GOT off. LD/ST imm. 11:3
Likewise for LD/ST; no check.
Dir. ADD imm. from bits 11:1
Likewise for bits 11:2
Likewise for bits 11:3
Dir. ADD imm. from bits 11:4
PC-rel. LD imm. from bits 20:2
GOT-rel. off. MOV{N,Z} imm. 15:0.
Likewise for MOVK; no check
GOT-rel. o. MOV{N,Z} imm. 31:16
Likewise for MOVK; no check
GOT-rel. o. MOV{N,Z} imm. 47:32
Likewise for MOVK; no check
GOT-rel. o. MOV{N,Z} imm. 63:48
PC-rel. MOV{N,Z} imm. from 15:0
Likewise for MOVK; no check
PC-rel. MOV{N,Z} imm. from 31:16.
Likewise for MOVK; no check
PC-rel. MOV{N,Z} imm. from 47:32.
Likewise for MOVK; no check
PC-rel. MOV{N,Z} imm. from 63:48.
Dir. MOV{N,Z} imm. from 15:0
Dir. MOV{N,Z} imm. from 31:16
Dir. MOV{N,Z} imm. from 47:32
Dir. MOVZ imm. from bits 15:0
Likewise for MOVK; no check
Dir. MOVZ imm. from bits 31:16
Likewise for MOVK; no check
Dir. MOVZ imm. from bits 47:32
Likewise for MOVK; no check
Dir. MOV{K,Z} imm. from 63:48
No relocation
Direct 32 bit
Copy symbol at runtime
Create GOT entry
STT_GNU_IFUNC relocation
Create PLT entry
Adjust by program base
TLS Descriptor
Module number, 32 bit
Module-relative offset, 32 bit
TP-relative offset, 32 bit
PC-relative 16-bit
PC-relative 32-bit
PC-relative 64-bit
Adjust by program base
TLS Descriptor
Relax ADD
Direct ADD imm. from 11:0
Page-rel. ADRP imm. 32:12
PC-rel. ADR immediate 20:0
Relax BLR
Direct LD off. from 11:3
Relax LDR
PC-rel. load immediate 20:2
GOT-rel. MOVK imm. 15:0; no ck
GOT-rel. MOV{N,Z} imm. 31:16
direct ADD imm. from 11:0
page-rel. ADRP imm. 32:12
PC-relative ADR imm. 20:0
GOT-rel. MOVK imm. 15:0
GOT-rel. MOV{N,Z} 31:16
Page-rel. ADRP 32:12
Direct LD off. 11:3
PC-rel. load imm. 20:2
GOT-rel. MOVK 15:0
GOT-rel. MOV{N,Z} 31:16
DTP-rel. ADD imm. from 23:12.
DTP-rel. ADD imm. from 11:0
Likewise; no ovfl. check
Like 514; local dynamic model
Like 513; local dynamic model
Like 512; local dynamic model
DTP-rel. LD/ST imm. 11:0
Likewise; no check
DTP-rel. LD/ST imm. 11:1
Likewise; no check
DTP-rel. LD/ST imm. 11:2
Likewise; no check
DTP-rel. LD/ST imm. 11:3
Likewise; no check
DTP-rel. LD/ST imm. 11:4.
Likewise; no check
TLS PC-rel. load imm. 20:2
TLS DTP-rel. MOV{N,Z} 15:0
Likewise; MOVK; no check
TLS DTP-rel. MOV{N,Z} 31:16
Likewise; MOVK; no check
TLS DTP-rel. MOV{N,Z} 47:32
Like 516; local dynamic model
Like 515; local dynamic model
TP-rel. ADD imm. 23:12
TP-rel. ADD imm. 11:0
Likewise; no ovfl. check
TP-rel. LD/ST off. 11:0
Likewise; no ovfl. check.
TP-rel. LD/ST off. 11:1
Likewise; no check
TP-rel. LD/ST off. 11:2
Likewise; no check
TP-rel. LD/ST off. 11:3
Likewise; no check
TP-rel. LD/ST off. 11:4
Likewise; no check
TLS TP-rel. MOV{N,Z} 15:0
Likewise; MOVK; no check
TLS TP-rel. MOV{N,Z} 31:16
Likewise; MOVK; no check
TLS TP-rel. MOV{N,Z} 47:32
Module number, 64 bit
Module-relative offset, 64 bit
TP-relative offset, 64 bit
PC-rel. TBZ/TBNZ imm. from 15:2
Direct 8 bit
Direct 12 bit
Direct 16 bit
Direct 32 bit
Direct 32-bit
Obsolete
Obsolete
Obsolete
PC relative (ADD, SUB)
PC relative (ADD, SUB)
PC relative (ADD, SUB)
PC relative (ADD, SUB)
PC relative (ADD, SUB)
Deprecated, prog. base relative
Deprecated, prog. base relative
Program base relative (ADD,SUB)
Program base relative (ADD,SUB)
Program base relative (ADD,SUB)
Program base relative (ADD,SUB)
Program base relative (ADD,SUB)
Adjust by program base
PC relative 24 bit (BL, BLX)
Copy symbol at runtime
Create GOT entry
32 bit GOT entry
32 bit offset to GOT
12 bit, GOT entry relative to GOT origin (LDR, STR)
32 bit PC relative offset to GOT
GOT entry
GOT entry relative to GOT origin (LDR)
PC relative GOT entry
PC relative 24 bit (B, BL
Create PLT entry
PC relative (LDC, STC)
PC relative (LDC, STC)
PC relative (LDC, STC)
Program base relative (LDC,STC)
Program base relative (LDC,STC)
Program base relative (LDC,STC)
PC relative (STR{D,H},LDR{D,SB,H,SH})
PC relative (STR{D,H},LDR{D,SB,H,SH})
PC relative (STR{D,H},LDR{D,SB,H,SH})
Program base relative (LDR, STR, LDRB, STRB)
Program base relative (LDR, STR, LDRB, STRB)
Program base relative (LDR, STR, LDRB, STRB)
PC relative (LDR,STR,LDRB,STRB)
PC relative (LDR,STR,LDRB,STRB)
Deprecated, prog. base relative
Program base relative (LDR,STR, LDRB, STRB)
Program base relative (LDR, STR, LDRB, STRB)
Program base relative (LDR, STR, LDRB, STRB)
Obsolete
Direct high 16-bit (MOVT)
Program base relative high 16 bit (MOVT)
PC relative (MOVT)
Direct 16-bit (MOVW)
Program base relative 16 bit (MOVW)
Program base relative 16 bit (MOVW)
PC relative 16-bit (MOVW)
No reloc
Keep this the last entry
Deprecated PC relative 26 bit branch
Deprecated, 32 bit PLT address
32 bit PC relative
PC relative 32 bit
PC relative 32-bit
Adjust by program base
Program base relative
Obsolete static relocation
Direct & 0x7C (LDR, STR)
PC relative 12 bit (Thumb32 ADR.W)
GOT entry relative to GOT origin, 12 bit (Thumb32 LDR)
PC relative X & 0x7E (Thumb16 CBZ, CBNZ)
PC relative 20 bit (Thumb32 B
PC relative 24 bit (Thumb32 B.W)
Direct high 16 bit (Thumb32 MOVT)
Program base relative high 16 bit (Thumb32 MOVT)
PC relative high 16 bit (Thumb32 MOVT)
Direct 16 bit (Thumb32 MOVW)
Program base relative 16 bit (Thumb32 MOVW)
Program base relative 16 bit (Thumb32 MOVW)
PC relative 16 bit (Thumb32 MOVW)
PC relative & 0x3FC(Thumb16 LDR, ADD, ADR).
PC relative & 0x1FE (Thumb16 B/B
PC relative & 0xFFE (Thumb16 B)
PC relative 12 bit (Thumb32 LDR{D,SB,H,SH})
PC relative 24 bit (Thumb32 BL)
Reserved
Reserved
Dynamic relocation
TLS relaxation
ID of module containing symbol
Offset in TLS block
PC-rel 32 bit for global dynamic thread local data
12 bit GOT entry relative to GOT origin (LDR)
PC-rel 32 bit for GOT entry of static TLS block offset
PC-rel 32 bit for local dynamic thread local data
12 bit relative to TLS block (LDR, STR)
32 bit offset relative to TLS block
12 bit relative to static TLS block (LDR, STR)
32 bit offset relative to static TLS block
Offset in static TLS block
Reserved
Direct 16 bit
Direct 26 bit shifted
Direct 32 bit
16 bit GOT entry for function
16 bit GOT entry
GP relative 16 bit
GP relative 32 bit
High 16 bit
16 bit literal entry
Low 16 bit
No reloc
PC relative 16 bit
PC relative 32 bit
Module number 32 bit
Module number 64 bit
Module-relative offset 32 bit
Module-relative offset 64 bit
Module-relative offset, high 16 bits
Module-relative offset, low 16 bits
16 bit GOT offset for GD
16 bit GOT offset for IE
16 bit GOT offset for LDM
TP-relative offset, 32 bit6
TP-relative offset, 64 bit
TP-relative offset, high 16 bits
TP-relative offset, low 16 bits
Runtime relocation: word32 = S + A
Runtime relocation: word64 = S + A
8-bit label addition: word8 = S + A
16-bit label addition: word16 = S + A
32-bit label addition: word32 = S + A
64-bit label addition: word64 = S + A
Alignment statement
PC-relative branch (SB-Type)
PC-relative call: MACRO call,tail (auipc+jalr pair)
PC-relative call (PLT): MACRO call,tail (auipc+jalr pair) PIC
Runtime relocation: must be in executable, not allowed in shared library
GNU C++ vtable member usage
GNU C++ vtable hierarchy
PC-relative GOT reference: MACRO la
GP-relative reference (I-Type)
GP-relative reference (S-Type)
Absolute address: %hi(symbol) (U-Type)
PC-relative jump (UJ-Type)
Runtime relocation: word32,64 = S; handled by PLT unless LD_BIND_NOW
Absolute address: %lo(symbol) (I-Type)
Absolute address: %lo(symbol) (S-Type)
None
PC-relative reference: %pcrel_hi(symbol) (U-Type)
PC-relative reference: %pcrel_lo(symbol) (I-Type)
PC-relative reference: %pcrel_lo(symbol) (S-Type)
Runtime relocation: word32,64 = B + A
Instruction pair can be relaxed
PC-relative branch offset (CB-Type)
PC-relative jump offset (CJ-Type)
Absolute address (CI-Type)
Local label subtraction
Local label subtraction
Local label subtraction
Local label subtraction
Local label subtraction
8-bit label subtraction: word8 = S - A
16-bit label subtraction: word16 = S - A
32-bit label subtraction: word32 = S - A
64-bit label subtraction: word64 = S - A
TLS relocation: word32 = S->TLSINDEX
TLS relocation: word64 = S->TLSINDEX
TLS relocation: word32 = TLS + S + A - TLS_TP_OFFSET
TLS relocation: word64 = TLS + S + A - TLS_TP_OFFSET
PC-relative TLS GD reference: MACRO la.tls.gd
PC-relative TLS IE GOT offset: MACRO la.tls.ie
TLS relocation: word32 = TLS + S + A + S_TLS_OFFSET - TLS_DTV_OFFSET
TLS relocation: word64 = TLS + S + A + S_TLS_OFFSET - TLS_DTV_OFFSET
TLS LE thread usage: %tprel_add(symbol)
TLS LE thread offset: %tprel_hi(symbol) (U-Type)
TP-relative TLS LE load (I-Type)
TLS LE thread offset: %tprel_lo(symbol) (I-Type)
TLS LE thread offset: %tprel_lo(symbol) (S-Type)
TP-relative TLS LE store (S-Type)
Direct 8 bit sign extended.
Direct 16 bit zero extended.
Direct 32 bit zero extended.
Direct 32 bit sign extended.
Direct 64 bit.
Copy symbol at runtime.
ID of module containing symbol.
Offset in TLS block.
Offset in module’s TLS block.
Create GOT entry.
32 bit GOT entry.
64-bit GOT entry offset.
64 bit offset to GOT.
32 bit signed pc relative offset to GOT.
GOT offset for TLS descriptor..
64-bit PC relative offset to GOT.
32 bit signed PC relative offset to GOT.
64-bit PC relative offset to GOT entry.
Load from 32 bit signed pc relative offset to GOT entry without REX prefix, relaxable.
like GOT64, says PLT entry needed.
32 bit signed PC relative offset to GOT entry for IE symbol.
Adjust indirectly by program base.
Create PLT entry.
No reloc.
8 bit sign extended pc relative.
16 bit sign extended pc relative.
PC relative 32 bit signed.
PC relative 64 bit.
32 bit PLT address.
64-bit GOT relative offset to PLT entry.
Adjust by program base.
64-bit adjust by program base.
Load from 32 bit signed pc relative offset to GOT entry with REX prefix, relaxable.
Size of symbol plus 32-bit addend.
Size of symbol plus 64-bit addend.
TLS descriptor..
Marker for call through TLS descriptor..
32 bit signed PC relative offset to two GOT entries for GD symbol.
32 bit signed PC relative offset to two GOT entries for LD symbol.
Offset in initial TLS block.
Offset in initial TLS block.