> On Sep 19, 2018, at 5:59 PM, Alexei Starovoitov <a...@fb.com> wrote:
>
> On 9/19/18 4:44 PM, Song Liu wrote:
>>
>>
>>> On Sep 19, 2018, at 3:39 PM, Alexei Starovoitov <a...@kernel.org> wrote:
>>>
>>> use perf_event_mmap_bpf_prog() helper to notify user space
>>> about JITed bpf programs.
>>> Use RECORD_MMAP perf event to tell user space where JITed bpf program was
>>> loaded.
>>> Use empty program name as unload indication.
>>>
>>> Signed-off-by: Alexei Starovoitov <a...@kernel.org>
>>> ---
>>> kernel/bpf/core.c | 22 ++++++++++++++++++++--
>>> 1 file changed, 20 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
>>> index 3f5bf1af0826..ddf11fdafd36 100644
>>> --- a/kernel/bpf/core.c
>>> +++ b/kernel/bpf/core.c
>>> @@ -384,7 +384,7 @@ bpf_get_prog_addr_region(const struct bpf_prog *prog,
>>> *symbol_end = addr + hdr->pages * PAGE_SIZE;
>>> }
>>>
>>> -static void bpf_get_prog_name(const struct bpf_prog *prog, char *sym)
>>> +static char *bpf_get_prog_name(const struct bpf_prog *prog, char *sym)
>>> {
>>> const char *end = sym + KSYM_NAME_LEN;
>>>
>>> @@ -402,9 +402,10 @@ static void bpf_get_prog_name(const struct bpf_prog
>>> *prog, char *sym)
>>> sym += snprintf(sym, KSYM_NAME_LEN, "bpf_prog_");
>>> sym = bin2hex(sym, prog->tag, sizeof(prog->tag));
>>> if (prog->aux->name[0])
>>> - snprintf(sym, (size_t)(end - sym), "_%s", prog->aux->name);
>>> + sym += snprintf(sym, (size_t)(end - sym), "_%s",
>>> prog->aux->name);
>>> else
>>> *sym = 0;
>>> + return sym;
>>> }
>>>
>>> static __always_inline unsigned long
>>> @@ -480,23 +481,40 @@ static bool bpf_prog_kallsyms_verify_off(const struct
>>> bpf_prog *fp)
>>>
>>> void bpf_prog_kallsyms_add(struct bpf_prog *fp)
>>> {
>>> + unsigned long symbol_start, symbol_end;
>>> + char buf[KSYM_NAME_LEN], *sym;
>>> +
>>> if (!bpf_prog_kallsyms_candidate(fp) ||
>>> !capable(CAP_SYS_ADMIN))
>>> return;
>>>
>>> + bpf_get_prog_addr_region(fp, &symbol_start, &symbol_end);
>>> + sym = bpf_get_prog_name(fp, buf);
>>> + sym++; /* sym - buf is the length of the name including trailing 0 */
>>> + while (!IS_ALIGNED(sym - buf, sizeof(u64)))
>>> + *sym++ = 0;
>>
>> nit: This logic feels a little weird to me. How about we wrap the extra logic
>> in a separate function:
>>
>> size_t bpf_get_prog_name_u64_aligned(const struct bpf_prog fp, char *buf)
>
> probably bpf_get_prog_name_u64_padded() ?
> would be cleaner indeed.
bpf_get_prog_name_u64_padded does sound better.
> Will send v2 once Peter and Arnaldo provide their feedback.
>
> Thanks for reviewing!
