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Subject[PATCH] bpf: Allow bpf_skb_event_output for a few prog types
From
    Software event output is only enabled by a few prog types right now (TC,
LWT out, XDP, sockops). Many other skb based prog types need
bpf_skb_event_output to produce software event.

Added socket_filter, cg_skb, sk_skb prog types to generate sw event.

Test bpf code is generated from code snippet:

struct TMP {
uint64_t tmp;
} tt;
tt.tmp = 5;
bpf_perf_event_output(skb, &connection_tracking_event_map, 0,
&tt, sizeof(tt));
return 1;

the bpf assembly from llvm is:
0: b7 02 00 00 05 00 00 00 r2 = 5
1: 7b 2a f8 ff 00 00 00 00 *(u64 *)(r10 - 8) = r2
2: bf a4 00 00 00 00 00 00 r4 = r10
3: 07 04 00 00 f8 ff ff ff r4 += -8
4: 18 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r2 = 0ll
6: b7 03 00 00 00 00 00 00 r3 = 0
7: b7 05 00 00 08 00 00 00 r5 = 8
8: 85 00 00 00 19 00 00 00 call 25
9: b7 00 00 00 01 00 00 00 r0 = 1
10: 95 00 00 00 00 00 00 00 exit

Patch 1 is enabling code.
Patch 2 is fullly covered selftest code.

Signed-off-by: allanzhang <allanzhang@google.com>
---
tools/testing/selftests/bpf/test_verifier.c | 38 +++++++-
.../selftests/bpf/verifier/event_output.c | 94 +++++++++++++++++++
2 files changed, 130 insertions(+), 2 deletions(-)
create mode 100644 tools/testing/selftests/bpf/verifier/event_output.c

diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index c5514daf8865..45ce9dd4323f 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -1,10 +1,13 @@
-// SPDX-License-Identifier: GPL-2.0-only
/*
* Testsuite for eBPF verifier
*
* Copyright (c) 2014 PLUMgrid, http://plumgrid.com
* Copyright (c) 2017 Facebook
* Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
*/

#include <endian.h>
@@ -50,7 +53,7 @@
#define MAX_INSNS BPF_MAXINSNS
#define MAX_TEST_INSNS 1000000
#define MAX_FIXUPS 8
-#define MAX_NR_MAPS 18
+#define MAX_NR_MAPS 19
#define MAX_TEST_RUNS 8
#define POINTER_VALUE 0xcafe4all
#define TEST_DATA_LEN 64
@@ -84,6 +87,7 @@ struct bpf_test {
int fixup_map_array_wo[MAX_FIXUPS];
int fixup_map_array_small[MAX_FIXUPS];
int fixup_sk_storage_map[MAX_FIXUPS];
+ int fixup_map_event_output[MAX_FIXUPS];
const char *errstr;
const char *errstr_unpriv;
uint32_t retval, retval_unpriv, insn_processed;
@@ -604,6 +608,28 @@ static int create_sk_storage_map(void)
return fd;
}

+static int create_event_output_map(void)
+{
+ struct bpf_create_map_attr attr = {
+ .name = "test_map",
+ .map_type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
+ .key_size = 4,
+ .value_size = 4,
+ .max_entries = 1,
+ };
+ int fd, btf_fd;
+
+ btf_fd = load_btf();
+ if (btf_fd < 0)
+ return -1;
+ attr.btf_fd = btf_fd;
+ fd = bpf_create_map_xattr(&attr);
+ close(attr.btf_fd);
+ if (fd < 0)
+ printf("Failed to create event_output\n");
+ return fd;
+}
+
static char bpf_vlog[UINT_MAX >> 8];

static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
@@ -627,6 +653,7 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
int *fixup_map_array_wo = test->fixup_map_array_wo;
int *fixup_map_array_small = test->fixup_map_array_small;
int *fixup_sk_storage_map = test->fixup_sk_storage_map;
+ int *fixup_map_event_output = test->fixup_map_event_output;

if (test->fill_helper) {
test->fill_insns = calloc(MAX_TEST_INSNS, sizeof(struct bpf_insn));
@@ -788,6 +815,13 @@ static void do_test_fixup(struct bpf_test *test, enum bpf_prog_type prog_type,
fixup_sk_storage_map++;
} while (*fixup_sk_storage_map);
}
+ if (*fixup_map_event_output) {
+ map_fds[18] = create_event_output_map();
+ do {
+ prog[*fixup_map_event_output].imm = map_fds[18];
+ fixup_map_event_output++;
+ } while (*fixup_map_event_output);
+ }
}

static int set_admin(bool admin)
diff --git a/tools/testing/selftests/bpf/verifier/event_output.c b/tools/testing/selftests/bpf/verifier/event_output.c
new file mode 100644
index 000000000000..b25eabcfaa56
--- /dev/null
+++ b/tools/testing/selftests/bpf/verifier/event_output.c
@@ -0,0 +1,94 @@
+/* instructions used to output a skb based software event, produced
+ * from code snippet:
+struct TMP {
+ uint64_t tmp;
+} tt;
+tt.tmp = 5;
+bpf_perf_event_output(skb, &connection_tracking_event_map, 0,
+ &tt, sizeof(tt));
+return 1;
+
+the bpf assembly from llvm is:
+ 0: b7 02 00 00 05 00 00 00 r2 = 5
+ 1: 7b 2a f8 ff 00 00 00 00 *(u64 *)(r10 - 8) = r2
+ 2: bf a4 00 00 00 00 00 00 r4 = r10
+ 3: 07 04 00 00 f8 ff ff ff r4 += -8
+ 4: 18 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 r2 = 0ll
+ 6: b7 03 00 00 00 00 00 00 r3 = 0
+ 7: b7 05 00 00 08 00 00 00 r5 = 8
+ 8: 85 00 00 00 19 00 00 00 call 25
+ 9: b7 00 00 00 01 00 00 00 r0 = 1
+ 10: 95 00 00 00 00 00 00 00 exit
+
+ The reason I put the code here instead of fill_helpers is that map fixup is
+ against the insns, instead of filled prog.
+*/
+
+#define __PERF_EVENT_INSNS__ \
+ BPF_MOV64_IMM(BPF_REG_2, 5), \
+ BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_2, -8), \
+ BPF_MOV64_REG(BPF_REG_4, BPF_REG_10), \
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, -8), \
+ BPF_LD_MAP_FD(BPF_REG_2, 0), \
+ BPF_MOV64_IMM(BPF_REG_3, 0), \
+ BPF_MOV64_IMM(BPF_REG_5, 8), \
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, \
+ BPF_FUNC_perf_event_output), \
+ BPF_MOV64_IMM(BPF_REG_0, 1), \
+ BPF_EXIT_INSN(),
+{
+ "perfevent for sockops",
+ .insns = { __PERF_EVENT_INSNS__ },
+ .prog_type = BPF_PROG_TYPE_SOCK_OPS,
+ .fixup_map_event_output = { 4 },
+ .result = ACCEPT,
+ .retval = 1,
+},
+{
+ "perfevent for tc",
+ .insns = { __PERF_EVENT_INSNS__ },
+ .prog_type = BPF_PROG_TYPE_SCHED_CLS,
+ .fixup_map_event_output = { 4 },
+ .result = ACCEPT,
+ .retval = 1,
+},
+{
+ "perfevent for lwt out",
+ .insns = { __PERF_EVENT_INSNS__ },
+ .prog_type = BPF_PROG_TYPE_LWT_OUT,
+ .fixup_map_event_output = { 4 },
+ .result = ACCEPT,
+ .retval = 1,
+},
+{
+ "perfevent for xdp",
+ .insns = { __PERF_EVENT_INSNS__ },
+ .prog_type = BPF_PROG_TYPE_XDP,
+ .fixup_map_event_output = { 4 },
+ .result = ACCEPT,
+ .retval = 1,
+},
+{
+ "perfevent for socket filter",
+ .insns = { __PERF_EVENT_INSNS__ },
+ .prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
+ .fixup_map_event_output = { 4 },
+ .result = ACCEPT,
+ .retval = 1,
+},
+{
+ "perfevent for sk_skb",
+ .insns = { __PERF_EVENT_INSNS__ },
+ .prog_type = BPF_PROG_TYPE_SK_SKB,
+ .fixup_map_event_output = { 4 },
+ .result = ACCEPT,
+ .retval = 1,
+},
+{
+ "perfevent for cgroup skb",
+ .insns = { __PERF_EVENT_INSNS__ },
+ .prog_type = BPF_PROG_TYPE_CGROUP_SKB,
+ .fixup_map_event_output = { 4 },
+ .result = ACCEPT,
+ .retval = 1,
+},
--
2.22.0.410.gd8fdbe21b5-goog
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