Commit f05e2c32 authored by Quentin Monnet's avatar Quentin Monnet Committed by David S. Miller

tools: bpftool: add JSON output for `bpftool prog dump xlated *` command

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: default avatarQuentin Monnet <quentin.monnet@netronome.com>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 107f0412
...@@ -214,3 +214,13 @@ char *get_fdinfo(int fd, const char *key) ...@@ -214,3 +214,13 @@ char *get_fdinfo(int fd, const char *key)
fclose(fdi); fclose(fdi);
return NULL; 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);
}
...@@ -156,6 +156,14 @@ void jsonw_name(json_writer_t *self, const char *name) ...@@ -156,6 +156,14 @@ void jsonw_name(json_writer_t *self, const char *name)
putc(' ', self->out); 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, ...) void jsonw_printf(json_writer_t *self, const char *fmt, ...)
{ {
va_list ap; va_list ap;
......
...@@ -17,6 +17,7 @@ ...@@ -17,6 +17,7 @@
#include <stdbool.h> #include <stdbool.h>
#include <stdint.h> #include <stdint.h>
#include <stdarg.h>
/* Opaque class structure */ /* Opaque class structure */
typedef struct json_writer json_writer_t; typedef struct json_writer json_writer_t;
...@@ -33,6 +34,7 @@ void jsonw_pretty(json_writer_t *self, bool on); ...@@ -33,6 +34,7 @@ void jsonw_pretty(json_writer_t *self, bool on);
void jsonw_name(json_writer_t *self, const char *name); void jsonw_name(json_writer_t *self, const char *name);
/* Add value */ /* 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_printf(json_writer_t *self, const char *fmt, ...);
void jsonw_string(json_writer_t *self, const char *value); void jsonw_string(json_writer_t *self, const char *value);
void jsonw_bool(json_writer_t *self, bool value); void jsonw_bool(json_writer_t *self, bool value);
......
...@@ -95,5 +95,6 @@ int do_map(int argc, char **arg); ...@@ -95,5 +95,6 @@ int do_map(int argc, char **arg);
int prog_parse_fd(int *argc, char ***argv); int prog_parse_fd(int *argc, char ***argv);
void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes); void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes);
void print_hex_data_json(uint8_t *data, size_t len);
#endif #endif
...@@ -385,7 +385,7 @@ static void print_insn(struct bpf_verifier_env *env, const char *fmt, ...) ...@@ -385,7 +385,7 @@ static void print_insn(struct bpf_verifier_env *env, const char *fmt, ...)
va_end(args); 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; struct bpf_insn *insn = buf;
bool double_insn = false; bool double_insn = false;
...@@ -414,6 +414,69 @@ static void dump_xlated(void *buf, unsigned int len, bool opcodes) ...@@ -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) static int do_dump(int argc, char **argv)
{ {
struct bpf_prog_info info = {}; struct bpf_prog_info info = {};
...@@ -523,7 +586,10 @@ static int do_dump(int argc, char **argv) ...@@ -523,7 +586,10 @@ static int do_dump(int argc, char **argv)
if (member_len == &info.jited_prog_len) if (member_len == &info.jited_prog_len)
disasm_print_insn(buf, *member_len, opcodes); disasm_print_insn(buf, *member_len, opcodes);
else 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); free(buf);
......
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