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LoongArch-ELF-ABI-EN.adoc

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LoongArch ELF ABI specification

Register Convention

Table 1. Integer Register Convention
Name Alias Meaning Preserved across calls

$r0

$zero

Constant zero

 — 

$r1

$ra

Return address

No

$r2

$tp

Thread pointer

--(Unallocatable)

$r3

$sp

Stack pointer

Yes

$r4-$r11

$a0-$a7

Argument registers

No

$r4-$r5

$v0-$v1

Return value

No

$r12-$r20

$t0-$t8

Temp registers

No

$r21

 — 

Reserved

--(Unallocatable)

$r22

$fp/$s9

Frame pointer/Saved register

Yes

$r23-$r31

$s0-$s8

Saved register

Yes
Table 2. Floating-point Register Convention
Name Alias Meaning Preserved across calls

$f0-$f7

$fa0-$fa7

Argument registers

No

$f0-$f1

$fv0-$fv7

Return value

No

$f8-$f23

$ft0-$ft15

Temp registers

No

$f24-$f31

$fs0-$fs7

Saved register

Yes

Type Size and Alignment

Table 3. LP64 ABI
Scalar type Size(Bytes) Alignment(Bytes)

bool/_Bool

1

1

unsigned/signed char

1

1

unsigned/signed short

2

2

unsigned/signed int

4

4

unsigned/signed long

8

8

unsigned/signed long long

8

8

pointer

8

8

float

4

4

double

8

8

long double

16

16

char is signed.

ELF Object Files

EI_CLASS: File class.

EI_CLASS Value Description

ELFCLASS32

1

32-bit objects

ELFCLASS64

2

64-bit objects

e_machine: Identifies the machine.

LoongArch (258)

e_flags: Identifies the ABIs of this ELF file.

ABIs Value Description

lp32

0x1

soft float

Reserved

0x2

 — 

lp64

0x3

64bit default ABI

lp32f

0x4

single float

lp32d

0x5

double float

Reserved

0x6--

 — 

ABI Version:

ABI Version: Value Description

v0

0

Stack operands base relocation type.

v1

1

Another relocation type IF needed.

 — 

2--

Reserved.

Relocations

Table 4. ELF Relocation types
Enum ELF reloc type Usage Detail

0

R_LARCH_NONE

1

R_LARCH_32

Runtime address resolving

*(int32_t *) PC = RtAddr + A

2

R_LARCH_64

Runtime address resolving

*(int64_t *) PC = RtAddr + A

3

R_LARCH_RELATIVE

Runtime fixup for load-address

(void *) PC = B + A

4

R_LARCH_COPY

Runtime memory copy in executable

memcpy (PC, RtAddr, sizeof (sym))

5

R_LARCH_JUMP_SLOT

Runtime PLT supporting

implementation-defined

6

R_LARCH_TLS_DTPMOD32

Runtime relocation for TLS-GD

*(int32_t *) PC = ID of module defining sym

7

R_LARCH_TLS_DTPMOD64

Runtime relocation for TLS-GD

*(int64_t *) PC = ID of module defining sym

8

R_LARCH_TLS_DTPREL32

Runtime relocation for TLS-GD

*(int32_t *) PC = DTV-relative offset for sym

9

R_LARCH_TLS_DTPREL64

Runtime relocation for TLS-GD

*(int64_t *) PC = DTV-relative offset for sym

10

R_LARCH_TLS_TPREL32

Runtime relocation for TLE-IE

*(int32_t *) PC = T

11

R_LARCH_TLS_TPREL64

Runtime relocation for TLE-IE

*(int64_t *) PC = T

12

R_LARCH_IRELATIVE

Runtime local indirect function resolving

(void *) PC = (void )()( (B + A)) ()

…​ Reserved for dynamic linker.

20

R_LARCH_MARK_LA

Mark la.abs

Load absolute address for static link.

21

R_LARCH_MARK_PCREL

Mark external label branch

Access PC relative address for static link.

22

R_LARCH_SOP_PUSH_PCREL

Push PC-relative offset

push (S - PC + A)

23

R_LARCH_SOP_PUSH_ABSOLUTE

Push constant or absolute address

push (S + A)

24

R_LARCH_SOP_PUSH_DUP

Duplicate stack top

opr1 = pop (), push (opr1), push (opr1)

25

R_LARCH_SOP_PUSH_GPREL

Push for access GOT entry

push (G)

26

R_LARCH_SOP_PUSH_TLS_TPREL

Push for TLS-LE

push (T)

27

R_LARCH_SOP_PUSH_TLS_GOT

Push for TLS-IE

push (IE)

28

R_LARCH_SOP_PUSH_TLS_GD

Push for TLS-GD

push (GD)

29

R_LARCH_SOP_PUSH_PLT_PCREL

Push for external function calling

push (PLT - PC)

30

R_LARCH_SOP_ASSERT

Assert stack top

assert (pop ())

31

R_LARCH_SOP_NOT

Stack top operation

push (!pop ())

32

R_LARCH_SOP_SUB

Stack top operation

opr2 = pop (), opr1 = pop (), push (opr1 - opr2)

33

R_LARCH_SOP_SL

Stack top operation

opr2 = pop (), opr1 = pop (), push (opr1 << opr2)

34

R_LARCH_SOP_SR

Stack top operation

opr2 = pop (), opr1 = pop (), push (opr1 >> opr2)

35

R_LARCH_SOP_ADD

Stack top operation

opr2 = pop (), opr1 = pop (), push (opr1 + opr2)

36

R_LARCH_SOP_AND

Stack top operation

opr2 = pop (), opr1 = pop (), push (opr1 & opr2)

37

R_LARCH_SOP_IF_ELSE

Stack top operation

opr3 = pop (), opr2 = pop (), opr1 = pop (), push (opr1 ? opr2 : opr3)

38

R_LARCH_SOP_POP_32_S_10_5

Instruction imm-field relocation

opr1 = pop (), (*(uint32_t *) PC) [14 …​ 10] = opr1 [4 …​ 0] with check 5-bit signed overflow

39

R_LARCH_SOP_POP_32_U_10_12

Instruction imm-field relocation

opr1 = pop (), (*(uint32_t *) PC) [21 …​ 10] = opr1 [11 …​ 0] with check 12-bit unsigned overflow

40

R_LARCH_SOP_POP_32_S_10_12

Instruction imm-field relocation

opr1 = pop (), (*(uint32_t *) PC) [21 …​ 10] = opr1 [11 …​ 0] with check 12-bit signed overflow

41

R_LARCH_SOP_POP_32_S_10_16

Instruction imm-field relocation

opr1 = pop (), (*(uint32_t *) PC) [25 …​ 10] = opr1 [15 …​ 0] with check 16-bit signed overflow

42

R_LARCH_SOP_POP_32_S_10_16_S2

Instruction imm-field relocation

opr1 = pop (), (*(uint32_t *) PC) [25 …​ 10] = opr1 [17 …​ 2] with check 18-bit signed overflow and 4-bit aligned

43

R_LARCH_SOP_POP_32_S_5_20

Instruction imm-field relocation

opr1 = pop (), (*(uint32_t *) PC) [24 …​ 5] = opr1 [19 …​ 0] with check 20-bit signed overflow

44

R_LARCH_SOP_POP_32_S_0_5_10_16_S2

Instruction imm-field relocation

opr1 = pop (), ((uint32_t *) PC) [4 …​ 0] = opr1 [22 …​ 18], ((uint32_t *) PC) [25 …​ 10] = opr1 [17 …​ 2] with check 23-bit signed overflow and 4-bit aligned

45

R_LARCH_SOP_POP_32_S_0_10_10_16_S2

Instruction imm-field relocation

opr1 = pop (), ((uint32_t *) PC) [9 …​ 0] = opr1 [27 …​ 18], ((uint32_t *) PC) [25 …​ 10] = opr1 [17 …​ 2] with check 28-bit signed overflow and 4-bit aligned

46

R_LARCH_SOP_POP_32_U

Instruction fixup

(*(uint32_t *) PC) = pop () with check 32-bit unsigned overflow

47

R_LARCH_ADD8

8-bit in-place addition

*(int8_t *) PC += S + A

48

R_LARCH_ADD16

16-bit in-place addition

*(int16_t *) PC += S + A

49

R_LARCH_ADD24

24-bit in-place addition

*(int24_t *) PC += S + A

50

R_LARCH_ADD32

32-bit in-place addition

*(int32_t *) PC += S + A

51

R_LARCH_ADD64

64-bit in-place addition

*(int64_t *) PC += S + A

52

R_LARCH_SUB8

8-bit in-place subtraction

*(int8_t *) PC -= S + A

53

R_LARCH_SUB16

16-bit in-place subtraction

*(int16_t *) PC -= S + A

54

R_LARCH_SUB24

24-bit in-place subtraction

*(int24_t *) PC -= S + A

55

R_LARCH_SUB32

32-bit in-place subtraction

*(int32_t *) PC -= S + A

56

R_LARCH_SUB64

64-bit in-place subtraction

*(int64_t *) PC -= S + A

57

R_LARCH_GNU_VTINHERIT

GNU C++ vtable hierarchy

58

R_LARCH_GNU_VTENTRY

GNU C++ vtable member usage