Re: [PATCH bpf-next v2 13/13] tools/bpf: bpftool: add support for jited func types
From: Edward Cree <hidden>
Date: 2018-10-17 19:06:54
On 17/10/18 08:24, Yonghong Song wrote:
quoted hunk ↗ jump to hunk
This patch added support to print function signature if btf func_info is available. Note that ksym now uses function name instead of prog_name as prog_name has a limit of 16 bytes including ending '\0'. The following is a sample output for selftests test_btf with file test_btf_haskv.o: $ bpftool prog dump jited id 1 int _dummy_tracepoint(struct dummy_tracepoint_args * ): bpf_prog_b07ccb89267cf242__dummy_tracepoint: 0: push %rbp 1: mov %rsp,%rbp ...... 3c: add $0x28,%rbp 40: leaveq 41: retq int test_long_fname_1(struct dummy_tracepoint_args * ): bpf_prog_2dcecc18072623fc_test_long_fname_1: 0: push %rbp 1: mov %rsp,%rbp ...... 3a: add $0x28,%rbp 3e: leaveq 3f: retq int test_long_fname_2(struct dummy_tracepoint_args * ): bpf_prog_89d64e4abf0f0126_test_long_fname_2: 0: push %rbp 1: mov %rsp,%rbp ...... 80: add $0x28,%rbp 84: leaveq 85: retq Signed-off-by: Yonghong Song <redacted> --- tools/bpf/bpftool/btf_dumper.c | 96 ++++++++++++++++++++++++++++++++++ tools/bpf/bpftool/main.h | 2 + tools/bpf/bpftool/prog.c | 54 +++++++++++++++++++ 3 files changed, 152 insertions(+)diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c index 55bc512a1831..a31df4202335 100644 --- a/tools/bpf/bpftool/btf_dumper.c +++ b/tools/bpf/bpftool/btf_dumper.c@@ -249,3 +249,99 @@ int btf_dumper_type(const struct btf_dumper *d, __u32 type_id, { return btf_dumper_do_type(d, type_id, 0, data); } + +#define BTF_PRINT_STRING(str) \ + { \ + pos += snprintf(func_sig + pos, size - pos, str); \ + if (pos >= size) \ + return -1; \ + }
Usual kernel practice for this sort of macro is to use
do { \
} while(0)
to ensure correct behaviour if the macro is used within another control
flow statement, e.g.
if (x)
BTF_PRINT_STRING(x);
else
do_something_else();
will not compile with the bare braces as the else will be detached.+#define BTF_PRINT_ONE_ARG(fmt, arg) \
+ { \
+ pos += snprintf(func_sig + pos, size - pos, fmt, arg); \
+ if (pos >= size) \
+ return -1; \
+ }Any reason for not just using a variadic macro?
+#define BTF_PRINT_TYPE_ONLY(type) \
+ { \
+ pos = __btf_dumper_type_only(btf, type, func_sig, \
+ pos, size); \
+ if (pos == -1) \
+ return -1; \
+ }
+
+static int __btf_dumper_type_only(struct btf *btf, __u32 type_id,
+ char *func_sig, int pos, int size)
+{
+ const struct btf_type *t = btf__type_by_id(btf, type_id);
+ const struct btf_array *array;
+ int i, vlen;
+
+ switch (BTF_INFO_KIND(t->info)) {
+ case BTF_KIND_INT:
+ BTF_PRINT_ONE_ARG("%s ",
+ btf__name_by_offset(btf, t->name_off));
+ break;
+ case BTF_KIND_STRUCT:
+ BTF_PRINT_ONE_ARG("struct %s ",
+ btf__name_by_offset(btf, t->name_off));
+ break;
+ case BTF_KIND_UNION:
+ BTF_PRINT_ONE_ARG("union %s ",
+ btf__name_by_offset(btf, t->name_off));
+ break;
+ case BTF_KIND_ENUM:
+ BTF_PRINT_ONE_ARG("enum %s ",
+ btf__name_by_offset(btf, t->name_off));
+ break;
+ case BTF_KIND_ARRAY:
+ array = (struct btf_array *)(t + 1);
+ BTF_PRINT_TYPE_ONLY(array->type);
+ BTF_PRINT_ONE_ARG("[%d]", array->nelems);
+ break;
+ case BTF_KIND_PTR:
+ BTF_PRINT_TYPE_ONLY(t->type);
+ BTF_PRINT_STRING("* ");
+ break;
+ case BTF_KIND_UNKN:
+ case BTF_KIND_FWD:
+ case BTF_KIND_TYPEDEF:
+ return -1;
+ case BTF_KIND_VOLATILE:
+ BTF_PRINT_STRING("volatile ");
+ BTF_PRINT_TYPE_ONLY(t->type);
+ break;
+ case BTF_KIND_CONST:
+ BTF_PRINT_STRING("const ");
+ BTF_PRINT_TYPE_ONLY(t->type);
+ break;
+ case BTF_KIND_RESTRICT:
+ BTF_PRINT_STRING("restrict ");
+ BTF_PRINT_TYPE_ONLY(t->type);
+ break;
+ case BTF_KIND_FUNC:
+ case BTF_KIND_FUNC_PROTO:
+ BTF_PRINT_TYPE_ONLY(t->type);
+ BTF_PRINT_ONE_ARG("%s(", btf__name_by_offset(btf, t->name_off));
+ vlen = BTF_INFO_VLEN(t->info);
+ for (i = 0; i < vlen; i++) {
+ __u32 arg_type = ((__u32 *)(t + 1))[i];
+
+ BTF_PRINT_TYPE_ONLY(arg_type);
+ if (i != (vlen - 1))
+ BTF_PRINT_STRING(", ");
+ }In this kind of loop I find it cleaner to print the comma before the item;
that way the test becomes i != 0. Thus:
for (i = 0; i < vlen; i++) {
__u32 arg_type = ((__u32 *)(t + 1))[i];
if (i)
BTF_PRINT_STRING(", ");
BTF_PRINT_TYPE_ONLY(arg_type);
}
-Ed