[glibc] elf: Introduce _dl_map_segment_align hook for segment alignment tuning

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=88c3f481de92808499464fa7e2ac1e9fce9d649c

commit 88c3f481de92808499464fa7e2ac1e9fce9d649c
Author: WANG Rui <[email protected]>
Date:   Tue Apr 14 15:16:07 2026 +0000

    elf: Introduce _dl_map_segment_align hook for segment alignment tuning
    
    Introduce a new helper function, _dl_map_segment_align, to allow
    architecture-specific adjustment of ELF load segment alignment during
    object mapping.
    
    The generic ELF loader now calls this hook when determining the maximum
    segment alignment.  The generic implementation is a no-op and preserves
    existing behavior.
    
    This provides a well-defined extension point for architectures that
    need to adjust segment alignment policies (for example, to improve
    mapping efficiency or enable platform-specific optimizations) without
    embedding such logic directly in the generic loader.
    
    Reviewed-by: Wilco Dijkstra  <[email protected]>
    Signed-off-by: WANG Rui <[email protected]>

Diff:
---
 elf/dl-load.c                          |  4 ++++
 sysdeps/generic/dl-map-segment-align.h | 26 ++++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/elf/dl-load.c b/elf/dl-load.c
index a5693a3a66..48575fff06 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -71,6 +71,7 @@ struct filebuf
 #include <dl-dst.h>
 #include <dl-load.h>
 #include <dl-map-segments.h>
+#include <dl-map-segment-align.h>
 #include <dl-unmap-segments.h>
 #include <dl-machine-reject-phdr.h>
 #include <dl-prop.h>
@@ -1171,6 +1172,9 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
 
 	  /* Optimize a common case.  */
 	  c->prot = pf_to_prot (ph->p_flags);
+
+	  /* Architecture-specific adjustment of segment alignment. */
+	  p_align_max = _dl_map_segment_align (c, p_align_max);
 	  break;
 
 	case PT_TLS:
diff --git a/sysdeps/generic/dl-map-segment-align.h b/sysdeps/generic/dl-map-segment-align.h
new file mode 100644
index 0000000000..f4a671f25f
--- /dev/null
+++ b/sysdeps/generic/dl-map-segment-align.h
@@ -0,0 +1,26 @@
+/* _dl_map_segment_align.  Generic version.
+   Copyright (C) 2026 Free Software Foundation, Inc.
+   Copyright The GNU Toolchain Authors.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <dl-load.h>
+
+static inline ElfW(Addr)
+_dl_map_segment_align (const struct loadcmd *c, ElfW(Addr) p_align_max)
+{
+  return p_align_max;
+}