Re: svn commit: r199498 - in head/sys: amd64/amd64 i386/i386 net

[Robert Watson]

On Wed, 18 Nov 2009, Jung-uk Kim wrote:
 - Change internal function bpf_jit_compile() to return allocated size of
 the generated binary and remove page size limitation for userland.
 - Use contigmalloc(9)/contigfree(9) instead of malloc(9)/free(9) to make
 sure the generated binary aligns properly and make it physically contiguous.

Is physical contiguity actually required here -- I would have thought virtual 
contiguity and alignment would be sufficient, in which case the normal trick 
is to allocate using malloc the size + min-align + 1 and then fudge the 
pointer forward until it's properly aligned.

Also, in 9.x I'm going to be looking at parallel execution within BPF 
descriptors, and I notice that the JIT compiles the register array pointer 
into the generated code, rather than allowing a pointer to be passed in to 
each instance.  I guess it's non-trivial to change that, suggesting that we 
have a pool of compiled instances, but it would be preferable to be able to do 
what the normal BPF code does: allocate a per-thread register block when 
needed.

Robert N M Watson
Computer Laboratory
University of Cambridge

Modified:
 head/sys/amd64/amd64/bpf_jit_machdep.c
 head/sys/i386/i386/bpf_jit_machdep.c
 head/sys/net/bpf_jitter.c
 head/sys/net/bpf_jitter.h

Modified: head/sys/amd64/amd64/bpf_jit_machdep.c
==============================================================================
--- head/sys/amd64/amd64/bpf_jit_machdep.c      Wed Nov 18 22:53:05 2009        
(r199497)
+++ head/sys/amd64/amd64/bpf_jit_machdep.c      Wed Nov 18 23:40:19 2009        
(r199498)
@@ -53,7 +53,7 @@ __FBSDID("$FreeBSD$");

#include <amd64/amd64/bpf_jit_machdep.h>

-bpf_filter_func        bpf_jit_compile(struct bpf_insn *, u_int, int *);
+bpf_filter_func        bpf_jit_compile(struct bpf_insn *, u_int, size_t *, int 
*);

/*
 * emit routine to update the jump table
@@ -97,7 +97,7 @@ emit_code(bpf_bin_stream *stream, u_int
 * Function that does the real stuff
 */
bpf_filter_func
-bpf_jit_compile(struct bpf_insn *prog, u_int nins, int *mem)
+bpf_jit_compile(struct bpf_insn *prog, u_int nins, size_t *size, int *mem)
{
        bpf_bin_stream stream;
        struct bpf_insn *ins;
@@ -481,23 +481,21 @@ bpf_jit_compile(struct bpf_insn *prog, u
#ifndef _KERNEL
                        if (mprotect(stream.ibuf, stream.cur_ip,
                            PROT_READ | PROT_EXEC) != 0) {
-                               munmap(stream.ibuf, BPF_JIT_MAXSIZE);
+                               munmap(stream.ibuf, stream.cur_ip);
                                stream.ibuf = NULL;
                        }
#endif
+                       *size = stream.cur_ip;
                        break;
                }

#ifdef _KERNEL
-               stream.ibuf = (char *)malloc(stream.cur_ip, M_BPFJIT, M_NOWAIT);
+               stream.ibuf = (char *)contigmalloc(stream.cur_ip, M_BPFJIT,
+                   M_NOWAIT, 0, ~0ULL, 16, 0);
                if (stream.ibuf == NULL)
                        break;
#else
-               if (stream.cur_ip > BPF_JIT_MAXSIZE) {
-                       stream.ibuf = NULL;
-                       break;
-               }
-               stream.ibuf = (char *)mmap(NULL, BPF_JIT_MAXSIZE,
+               stream.ibuf = (char *)mmap(NULL, stream.cur_ip,
                    PROT_READ | PROT_WRITE, MAP_ANON, -1, 0);
                if (stream.ibuf == MAP_FAILED) {
                        stream.ibuf = NULL;

Modified: head/sys/i386/i386/bpf_jit_machdep.c
==============================================================================
--- head/sys/i386/i386/bpf_jit_machdep.c        Wed Nov 18 22:53:05 2009        
(r199497)
+++ head/sys/i386/i386/bpf_jit_machdep.c        Wed Nov 18 23:40:19 2009        
(r199498)
@@ -53,7 +53,7 @@ __FBSDID("$FreeBSD$");

#include <i386/i386/bpf_jit_machdep.h>

-bpf_filter_func        bpf_jit_compile(struct bpf_insn *, u_int, int *);
+bpf_filter_func        bpf_jit_compile(struct bpf_insn *, u_int, size_t *, int 
*);

/*
 * emit routine to update the jump table
@@ -97,7 +97,7 @@ emit_code(bpf_bin_stream *stream, u_int
 * Function that does the real stuff
 */
bpf_filter_func
-bpf_jit_compile(struct bpf_insn *prog, u_int nins, int *mem)
+bpf_jit_compile(struct bpf_insn *prog, u_int nins, size_t *size, int *mem)
{
        bpf_bin_stream stream;
        struct bpf_insn *ins;
@@ -504,23 +504,21 @@ bpf_jit_compile(struct bpf_insn *prog, u
#ifndef _KERNEL
                        if (mprotect(stream.ibuf, stream.cur_ip,
                            PROT_READ | PROT_EXEC) != 0) {
-                               munmap(stream.ibuf, BPF_JIT_MAXSIZE);
+                               munmap(stream.ibuf, stream.cur_ip);
                                stream.ibuf = NULL;
                        }
#endif
+                       *size = stream.cur_ip;
                        break;
                }

#ifdef _KERNEL
-               stream.ibuf = (char *)malloc(stream.cur_ip, M_BPFJIT, M_NOWAIT);
+               stream.ibuf = (char *)contigmalloc(stream.cur_ip, M_BPFJIT,
+                   M_NOWAIT, 0, ~0ULL, 16, 0);
                if (stream.ibuf == NULL)
                        break;
#else
-               if (stream.cur_ip > BPF_JIT_MAXSIZE) {
-                       stream.ibuf = NULL;
-                       break;
-               }
-               stream.ibuf = (char *)mmap(NULL, BPF_JIT_MAXSIZE,
+               stream.ibuf = (char *)mmap(NULL, stream.cur_ip,
                    PROT_READ | PROT_WRITE, MAP_ANON, -1, 0);
                if (stream.ibuf == MAP_FAILED) {
                        stream.ibuf = NULL;

Modified: head/sys/net/bpf_jitter.c
==============================================================================
--- head/sys/net/bpf_jitter.c   Wed Nov 18 22:53:05 2009        (r199497)
+++ head/sys/net/bpf_jitter.c   Wed Nov 18 23:40:19 2009        (r199498)
@@ -51,7 +51,7 @@ __FBSDID("$FreeBSD$");
#include <net/bpf.h>
#include <net/bpf_jitter.h>

-bpf_filter_func        bpf_jit_compile(struct bpf_insn *, u_int, int *);
+bpf_filter_func        bpf_jit_compile(struct bpf_insn *, u_int, size_t *, int 
*);

static u_int    bpf_jit_accept_all(u_char *, u_int, u_int);

@@ -81,7 +81,8 @@ bpf_jitter(struct bpf_insn *fp, int nins
        }

        /* Create the binary */
-       if ((filter->func = bpf_jit_compile(fp, nins, filter->mem)) == NULL) {
+       if ((filter->func = bpf_jit_compile(fp, nins, &filter->size,
+           filter->mem)) == NULL) {
                free(filter, M_BPFJIT);
                return (NULL);
        }
@@ -94,7 +95,7 @@ bpf_destroy_jit_filter(bpf_jit_filter *f
{

        if (filter->func != bpf_jit_accept_all)
-               free(filter->func, M_BPFJIT);
+               contigfree(filter->func, filter->size, M_BPFJIT);
        free(filter, M_BPFJIT);
}
#else
@@ -116,7 +117,8 @@ bpf_jitter(struct bpf_insn *fp, int nins
        }

        /* Create the binary */
-       if ((filter->func = bpf_jit_compile(fp, nins, filter->mem)) == NULL) {
+       if ((filter->func = bpf_jit_compile(fp, nins, &filter->size,
+           filter->mem)) == NULL) {
                free(filter);
                return (NULL);
        }
@@ -129,7 +131,7 @@ bpf_destroy_jit_filter(bpf_jit_filter *f
{

        if (filter->func != bpf_jit_accept_all)
-               munmap(filter->func, BPF_JIT_MAXSIZE);
+               munmap(filter->func, filter->size);
        free(filter);
}
#endif

Modified: head/sys/net/bpf_jitter.h
==============================================================================
--- head/sys/net/bpf_jitter.h   Wed Nov 18 22:53:05 2009        (r199497)
+++ head/sys/net/bpf_jitter.h   Wed Nov 18 23:40:19 2009        (r199498)
@@ -36,8 +36,6 @@

#ifdef _KERNEL
MALLOC_DECLARE(M_BPFJIT);
-#else
-#define        BPF_JIT_MAXSIZE         PAGE_SIZE
#endif

extern int bpf_jitter_enable;
@@ -55,7 +53,7 @@ typedef u_int (*bpf_filter_func)(u_char
typedef struct bpf_jit_filter {
        /* The native filtering binary, in the form of a bpf_filter_func. */
        bpf_filter_func func;
-
+       size_t          size;
        int             mem[BPF_MEMWORDS];      /* Scratch memory */
} bpf_jit_filter;


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