[glibc/release/2.35/master] Revert "elf: Remove unused l_text_end field from struct link_map"

[Florian Weimer <fw@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=6aa8380cf5c17d533285cbd575c3eb33c020800a

commit 6aa8380cf5c17d533285cbd575c3eb33c020800a
Author: Florian Weimer <fweimer@redhat.com>
Date:   Wed Oct 18 14:32:12 2023 +0200

    Revert "elf: Remove unused l_text_end field from struct link_map"
    
    This reverts commit 34b07bdbdd69121d6e7d3ccf51a61cc4fa2c408d.
    
    Reason for revert: Preserve ABI after revert of commit 02a67e102f0.

Diff:
---
 elf/dl-load.c    | 2 +-
 elf/dl-load.h    | 7 +++++--
 elf/rtld.c       | 6 ++++++
 elf/setup-vdso.h | 4 ++++
 include/link.h   | 2 ++
 5 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/elf/dl-load.c b/elf/dl-load.c
index 35c0b579b8..5b0ff41ee1 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -1253,7 +1253,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
 
     /* Now process the load commands and map segments into memory.
        This is responsible for filling in:
-       l_map_start, l_map_end, l_addr, l_contiguous, l_phdr
+       l_map_start, l_map_end, l_addr, l_contiguous, l_text_end, l_phdr
      */
     errstring = _dl_map_segments (l, fd, header, type, loadcmds, nloadcmds,
 				  maplength, has_holes, loader);
diff --git a/elf/dl-load.h b/elf/dl-load.h
index ebf7d74cd0..f98d264e90 100644
--- a/elf/dl-load.h
+++ b/elf/dl-load.h
@@ -83,11 +83,14 @@ struct loadcmd
 
 /* This is a subroutine of _dl_map_segments.  It should be called for each
    load command, some time after L->l_addr has been set correctly.  It is
-   responsible for setting the l_phdr fields  */
+   responsible for setting up the l_text_end and l_phdr fields.  */
 static __always_inline void
 _dl_postprocess_loadcmd (struct link_map *l, const ElfW(Ehdr) *header,
                          const struct loadcmd *c)
 {
+  if (c->prot & PROT_EXEC)
+    l->l_text_end = l->l_addr + c->mapend;
+
   if (l->l_phdr == 0
       && c->mapoff <= header->e_phoff
       && ((size_t) (c->mapend - c->mapstart + c->mapoff)
@@ -100,7 +103,7 @@ _dl_postprocess_loadcmd (struct link_map *l, const ElfW(Ehdr) *header,
 
 /* This is a subroutine of _dl_map_object_from_fd.  It is responsible
    for filling in several fields in *L: l_map_start, l_map_end, l_addr,
-   l_contiguous, l_phdr.  On successful return, all the
+   l_contiguous, l_text_end, l_phdr.  On successful return, all the
    segments are mapped (or copied, or whatever) from the file into their
    final places in the address space, with the correct page permissions,
    and any bss-like regions already zeroed.  It returns a null pointer
diff --git a/elf/rtld.c b/elf/rtld.c
index 26ccb7bf84..86354fb0c2 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -489,6 +489,7 @@ _dl_start_final (void *arg, struct dl_start_final_info *info)
   GL(dl_rtld_map).l_real = &GL(dl_rtld_map);
   GL(dl_rtld_map).l_map_start = (ElfW(Addr)) &__ehdr_start;
   GL(dl_rtld_map).l_map_end = (ElfW(Addr)) _end;
+  GL(dl_rtld_map).l_text_end = (ElfW(Addr)) _etext;
   /* Copy the TLS related data if necessary.  */
 #ifndef DONT_USE_BOOTSTRAP_MAP
 # if NO_TLS_OFFSET != 0
@@ -1142,6 +1143,7 @@ rtld_setup_main_map (struct link_map *main_map)
   bool has_interp = false;
 
   main_map->l_map_end = 0;
+  main_map->l_text_end = 0;
   /* Perhaps the executable has no PT_LOAD header entries at all.  */
   main_map->l_map_start = ~0;
   /* And it was opened directly.  */
@@ -1233,6 +1235,8 @@ rtld_setup_main_map (struct link_map *main_map)
 	  allocend = main_map->l_addr + ph->p_vaddr + ph->p_memsz;
 	  if (main_map->l_map_end < allocend)
 	    main_map->l_map_end = allocend;
+	  if ((ph->p_flags & PF_X) && allocend > main_map->l_text_end)
+	    main_map->l_text_end = allocend;
 
 	  /* The next expected address is the page following this load
 	     segment.  */
@@ -1292,6 +1296,8 @@ rtld_setup_main_map (struct link_map *main_map)
       = (char *) main_map->l_tls_initimage + main_map->l_addr;
   if (! main_map->l_map_end)
     main_map->l_map_end = ~0;
+  if (! main_map->l_text_end)
+    main_map->l_text_end = ~0;
   if (! GL(dl_rtld_map).l_libname && GL(dl_rtld_map).l_name)
     {
       /* We were invoked directly, so the program might not have a
diff --git a/elf/setup-vdso.h b/elf/setup-vdso.h
index 6838615b30..db639b0d4f 100644
--- a/elf/setup-vdso.h
+++ b/elf/setup-vdso.h
@@ -51,6 +51,9 @@ setup_vdso (struct link_map *main_map __attribute__ ((unused)),
 		l->l_addr = ph->p_vaddr;
 	      if (ph->p_vaddr + ph->p_memsz >= l->l_map_end)
 		l->l_map_end = ph->p_vaddr + ph->p_memsz;
+	      if ((ph->p_flags & PF_X)
+		  && ph->p_vaddr + ph->p_memsz >= l->l_text_end)
+		l->l_text_end = ph->p_vaddr + ph->p_memsz;
 	    }
 	  else
 	    /* There must be no TLS segment.  */
@@ -59,6 +62,7 @@ setup_vdso (struct link_map *main_map __attribute__ ((unused)),
       l->l_map_start = (ElfW(Addr)) GLRO(dl_sysinfo_dso);
       l->l_addr = l->l_map_start - l->l_addr;
       l->l_map_end += l->l_addr;
+      l->l_text_end += l->l_addr;
       l->l_ld = (void *) ((ElfW(Addr)) l->l_ld + l->l_addr);
       elf_get_dynamic_info (l, false, false);
       _dl_setup_hash (l);
diff --git a/include/link.h b/include/link.h
index c7b38a05d0..041a518100 100644
--- a/include/link.h
+++ b/include/link.h
@@ -255,6 +255,8 @@ struct link_map
     /* Start and finish of memory map for this object.  l_map_start
        need not be the same as l_addr.  */
     ElfW(Addr) l_map_start, l_map_end;
+    /* End of the executable part of the mapping.  */
+    ElfW(Addr) l_text_end;
 
     /* Linked list of objects in reverse ELF constructor execution
        order.  Head of list is stored in _dl_init_called_list.  */