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Date: Mon, 23 Oct 2017 09:24:10 -0700
From: Jakub Kicinski <jakub.kicinski@...ronome.com>
To: netdev@...r.kernel.org
Cc: oss-drivers@...ronome.com, alexei.starovoitov@...il.com,
daniel@...earbox.net, Quentin Monnet <quentin.monnet@...ronome.com>
Subject: [PATCH net-next 06/12] tools: bpftool: add JSON output for `bpftool prog dump xlated *` command
From: Quentin Monnet <quentin.monnet@...ronome.com>
Add a new printing function to dump translated eBPF instructions as
JSON. As for plain output, opcodes are printed only on request (when
`opcodes` is provided on the command line).
The disassembled output is generated by the same code that is used by
the kernel verifier.
Example output:
$ bpftool --json --pretty prog dump xlated id 1
[{
"disasm": "(bf) r6 = r1"
},{
"disasm": "(61) r7 = *(u32 *)(r6 +16)"
},{
"disasm": "(95) exit"
}
]
$ bpftool --json --pretty prog dump xlated id 1 opcodes
[{
"disasm": "(bf) r6 = r1",
"opcodes": {
"code": "0xbf",
"src_reg": "0x1",
"dst_reg": "0x6",
"off": ["0x00","0x00"
],
"imm": ["0x00","0x00","0x00","0x00"
]
}
},{
"disasm": "(61) r7 = *(u32 *)(r6 +16)",
"opcodes": {
"code": "0x61",
"src_reg": "0x6",
"dst_reg": "0x7",
"off": ["0x10","0x00"
],
"imm": ["0x00","0x00","0x00","0x00"
]
}
},{
"disasm": "(95) exit",
"opcodes": {
"code": "0x95",
"src_reg": "0x0",
"dst_reg": "0x0",
"off": ["0x00","0x00"
],
"imm": ["0x00","0x00","0x00","0x00"
]
}
}
]
Signed-off-by: Quentin Monnet <quentin.monnet@...ronome.com>
---
tools/bpf/bpftool/common.c | 10 ++++++
tools/bpf/bpftool/json_writer.c | 8 +++++
tools/bpf/bpftool/json_writer.h | 2 ++
tools/bpf/bpftool/main.h | 1 +
tools/bpf/bpftool/prog.c | 70 +++++++++++++++++++++++++++++++++++++++--
5 files changed, 89 insertions(+), 2 deletions(-)
diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index df8396a0c400..e7a756b8ee21 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -214,3 +214,13 @@ char *get_fdinfo(int fd, const char *key)
fclose(fdi);
return NULL;
}
+
+void print_hex_data_json(uint8_t *data, size_t len)
+{
+ unsigned int i;
+
+ jsonw_start_array(json_wtr);
+ for (i = 0; i < len; i++)
+ jsonw_printf(json_wtr, "\"0x%02hhx\"", data[i]);
+ jsonw_end_array(json_wtr);
+}
diff --git a/tools/bpf/bpftool/json_writer.c b/tools/bpf/bpftool/json_writer.c
index 6b77d288cce2..c6eef76322ae 100644
--- a/tools/bpf/bpftool/json_writer.c
+++ b/tools/bpf/bpftool/json_writer.c
@@ -156,6 +156,14 @@ void jsonw_name(json_writer_t *self, const char *name)
putc(' ', self->out);
}
+void jsonw_vprintf_enquote(json_writer_t *self, const char *fmt, va_list ap)
+{
+ jsonw_eor(self);
+ putc('"', self->out);
+ vfprintf(self->out, fmt, ap);
+ putc('"', self->out);
+}
+
void jsonw_printf(json_writer_t *self, const char *fmt, ...)
{
va_list ap;
diff --git a/tools/bpf/bpftool/json_writer.h b/tools/bpf/bpftool/json_writer.h
index 1516aafba59d..0fa2fb1b6351 100644
--- a/tools/bpf/bpftool/json_writer.h
+++ b/tools/bpf/bpftool/json_writer.h
@@ -17,6 +17,7 @@
#include <stdbool.h>
#include <stdint.h>
+#include <stdarg.h>
/* Opaque class structure */
typedef struct json_writer json_writer_t;
@@ -33,6 +34,7 @@ void jsonw_pretty(json_writer_t *self, bool on);
void jsonw_name(json_writer_t *self, const char *name);
/* Add value */
+void jsonw_vprintf_enquote(json_writer_t *self, const char *fmt, va_list ap);
void jsonw_printf(json_writer_t *self, const char *fmt, ...);
void jsonw_string(json_writer_t *self, const char *value);
void jsonw_bool(json_writer_t *self, bool value);
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index 15927fc9fb31..693fc9710be1 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -95,5 +95,6 @@ int do_map(int argc, char **arg);
int prog_parse_fd(int *argc, char ***argv);
void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes);
+void print_hex_data_json(uint8_t *data, size_t len);
#endif
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index f373f2baef5a..43e49799a624 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -385,7 +385,7 @@ static void print_insn(struct bpf_verifier_env *env, const char *fmt, ...)
va_end(args);
}
-static void dump_xlated(void *buf, unsigned int len, bool opcodes)
+static void dump_xlated_plain(void *buf, unsigned int len, bool opcodes)
{
struct bpf_insn *insn = buf;
bool double_insn = false;
@@ -414,6 +414,69 @@ static void dump_xlated(void *buf, unsigned int len, bool opcodes)
}
}
+static void print_insn_json(struct bpf_verifier_env *env, const char *fmt, ...)
+{
+ unsigned int l = strlen(fmt);
+ char chomped_fmt[l];
+ va_list args;
+
+ va_start(args, fmt);
+ if (l > 0) {
+ strncpy(chomped_fmt, fmt, l - 1);
+ chomped_fmt[l - 1] = '\0';
+ }
+ jsonw_vprintf_enquote(json_wtr, chomped_fmt, args);
+ va_end(args);
+}
+
+static void dump_xlated_json(void *buf, unsigned int len, bool opcodes)
+{
+ struct bpf_insn *insn = buf;
+ bool double_insn = false;
+ unsigned int i;
+
+ jsonw_start_array(json_wtr);
+ for (i = 0; i < len / sizeof(*insn); i++) {
+ if (double_insn) {
+ double_insn = false;
+ continue;
+ }
+ double_insn = insn[i].code == (BPF_LD | BPF_IMM | BPF_DW);
+
+ jsonw_start_object(json_wtr);
+ jsonw_name(json_wtr, "disasm");
+ print_bpf_insn(print_insn_json, NULL, insn + i, true);
+
+ if (opcodes) {
+ jsonw_name(json_wtr, "opcodes");
+ jsonw_start_object(json_wtr);
+
+ jsonw_name(json_wtr, "code");
+ jsonw_printf(json_wtr, "\"0x%02hhx\"", insn[i].code);
+
+ jsonw_name(json_wtr, "src_reg");
+ jsonw_printf(json_wtr, "\"0x%hhx\"", insn[i].src_reg);
+
+ jsonw_name(json_wtr, "dst_reg");
+ jsonw_printf(json_wtr, "\"0x%hhx\"", insn[i].dst_reg);
+
+ jsonw_name(json_wtr, "off");
+ print_hex_data_json((uint8_t *)(&insn[i].off), 2);
+
+ jsonw_name(json_wtr, "imm");
+ if (double_insn && i < len - 1)
+ print_hex_data_json((uint8_t *)(&insn[i].imm),
+ 12);
+ else
+ print_hex_data_json((uint8_t *)(&insn[i].imm),
+ 4);
+ jsonw_end_object(json_wtr);
+ }
+ jsonw_end_object(json_wtr);
+ }
+ jsonw_end_array(json_wtr);
+}
+
static int do_dump(int argc, char **argv)
{
struct bpf_prog_info info = {};
@@ -523,7 +586,10 @@ static int do_dump(int argc, char **argv)
if (member_len == &info.jited_prog_len)
disasm_print_insn(buf, *member_len, opcodes);
else
- dump_xlated(buf, *member_len, opcodes);
+ if (json_output)
+ dump_xlated_json(buf, *member_len, opcodes);
+ else
+ dump_xlated_plain(buf, *member_len, opcodes);
}
free(buf);
--
2.14.1
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