| Message ID | 67ffe6998af5cf88bdda6eaa1e6b085db1e093ed.1609855479.git.sean@mess.org (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF |
| Headers | show |
| Series | btf: support ints larger than 128 bits | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Not a local patch |
On Tue, Jan 5, 2021 at 6:45 AM Sean Young <sean@mess.org> wrote: > > clang supports arbitrary length ints using the _ExtInt extension. This > can be useful to hold very large values, e.g. 256 bit or 512 bit types. > > This requires the _ExtInt extension enabled in clang, which is under > review. > > Link: https://clang.llvm.org/docs/LanguageExtensions.html#extended-integer-types > Link: https://reviews.llvm.org/D93103 > > Signed-off-by: Sean Young <sean@mess.org> > --- all the same comments as in patch #1 > tools/bpf/bpftool/btf_dumper.c | 40 ++++++++++++++++++++++++++++++++++ > 1 file changed, 40 insertions(+) > > diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c > index 0e9310727281..8b5318ec5c26 100644 > --- a/tools/bpf/bpftool/btf_dumper.c > +++ b/tools/bpf/bpftool/btf_dumper.c > @@ -271,6 +271,41 @@ static void btf_int128_print(json_writer_t *jw, const void *data, > } > } [...]
diff --git a/tools/bpf/bpftool/btf_dumper.c b/tools/bpf/bpftool/btf_dumper.c index 0e9310727281..8b5318ec5c26 100644 --- a/tools/bpf/bpftool/btf_dumper.c +++ b/tools/bpf/bpftool/btf_dumper.c @@ -271,6 +271,41 @@ static void btf_int128_print(json_writer_t *jw, const void *data, } } +static void btf_bigint_print(json_writer_t *jw, const void *data, int nr_bits, + bool is_plain_text) +{ + char buf[nr_bits / 4 + 1]; + int last_u64 = nr_bits / 64 - 1; + bool seen_nonzero = false; + int i; + + for (i = 0; i <= last_u64; i++) { +#ifdef __BIG_ENDIAN_BITFIELD + __u64 v = ((__u64 *)data)[i]; +#else + __u64 v = ((__u64 *)data)[last_u64 - i]; +#endif + + if (!seen_nonzero) { + if (!v && i != last_u64) + continue; + + snprintf(buf, sizeof(buf), "%llx", v); + + seen_nonzero = true; + } else { + size_t off = strlen(buf); + + snprintf(buf + off, sizeof(buf) - off, "%016llx", v); + } + } + + if (is_plain_text) + jsonw_printf(jw, "0x%s", buf); + else + jsonw_printf(jw, "\"0x%s\"", buf); +} + static void btf_int128_shift(__u64 *print_num, __u16 left_shift_bits, __u16 right_shift_bits) { @@ -373,6 +408,11 @@ static int btf_dumper_int(const struct btf_type *t, __u8 bit_offset, return 0; } + if (nr_bits > 128) { + btf_bigint_print(jw, data, nr_bits, is_plain_text); + return 0; + } + if (nr_bits == 128) { btf_int128_print(jw, data, is_plain_text); return 0;
clang supports arbitrary length ints using the _ExtInt extension. This can be useful to hold very large values, e.g. 256 bit or 512 bit types. This requires the _ExtInt extension enabled in clang, which is under review. Link: https://clang.llvm.org/docs/LanguageExtensions.html#extended-integer-types Link: https://reviews.llvm.org/D93103 Signed-off-by: Sean Young <sean@mess.org> --- tools/bpf/bpftool/btf_dumper.c | 40 ++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+)