Re: [PATCH 7/7] s390x: Use <gcc-macros.h> in early HWCAP check

[Florian Weimer <fweimer@redhat.com>]

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* Stefan Liebler:

> I'm not quite sure if all your patches are already committed. I've just
> give it a try with commit f8b765bec44e6c464a7eabf80e58c6851ca15ac3:
>
> - configure glibc with --with-rtld-early-cflags=-march=zEC12 and
> CFLAGS=-march=z15 on a z15.
>
> - Rebooted with novx-kernel-parameter => vector-related HWCAPs are
> disabled and executing vector-instructions leads to a crash
>
> - run a helloworld-program: crash due to vector-instruction in
> _dl_setup_hash, which is called in _dl_start_final before
> _dl_sysdep_start is called which runs dl_hwcap_check.
>
> I've checked the build-log and see that the following files are compiled
> with -march=zEC12:
> - dl-printf.c
> - ../sysdeps/unix/sysv/linux/dl-write.c
> - dl-tunables.c
> - ../sysdeps/unix/sysv/linux/dl-sysdep.c
> - rtld.c

Sorry, I missed that requirement.

Would you mind testing the attached patch?

Thanks,
Florian

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From dae7882e11191cab17afb22dba4ebba69f433d93 Mon Sep 17 00:00:00 2001
Message-Id: <dae7882e11191cab17afb22dba4ebba69f433d93.1642510437.git.fweimer@redhat.com>
From: Florian Weimer <fweimer@redhat.com>
Date: Tue, 18 Jan 2022 13:53:11 +0100
Subject: [PATCH] elf: Move _dl_setup_hash to its own file
To: libc-alpha@sourceware.org

And compile it with the early CFLAGS.  _dl_setup_hash is called
very early for the ld.so link map, so it should be compiled
differently.
---
 elf/Makefile        |  2 ++
 elf/dl-lookup.c     | 45 --------------------------------
 elf/dl-setup_hash.c | 63 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 65 insertions(+), 45 deletions(-)
 create mode 100644 elf/dl-setup_hash.c

diff --git a/elf/Makefile b/elf/Makefile
index c6c4710e16..692a65b061 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -74,6 +74,7 @@ dl-routines = \
   dl-reloc \
   dl-runtime \
   dl-scope \
+  dl-setup_hash \
   dl-sort-maps \
   dl-thread_gscope_wait \
   dl-tls \
@@ -169,6 +170,7 @@ CFLAGS-.os += $(call elide-stack-protector,.os,$(all-rtld-routines))
 
 # Add the requested compiler flags to the early startup code.
 CFLAGS-dl-printf.os += $(rtld-early-cflags)
+CFLAGS-dl-setup_hash.os += $(rtld-early-cflags)
 CFLAGS-dl-sysdep.os += $(rtld-early-cflags)
 CFLAGS-dl-tunables.os += $(rtld-early-cflags)
 CFLAGS-dl-write.os += $(rtld-early-cflags)
diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index f43ae150b7..cbf46fda62 100644
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -953,51 +953,6 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
 }
 
 
-/* Cache the location of MAP's hash table.  */
-
-void
-_dl_setup_hash (struct link_map *map)
-{
-  Elf_Symndx *hash;
-
-  if (__glibc_likely (map->l_info[ELF_MACHINE_GNU_HASH_ADDRIDX] != NULL))
-    {
-      Elf32_Word *hash32
-	= (void *) D_PTR (map, l_info[ELF_MACHINE_GNU_HASH_ADDRIDX]);
-      map->l_nbuckets = *hash32++;
-      Elf32_Word symbias = *hash32++;
-      Elf32_Word bitmask_nwords = *hash32++;
-      /* Must be a power of two.  */
-      assert ((bitmask_nwords & (bitmask_nwords - 1)) == 0);
-      map->l_gnu_bitmask_idxbits = bitmask_nwords - 1;
-      map->l_gnu_shift = *hash32++;
-
-      map->l_gnu_bitmask = (ElfW(Addr) *) hash32;
-      hash32 += __ELF_NATIVE_CLASS / 32 * bitmask_nwords;
-
-      map->l_gnu_buckets = hash32;
-      hash32 += map->l_nbuckets;
-      map->l_gnu_chain_zero = hash32 - symbias;
-
-      /* Initialize MIPS xhash translation table.  */
-      ELF_MACHINE_XHASH_SETUP (hash32, symbias, map);
-
-      return;
-    }
-
-  if (!map->l_info[DT_HASH])
-    return;
-  hash = (void *) D_PTR (map, l_info[DT_HASH]);
-
-  map->l_nbuckets = *hash++;
-  /* Skip nchain.  */
-  hash++;
-  map->l_buckets = hash;
-  hash += map->l_nbuckets;
-  map->l_chain = hash;
-}
-
-
 static void
 _dl_debug_bindings (const char *undef_name, struct link_map *undef_map,
 		    const ElfW(Sym) **ref, struct sym_val *value,
diff --git a/elf/dl-setup_hash.c b/elf/dl-setup_hash.c
new file mode 100644
index 0000000000..6dd57c5c94
--- /dev/null
+++ b/elf/dl-setup_hash.c
@@ -0,0 +1,63 @@
+/* Cache the location of a link map hash table.
+   Copyright (C) 1995-2022 Free Software Foundation, Inc.
+   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 <assert.h>
+#include <link.h>
+#include <ldsodefs.h>
+
+void
+_dl_setup_hash (struct link_map *map)
+{
+  Elf_Symndx *hash;
+
+  if (__glibc_likely (map->l_info[ELF_MACHINE_GNU_HASH_ADDRIDX] != NULL))
+    {
+      Elf32_Word *hash32
+        = (void *) D_PTR (map, l_info[ELF_MACHINE_GNU_HASH_ADDRIDX]);
+      map->l_nbuckets = *hash32++;
+      Elf32_Word symbias = *hash32++;
+      Elf32_Word bitmask_nwords = *hash32++;
+      /* Must be a power of two.  */
+      assert ((bitmask_nwords & (bitmask_nwords - 1)) == 0);
+      map->l_gnu_bitmask_idxbits = bitmask_nwords - 1;
+      map->l_gnu_shift = *hash32++;
+
+      map->l_gnu_bitmask = (ElfW(Addr) *) hash32;
+      hash32 += __ELF_NATIVE_CLASS / 32 * bitmask_nwords;
+
+      map->l_gnu_buckets = hash32;
+      hash32 += map->l_nbuckets;
+      map->l_gnu_chain_zero = hash32 - symbias;
+
+      /* Initialize MIPS xhash translation table.  */
+      ELF_MACHINE_XHASH_SETUP (hash32, symbias, map);
+
+      return;
+    }
+
+  if (!map->l_info[DT_HASH])
+    return;
+  hash = (void *) D_PTR (map, l_info[DT_HASH]);
+
+  map->l_nbuckets = *hash++;
+  /* Skip nchain.  */
+  hash++;
+  map->l_buckets = hash;
+  hash += map->l_nbuckets;
+  map->l_chain = hash;
+}
-- 
2.34.1