[glibc] Allow glibc to be compiled without EXEC_PAGESIZE

[Samuel Thibault <sthibaul@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=49aa652db810ebdca3a662ebd5b0468bd08ec688

commit 49aa652db810ebdca3a662ebd5b0468bd08ec688
Author: Sergey Bugaev <bugaevc@gmail.com>
Date:   Sat Mar 23 20:32:44 2024 +0300

    Allow glibc to be compiled without EXEC_PAGESIZE
    
    We would like to avoid statically defining any specific page size on
    aarch64-gnu, and instead make sure that everything uses the dynamic
    page size, available via vm_page_size and GLRO(dl_pagesize).
    
    There are currently a few places in glibc that require EXEC_PAGESIZE
    to be defined. Per Roland's suggestion [0], drop the static
    GLRO(dl_pagesize) initializers (for now, only if EXEC_PAGESIZE is not
    defined), and don't require EXEC_PAGESIZE definition for libio to
    enable mmap usage.
    
    [0]: https://mail.gnu.org/archive/html/bug-hurd/2011-10/msg00035.html
    
    Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
    Message-ID: <20240323173301.151066-4-bugaevc@gmail.com>

Diff:
---
 elf/dl-support.c | 6 +++++-
 elf/rtld.c       | 2 ++
 libio/libioP.h   | 2 +-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/elf/dl-support.c b/elf/dl-support.c
index 451932dd03..cb0bbd213f 100644
--- a/elf/dl-support.c
+++ b/elf/dl-support.c
@@ -135,7 +135,11 @@ void *_dl_random;
 #include <dl-procruntime.c>
 #include <dl-procinfo.c>
 
-size_t _dl_pagesize = EXEC_PAGESIZE;
+size_t _dl_pagesize
+#ifdef EXEC_PAGESIZE
+  = EXEC_PAGESIZE
+#endif
+;
 
 size_t _dl_minsigstacksize = CONSTANT_MINSIGSTKSZ;
 
diff --git a/elf/rtld.c b/elf/rtld.c
index ac4bb23652..18d73f19c6 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -358,7 +358,9 @@ struct rtld_global_ro _rtld_global_ro attribute_relro =
     ._dl_debug_fd = STDERR_FILENO,
     ._dl_lazy = 1,
     ._dl_fpu_control = _FPU_DEFAULT,
+#ifdef EXEC_PAGESIZE
     ._dl_pagesize = EXEC_PAGESIZE,
+#endif
     ._dl_inhibit_cache = 0,
     ._dl_profile_output = "/var/tmp",
 
diff --git a/libio/libioP.h b/libio/libioP.h
index 1af287b19f..1a7f547e0c 100644
--- a/libio/libioP.h
+++ b/libio/libioP.h
@@ -852,7 +852,7 @@ extern off64_t _IO_seekpos_unlocked (FILE *, off64_t, int)
 #  define MAP_ANONYMOUS MAP_ANON
 # endif
 
-# if !defined(MAP_ANONYMOUS) || !defined(EXEC_PAGESIZE)
+# if !defined(MAP_ANONYMOUS)
 #  undef _G_HAVE_MMAP
 #  define _G_HAVE_MMAP 0
 # endif