[glibc/release/2.43/master] elf: Use dl-symbol-redir-ifunc.h instead _dl_strlen

[Aurelien Jarno]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=02ffd413cf83c07c5c419b5cba72990e1ed140ca

commit 02ffd413cf83c07c5c419b5cba72990e1ed140ca
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Thu Feb 12 09:48:53 2026 -0300

    elf: Use dl-symbol-redir-ifunc.h instead _dl_strlen
    
    Also replace the loop with strlen And remove
    -fno-tree-loop-distribute-patterns usage.
    
    It requires redirect the strlen to the baseline implementation
    for x86_64, aarch64, and loongarch64.
    
    Checked on x86_64-linux-gnu{-v2,v3} and aarch64-linux-gnu with
    both gcc-15 and clang-21.
    
    Reviewed-by: DJ Delorie <dj@redhat.com>
    (cherry picked from commit 15cc350e507101ac7b01e1343ac55087a6cd9317)

Diff:
---
 elf/Makefile                                             |  6 ------
 elf/dl-tunables.c                                        | 14 +-------------
 string/Makefile                                          |  1 +
 sysdeps/aarch64/multiarch/dl-symbol-redir-ifunc.h        |  1 +
 sysdeps/aarch64/multiarch/strlen_generic.S               |  4 ++++
 sysdeps/loongarch/lp64/multiarch/dl-symbol-redir-ifunc.h |  1 +
 sysdeps/unix/sysv/linux/riscv/multiarch/Makefile         |  2 ++
 sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h         | 10 ++++++++++
 8 files changed, 20 insertions(+), 19 deletions(-)

diff --git a/elf/Makefile b/elf/Makefile
index 01cc51636e..11029be0ae 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -97,12 +97,6 @@ ifeq (yesyes,$(build-shared)$(run-built-tests))
 tests-special += $(objpfx)list-tunables.out
 endif
 
-# Make sure that the compiler does not insert any library calls in tunables
-# code paths.
-ifeq (yes,$(have-loop-to-function))
-CFLAGS-dl-tunables.c += -fno-tree-loop-distribute-patterns
-endif
-
 all-dl-routines = $(dl-routines) $(sysdep-dl-routines)
 # But they are absent from the shared libc, because that code is in ld.so.
 elide-routines.os = \
diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
index 37ade374c6..bdb1de4ceb 100644
--- a/elf/dl-tunables.c
+++ b/elf/dl-tunables.c
@@ -37,16 +37,6 @@
 #define TUNABLES_INTERNAL 1
 #include "dl-tunables.h"
 
-/* The function might be called before the process is self-relocated.  */
-static size_t
-__attribute_optimization_barrier__
-_dl_strlen (const char *s)
-{
-  const char *p = s;
-  for (; *s != '\0'; s++);
-  return s - p;
-}
-
 static char **
 get_next_env (char **envp, char **name, char **val, char ***prev_envp)
 {
@@ -335,10 +325,8 @@ __tunables_init (char **envp)
 	  if (tunable_is_name (name, envname))
 	    {
 	      /* The environment variable is always null-terminated.  */
-	      size_t envvallen = _dl_strlen (envval);
-
 	      tunables_env_alias[i] =
-		(struct tunable_toset_t) { cur, envval, envvallen };
+		(struct tunable_toset_t) { cur, envval, strlen (envval) };
 	      break;
 	    }
 	}
diff --git a/string/Makefile b/string/Makefile
index c4423c0437..aa0b0c2f57 100644
--- a/string/Makefile
+++ b/string/Makefile
@@ -286,6 +286,7 @@ CFLAGS-wordcopy.c += $(no-stack-protector)
 # Called during static initialization
 CFLAGS-strncmp.c += $(no-stack-protector)
 CFLAGS-memset.c += $(no-stack-protector)
+CFLAGS-strlen.c += $(no-stack-protector)
 
 ifeq ($(run-built-tests),yes)
 $(objpfx)tst-svc-cmp.out: tst-svc.expect $(objpfx)tst-svc.out
diff --git a/sysdeps/aarch64/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/aarch64/multiarch/dl-symbol-redir-ifunc.h
index 647bdd66dd..9f772614bf 100644
--- a/sysdeps/aarch64/multiarch/dl-symbol-redir-ifunc.h
+++ b/sysdeps/aarch64/multiarch/dl-symbol-redir-ifunc.h
@@ -20,5 +20,6 @@
 #define _DL_IFUNC_GENERIC_H
 
 asm ("memset = __memset_generic");
+asm ("strlen = __strlen_generic");
 
 #endif
diff --git a/sysdeps/aarch64/multiarch/strlen_generic.S b/sysdeps/aarch64/multiarch/strlen_generic.S
index cb9d5759ac..a362328142 100644
--- a/sysdeps/aarch64/multiarch/strlen_generic.S
+++ b/sysdeps/aarch64/multiarch/strlen_generic.S
@@ -40,3 +40,7 @@
 #endif
 
 #include "../strlen.S"
+
+#if IS_IN (rtld)
+strong_alias (strlen, __strlen_generic)
+#endif
diff --git a/sysdeps/loongarch/lp64/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/loongarch/lp64/multiarch/dl-symbol-redir-ifunc.h
index 9fdd039da0..8af00d2846 100644
--- a/sysdeps/loongarch/lp64/multiarch/dl-symbol-redir-ifunc.h
+++ b/sysdeps/loongarch/lp64/multiarch/dl-symbol-redir-ifunc.h
@@ -22,6 +22,7 @@
 #ifndef SHARED
 asm ("memset = __memset_aligned");
 asm ("memcmp = __memcmp_aligned");
+asm ("strlen = __strlen_aligned");
 #endif
 
 #endif
diff --git a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
index 1d26966ded..a865090a53 100644
--- a/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
+++ b/sysdeps/unix/sysv/linux/riscv/multiarch/Makefile
@@ -9,4 +9,6 @@ sysdep_routines += \
   # sysdep_routines
 
 CFLAGS-memcpy_noalignment.c += -mno-strict-align
+# Called during static initialization
+CFLAGS-memset-generic.c += $(no-stack-protector)
 endif
diff --git a/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h
index 04b6c1e6a3..b607e525f2 100644
--- a/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h
+++ b/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h
@@ -44,6 +44,16 @@ asm ("memset = " HAVE_MEMSET_IFUNC_GENERIC);
 
 asm ("memcmp = " HAVE_MEMCMP_IFUNC_GENERIC);
 
+#if MINIMUM_X86_ISA_LEVEL >= 4
+# define HAVE_STRCMP_IFUNC_GENERIC "__strlen_evex"
+#elif MINIMUM_X86_ISA_LEVEL == 3
+# define HAVE_STRCMP_IFUNC_GENERIC "__strlen_avx2"
+#else
+# define HAVE_STRCMP_IFUNC_GENERIC "__strlen_sse2"
+#endif
+
+asm ("strlen = " HAVE_STRCMP_IFUNC_GENERIC);
+
 #endif /* SHARED */
 
 #endif