svn commit: r351783 - head/sys/amd64/linux

[Edward Tomasz Napierala]

Author: trasz
Date: Tue Sep  3 19:48:23 2019
New Revision: 351783
URL: https://svnweb.freebsd.org/changeset/base/351783

Log:
  Unbreak Linux binaries linked against new glibc, such as the ones
  from recent Ubuntu versions.  Without it they segfault on startup.
  
  Reviewed by:	emaste
  MFC after:	2 weeks
  Sponsored by:	The FreeBSD Foundation
  Differential Revision:	https://reviews.freebsd.org/D20687

Modified:
  head/sys/amd64/linux/linux_sysvec.c

Modified: head/sys/amd64/linux/linux_sysvec.c
==============================================================================
--- head/sys/amd64/linux/linux_sysvec.c	Tue Sep  3 19:48:02 2019	(r351782)
+++ head/sys/amd64/linux/linux_sysvec.c	Tue Sep  3 19:48:23 2019	(r351783)
@@ -343,6 +343,12 @@ linux_copyout_strings(struct image_params *imgp)
 	 */
 	vectp -= imgp->args->argc + 1 + imgp->args->envc + 1;
 
+	/*
+	 * Starting with 2.24, glibc depends on a 16-byte stack alignment.
+	 * One "long argc" will be prepended later.
+	 */
+	vectp = (char **)((((uintptr_t)vectp + 8) & ~0xF) - 8);
+
 	/* vectp also becomes our initial stack base. */
 	stack_base = (register_t *)vectp;