svn commit: r364258 - stable/12/sys/amd64/linux

[Edward Tomasz Napierala]

Author: trasz
Date: Sat Aug 15 17:02:23 2020
New Revision: 364258
URL: https://svnweb.freebsd.org/changeset/base/364258

Log:
  MFC r351783:
  
  Unbreak Linux binaries linked against new glibc, such as the ones
  from recent Ubuntu versions.  Without it they segfault on startup.
  
  Sponsored by:	The FreeBSD Foundation

Modified:
  stable/12/sys/amd64/linux/linux_sysvec.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/amd64/linux/linux_sysvec.c
==============================================================================
--- stable/12/sys/amd64/linux/linux_sysvec.c	Sat Aug 15 16:48:58 2020	(r364257)
+++ stable/12/sys/amd64/linux/linux_sysvec.c	Sat Aug 15 17:02:23 2020	(r364258)
@@ -357,6 +357,12 @@ 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;