[src/trunk]: src/sys/kern exec_loadvm: Isolate stack size calc logic into sep...

[uebayasi <uebayasi%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/e46eeaebe824
branches:  trunk
changeset: 795489:e46eeaebe824
user:      uebayasi <uebayasi%NetBSD.org@localhost>
date:      Tue Apr 15 15:50:16 2014 +0000

description:
exec_loadvm: Isolate stack size calc logic into separate functions.

diffstat:

 sys/kern/kern_exec.c |  102 ++++++++++++++++++++++++++++++---------------------
 1 files changed, 60 insertions(+), 42 deletions(-)

diffs (160 lines):

diff -r 1ef78f62432c -r e46eeaebe824 sys/kern/kern_exec.c
--- a/sys/kern/kern_exec.c      Tue Apr 15 13:47:06 2014 +0000
+++ b/sys/kern/kern_exec.c      Tue Apr 15 15:50:16 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: kern_exec.c,v 1.395 2014/04/14 13:14:38 uebayasi Exp $ */
+/*     $NetBSD: kern_exec.c,v 1.396 2014/04/15 15:50:16 uebayasi Exp $ */
 
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -59,7 +59,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.395 2014/04/14 13:14:38 uebayasi Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.396 2014/04/15 15:50:16 uebayasi Exp $");
 
 #include "opt_exec.h"
 #include "opt_execfmt.h"
@@ -122,6 +122,8 @@
 
 struct execve_data;
 
+static size_t calcargs(struct execve_data * restrict, const size_t);
+static size_t calcstack(struct execve_data * restrict, const size_t);
 static int copyinargs(struct execve_data * restrict, char * const *,
     char * const *, execve_fetch_element_t, char **);
 static int copyinargstrs(struct execve_data * restrict, char * const *,
@@ -250,6 +252,7 @@
        char                    *ed_resolvedpathbuf;
        size_t                  ed_ps_strings_sz;
        int                     ed_szsigcode;
+       size_t                  ed_argslen;
        long                    ed_argc;
        long                    ed_envc;
 };
@@ -700,29 +703,10 @@
         * Calculate the new stack size.
         */
 
-       const size_t nargenvptrs =
-           data->ed_argc +             /* char *argv[] */
-           1 +                         /* \0 */
-           data->ed_envc +             /* char *env[] */
-           1 +                         /* \0 */
-           epp->ep_esch->es_arglen;    /* auxinfo */
-
-       const size_t ptrsz = (epp->ep_flags & EXEC_32) ?
-           sizeof(int) : sizeof(char *);
-
-       const size_t argenvstrlen = (char *)ALIGN(dp) - data->ed_argp;
-
-       data->ed_szsigcode = epp->ep_esch->es_emul->e_esigcode -
-           epp->ep_esch->es_emul->e_sigcode;
-
-       data->ed_ps_strings_sz = (epp->ep_flags & EXEC_32) ?
-           sizeof(struct ps_strings32) : sizeof(struct ps_strings);
-
-       const size_t aslrgap =
 #ifdef PAX_ASLR
-           pax_aslr_active(l) ? (cprng_fast32() % PAGE_SIZE) : 0;
+#define        ASLR_GAP(l)     (pax_aslr_active(l) ? (cprng_fast32() % PAGE_SIZE) : 0)
 #else
-           0;
+#define        ASLR_GAP(l)     0
 #endif
 
 #ifdef __MACHINE_STACK_GROWS_UP
@@ -736,32 +720,19 @@
 #define        RTLD_GAP        0
 #endif
 
-       const size_t argenvlen =
-           RTLD_GAP +                  /* reserved for _rtld() */
-           sizeof(int) +               /* XXX argc in stack is long, not int */
-           (nargenvptrs * ptrsz);      /* XXX auxinfo multiplied by ptr size? */
+       const size_t argenvstrlen = (char *)ALIGN(dp) - data->ed_argp;
 
-       const size_t sigcode_psstr_sz =
-           data->ed_szsigcode +        /* sigcode */
-           data->ed_ps_strings_sz +    /* ps_strings */
-           STACK_PTHREADSPACE;         /* pthread space */
+       data->ed_argslen = calcargs(data, argenvstrlen);
 
-       const size_t stacklen =
-           argenvlen +
-           argenvstrlen +
-           aslrgap +
-           sigcode_psstr_sz;
+       const size_t len = calcstack(data, ASLR_GAP(l) + RTLD_GAP);
 
-       /* make the stack "safely" aligned */
-       const size_t aligned_stacklen = STACK_LEN_ALIGN(stacklen, STACK_ALIGNBYTES);
-
-       if (aligned_stacklen > epp->ep_ssize) {
+       if (len > epp->ep_ssize) {
                /* in effect, compare to initial limit */
-               DPRINTF(("%s: stack limit exceeded %zu\n", __func__, aligned_stacklen));
+               DPRINTF(("%s: stack limit exceeded %zu\n", __func__, len));
                goto bad;
        }
        /* adjust "active stack depth" for process VSZ */
-       epp->ep_ssize = aligned_stacklen;
+       epp->ep_ssize = len;
 
        return 0;
 
@@ -1397,6 +1368,53 @@
        return error;
 }
 
+static size_t
+calcargs(struct execve_data * restrict data, const size_t argenvstrlen)
+{
+       struct exec_package     * const epp = &data->ed_pack;
+
+       const size_t nargenvptrs =
+           data->ed_argc +             /* char *argv[] */
+           1 +                         /* \0 */
+           data->ed_envc +             /* char *env[] */
+           1 +                         /* \0 */
+           epp->ep_esch->es_arglen;    /* auxinfo */
+
+       const size_t ptrsz = (epp->ep_flags & EXEC_32) ?
+           sizeof(int) : sizeof(char *);
+
+       const size_t argenvlen =
+           sizeof(int) +               /* XXX argc in stack is long, not int */
+           (nargenvptrs * ptrsz);      /* XXX auxinfo multiplied by ptr size? */
+
+       return argenvlen + argenvstrlen;
+}
+
+static size_t
+calcstack(struct execve_data * restrict data, const size_t gaplen)
+{
+       struct exec_package     * const epp = &data->ed_pack;
+
+       data->ed_szsigcode = epp->ep_esch->es_emul->e_esigcode -
+           epp->ep_esch->es_emul->e_sigcode;
+
+       data->ed_ps_strings_sz = (epp->ep_flags & EXEC_32) ?
+           sizeof(struct ps_strings32) : sizeof(struct ps_strings);
+
+       const size_t sigcode_psstr_sz =
+           data->ed_szsigcode +        /* sigcode */
+           data->ed_ps_strings_sz +    /* ps_strings */
+           STACK_PTHREADSPACE;         /* pthread space */
+
+       const size_t stacklen =
+           data->ed_argslen +
+           gaplen +
+           sigcode_psstr_sz;
+
+       /* make the stack "safely" aligned */
+       return STACK_LEN_ALIGN(stacklen, STACK_ALIGNBYTES);
+}
+
 static int
 copyinargs(struct execve_data * restrict data, char * const *args,
     char * const *envs, execve_fetch_element_t fetch_element, char **dpp)