[PATCH] riscv: Change the relocations handled for RTLD_BOOTSTRAP

[Fangrui Song]

On 2022-06-05, Fangrui Song wrote:
>The RTLD_BOOTSTRAP branch is used to relocate ld.so itself.  It only
>needs to handle RELATIVE, GLOB_DAT, and the symbolic relocation type
>(R_RISCV_{32,64}).  NONE and IRELATIVE can be removed.
>
>The code relies on ld.so having DT_RELACOUNT so that the RTLD_BOOTSTRAP
>branch does not need handle RELATIVE.  Drop this minor size
>optimization for clarity.
>---
> sysdeps/riscv/dl-machine.h | 23 ++++++++++-------------
> 1 file changed, 10 insertions(+), 13 deletions(-)
>
>diff --git a/sysdeps/riscv/dl-machine.h b/sysdeps/riscv/dl-machine.h
>index 9e026ae011..a60a452952 100644
>--- a/sysdeps/riscv/dl-machine.h
>+++ b/sysdeps/riscv/dl-machine.h
>@@ -181,7 +181,15 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
>
>   switch (r_type)
>     {
>-#ifndef RTLD_BOOTSTRAP
>+    case R_RISCV_RELATIVE:
>+      *addr_field = map->l_addr + reloc->r_addend;
>+      break;
>+    case R_RISCV_JUMP_SLOT:
>+    case __WORDSIZE == 64 ? R_RISCV_64 : R_RISCV_32:
>+      *addr_field = value;
>+      break;
>+
>+# ifndef RTLD_BOOTSTRAP
>     case __WORDSIZE == 64 ? R_RISCV_TLS_DTPMOD64 : R_RISCV_TLS_DTPMOD32:
>       if (sym_map)
> 	*addr_field = sym_map->l_tls_modid;
>@@ -232,13 +240,6 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
> 	memcpy (reloc_addr, (void *)value, size);
> 	break;
>       }
>-#endif
>-
>-#if !defined RTLD_BOOTSTRAP
>-    case R_RISCV_RELATIVE:
>-      *addr_field = map->l_addr + reloc->r_addend;
>-      break;
>-#endif
>
>     case R_RISCV_IRELATIVE:
>       value = map->l_addr + reloc->r_addend;
>@@ -247,13 +248,9 @@ elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
>       *addr_field = value;
>       break;
>
>-    case R_RISCV_JUMP_SLOT:
>-    case __WORDSIZE == 64 ? R_RISCV_64 : R_RISCV_32:
>-      *addr_field = value;
>-      break;
>-
>     case R_RISCV_NONE:
>       break;
>+# endif /* !RTLD_BOOTSTRAP */
>
>     default:
>       _dl_reloc_bad_type (map, r_type, 0);
>-- 
>2.36.1.255.ge46751e96f-goog