svn commit: r343748 - head/sys/i386/i386

[Dimitry Andric]

Author: dim
Date: Mon Feb  4 18:07:03 2019
New Revision: 343748
URL: https://svnweb.freebsd.org/changeset/base/343748

Log:
  Use NLDT to get number of LDTs on i386
  
  Compiling a GENERIC kernel for i386 with clang 8.0 results in the
  following warning:
  
  /usr/src/sys/i386/i386/sys_machdep.c:542:40: error: 'sizeof ((ldt))' will return the size of the pointer, not the array itself [-Werror,-Wsizeof-pointer-div]
          nldt = pldt != NULL ? pldt->ldt_len : nitems(ldt);
                                                ^~~~~~~~~~~
  /usr/src/sys/sys/param.h:299:32: note: expanded from macro 'nitems'
  #define nitems(x)       (sizeof((x)) / sizeof((x)[0]))
                           ~~~~~~~~~~~ ^
  
  Indeed, 'ldt' is declared as 'union descriptor *', so nitems() is not
  the right way to determine the number of LDTs.  Instead, the NLDT define
  from sys/x86/include/segments.h should be used.
  
  Reviewed by:	kib
  MFC after:	3 days
  Differential Revision: https://reviews.freebsd.org/D19074

Modified:
  head/sys/i386/i386/sys_machdep.c

Modified: head/sys/i386/i386/sys_machdep.c
==============================================================================
--- head/sys/i386/i386/sys_machdep.c	Mon Feb  4 17:53:29 2019	(r343747)
+++ head/sys/i386/i386/sys_machdep.c	Mon Feb  4 18:07:03 2019	(r343748)
@@ -539,7 +539,7 @@ i386_get_ldt(struct thread *td, struct i386_ldt_args *
 	data = malloc(num * sizeof(union descriptor), M_TEMP, M_WAITOK);
 	mtx_lock_spin(&dt_lock);
 	pldt = td->td_proc->p_md.md_ldt;
-	nldt = pldt != NULL ? pldt->ldt_len : nitems(ldt);
+	nldt = pldt != NULL ? pldt->ldt_len : NLDT;
 	if (uap->start >= nldt) {
 		num = 0;
 	} else {