[src/trunk]: src/sys/net Default initialize external memwords.

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

details:   https://anonhg.NetBSD.org/src/rev/79228c9a6f5a
branches:  trunk
changeset: 330158:79228c9a6f5a
user:      alnsn <alnsn%NetBSD.org@localhost>
date:      Wed Jun 25 13:53:40 2014 +0000

description:
Default initialize external memwords.

This change doesn't affect performance of valid bpf kernel programs
because bpf_filter_ext() checks that all memwords are initialized
explicitly.

diffstat:

 sys/net/bpfjit.c |  30 +++++++++++++++++++-----------
 1 files changed, 19 insertions(+), 11 deletions(-)

diffs (82 lines):

diff -r 70c85c1c3087 -r 79228c9a6f5a sys/net/bpfjit.c
--- a/sys/net/bpfjit.c  Wed Jun 25 13:10:27 2014 +0000
+++ b/sys/net/bpfjit.c  Wed Jun 25 13:53:40 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: bpfjit.c,v 1.17 2014/06/25 11:58:15 alnsn Exp $        */
+/*     $NetBSD: bpfjit.c,v 1.18 2014/06/25 13:53:40 alnsn Exp $        */
 
 /*-
  * Copyright (c) 2011-2014 Alexander Nasonov.
@@ -31,9 +31,9 @@
 
 #include <sys/cdefs.h>
 #ifdef _KERNEL
-__KERNEL_RCSID(0, "$NetBSD: bpfjit.c,v 1.17 2014/06/25 11:58:15 alnsn Exp $");
+__KERNEL_RCSID(0, "$NetBSD: bpfjit.c,v 1.18 2014/06/25 13:53:40 alnsn Exp $");
 #else
-__RCSID("$NetBSD: bpfjit.c,v 1.17 2014/06/25 11:58:15 alnsn Exp $");
+__RCSID("$NetBSD: bpfjit.c,v 1.18 2014/06/25 13:53:40 alnsn Exp $");
 #endif
 
 #include <sys/types.h>
@@ -1594,6 +1594,10 @@
        bpf_memword_init_t initmask;
        int nscratches, ncopfuncs;
 
+       /* memory store location for initial zero initialization */
+       sljit_si mem_reg;
+       sljit_sw mem_off;
+
        /* a list of jumps to out-of-bound return from a generated function */
        struct sljit_jump **ret0;
        size_t ret0_size, ret0_maxsize;
@@ -1665,7 +1669,10 @@
                        goto fail;
        }
 
-       if (extwords != 0) {
+       if (extwords == 0) {
+               mem_reg = SLJIT_MEM1(SLJIT_LOCALS_REG);
+               mem_off = offsetof(struct bpfjit_stack, mem);
+       } else {
                /* copy "mem" argument from bpf_args to bpfjit_stack */
                status = sljit_emit_op1(compiler,
                    SLJIT_MOV_P,
@@ -1681,12 +1688,11 @@
                    BJ_TMP1REG, 0);
                if (status != SLJIT_SUCCESS)
                        goto fail;
+
+               mem_reg = SLJIT_MEM1(BJ_TMP1REG);
+               mem_off = 0;
        }
 
-       status = load_buf_buflen(compiler);
-       if (status != SLJIT_SUCCESS)
-               goto fail;
-
        /*
         * Exclude pre-initialised external memory words but keep
         * initialization statuses of A and X registers in case
@@ -1703,9 +1709,7 @@
                        /* M[i] = 0; */
                        status = sljit_emit_op1(compiler,
                            SLJIT_MOV_UI,
-                           SLJIT_MEM1(SLJIT_LOCALS_REG),
-                           offsetof(struct bpfjit_stack, mem) +
-                               i * sizeof(uint32_t),
+                           mem_reg, mem_off + i * sizeof(uint32_t),
                            SLJIT_IMM, 0);
                        if (status != SLJIT_SUCCESS)
                                goto fail;
@@ -1732,6 +1736,10 @@
                        goto fail;
        }
 
+       status = load_buf_buflen(compiler);
+       if (status != SLJIT_SUCCESS)
+               goto fail;
+
        for (i = 0; i < insn_count; i++) {
                if (insn_dat[i].unreachable)
                        continue;