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Date: Wed, 16 Nov 2016 18:46:25 -0800
From: Joe Stringer <joe@....org>
To: "Wangnan (F)" <wangnan0@...wei.com>
Cc: Joe Stringer <joe@....org>, LKML <linux-kernel@...r.kernel.org>,
netdev <netdev@...r.kernel.org>, ast@...com,
daniel@...earbox.net, acme@...nel.org
Subject: Re: [PATCHv2 perf/core 2/2] tools lib bpf: Sync with samples/bpf/libbpf
On 16 November 2016 at 18:10, Wangnan (F) <wangnan0@...wei.com> wrote:
> I'm also working on improving bpf.c. Please have a look at:
>
> https://lkml.org/lkml/2016/11/14/1078
>
> Since bpf.c is simple, I think we can add more functions and fixes
> gradually, instead of a full copy.
>
> See my inline comment below.
Ah, I missed this, my apologies. It looks like it will provide much of
what I need, I can reassess this patch with your series in mind.
One comment though for your patch (I don't have the original thread to
respond to unfortunately): The map_pin and map_get functions in your
patch series can be used to pin progs too, so maybe there is a better
name? You'll see that this patch uses bpf_obj_{pin,get}() - although I
wouldn't want those to be confused with the libbpf.c objects so maybe
there's a clearer name that could be used.
I also have some patches to rework the samples/bpf/* code to use
libbpf instead of the sample code that is there, is it worth me
submitting that? It will need to wait for your patch to go in, plus a
merge with davem's tree.
>
> On 2016/11/17 1:43, Joe Stringer wrote:
>>
>> Extend the tools/ version of libbpf to include all of the functionality
>> provided in the samples/bpf version.
>>
>> Signed-off-by: Joe Stringer <joe@....org>
>> ---
>> v2: Don't shift non-bpf changes across.
>> Various type cleanups, removal of extraneous declarations
>> ---
>> tools/lib/bpf/bpf.c | 107 ++++++++++++++++++++------
>> tools/lib/bpf/bpf.h | 202
>> +++++++++++++++++++++++++++++++++++++++++++++++--
>> tools/lib/bpf/libbpf.c | 3 +-
>> 3 files changed, 279 insertions(+), 33 deletions(-)
>>
>> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
>> index 4212ed62235b..5e061851ac00 100644
>> --- a/tools/lib/bpf/bpf.c
>> +++ b/tools/lib/bpf/bpf.c
>> @@ -20,10 +20,17 @@
>> */
>> #include <stdlib.h>
>> -#include <memory.h>
>> +#include <stdio.h>
>> #include <unistd.h>
>> #include <asm/unistd.h>
>> +#include <string.h>
>> +#include <linux/netlink.h>
>> #include <linux/bpf.h>
>> +#include <errno.h>
>> +#include <net/ethernet.h>
>> +#include <net/if.h>
>> +#include <linux/if_packet.h>
>> +#include <arpa/inet.h>
>> #include "bpf.h"
>>
>
>
> Why we need these network related headers?
I started with a copy/paste, assuming that the headers were all in use
but I guess that assumption was wrong.
>> /*
>> @@ -53,24 +60,71 @@ static int sys_bpf(enum bpf_cmd cmd, union bpf_attr
>> *attr,
>> return syscall(__NR_bpf, cmd, attr, size);
>> }
>> -int bpf_create_map(enum bpf_map_type map_type, int key_size,
>> - int value_size, int max_entries)
>> +int bpf_create_map(enum bpf_map_type map_type, int key_size, int
>> value_size,
>> + int max_entries, int map_flags)
>> {
>> - union bpf_attr attr;
>> + union bpf_attr attr = {
>> + .map_type = map_type,
>> + .key_size = key_size,
>> + .value_size = value_size,
>> + .max_entries = max_entries,
>> + .map_flags = map_flags,
>> + };
>> - memset(&attr, '\0', sizeof(attr));
>> + return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
>> +}
>>
>
>
> I lost map_flags in original bpf.c. Thanks to your patch. map_flags is
> useful
> when creating BPF_MAP_TYPE_PERCPU_HASH: BPF_F_NO_PREALLOC is meanful in this
> case.
Do you want me to resubmit this piece as a separate patch or will you
address this?
> Although it is okay in samples, I still prefer a explicit bzero() or
> memset(),
> because kernel checks if unused field in this union is zero. However I'll
> check
> c standard to see how unused field would be initialized.
OK.
>> diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
>> index e8ba54087497..4dba36995771 100644
>> --- a/tools/lib/bpf/bpf.h
>> +++ b/tools/lib/bpf/bpf.h
>> @@ -23,16 +23,202 @@
>> #include <linux/bpf.h>
>> +struct bpf_insn;
>> +
>> int bpf_create_map(enum bpf_map_type map_type, int key_size, int
>> value_size,
>> - int max_entries);
>> + int max_entries, int map_flags);
>> +int bpf_update_elem(int fd, void *key, void *value, unsigned long long
>> flags);
>> +int bpf_lookup_elem(int fd, void *key, void *value);
>> +int bpf_delete_elem(int fd, void *key);
>> +int bpf_get_next_key(int fd, void *key, void *next_key);
>> +
>> +int bpf_load_program(enum bpf_prog_type prog_type,
>> + const struct bpf_insn *insns, int insn_len,
>> + const char *license, int kern_version,
>> + char *log_buf, size_t log_buf_sz);
>> +
>> +int bpf_obj_pin(int fd, const char *pathname);
>> +int bpf_obj_get(const char *pathname);
>> -/* Recommend log buffer size */
>> #define BPF_LOG_BUF_SIZE 65536
>> -int bpf_load_program(enum bpf_prog_type type, struct bpf_insn *insns,
>> - size_t insns_cnt, char *license,
>> - u32 kern_version, char *log_buf,
>> - size_t log_buf_sz);
>> -int bpf_map_update_elem(int fd, void *key, void *value,
>> - u64 flags);
>> +/* ALU ops on registers, bpf_add|sub|...: dst_reg += src_reg */
>> +
>> +#define BPF_ALU64_REG(OP, DST, SRC) \
>> + ((struct bpf_insn) { \
>> + .code = BPF_ALU64 | BPF_OP(OP) | BPF_X, \
>> + .dst_reg = DST, \
>> + .src_reg = SRC, \
>> + .off = 0, \
>> + .imm = 0 })
>> +
>
>
> Should we define these macros here? They are in include/linux/filter.h
> and duplicated in tools/include/linux/filter.h. Redefining them here
> would cause conflict.
Probably not; including the correct header file would be sufficient.
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