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Code Issues Releases Activity

Use NLDT to get number of LDTs on i386

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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
This commit is contained in:
Dimitry Andric 2019-02-04 18:07:03 +00:00
parent 2d01f2dee3
commit 0f166953f7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=343748
1 changed files with 1 additions and 1 deletions
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2
sys/i386/i386/sys_machdep.c
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@ -539,7 +539,7 @@ i386_get_ldt(struct thread *td, struct i386_ldt_args *uap)
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 {