[src/trunk]: src/sys/net Don't use scratch registers for X and to restore A a...

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

details:   https://anonhg.NetBSD.org/src/rev/3f4e3564550a
branches:  trunk
changeset: 797562:3f4e3564550a
user:      alnsn <alnsn%NetBSD.org@localhost>
date:      Tue Jul 22 08:20:08 2014 +0000

description:
Don't use scratch registers for X and to restore A after BPF_COPX call.

diffstat:

 sys/net/bpfjit.c |  80 +++++++++++++++++++++++++++----------------------------
 1 files changed, 39 insertions(+), 41 deletions(-)

diffs (176 lines):

diff -r 42f8eb7e7a45 -r 3f4e3564550a sys/net/bpfjit.c
--- a/sys/net/bpfjit.c  Tue Jul 22 08:18:33 2014 +0000
+++ b/sys/net/bpfjit.c  Tue Jul 22 08:20:08 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: bpfjit.c,v 1.28 2014/07/13 21:54:46 alnsn Exp $        */
+/*     $NetBSD: bpfjit.c,v 1.29 2014/07/22 08:20:08 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 1.28 2014/07/13 21:54:46 alnsn Exp $");
+__KERNEL_RCSID(0, "$NetBSD: bpfjit.c,v 1.29 2014/07/22 08:20:08 alnsn Exp $");
 #else
-__RCSID("$NetBSD: bpfjit.c,v 1.28 2014/07/13 21:54:46 alnsn Exp $");
+__RCSID("$NetBSD: bpfjit.c,v 1.29 2014/07/22 08:20:08 alnsn Exp $");
 #endif
 
 #include <sys/types.h>
@@ -89,11 +89,12 @@
 #define BJ_BUF         SLJIT_SAVED_REG1
 //#define BJ_ARGS      SLJIT_SAVED_REG2
 #define BJ_BUFLEN      SLJIT_SAVED_REG3
+#define BJ_XREG                SLJIT_SAVED_EREG1
+#define BJ_ASAVE       SLJIT_SAVED_EREG2
 #define BJ_AREG                SLJIT_SCRATCH_REG1
 #define BJ_TMP1REG     SLJIT_SCRATCH_REG2
 #define BJ_TMP2REG     SLJIT_SCRATCH_REG3
-#define BJ_XREG                SLJIT_TEMPORARY_EREG1
-#define BJ_TMP3REG     SLJIT_TEMPORARY_EREG2
+#define BJ_TMP3REG     SLJIT_TEMPORARY_EREG1
 
 #ifdef _KERNEL
 #define MAX_MEMWORDS BPF_MAX_MEMWORDS
@@ -118,11 +119,12 @@
 typedef unsigned int bpfjit_hint_t;
 #define BJ_HINT_ABS  0x01 /* packet read at absolute offset   */
 #define BJ_HINT_IND  0x02 /* packet read at variable offset   */
-#define BJ_HINT_COP  0x04 /* BPF_COP or BPF_COPX instruction  */
-#define BJ_HINT_COPX 0x08 /* BPF_COPX instruction             */
-#define BJ_HINT_XREG 0x10 /* BJ_XREG is needed                */
-#define BJ_HINT_LDX  0x20 /* BPF_LDX instruction              */
-#define BJ_HINT_PKT  (BJ_HINT_ABS|BJ_HINT_IND) /* packet read */
+#define BJ_HINT_MSH  0x04 /* BPF_MSH instruction              */
+#define BJ_HINT_COP  0x08 /* BPF_COP or BPF_COPX instruction  */
+#define BJ_HINT_COPX 0x10 /* BPF_COPX instruction             */
+#define BJ_HINT_XREG 0x20 /* BJ_XREG is needed                */
+#define BJ_HINT_LDX  0x40 /* BPF_LDX instruction              */
+#define BJ_HINT_PKT  (BJ_HINT_ABS|BJ_HINT_IND|BJ_HINT_MSH)
 
 /*
  * Datatype for Array Bounds Check Elimination (ABC) pass.
@@ -257,17 +259,29 @@
        if (hints & BJ_HINT_COP)
                rv = 3; /* calls copfunc with three arguments */
 
+       if (hints & BJ_HINT_COPX)
+               rv = 4; /* uses BJ_TMP3REG */
+
+       return rv;
+}
+
+/*
+ * Return a number of saved registers to pass
+ * to sljit_emit_enter() function.
+ */
+static sljit_si
+nsaveds(bpfjit_hint_t hints)
+{
+       sljit_si rv = 3;
+
        if (hints & BJ_HINT_XREG)
                rv = 4; /* uses BJ_XREG */
 
 #ifdef _KERNEL
        if (hints & BJ_HINT_LDX)
-               rv = 5; /* uses BJ_TMP3REG */
+               rv = 5; /* uses BJ_ASAVE */
 #endif
 
-       if (hints & BJ_HINT_COPX)
-               rv = 5; /* uses BJ_TMP3REG */
-
        return rv;
 }
 
@@ -518,26 +532,16 @@
     int dst, struct sljit_jump ***ret0, size_t *ret0_size, size_t *ret0_maxsize,
     uint32_t (*fn)(const struct mbuf *, uint32_t, int *))
 {
-#if BJ_XREG    == SLJIT_RETURN_REG   || \
-    BJ_XREG    == SLJIT_SCRATCH_REG1 || \
-    BJ_XREG    == SLJIT_SCRATCH_REG2 || \
-    BJ_XREG    == SLJIT_SCRATCH_REG3 || \
-    BJ_TMP3REG == SLJIT_RETURN_REG   || \
-    BJ_TMP3REG == SLJIT_SCRATCH_REG1 || \
-    BJ_TMP3REG == SLJIT_SCRATCH_REG2 || \
-    BJ_TMP3REG == SLJIT_SCRATCH_REG3
-#error "Not supported assignment of registers."
-#endif
        struct sljit_jump *jump;
        int status;
 
-       BJ_ASSERT(dst != BJ_TMP2REG && dst != BJ_TMP3REG);
+       BJ_ASSERT(dst != BJ_ASAVE);
 
        if (BPF_CLASS(pc->code) == BPF_LDX) {
                /* save A */
                status = sljit_emit_op1(compiler,
                    SLJIT_MOV,
-                   BJ_TMP3REG, 0,
+                   BJ_ASAVE, 0,
                    BJ_AREG, 0);
                if (status != SLJIT_SUCCESS)
                        return status;
@@ -633,7 +637,7 @@
                status = sljit_emit_op1(compiler,
                    SLJIT_MOV,
                    BJ_AREG, 0,
-                   BJ_TMP3REG, 0);
+                   BJ_ASAVE, 0);
                if (status != SLJIT_SUCCESS)
                        return status;
        }
@@ -650,11 +654,7 @@
     const bpf_ctx_t *bc, const struct bpf_insn *pc,
     struct sljit_jump ***ret0, size_t *ret0_size, size_t *ret0_maxsize)
 {
-#if BJ_XREG    == SLJIT_RETURN_REG   || \
-    BJ_XREG    == SLJIT_SCRATCH_REG1 || \
-    BJ_XREG    == SLJIT_SCRATCH_REG2 || \
-    BJ_XREG    == SLJIT_SCRATCH_REG3 || \
-    BJ_TMP3REG == SLJIT_SCRATCH_REG1 || \
+#if BJ_TMP3REG == SLJIT_SCRATCH_REG1 || \
     BJ_TMP3REG == SLJIT_SCRATCH_REG2 || \
     BJ_TMP3REG == SLJIT_SCRATCH_REG3
 #error "Not supported assignment of registers."
@@ -1105,13 +1105,6 @@
 {
        int status;
 
-#if BJ_XREG == SLJIT_RETURN_REG   || \
-    BJ_XREG == SLJIT_SCRATCH_REG1 || \
-    BJ_XREG == SLJIT_SCRATCH_REG2 || \
-    BJ_AREG == SLJIT_SCRATCH_REG2
-#error "Not supported assignment of registers."
-#endif
-
 #if BJ_AREG != SLJIT_SCRATCH_REG1
        status = sljit_emit_op1(compiler,
            SLJIT_MOV,
@@ -1285,6 +1278,11 @@
                                *initmask |= invalid & BJ_INIT_MBIT(insns[i].k);
                        }
 
+                       if (BPF_MODE(insns[i].code) == BPF_MSH &&
+                           BPF_SIZE(insns[i].code) == BPF_B) {
+                               *hints |= BJ_HINT_MSH;
+                       }
+
                        invalid &= ~BJ_INIT_XBIT;
                        continue;
 
@@ -2109,8 +2107,8 @@
        sljit_compiler_verbose(compiler, stderr);
 #endif
 
-       status = sljit_emit_enter(compiler,
-           2, nscratches(hints), 3, sizeof(struct bpfjit_stack));
+       status = sljit_emit_enter(compiler, 2, nscratches(hints),
+           nsaveds(hints), sizeof(struct bpfjit_stack));
        if (status != SLJIT_SUCCESS)
                goto fail;