elf: Do not run IFUNC resolvers for LD_DEBUG=unused [BZ #24214]fw/bug24214

This commit adds missing skip_ifunc checks to aarch64, arm, i386,
sparc, and x86_64.  A new test case ensures that IRELATIVE IFUNC
resolvers do not run in various diagnostic modes of the dynamic
loader.

Tested on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
s390-linux-gnu, s390x-linux-gnu, powerpc64le-linux-gnu.  Built with
build-many-glibcs.py.

6 files changed, 20 insertions, 10 deletions

diff --git a/sysdeps/aarch64/dl-machine.h b/sysdeps/aarch64/dl-machine.h
index 10b91c33ae..bf6b9d0e7d 100644
--- a/sysdeps/aarch64/dl-machine.h
+++ b/sysdeps/aarch64/dl-machine.h
@@ -358,7 +358,8 @@ elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc,
 
 	case AARCH64_R(IRELATIVE):
 	  value = map->l_addr + reloc->r_addend;
-	  value = elf_ifunc_invoke (value);
+	  if (__glibc_likely (!skip_ifunc))
+	    value = elf_ifunc_invoke (value);
 	  *reloc_addr = value;
 	  break;
 
diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h
index eeb3adfff2..27dffc71bf 100644
--- a/sysdeps/arm/dl-machine.h
+++ b/sysdeps/arm/dl-machine.h
@@ -522,7 +522,8 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc,
 	  break;
 	case R_ARM_IRELATIVE:
 	  value = map->l_addr + *reloc_addr;
-	  value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap));
+	  if (__glibc_likely (!skip_ifunc))
+	    value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap));
 	  *reloc_addr = value;
 	  break;
 #endif
@@ -614,7 +615,8 @@ elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 	  break;
 	case R_ARM_IRELATIVE:
 	  value = map->l_addr + reloc->r_addend;
-	  value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap));
+	  if (__glibc_likely (!skip_ifunc))
+	    value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap));
 	  *reloc_addr = value;
 	  break;
 #endif
diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h
index 1e2a3b333d..e225aa3739 100644
--- a/sysdeps/i386/dl-machine.h
+++ b/sysdeps/i386/dl-machine.h
@@ -480,7 +480,8 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc,
 	  break;
 	case R_386_IRELATIVE:
 	  value = map->l_addr + *reloc_addr;
-	  value = ((Elf32_Addr (*) (void)) value) ();
+	  if (__glibc_likely (!skip_ifunc))
+	    value = ((Elf32_Addr (*) (void)) value) ();
 	  *reloc_addr = value;
 	  break;
 	default:
@@ -627,7 +628,8 @@ elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 #  endif /* !RESOLVE_CONFLICT_FIND_MAP */
 	case R_386_IRELATIVE:
 	  value = map->l_addr + reloc->r_addend;
-	  value = ((Elf32_Addr (*) (void)) value) ();
+	  if (__glibc_likely (!skip_ifunc))
+	    value = ((Elf32_Addr (*) (void)) value) ();
 	  *reloc_addr = value;
 	  break;
 	default:
diff --git a/sysdeps/sparc/sparc32/dl-machine.h b/sysdeps/sparc/sparc32/dl-machine.h
index 1d8da32c47..359a004271 100644
--- a/sysdeps/sparc/sparc32/dl-machine.h
+++ b/sysdeps/sparc/sparc32/dl-machine.h
@@ -425,11 +425,13 @@ elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
       *reloc_addr = value;
       break;
     case R_SPARC_IRELATIVE:
-      value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap));
+      if (__glibc_likely (!skip_ifunc))
+	value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap));
       *reloc_addr = value;
       break;
     case R_SPARC_JMP_IREL:
-      value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap));
+      if (__glibc_likely (!skip_ifunc))
+	value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap));
       /* Fall thru */
     case R_SPARC_JMP_SLOT:
       {
diff --git a/sysdeps/sparc/sparc64/dl-machine.h b/sysdeps/sparc/sparc64/dl-machine.h
index ce1261d2a0..0acaf92a53 100644
--- a/sysdeps/sparc/sparc64/dl-machine.h
+++ b/sysdeps/sparc/sparc64/dl-machine.h
@@ -450,11 +450,13 @@ elf_machine_rela (struct link_map *map, const Elf64_Rela *reloc,
       *reloc_addr = value;
       break;
     case R_SPARC_IRELATIVE:
-      value = ((Elf64_Addr (*) (int)) value) (GLRO(dl_hwcap));
+      if (__glibc_likely (!skip_ifunc))
+	value = ((Elf64_Addr (*) (int)) value) (GLRO(dl_hwcap));
       *reloc_addr = value;
       break;
     case R_SPARC_JMP_IREL:
-      value = ((Elf64_Addr (*) (int)) value) (GLRO(dl_hwcap));
+      if (__glibc_likely (!skip_ifunc))
+	value = ((Elf64_Addr (*) (int)) value) (GLRO(dl_hwcap));
       /* 'high' is always zero, for large PLT entries the linker
 	 emits an R_SPARC_IRELATIVE.  */
 #ifdef RESOLVE_CONFLICT_FIND_MAP
diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
index f17f5fb7cd..58260c7876 100644
--- a/sysdeps/x86_64/dl-machine.h
+++ b/sysdeps/x86_64/dl-machine.h
@@ -512,7 +512,8 @@ elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc,
 #  endif
 	case R_X86_64_IRELATIVE:
 	  value = map->l_addr + reloc->r_addend;
-	  value = ((ElfW(Addr) (*) (void)) value) ();
+	  if (__glibc_likely (!skip_ifunc))
+	    value = ((ElfW(Addr) (*) (void)) value) ();
 	  *reloc_addr = value;
 	  break;
 	default: