* [PATCH v2 net-next 1/2] bpf: introduce bpf_skb_vlan_push/pop() helpers
2015-07-21 3:34 [PATCH v2 net-next 0/2] bpf: introduce bpf_skb_vlan_push/pop() helpers Alexei Starovoitov
@ 2015-07-21 3:34 ` Alexei Starovoitov
2015-07-21 3:34 ` [PATCH v2 net-next 2/2] test_bpf: add bpf_skb_vlan_push/pop() tests Alexei Starovoitov
2015-07-21 3:52 ` [PATCH v2 net-next 0/2] bpf: introduce bpf_skb_vlan_push/pop() helpers David Miller
2 siblings, 0 replies; 4+ messages in thread
From: Alexei Starovoitov @ 2015-07-21 3:34 UTC (permalink / raw)
To: David S. Miller; +Cc: Eric Dumazet, Michael Holzheu, Daniel Borkmann, netdev
Allow eBPF programs attached to TC qdiscs call skb_vlan_push/pop via
helper functions. These functions may change skb->data/hlen which are
cached by some JITs to improve performance of ld_abs/ld_ind instructions.
Therefore JITs need to recognize bpf_skb_vlan_push/pop() calls,
re-compute header len and re-cache skb->data/hlen back into cpu registers.
Note, skb->data/hlen are not directly accessible from the programs,
so any changes to skb->data done either by these helpers or by other
TC actions are safe.
eBPF JIT supported by three architectures:
- arm64 JIT is using bpf_load_pointer() without caching, so it's ok as-is.
- x64 JIT re-caches skb->data/hlen unconditionally after vlan_push/pop calls
(experiments showed that conditional re-caching is slower).
- s390 JIT falls back to interpreter for now when bpf_skb_vlan_push() is present
in the program (re-caching is tbd).
These helpers allow more scalable handling of vlan from the programs.
Instead of creating thousands of vlan netdevs on top of eth0 and attaching
TC+ingress+bpf to all of them, the program can be attached to eth0 directly
and manipulate vlans as necessary.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
---
arch/s390/net/bpf_jit_comp.c | 4 +++
arch/x86/net/bpf_jit_comp.c | 80 ++++++++++++++++++++++--------------------
include/linux/bpf.h | 2 ++
include/linux/filter.h | 1 +
include/uapi/linux/bpf.h | 2 ++
net/core/filter.c | 48 +++++++++++++++++++++++++
6 files changed, 99 insertions(+), 38 deletions(-)
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index fee782acc2ee..79c731e8d178 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -973,6 +973,10 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
*/
const u64 func = (u64)__bpf_call_base + imm;
+ if (bpf_helper_changes_skb_data((void *)func))
+ /* TODO reload skb->data, hlen */
+ return -1;
+
REG_SET_SEEN(BPF_REG_5);
jit->seen |= SEEN_FUNC;
/* lg %w1,<d(imm)>(%l) */
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 579a8fd74be0..6c335a8fc086 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -315,6 +315,26 @@ static void emit_bpf_tail_call(u8 **pprog)
*pprog = prog;
}
+
+static void emit_load_skb_data_hlen(u8 **pprog)
+{
+ u8 *prog = *pprog;
+ int cnt = 0;
+
+ /* r9d = skb->len - skb->data_len (headlen)
+ * r10 = skb->data
+ */
+ /* mov %r9d, off32(%rdi) */
+ EMIT3_off32(0x44, 0x8b, 0x8f, offsetof(struct sk_buff, len));
+
+ /* sub %r9d, off32(%rdi) */
+ EMIT3_off32(0x44, 0x2b, 0x8f, offsetof(struct sk_buff, data_len));
+
+ /* mov %r10, off32(%rdi) */
+ EMIT3_off32(0x4c, 0x8b, 0x97, offsetof(struct sk_buff, data));
+ *pprog = prog;
+}
+
static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
int oldproglen, struct jit_context *ctx)
{
@@ -329,36 +349,8 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
emit_prologue(&prog);
- if (seen_ld_abs) {
- /* r9d : skb->len - skb->data_len (headlen)
- * r10 : skb->data
- */
- if (is_imm8(offsetof(struct sk_buff, len)))
- /* mov %r9d, off8(%rdi) */
- EMIT4(0x44, 0x8b, 0x4f,
- offsetof(struct sk_buff, len));
- else
- /* mov %r9d, off32(%rdi) */
- EMIT3_off32(0x44, 0x8b, 0x8f,
- offsetof(struct sk_buff, len));
-
- if (is_imm8(offsetof(struct sk_buff, data_len)))
- /* sub %r9d, off8(%rdi) */
- EMIT4(0x44, 0x2b, 0x4f,
- offsetof(struct sk_buff, data_len));
- else
- EMIT3_off32(0x44, 0x2b, 0x8f,
- offsetof(struct sk_buff, data_len));
-
- if (is_imm8(offsetof(struct sk_buff, data)))
- /* mov %r10, off8(%rdi) */
- EMIT4(0x4c, 0x8b, 0x57,
- offsetof(struct sk_buff, data));
- else
- /* mov %r10, off32(%rdi) */
- EMIT3_off32(0x4c, 0x8b, 0x97,
- offsetof(struct sk_buff, data));
- }
+ if (seen_ld_abs)
+ emit_load_skb_data_hlen(&prog);
for (i = 0; i < insn_cnt; i++, insn++) {
const s32 imm32 = insn->imm;
@@ -367,6 +359,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
u8 b1 = 0, b2 = 0, b3 = 0;
s64 jmp_offset;
u8 jmp_cond;
+ bool reload_skb_data;
int ilen;
u8 *func;
@@ -818,12 +811,18 @@ xadd: if (is_imm8(insn->off))
func = (u8 *) __bpf_call_base + imm32;
jmp_offset = func - (image + addrs[i]);
if (seen_ld_abs) {
- EMIT2(0x41, 0x52); /* push %r10 */
- EMIT2(0x41, 0x51); /* push %r9 */
- /* need to adjust jmp offset, since
- * pop %r9, pop %r10 take 4 bytes after call insn
- */
- jmp_offset += 4;
+ reload_skb_data = bpf_helper_changes_skb_data(func);
+ if (reload_skb_data) {
+ EMIT1(0x57); /* push %rdi */
+ jmp_offset += 22; /* pop, mov, sub, mov */
+ } else {
+ EMIT2(0x41, 0x52); /* push %r10 */
+ EMIT2(0x41, 0x51); /* push %r9 */
+ /* need to adjust jmp offset, since
+ * pop %r9, pop %r10 take 4 bytes after call insn
+ */
+ jmp_offset += 4;
+ }
}
if (!imm32 || !is_simm32(jmp_offset)) {
pr_err("unsupported bpf func %d addr %p image %p\n",
@@ -832,8 +831,13 @@ xadd: if (is_imm8(insn->off))
}
EMIT1_off32(0xE8, jmp_offset);
if (seen_ld_abs) {
- EMIT2(0x41, 0x59); /* pop %r9 */
- EMIT2(0x41, 0x5A); /* pop %r10 */
+ if (reload_skb_data) {
+ EMIT1(0x5F); /* pop %rdi */
+ emit_load_skb_data_hlen(&prog);
+ } else {
+ EMIT2(0x41, 0x59); /* pop %r9 */
+ EMIT2(0x41, 0x5A); /* pop %r10 */
+ }
}
break;
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 4383476a0d48..139d6d2e123f 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -192,5 +192,7 @@ extern const struct bpf_func_proto bpf_ktime_get_ns_proto;
extern const struct bpf_func_proto bpf_get_current_pid_tgid_proto;
extern const struct bpf_func_proto bpf_get_current_uid_gid_proto;
extern const struct bpf_func_proto bpf_get_current_comm_proto;
+extern const struct bpf_func_proto bpf_skb_vlan_push_proto;
+extern const struct bpf_func_proto bpf_skb_vlan_pop_proto;
#endif /* _LINUX_BPF_H */
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 17724f6ea983..69d00555ce35 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -411,6 +411,7 @@ void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp);
u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
void bpf_int_jit_compile(struct bpf_prog *fp);
+bool bpf_helper_changes_skb_data(void *func);
#ifdef CONFIG_BPF_JIT
typedef void (*bpf_jit_fill_hole_t)(void *area, unsigned int size);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 2de87e58b12b..2f6c83d714e9 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -256,6 +256,8 @@ enum bpf_func_id {
* Return: classid if != 0
*/
BPF_FUNC_get_cgroup_classid,
+ BPF_FUNC_skb_vlan_push, /* bpf_skb_vlan_push(skb, vlan_proto, vlan_tci) */
+ BPF_FUNC_skb_vlan_pop, /* bpf_skb_vlan_pop(skb) */
__BPF_FUNC_MAX_ID,
};
diff --git a/net/core/filter.c b/net/core/filter.c
index 247450a5e387..50338071fac4 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1437,6 +1437,50 @@ static const struct bpf_func_proto bpf_get_cgroup_classid_proto = {
.arg1_type = ARG_PTR_TO_CTX,
};
+static u64 bpf_skb_vlan_push(u64 r1, u64 r2, u64 vlan_tci, u64 r4, u64 r5)
+{
+ struct sk_buff *skb = (struct sk_buff *) (long) r1;
+ __be16 vlan_proto = (__force __be16) r2;
+
+ if (unlikely(vlan_proto != htons(ETH_P_8021Q) &&
+ vlan_proto != htons(ETH_P_8021AD)))
+ vlan_proto = htons(ETH_P_8021Q);
+
+ return skb_vlan_push(skb, vlan_proto, vlan_tci);
+}
+
+const struct bpf_func_proto bpf_skb_vlan_push_proto = {
+ .func = bpf_skb_vlan_push,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_ANYTHING,
+ .arg3_type = ARG_ANYTHING,
+};
+
+static u64 bpf_skb_vlan_pop(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+ struct sk_buff *skb = (struct sk_buff *) (long) r1;
+
+ return skb_vlan_pop(skb);
+}
+
+const struct bpf_func_proto bpf_skb_vlan_pop_proto = {
+ .func = bpf_skb_vlan_pop,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
+bool bpf_helper_changes_skb_data(void *func)
+{
+ if (func == bpf_skb_vlan_push)
+ return true;
+ if (func == bpf_skb_vlan_pop)
+ return true;
+ return false;
+}
+
static const struct bpf_func_proto *
sk_filter_func_proto(enum bpf_func_id func_id)
{
@@ -1476,6 +1520,10 @@ tc_cls_act_func_proto(enum bpf_func_id func_id)
return &bpf_clone_redirect_proto;
case BPF_FUNC_get_cgroup_classid:
return &bpf_get_cgroup_classid_proto;
+ case BPF_FUNC_skb_vlan_push:
+ return &bpf_skb_vlan_push_proto;
+ case BPF_FUNC_skb_vlan_pop:
+ return &bpf_skb_vlan_pop_proto;
default:
return sk_filter_func_proto(func_id);
}
--
1.7.9.5
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH v2 net-next 2/2] test_bpf: add bpf_skb_vlan_push/pop() tests
2015-07-21 3:34 [PATCH v2 net-next 0/2] bpf: introduce bpf_skb_vlan_push/pop() helpers Alexei Starovoitov
2015-07-21 3:34 ` [PATCH v2 net-next 1/2] " Alexei Starovoitov
@ 2015-07-21 3:34 ` Alexei Starovoitov
2015-07-21 3:52 ` [PATCH v2 net-next 0/2] bpf: introduce bpf_skb_vlan_push/pop() helpers David Miller
2 siblings, 0 replies; 4+ messages in thread
From: Alexei Starovoitov @ 2015-07-21 3:34 UTC (permalink / raw)
To: David S. Miller; +Cc: Eric Dumazet, Michael Holzheu, Daniel Borkmann, netdev
improve accuracy of timing in test_bpf and add two stress tests:
- {skb->data[0], get_smp_processor_id} repeated 2k times
- {skb->data[0], vlan_push} x 68 followed by {skb->data[0], vlan_pop} x 68
1st test is useful to test performance of JIT implementation of BPF_LD_ABS
together with BPF_CALL instructions.
2nd test is stressing skb_vlan_push/pop logic together with skb->data access
via BPF_LD_ABS insn which checks that re-caching of skb->data is done correctly.
In order to call bpf_skb_vlan_push() from test_bpf.ko have to add
three export_symbol_gpl.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
---
kernel/bpf/core.c | 1 +
lib/test_bpf.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++--
net/core/filter.c | 2 ++
3 files changed, 98 insertions(+), 3 deletions(-)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index bf38f5e8196c..fafa74161445 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -177,6 +177,7 @@ noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
{
return 0;
}
+EXPORT_SYMBOL_GPL(__bpf_call_base);
/**
* __bpf_prog_run - run eBPF program on a given context
diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index 9198f28a5528..8b5e66f008b0 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -18,6 +18,7 @@
#include <linux/init.h>
#include <linux/module.h>
#include <linux/filter.h>
+#include <linux/bpf.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/if_vlan.h>
@@ -355,6 +356,81 @@ static int bpf_fill_ja(struct bpf_test *self)
return __bpf_fill_ja(self, 12, 9);
}
+static int bpf_fill_ld_abs_get_processor_id(struct bpf_test *self)
+{
+ unsigned int len = BPF_MAXINSNS;
+ struct sock_filter *insn;
+ int i;
+
+ insn = kmalloc_array(len, sizeof(*insn), GFP_KERNEL);
+ if (!insn)
+ return -ENOMEM;
+
+ for (i = 0; i < len - 1; i += 2) {
+ insn[i] = __BPF_STMT(BPF_LD | BPF_B | BPF_ABS, 0);
+ insn[i + 1] = __BPF_STMT(BPF_LD | BPF_W | BPF_ABS,
+ SKF_AD_OFF + SKF_AD_CPU);
+ }
+
+ insn[len - 1] = __BPF_STMT(BPF_RET | BPF_K, 0xbee);
+
+ self->u.ptr.insns = insn;
+ self->u.ptr.len = len;
+
+ return 0;
+}
+
+#define PUSH_CNT 68
+/* test: {skb->data[0], vlan_push} x 68 + {skb->data[0], vlan_pop} x 68 */
+static int bpf_fill_ld_abs_vlan_push_pop(struct bpf_test *self)
+{
+ unsigned int len = BPF_MAXINSNS;
+ struct bpf_insn *insn;
+ int i = 0, j, k = 0;
+
+ insn = kmalloc_array(len, sizeof(*insn), GFP_KERNEL);
+ if (!insn)
+ return -ENOMEM;
+
+ insn[i++] = BPF_MOV64_REG(R6, R1);
+loop:
+ for (j = 0; j < PUSH_CNT; j++) {
+ insn[i++] = BPF_LD_ABS(BPF_B, 0);
+ insn[i] = BPF_JMP_IMM(BPF_JNE, R0, 0x34, len - i - 2);
+ i++;
+ insn[i++] = BPF_MOV64_REG(R1, R6);
+ insn[i++] = BPF_MOV64_IMM(R2, 1);
+ insn[i++] = BPF_MOV64_IMM(R3, 2);
+ insn[i++] = BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+ bpf_skb_vlan_push_proto.func - __bpf_call_base);
+ insn[i] = BPF_JMP_IMM(BPF_JNE, R0, 0, len - i - 2);
+ i++;
+ }
+
+ for (j = 0; j < PUSH_CNT; j++) {
+ insn[i++] = BPF_LD_ABS(BPF_B, 0);
+ insn[i] = BPF_JMP_IMM(BPF_JNE, R0, 0x34, len - i - 2);
+ i++;
+ insn[i++] = BPF_MOV64_REG(R1, R6);
+ insn[i++] = BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+ bpf_skb_vlan_pop_proto.func - __bpf_call_base);
+ insn[i] = BPF_JMP_IMM(BPF_JNE, R0, 0, len - i - 2);
+ i++;
+ }
+ if (++k < 5)
+ goto loop;
+
+ for (; i < len - 1; i++)
+ insn[i] = BPF_ALU32_IMM(BPF_MOV, R0, 0xbef);
+
+ insn[len - 1] = BPF_EXIT_INSN();
+
+ self->u.ptr.insns = insn;
+ self->u.ptr.len = len;
+
+ return 0;
+}
+
static struct bpf_test tests[] = {
{
"TAX",
@@ -4398,6 +4474,22 @@ static struct bpf_test tests[] = {
{ { 0, 0xababcbac } },
.fill_helper = bpf_fill_maxinsns11,
},
+ {
+ "BPF_MAXINSNS: ld_abs+get_processor_id",
+ { },
+ CLASSIC,
+ { },
+ { { 1, 0xbee } },
+ .fill_helper = bpf_fill_ld_abs_get_processor_id,
+ },
+ {
+ "BPF_MAXINSNS: ld_abs+vlan_push/pop",
+ { },
+ INTERNAL,
+ { 0x34 },
+ { { 1, 0xbef } },
+ .fill_helper = bpf_fill_ld_abs_vlan_push_pop,
+ },
};
static struct net_device dev;
@@ -4551,14 +4643,14 @@ static int __run_one(const struct bpf_prog *fp, const void *data,
u64 start, finish;
int ret = 0, i;
- start = ktime_to_us(ktime_get());
+ start = ktime_get_ns();
for (i = 0; i < runs; i++)
ret = BPF_PROG_RUN(fp, data);
- finish = ktime_to_us(ktime_get());
+ finish = ktime_get_ns();
- *duration = (finish - start) * 1000ULL;
+ *duration = finish - start;
do_div(*duration, runs);
return ret;
diff --git a/net/core/filter.c b/net/core/filter.c
index 50338071fac4..786722a9c6f2 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1457,6 +1457,7 @@ const struct bpf_func_proto bpf_skb_vlan_push_proto = {
.arg2_type = ARG_ANYTHING,
.arg3_type = ARG_ANYTHING,
};
+EXPORT_SYMBOL_GPL(bpf_skb_vlan_push_proto);
static u64 bpf_skb_vlan_pop(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
{
@@ -1471,6 +1472,7 @@ const struct bpf_func_proto bpf_skb_vlan_pop_proto = {
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
};
+EXPORT_SYMBOL_GPL(bpf_skb_vlan_pop_proto);
bool bpf_helper_changes_skb_data(void *func)
{
--
1.7.9.5
^ permalink raw reply related [flat|nested] 4+ messages in thread