Re: turn off VDSO on glibc side

[heroxbd <heroxbd at gentoo dot org>]

Hey Mike,

Mike Frysinger <vapier@gentoo.org> writes:

> there aren't any configure flags or runtime knobs that i know of on
> the glibc side of things.  you could edit elf/dl-support.c and try
> commenting out the parts that handle AT_SYSINFO and AT_SYSINFO_EHDR.

I've pursued this approach. So far a base system was built around the
patched glibc on that vdso-buggy kernel, verifying that it works. Here I
attach a simple (and ugly) patch I used to disable VDSO completely for
completeness.

Thanks a lot!

Benda

Index: work/glibc-2.17/elf/dl-support.c
===================================================================
--- work.orig/glibc-2.17/elf/dl-support.c
+++ work/glibc-2.17/elf/dl-support.c
@@ -212,16 +212,6 @@ _dl_aux_init (ElfW(auxv_t) *av)
       case AT_HWCAP:
 	GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
 	break;
-#ifdef NEED_DL_SYSINFO
-      case AT_SYSINFO:
-	GL(dl_sysinfo) = av->a_un.a_val;
-	break;
-#endif
-#if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
-      case AT_SYSINFO_EHDR:
-	GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
-	break;
-#endif
       case AT_UID:
 	uid ^= av->a_un.a_val;
 	seen |= 1;
Index: work/glibc-2.17/elf/setup-vdso.h
===================================================================
--- work.orig/glibc-2.17/elf/setup-vdso.h
+++ work/glibc-2.17/elf/setup-vdso.h
@@ -20,7 +20,7 @@ static inline void __attribute__ ((alway
 setup_vdso (struct link_map *main_map __attribute__ ((unused)),
 	    struct link_map ***first_preload __attribute__ ((unused)))
 {
-#if defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO
+#if 0
   if (GLRO(dl_sysinfo_dso) == NULL)
     return;

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