[RFC PATCH 19/22] perf bpf: dump eBPF program before loading.

Wang Nan
2015-04-30T10:59:18Z

Copy print_bpf_insn() from kernel/bpf/verifier.c to bpf.c, dump the
program if called by -vv.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
tools/perf/util/bpf-loader.c | 14 +++-
tools/perf/util/bpf.c | 156 +++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/bpf.h | 1 +
3 files changed, 170 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 0395483..6587e99 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -849,6 +849,16 @@ static __u64 ptr_to_u64(void *ptr)
return (__u64) (unsigned long) ptr;
}

+static void
+dump_perf_prog(struct bpf_perf_prog *prog)
+{
+ if (verbose < 2)
+ return;
+ pr_info("-- BEGIN DUMP '%s' --\n", prog->name);
+ bpf_dump_prog(prog->insns, prog->insns_cnt);
+ pr_info("-- FINISH DUMP '%s' --\n", prog->name);
+}
+
static int
bpf_perf_prog_load(struct bpf_obj *obj, struct bpf_perf_prog *prog)
{
@@ -857,6 +867,8 @@ bpf_perf_prog_load(struct bpf_obj *obj, struct bpf_perf_prog *prog)
#define LOG_BUF_SIZE 65536
static char bpf_log_buf[LOG_BUF_SIZE];

+ dump_perf_prog(prog);
+
bzero(&attr, sizeof(attr));

attr.prog_type = BPF_PROG_TYPE_KPROBE;
@@ -902,7 +914,7 @@ int bpf__load(const char *path)
struct bpf_obj *obj;
int err;

- pr_debug("bpf: loading %s\n", path);
+ pr_debug("bpf: loading %s, verbose=%d\n", path, verbose);

if (elf_version(EV_CURRENT) == EV_NONE) {
pr_err("bpf: failed to init libelf for %s\n", path);
diff --git a/tools/perf/util/bpf.c b/tools/perf/util/bpf.c
index f752723..eb3411b 100644
--- a/tools/perf/util/bpf.c
+++ b/tools/perf/util/bpf.c
@@ -8,12 +8,14 @@
*/

#include <stdlib.h>
+#include <stdio.h>
#include <string.h>
#include <linux/unistd.h>
#include <unistd.h>
#include <linux/bpf.h>
#include <errno.h>
#include "perf.h"
+#include "debug.h"
#include "bpf.h"

int sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr, size_t size)
@@ -37,3 +39,157 @@ int bpf_create_map(struct bpf_map_def *map_def)

return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
}
+
+/* Taken from kernel/bpf/verifier.c, s/verbose/_verbose/g*/
+static const char *const bpf_class_string[] = {
+ [BPF_LD] = "ld",
+ [BPF_LDX] = "ldx",
+ [BPF_ST] = "st",
+ [BPF_STX] = "stx",
+ [BPF_ALU] = "alu",
+ [BPF_JMP] = "jmp",
+ [BPF_RET] = "BUG",
+ [BPF_ALU64] = "alu64",
+};
+
+static const char *const bpf_alu_string[] = {
+ [BPF_ADD >> 4] = "+=",
+ [BPF_SUB >> 4] = "-=",
+ [BPF_MUL >> 4] = "*=",
+ [BPF_DIV >> 4] = "/=",
+ [BPF_OR >> 4] = "|=",
+ [BPF_AND >> 4] = "&=",
+ [BPF_LSH >> 4] = "<<=",
+ [BPF_RSH >> 4] = ">>=",
+ [BPF_NEG >> 4] = "neg",
+ [BPF_MOD >> 4] = "%=",
+ [BPF_XOR >> 4] = "^=",
+ [BPF_MOV >> 4] = "=",
+ [BPF_ARSH >> 4] = "s>>=",
+ [BPF_END >> 4] = "endian",
+};
+
+static const char *const bpf_ldst_string[] = {
+ [BPF_W >> 3] = "u32",
+ [BPF_H >> 3] = "u16",
+ [BPF_B >> 3] = "u8",
+ [BPF_DW >> 3] = "u64",
+};
+
+static const char *const bpf_jmp_string[] = {
+ [BPF_JA >> 4] = "jmp",
+ [BPF_JEQ >> 4] = "==",
+ [BPF_JGT >> 4] = ">",
+ [BPF_JGE >> 4] = ">=",
+ [BPF_JSET >> 4] = "&",
+ [BPF_JNE >> 4] = "!=",
+ [BPF_JSGT >> 4] = "s>",
+ [BPF_JSGE >> 4] = "s>=",
+ [BPF_CALL >> 4] = "call",
+ [BPF_EXIT >> 4] = "exit",
+};
+#define _verbose pr_info
+static void print_bpf_insn(struct bpf_insn *insn)
+{
+ u8 class = BPF_CLASS(insn->code);
+
+ if (class == BPF_ALU || class == BPF_ALU64) {
+ if (BPF_SRC(insn->code) == BPF_X)
+ _verbose("(%02x) %sr%d %s %sr%d\n",
+ insn->code, class == BPF_ALU ? "(u32) " : "",
+ insn->dst_reg,
+ bpf_alu_string[BPF_OP(insn->code) >> 4],
+ class == BPF_ALU ? "(u32) " : "",
+ insn->src_reg);
+ else
+ _verbose("(%02x) %sr%d %s %s%d\n",
+ insn->code, class == BPF_ALU ? "(u32) " : "",
+ insn->dst_reg,
+ bpf_alu_string[BPF_OP(insn->code) >> 4],
+ class == BPF_ALU ? "(u32) " : "",
+ insn->imm);
+ } else if (class == BPF_STX) {
+ if (BPF_MODE(insn->code) == BPF_MEM)
+ _verbose("(%02x) *(%s *)(r%d %+d) = r%d\n",
+ insn->code,
+ bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
+ insn->dst_reg,
+ insn->off, insn->src_reg);
+ else if (BPF_MODE(insn->code) == BPF_XADD)
+ _verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n",
+ insn->code,
+ bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
+ insn->dst_reg, insn->off,
+ insn->src_reg);
+ else
+ _verbose("BUG_%02x\n", insn->code);
+ } else if (class == BPF_ST) {
+ if (BPF_MODE(insn->code) != BPF_MEM) {
+ _verbose("BUG_st_%02x\n", insn->code);
+ return;
+ }
+ _verbose("(%02x) *(%s *)(r%d %+d) = %d\n",
+ insn->code,
+ bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
+ insn->dst_reg,
+ insn->off, insn->imm);
+ } else if (class == BPF_LDX) {
+ if (BPF_MODE(insn->code) != BPF_MEM) {
+ _verbose("BUG_ldx_%02x\n", insn->code);
+ return;
+ }
+ _verbose("(%02x) r%d = *(%s *)(r%d %+d)\n",
+ insn->code, insn->dst_reg,
+ bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
+ insn->src_reg, insn->off);
+ } else if (class == BPF_LD) {
+ if (BPF_MODE(insn->code) == BPF_ABS) {
+ _verbose("(%02x) r0 = *(%s *)skb[%d]\n",
+ insn->code,
+ bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
+ insn->imm);
+ } else if (BPF_MODE(insn->code) == BPF_IND) {
+ _verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n",
+ insn->code,
+ bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
+ insn->src_reg, insn->imm);
+ } else if (BPF_MODE(insn->code) == BPF_IMM) {
+ _verbose("(%02x) r%d = 0x%x\n",
+ insn->code, insn->dst_reg, insn->imm);
+ } else {
+ _verbose("BUG_ld_%02x\n", insn->code);
+ return;
+ }
+ } else if (class == BPF_JMP) {
+ u8 opcode = BPF_OP(insn->code);
+
+ if (opcode == BPF_CALL) {
+ _verbose("(%02x) call %d\n", insn->code, insn->imm);
+ } else if (insn->code == (BPF_JMP | BPF_JA)) {
+ _verbose("(%02x) goto pc%+d\n",
+ insn->code, insn->off);
+ } else if (insn->code == (BPF_JMP | BPF_EXIT)) {
+ _verbose("(%02x) exit\n", insn->code);
+ } else if (BPF_SRC(insn->code) == BPF_X) {
+ _verbose("(%02x) if r%d %s r%d goto pc%+d\n",
+ insn->code, insn->dst_reg,
+ bpf_jmp_string[BPF_OP(insn->code) >> 4],
+ insn->src_reg, insn->off);
+ } else {
+ _verbose("(%02x) if r%d %s 0x%x goto pc%+d\n",
+ insn->code, insn->dst_reg,
+ bpf_jmp_string[BPF_OP(insn->code) >> 4],
+ insn->imm, insn->off);
+ }
+ } else {
+ _verbose("(%02x) %s\n", insn->code, bpf_class_string[class]);
+ }
+}
+
+void bpf_dump_prog(struct bpf_insn *insn, size_t nr_insn)
+{
+ unsigned int i;
+
+ for (i = 0; i < nr_insn; i++)
+ print_bpf_insn(&insn[i]);
+}
diff --git a/tools/perf/util/bpf.h b/tools/perf/util/bpf.h
index be106b0..b4a6802 100644
--- a/tools/perf/util/bpf.h
+++ b/tools/perf/util/bpf.h
@@ -19,4 +19,5 @@ struct bpf_map_def {
int sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr, size_t size);

int bpf_create_map(struct bpf_map_def *map_def);
+void bpf_dump_prog(struct bpf_insn *insn, size_t nr_insn);
#endif
--
1.8.3.4