ELF relocation memo

.dynsym => ElfW(Sym) dynsym
.dynstr => char *strtab

.rel.plt => PLTREL *reloc = jmprel[i] 
ElfW(Sym) *sym = &symtab[ELFW(R_SYM)(reloc->r_info)]
void *reladdr = reloc->r_offset;	/* .got */
char *symname = &strtab[sym->stname]


.rel.dyn => data relocation

elf/dl-runtime.c
PLTREL -> ElfW(Rel), ElfW(RelA)

glibc/elf/elf.h

ELF32_R_SYM(val)	val>>8
ELF32_R_TYPE(val)	val&0xff

ElfW(Sym)
typedef struct
{
  Elf32_Word    st_name;                /* Symbol name (string tbl index) */
  Elf32_Addr    st_value;               /* Symbol value */
  Elf32_Word    st_size;                /* Symbol size */
  unsigned char st_info;                /* Symbol type and binding */
  unsigned char st_other;               /* Symbol visibility */
  Elf32_Section st_shndx;               /* Section index */
} Elf32_Sym; // 16 = 4 + 4 + 4 + 1 + 1 + 2

ElfW(Rel)
typedef struct
{
  Elf32_Addr    r_offset;               /* Address */
  Elf32_Word    r_info;                 /* Relocation type and symbol index */
} Elf32_Rel;
   
typedef struct
{
  Elf32_Addr    r_offset;               /* Address */
  Elf32_Word    r_info;                 /* Relocation type and symbol index */
  Elf32_Sword   r_addend;               /* Addend */
} Elf32_Rela;