RISC-V relocs

typedef void (*fptr)(void);

void func1(void) {}
void func2(void) {}

const fptr table[] = {
    func1,
    func2,
};

int _start(int i)
{
    table[i]();
}

-------------------------------------------------------------------------------
$ riscv64-unknown-elf-gcc -nostdlib -nostartfiles -T linker.ld -fPIE -static-pie simple.c

$ riscv64-unknown-elf-readelf -a a.out -W
ELF Header:
  Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
  Class:                             ELF64
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              EXEC (Executable file)
  Machine:                           RISC-V
  Version:                           0x1
  Entry point address:               0x1038
  Start of program headers:          64 (bytes into file)
  Start of section headers:          4584 (bytes into file)
  Flags:                             0x2, single-float ABI
  Size of this header:               64 (bytes)
  Size of program headers:           56 (bytes)
  Number of program headers:         1
  Size of section headers:           64 (bytes)
  Number of section headers:         7
  Section header string table index: 6

Section Headers:
  [Nr] Name              Type            Address          Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            0000000000000000 000000 000000 00      0   0  0
  [ 1] .text             PROGBITS        0000000000001000 001000 000084 00  AX  0   0  4
  [ 2] .data.rel.ro.local PROGBITS        0000000000001088 001088 000010 00  WA  0   0  8
  [ 3] .comment          PROGBITS        0000000000000000 001098 000011 01  MS  0   0  1
  [ 4] .symtab           SYMTAB          0000000000000000 0010b0 0000d8 18      5   5  8
  [ 5] .strtab           STRTAB          0000000000000000 001188 000023 00      0   0  1
  [ 6] .shstrtab         STRTAB          0000000000000000 0011ab 00003d 00      0   0  1
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
  L (link order), O (extra OS processing required), G (group), T (TLS),
  C (compressed), x (unknown), o (OS specific), E (exclude),
  p (processor specific)

There are no section groups in this file.

Program Headers:
  Type           Offset   VirtAddr           PhysAddr           FileSiz  MemSiz   Flg Align
  LOAD           0x001000 0x0000000000001000 0x0000000000001000 0x000098 0x000098 RWE 0x1000

 Section to Segment mapping:
  Segment Sections...
   00     .text .data.rel.ro.local

There is no dynamic section in this file.

There are no relocations in this file.

The decoding of unwind sections for machine type RISC-V is not currently supported.

Symbol table '.symtab' contains 9 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 0000000000001000     0 SECTION LOCAL  DEFAULT    1
     2: 0000000000001088     0 SECTION LOCAL  DEFAULT    2
     3: 0000000000000000     0 SECTION LOCAL  DEFAULT    3
     4: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS simple.c
     5: 0000000000001088    16 OBJECT  GLOBAL DEFAULT    2 table
     6: 0000000000001000    28 FUNC    GLOBAL DEFAULT    1 func1
     7: 0000000000001038    76 FUNC    GLOBAL DEFAULT    1 _start
     8: 000000000000101c    28 FUNC    GLOBAL DEFAULT    1 func2

No version information found in this file.

$ riscv64-unknown-elf-readelf -r a.out -W
There are no relocations in this file.

$ riscv64-unknown-elf-objdump -r -D -S a.out

    1050:   00000717            auipc   a4,0x0
    1054:   03870713            addi    a4,a4,56 # 1088 <table>
    1058:   fec42783            lw  a5,-20(s0)
    105c:   00379793            slli    a5,a5,0x3
    1060:   00f707b3            add a5,a4,a5
    1064:   0007b783            ld  a5,0(a5)
    1068:   000780e7            jalr    a5
Disassembly of section .data.rel.ro.local:

0000000000001088 <table>:
    1088:   1000                    addi    s0,sp,32
    108a:   0000                    unimp
    108c:   0000                    unimp
    108e:   0000                    unimp
    1090:   101c                    addi    a5,sp,32
    1092:   0000                    unimp
    1094:   0000                    unimp
    ...

-------------------------------------------------------------------------------

$ riscv64-unknown-elf-gcc -g3 -nostdlib -nostartfiles -T linker.ld -fPIE -static-pie -c simple.c

$ riscv64-unknown-elf-readelf -r simple.o -W

Relocation section '.rela.text' at offset 0x6108 contains 4 entries:
    Offset             Info             Type               Symbol's Value  Symbol's Name + Addend
0000000000000050  0000018100000017 R_RISCV_PCREL_HI20     0000000000000000 table + 0
0000000000000050  0000000000000033 R_RISCV_RELAX                             0
0000000000000054  0000001e00000018 R_RISCV_PCREL_LO12_I   0000000000000050 .L0  + 0
0000000000000054  0000000000000033 R_RISCV_RELAX                             0

Relocation section '.rela.data.rel.ro.local' at offset 0x6168 contains 2 entries:
    Offset             Info             Type               Symbol's Value  Symbol's Name + Addend
0000000000000000  0000017f00000002 R_RISCV_64             0000000000000000 func1 + 0
0000000000000008  0000018000000002 R_RISCV_64             000000000000001c func2 + 0


$ riscv64-unknown-elf-objdump -r -D -S simple.o

0000000000000050 <.L0 >:
    table[i]();
  50:   00000717                auipc   a4,0x0
                        50: R_RISCV_PCREL_HI20  table
                        50: R_RISCV_RELAX       *ABS*
  54:   00070713                mv      a4,a4
                        54: R_RISCV_PCREL_LO12_I        .L0
                        54: R_RISCV_RELAX       *ABS*
  58:   fec42783                lw      a5,-20(s0)
  5c:   00379793                slli    a5,a5,0x3
  60:   00f707b3                add     a5,a4,a5
  64:   0007b783                ld      a5,0(a5)

0000000000000068 <.L0 >:
  68:   000780e7                jalr    a5


Disassembly of section .data.rel.ro.local:

0000000000000000 <table>:
        ...
                        0: R_RISCV_64   func1
                        8: R_RISCV_64   func2

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