Our goal is to access no more than one cache line access per skb in
a write or receive queue when doing the various walks.

After recent TCP_SKB_CB() reorganizations, it is almost done.

Last part is tcp_skb_pcount() which currently uses
skb_shinfo(skb)->gso_segs, which is a terrible choice, because it needs
3 cache lines in current kernel (skb->head, skb->end, and
shinfo->gso_segs are all in 3 different cache lines, far from skb->cb)

This very simple patch reuses space currently taken by tcp_tw_isn
only in input path, as tcp_skb_pcount is only needed for skb stored in
write queue.

This considerably speeds up tcp_ack(), granted we avoid shinfo->tx_flags
to get SKBTX_ACK_TSTAMP, which seems possible.

This also speeds up all sack processing in general.

This speeds up tcp_sendmsg() because it no longer has to access/dirty
shinfo.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Eric Dumazet says:

====================
tcp: better TCP_SKB_CB layout

TCP had the assumption that IPCB and IP6CB are first members of skb->cb[]

This is fine, except that IPCB/IP6CB are used in TCP for a very short time
in input path.

What really matters for TCP stack is to get skb->next,
TCP_SKB_CB(skb)->seq, and TCP_SKB_CB(skb)->end_seq in the same cache line.

skb that are immediately consumed do not care because whole skb->cb[] is
hot in cpu cache, while skb that sit in wocket write queue or receive queues
do not need TCP_SKB_CB(skb)->header at all.

This patch set implements the prereq for IPv4, IPv6, and TCP to make this
possible. This makes TCP more efficient.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

TCP maintains lists of skb in write queue, and in receive queues
(in order and out of order queues)

Scanning these lists both in input and output path usually requires
access to skb->next, TCP_SKB_CB(skb)->seq, and TCP_SKB_CB(skb)->end_seq

These fields are currently in two different cache lines, meaning we
waste lot of memory bandwidth when these queues are big and flows
have either packet drops or packet reorders.

We can move TCP_SKB_CB(skb)->header at the end of TCP_SKB_CB, because
this header is not used in fast path. This allows TCP to search much faster
in the skb lists.

Even with regular flows, we save one cache line miss in fast path.

Thanks to Christoph Paasch for noticing we need to cleanup
skb->cb[] (IPCB/IP6CB) before entering IP stack in tx path,
and that I forgot IPCB use in tcp_v4_hnd_req() and tcp_v4_save_options().
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

ipv6_opt_accepted() assumes IP6CB(skb) holds the struct inet6_skb_parm
that it needs. Lets not assume this, as TCP stack might use a different
place.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

ip_options_echo() assumes struct ip_options is provided in &IPCB(skb)->opt
Lets break this assumption, but provide a helper to not change all call points.

ip_send_unicast_reply() gets a new struct ip_options pointer.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Cache skb_shinfo(skb) in a variable to avoid computing it multiple
times.

Reorganize the tests to remove one indentation level.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

BPF_LD | BPF_W | BPF_LEN instruction is occasionally used by tcpdump
and present in 11 tests in lib/test_bpf.c
Teach sparc JIT compiler to emit it.
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

bcmgenet_wol_resume() is only used in bcmgenet_resume(), which is only
defined when CONFIG_PM_SLEEP is enabled. This leads to the following
compile warning when building with !CONFIG_PM_SLEEP:

drivers/net/ethernet/broadcom/genet/bcmgenet.c:1967:12: warning: ‘bcmgenet_wol_resume’ defined but not used [-Wunused-function]

Since bcmgenet_resume() is the only user of bcmgenet_wol_resume(), fix
this by directly inlining the function there.
Reported-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NTobias Klauser <tklauser@distanz.ch>
Acked-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Remove the duplicated comment
"/* The following definitions are for users of the vport subsytem: */"
in vport.h
Signed-off-by: NWang Sheng-Hui <shhuiw@gmail.com>
Acked-by: NPravin B Shelar <pshelar@nicira.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Jeff Kirsher says:

====================
Intel Wired LAN Driver Updates 2014-09-23

This patch series adds support for the FM10000 Ethernet switch host
interface.  The Intel FM10000 Ethernet Switch is a 48-port Ethernet switch
supporting both Ethernet ports and PCI Express host interfaces.  The fm10k
driver provides support for the host interface portion of the switch, both
PF and VF.

As the host interfaces are directly connected to the switch this results in
some significant differences versus a standard network driver.  For example
there is no PHY or MII on the device.  Since packets are delivered directly
from the switch to the host interface these are unnecessary.  Otherwise most
of the functionality is very similar to our other network drivers such as
ixgbe or igb.  For example we support all the standard network offloads,
jumbo frames, SR-IOV (64 VFS), PTP, and some VXLAN and NVGRE offloads.

v2: converted dev_consume_skb_any() to dev_kfree_skb_any()
    fix up PTP code based on feedback from the community
v3: converted the use of smb_mb__before_clear_bit() to smb_mb__before_atomic()
    added vmalloc header to patch 15
    added prefetch header to patch 16
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

csum_partial() is a generic function which is not optimised for small fixed
length calculations, and its use requires to store "from" and "to" values in
memory while we already have them available in registers. This also has impact,
especially on RISC processors. In the same spirit as the change done by
Eric Dumazet on csum_replace2(), this patch rewrites inet_proto_csum_replace4()
taking into account RFC1624.

I spotted during a NATted tcp transfert that csum_partial() is one of top 5
consuming functions (around 8%), and the second user of csum_partial() is
inet_proto_csum_replace4().
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

csum_partial() is a generic function which is not optimised for small fixed
length calculations, and its use requires to store "from" and "to" values in
memory while we already have them available in registers. This also has impact,
especially on RISC processors. In the same spirit as the change done by
Eric Dumazet on csum_replace2(), this patch rewrites inet_proto_csum_replace4()
taking into account RFC1624.

I spotted during a NATted tcp transfert that csum_partial() is one of top 5
consuming functions (around 8%), and the second user of csum_partial() is
inet_proto_csum_replace4().

I have proposed the same modification to inet_proto_csum_replace4() in another
patch.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Fugang Duan says:

====================
net: fec: Code cleanup

This patches does several things:
  - Fixing multiqueue issue.
  - Removing the unnecessary errata workaround.
  - Aligning the data buffer dma map/unmap size.
  - Freeing resource after probe failed.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Free memory and disable all related clocks when there has no phy
connection or phy probe failed.
Signed-off-by: NFugang Duan <B38611@freescale.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Align allocated rx data buffer size for dma map/unmap, otherwise
kernel print warning when enable DMA_API_DEBUG.
Signed-off-by: NFugang Duan <B38611@freescale.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Remove the ERR006358 workaround for imx6sx enet since the hw issue
was fixed on the SOC.
Signed-off-by: NFugang Duan <B38611@freescale.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The current driver loss Ftype field init for BD, which cause tx
queue #1 and #2 cannot work well.

Add Ftype field to BD to distiguish three queues for AVB:
0 -> Best Effort
1 -> ClassA
2 -> ClassB
Signed-off-by: NFugang Duan <B38611@freescale.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

While profiling TCP stack, I noticed one useless atomic operation
in tcp_sendmsg(), caused by skb_header_release().

It turns out all current skb_header_release() users have a fresh skb,
that no other user can see, so we can avoid one atomic operation.

Introduce __skb_header_release() to clearly document this.

This gave me a 1.5 % improvement on TCP_RR workload.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Sparse complains about fec_enet_select_queue() not being static.

Feedback from David Miller [1] was to remove this function instead of making it
static:

"Please just delete this function.

It's overriding code which does exactly the same thing.

Actually, more precisely, this code is duplicating code in a way that
bypasses many core facilitites of the networking.  For example, this
override means that socket based flow steering, XPS, etc. are all
not happening on these devices.

Without ->ndo_select_queue(), the flow dissector does __netdev_pick_tx
which is exactly what you want to happen."

[1] http://www.spinics.net/lists/netdev/msg297653.htmlSigned-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Merge tag 'master-2014-09-16' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next

John W. Linville says:

====================
pull request: wireless-next 2014-09-22

Please pull this batch of updates intended for the 3.18 stream...

For the mac80211 bits, Johannes says:

"This time, I have some rate minstrel improvements, support for a very
small feature from CCX that Steinar reverse-engineered, dynamic ACK
timeout support, a number of changes for TDLS, early support for radio
resource measurement and many fixes. Also, I'm changing a number of
places to clear key memory when it's freed and Intel claims copyright
for code they developed."

For the bluetooth bits, Johan says:

"Here are some more patches intended for 3.18. Most of them are cleanups
or fixes for SMP. The only exception is a fix for BR/EDR L2CAP fixed
channels which should now work better together with the L2CAP
information request procedure."

For the iwlwifi bits, Emmanuel says:

"I fix here dvm which was broken by my last pull request. Arik
continues to work on TDLS and Luca solved a few issues in CT-Kill. Eyal
keeps digging into rate scaling code, more to come soon. Besides this,
nothing really special here."

Beyond that, there are the usual big batches of updates to ath9k, b43,
mwifiex, and wil6210 as well as a handful of other bits here and there.
Also, rtlwifi gets some btcoexist attention from Larry.

Please let me know if there are problems!
====================

Had to adjust the wil6210 code to comply with Joe Perches's recent
change in net-next to make the netdev_*() routines return void instead
of 'int'.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

No caller or macro uses the return value so make all
the functions return void.
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

No caller or macro uses the return value so make it void.
Signed-off-by: NJoe Perches <joe@perches.com>
Acked-By: NAmir Vadai <amirv@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Alexei Starovoitov says:

====================
eBPF syscall, verifier, testsuite

v14 -> v15:
- got rid of macros with hidden control flow (suggested by David)
  replaced macro with explicit goto or return and simplified
  where possible (affected patches #9 and #10)
- rebased, retested

v13 -> v14:
- small change to 1st patch to ease 'new userspace with old kernel'
  problem (done similar to perf_copy_attr()) (suggested by Daniel)
- the rest unchanged

v12 -> v13:
- replaced 'foo __user *' pointers with __aligned_u64 (suggested by David)
- added __attribute__((aligned(8)) to 'union bpf_attr' to keep
  constant alignment between patches
- updated manpage and syscall wrappers due to __aligned_u64
- rebased, retested on x64 with 32-bit and 64-bit userspace and on i386,
  build tested on arm32,sparc64

v11 -> v12:
- dropped patch 11 and copied few macros to libbpf.h (suggested by Daniel)
- replaced 'enum bpf_prog_type' with u32 to be safe in compat (.. Andy)
- implemented and tested compat support (not part of this set) (.. Daniel)
- changed 'void *log_buf' to 'char *' (.. Daniel)
- combined struct bpf_work_struct and bpf_prog_info (.. Daniel)
- added better return value explanation to manpage (.. Andy)
- added log_buf/log_size explanation to manpage (.. Andy & Daniel)
- added a lot more info about prog_type and map_type to manpage (.. Andy)
- rebased, tweaked test_stubs

Patches 1-4 establish BPF syscall shell for maps and programs.
Patches 5-10 add verifier step by step
Patch 11 adds test stubs for 'unspec' program type and verifier testsuite
  from user space

Note that patches 1,3,4,7 add commands and attributes to the syscall
while being backwards compatible from each other, which should demonstrate
how other commands can be added in the future.

After this set the programs can be loaded for testing only. They cannot
be attached to any events. Though manpage talks about tracing and sockets,
it will be a subject of future patches.

Please take a look at manpage:

BPF(2)                     Linux Programmer's Manual                    BPF(2)

NAME
       bpf - perform a command on eBPF map or program

SYNOPSIS
       #include <linux/bpf.h>

       int bpf(int cmd, union bpf_attr *attr, unsigned int size);

DESCRIPTION
       bpf()  syscall  is a multiplexor for a range of different operations on
       eBPF  which  can  be  characterized  as  "universal  in-kernel  virtual
       machine".  eBPF  is  similar  to  original  Berkeley  Packet Filter (or
       "classic BPF") used to filter network packets. Both statically  analyze
       the  programs  before  loading  them  into  the  kernel  to ensure that
       programs cannot harm the running system.

       eBPF extends classic BPF in multiple ways including ability to call in-
       kernel  helper  functions  and  access shared data structures like eBPF
       maps.  The programs can be written in a restricted C that  is  compiled
       into  eBPF  bytecode  and executed on the eBPF virtual machine or JITed
       into native instruction set.

   eBPF Design/Architecture
       eBPF maps is a generic storage of different types.   User  process  can
       create  multiple  maps  (with key/value being opaque bytes of data) and
       access them via file descriptor. In parallel eBPF programs  can  access
       maps  from inside the kernel.  It's up to user process and eBPF program
       to decide what they store inside maps.

       eBPF programs are similar to kernel modules. They  are  loaded  by  the
       user  process  and automatically unloaded when process exits. Each eBPF
       program is a safe run-to-completion set of instructions. eBPF  verifier
       statically  determines  that  the  program  terminates  and  is safe to
       execute. During verification the program takes a hold of maps  that  it
       intends to use, so selected maps cannot be removed until the program is
       unloaded. The program can be attached to different events. These events
       can  be packets, tracepoint events and other types in the future. A new
       event triggers execution of the program  which  may  store  information
       about the event in the maps.  Beyond storing data the programs may call
       into in-kernel helper functions which may, for example, dump stack,  do
       trace_printk  or other forms of live kernel debugging. The same program
       can be attached to multiple events. Different programs can  access  the
       same map:
         tracepoint  tracepoint  tracepoint    sk_buff    sk_buff
          event A     event B     event C      on eth0    on eth1
           |             |          |            |          |
           |             |          |            |          |
           --> tracing <--      tracing       socket      socket
                prog_1           prog_2       prog_3      prog_4
                |  |               |            |
             |---  -----|  |-------|           map_3
           map_1       map_2

   Syscall Arguments
       bpf()  syscall  operation  is determined by cmd which can be one of the
       following:

       BPF_MAP_CREATE
              Create a map with given type and attributes and return map FD

       BPF_MAP_LOOKUP_ELEM
              Lookup element by key in a given map and return its value

       BPF_MAP_UPDATE_ELEM
              Create or update element (key/value pair) in a given map

       BPF_MAP_DELETE_ELEM
              Lookup and delete element by key in a given map

       BPF_MAP_GET_NEXT_KEY
              Lookup element by key in a given map  and  return  key  of  next
              element

       BPF_PROG_LOAD
              Verify and load eBPF program

       attr   is a pointer to a union of type bpf_attr as defined below.

       size   is the size of the union.

       union bpf_attr {
           struct { /* anonymous struct used by BPF_MAP_CREATE command */
               __u32             map_type;
               __u32             key_size;    /* size of key in bytes */
               __u32             value_size;  /* size of value in bytes */
               __u32             max_entries; /* max number of entries in a map */
           };

           struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
               __u32             map_fd;
               __aligned_u64     key;
               union {
                   __aligned_u64 value;
                   __aligned_u64 next_key;
               };
           };

           struct { /* anonymous struct used by BPF_PROG_LOAD command */
               __u32         prog_type;
               __u32         insn_cnt;
               __aligned_u64 insns;     /* 'const struct bpf_insn *' */
               __aligned_u64 license;   /* 'const char *' */
               __u32         log_level; /* verbosity level of eBPF verifier */
               __u32         log_size;  /* size of user buffer */
               __aligned_u64 log_buf;   /* user supplied 'char *' buffer */
           };
       } __attribute__((aligned(8)));

   eBPF maps
       maps  is  a generic storage of different types for sharing data between
       kernel and userspace.

       Any map type has the following attributes:
         . type
         . max number of elements
         . key size in bytes
         . value size in bytes

       The following wrapper functions demonstrate how  this  syscall  can  be
       used  to  access the maps. The functions use the cmd argument to invoke
       different operations.

       BPF_MAP_CREATE
              int bpf_create_map(enum bpf_map_type map_type, int key_size,
                                 int value_size, int max_entries)
              {
                  union bpf_attr attr = {
                      .map_type = map_type,
                      .key_size = key_size,
                      .value_size = value_size,
                      .max_entries = max_entries
                  };

                  return bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
              }
              bpf()  syscall  creates  a  map  of  map_type  type  and   given
              attributes  key_size,  value_size,  max_entries.   On success it
              returns process-local file descriptor. On error, -1 is  returned
              and errno is set to EINVAL or EPERM or ENOMEM.

              The  attributes key_size and value_size will be used by verifier
              during  program  loading  to  check  that  program  is   calling
              bpf_map_*_elem() helper functions with correctly initialized key
              and  that  program  doesn't  access  map  element  value  beyond
              specified  value_size.   For  example,  when map is created with
              key_size = 8 and program does:
              bpf_map_lookup_elem(map_fd, fp - 4)
              such program will be rejected, since in-kernel  helper  function
              bpf_map_lookup_elem(map_fd,  void  *key) expects to read 8 bytes
              from 'key' pointer, but 'fp - 4' starting address will cause out
              of bounds stack access.

              Similarly,  when  map is created with value_size = 1 and program
              does:
              value = bpf_map_lookup_elem(...);
              *(u32 *)value = 1;
              such program will be rejected, since it accesses  value  pointer
              beyond specified 1 byte value_size limit.

              Currently only hash table map_type is supported:
              enum bpf_map_type {
                 BPF_MAP_TYPE_UNSPEC,
                 BPF_MAP_TYPE_HASH,
              };
              map_type  selects  one  of  the available map implementations in
              kernel. For all map_types eBPF programs  access  maps  with  the
              same      bpf_map_lookup_elem()/bpf_map_update_elem()     helper
              functions.

       BPF_MAP_LOOKUP_ELEM
              int bpf_lookup_elem(int fd, void *key, void *value)
              {
                  union bpf_attr attr = {
                      .map_fd = fd,
                      .key = ptr_to_u64(key),
                      .value = ptr_to_u64(value),
                  };

                  return bpf(BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
              }
              bpf() syscall looks up an element with given key in  a  map  fd.
              If  element  is found it returns zero and stores element's value
              into value.  If element is not found  it  returns  -1  and  sets
              errno to ENOENT.

       BPF_MAP_UPDATE_ELEM
              int bpf_update_elem(int fd, void *key, void *value)
              {
                  union bpf_attr attr = {
                      .map_fd = fd,
                      .key = ptr_to_u64(key),
                      .value = ptr_to_u64(value),
                  };

                  return bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
              }
              The  call  creates  or updates element with given key/value in a
              map fd.  On success it returns zero.  On error, -1  is  returned
              and  errno  is set to EINVAL or EPERM or ENOMEM or E2BIG.  E2BIG
              indicates that number of elements in the map reached max_entries
              limit specified at map creation time.

       BPF_MAP_DELETE_ELEM
              int bpf_delete_elem(int fd, void *key)
              {
                  union bpf_attr attr = {
                      .map_fd = fd,
                      .key = ptr_to_u64(key),
                  };

                  return bpf(BPF_MAP_DELETE_ELEM, &attr, sizeof(attr));
              }
              The call deletes an element in a map fd with given key.  Returns
              zero on success. If element is not found it returns -1 and  sets
              errno to ENOENT.

       BPF_MAP_GET_NEXT_KEY
              int bpf_get_next_key(int fd, void *key, void *next_key)
              {
                  union bpf_attr attr = {
                      .map_fd = fd,
                      .key = ptr_to_u64(key),
                      .next_key = ptr_to_u64(next_key),
                  };

                  return bpf(BPF_MAP_GET_NEXT_KEY, &attr, sizeof(attr));
              }
              The  call  looks  up  an  element  by  key in a given map fd and
              returns key of the next element into next_key pointer. If key is
              not  found,  it return zero and returns key of the first element
              into next_key. If key is the last element,  it  returns  -1  and
              sets  errno  to  ENOENT. Other possible errno values are ENOMEM,
              EFAULT, EPERM, EINVAL.  This method can be used to iterate  over
              all elements of the map.

       close(map_fd)
              will  delete  the  map  map_fd.  Exiting process will delete all
              maps automatically.

   eBPF programs
       BPF_PROG_LOAD
              This cmd is used to load eBPF program into the kernel.

              char bpf_log_buf[LOG_BUF_SIZE];

              int bpf_prog_load(enum bpf_prog_type prog_type,
                                const struct bpf_insn *insns, int insn_cnt,
                                const char *license)
              {
                  union bpf_attr attr = {
                      .prog_type = prog_type,
                      .insns = ptr_to_u64(insns),
                      .insn_cnt = insn_cnt,
                      .license = ptr_to_u64(license),
                      .log_buf = ptr_to_u64(bpf_log_buf),
                      .log_size = LOG_BUF_SIZE,
                      .log_level = 1,
                  };

                  return bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
              }
              prog_type is one of the available program types:
              enum bpf_prog_type {
                      BPF_PROG_TYPE_UNSPEC,
                      BPF_PROG_TYPE_SOCKET,
                      BPF_PROG_TYPE_TRACING,
              };
              By picking prog_type program author  selects  a  set  of  helper
              functions callable from eBPF program and corresponding format of
              struct bpf_context (which is  the  data  blob  passed  into  the
              program  as  the  first  argument).   For  example, the programs
              loaded with  prog_type  =  TYPE_TRACING  may  call  bpf_printk()
              helper,  whereas  TYPE_SOCKET  programs  may  not.   The  set of
              functions  available  to  the  programs  under  given  type  may
              increase in the future.

              Currently the set of functions for TYPE_TRACING is:
              bpf_map_lookup_elem(map_fd, void *key)              // lookup key in a map_fd
              bpf_map_update_elem(map_fd, void *key, void *value) // update key/value
              bpf_map_delete_elem(map_fd, void *key)              // delete key in a map_fd
              bpf_ktime_get_ns(void)                              // returns current ktime
              bpf_printk(char *fmt, int fmt_size, ...)            // prints into trace buffer
              bpf_memcmp(void *ptr1, void *ptr2, int size)        // non-faulting memcmp
              bpf_fetch_ptr(void *ptr)    // non-faulting load pointer from any address
              bpf_fetch_u8(void *ptr)     // non-faulting 1 byte load
              bpf_fetch_u16(void *ptr)    // other non-faulting loads
              bpf_fetch_u32(void *ptr)
              bpf_fetch_u64(void *ptr)

              and bpf_context is defined as:
              struct bpf_context {
                  /* argN fields match one to one to arguments passed to trace events */
                  u64 arg1, arg2, arg3, arg4, arg5, arg6;
                  /* return value from kretprobe event or from syscall_exit event */
                  u64 ret;
              };

              The set of helper functions for TYPE_SOCKET is TBD.

              More   program   types   may   be  added  in  the  future.  Like
              BPF_PROG_TYPE_USER_TRACING for unprivileged programs.

              BPF_PROG_TYPE_UNSPEC is used for  testing  only.  Such  programs
              cannot be attached to events.

              insns array of "struct bpf_insn" instructions

              insn_cnt number of instructions in the program

              license  license  string,  which  must be GPL compatible to call
              helper functions marked gpl_only

              log_buf user supplied buffer that in-kernel verifier is using to
              store  verification  log. Log is a multi-line string that should
              be used by program author to understand  how  verifier  came  to
              conclusion  that program is unsafe. The format of the output can
              change at any time as verifier evolves.

              log_size size of user buffer. If size of the buffer is not large
              enough  to store all verifier messages, -1 is returned and errno
              is set to ENOSPC.

              log_level verbosity level of eBPF verifier, where zero means  no
              logs provided

       close(prog_fd)
              will unload eBPF program

       The  maps  are  accesible  from  programs  and  generally  tie  the two
       together.  Programs process various events  (like  tracepoint,  kprobe,
       packets)  and  store  the  data into maps. User space fetches data from
       maps.  Either the same or a different map may be used by user space  as
       configuration space to alter program behavior on the fly.

   Events
       Once an eBPF program is loaded, it can be attached to an event. Various
       kernel subsystems have different ways to do so. For example:

       setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd, sizeof(prog_fd));
       will attach the program prog_fd to socket sock which  was  received  by
       prior call to socket().

       ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
       will  attach  the  program  prog_fd  to  perf  event event_fd which was
       received by prior call to perf_event_open().

       Another way to attach the program to a tracing event is:
       event_fd = open("/sys/kernel/debug/tracing/events/skb/kfree_skb/filter");
       write(event_fd, "bpf-123"); /* where 123 is eBPF program FD */
       /* here program is attached and will be triggered by events */
       close(event_fd); /* to detach from event */

EXAMPLES
       /* eBPF+sockets example:
        * 1. create map with maximum of 2 elements
        * 2. set map[6] = 0 and map[17] = 0
        * 3. load eBPF program that counts number of TCP and UDP packets received
        *    via map[skb->ip->proto]++
        * 4. attach prog_fd to raw socket via setsockopt()
        * 5. print number of received TCP/UDP packets every second
        */
       int main(int ac, char **av)
       {
           int sock, map_fd, prog_fd, key;
           long long value = 0, tcp_cnt, udp_cnt;

           map_fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(key), sizeof(value), 2);
           if (map_fd < 0) {
               printf("failed to create map '%s'\n", strerror(errno));
               /* likely not run as root */
               return 1;
           }

           key = 6; /* ip->proto == tcp */
           assert(bpf_update_elem(map_fd, &key, &value) == 0);

           key = 17; /* ip->proto == udp */
           assert(bpf_update_elem(map_fd, &key, &value) == 0);

           struct bpf_insn prog[] = {
               BPF_MOV64_REG(BPF_REG_6, BPF_REG_1),          /* r6 = r1 */
               BPF_LD_ABS(BPF_B, 14 + 9),                    /* r0 = ip->proto */
               BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4),/* *(u32 *)(fp - 4) = r0 */
               BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),         /* r2 = fp */
               BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4),        /* r2 = r2 - 4 */
               BPF_LD_MAP_FD(BPF_REG_1, map_fd),             /* r1 = map_fd */
               BPF_CALL_FUNC(BPF_FUNC_map_lookup_elem),      /* r0 = map_lookup(r1, r2) */
               BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2),        /* if (r0 == 0) goto pc+2 */
               BPF_MOV64_IMM(BPF_REG_1, 1),                  /* r1 = 1 */
               BPF_XADD(BPF_DW, BPF_REG_0, BPF_REG_1, 0, 0), /* lock *(u64 *)r0 += r1 */
               BPF_MOV64_IMM(BPF_REG_0, 0),                  /* r0 = 0 */
               BPF_EXIT_INSN(),                              /* return r0 */
           };
           prog_fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET, prog, sizeof(prog), "GPL");
           assert(prog_fd >= 0);

           sock = open_raw_sock("lo");

           assert(setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd,
                             sizeof(prog_fd)) == 0);

           for (;;) {
               key = 6;
               assert(bpf_lookup_elem(map_fd, &key, &tcp_cnt) == 0);
               key = 17;
               assert(bpf_lookup_elem(map_fd, &key, &udp_cnt) == 0);
               printf("TCP %lld UDP %lld packets0, tcp_cnt, udp_cnt);
               sleep(1);
           }

           return 0;
       }

RETURN VALUE
       For a successful call, the return value depends on the operation:

       BPF_MAP_CREATE
              The new file descriptor associated with eBPF map.

       BPF_PROG_LOAD
              The new file descriptor associated with eBPF program.

       All other commands
              Zero.

       On error, -1 is returned, and errno is set appropriately.

ERRORS
       EPERM  bpf() syscall was made without sufficient privilege (without the
              CAP_SYS_ADMIN capability).

       ENOMEM Cannot allocate sufficient memory.

       EBADF  fd is not an open file descriptor

       EFAULT One  of  the  pointers  (  key or value or log_buf or insns ) is
              outside accessible address space.

       EINVAL The value specified in cmd is not recognized by this kernel.

       EINVAL For BPF_MAP_CREATE, either map_type or attributes are invalid.

       EINVAL For BPF_MAP_*_ELEM  commands,  some  of  the  fields  of  "union
              bpf_attr" unused by this command are not set to zero.

       EINVAL For BPF_PROG_LOAD, attempt to load invalid program (unrecognized
              instruction or uses reserved fields or jumps  out  of  range  or
              loop detected or calls unknown function).

       EACCES For BPF_PROG_LOAD, though program has valid instructions, it was
              rejected, since it was  deemed  unsafe  (may  access  disallowed
              memory   region  or  uninitialized  stack/register  or  function
              constraints don't match actual types or misaligned  access).  In
              such case it is recommended to call bpf() again with log_level =
              1 and examine log_buf for specific reason provided by verifier.

       ENOENT For BPF_MAP_LOOKUP_ELEM or BPF_MAP_DELETE_ELEM,  indicates  that
              element with given key was not found.

       E2BIG  program  is  too  large  or a map reached max_entries limit (max
              number of elements).

NOTES
       These commands may be used only by a privileged process (one having the
       CAP_SYS_ADMIN capability).

SEE ALSO
       eBPF    architecture    and    instruction    set   is   explained   in
       Documentation/networking/filter.txt

Linux                             2014-09-16                            BPF(2)
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

1.
the library includes a trivial set of BPF syscall wrappers:
int bpf_create_map(int key_size, int value_size, int max_entries);
int bpf_update_elem(int fd, void *key, void *value);
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_prog_load(enum bpf_prog_type prog_type,
		  const struct sock_filter_int *insns, int insn_len,
		  const char *license);
bpf_prog_load() stores verifier log into global bpf_log_buf[] array

and BPF_*() macros to build instructions

2.
test stubs configure eBPF infra with 'unspec' map and program types.
These are fake types used by user space testsuite only.

3.
verifier tests valid and invalid programs and expects predefined
error log messages from kernel.
40 tests so far.

$ sudo ./test_verifier
 #0 add+sub+mul OK
 #1 unreachable OK
 #2 unreachable2 OK
 #3 out of range jump OK
 #4 out of range jump2 OK
 #5 test1 ld_imm64 OK
 ...
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds verifier core which simulates execution of every insn and
records the state of registers and program stack. Every branch instruction seen
during simulation is pushed into state stack. When verifier reaches BPF_EXIT,
it pops the state from the stack and continues until it reaches BPF_EXIT again.
For program:
1: bpf_mov r1, xxx
2: if (r1 == 0) goto 5
3: bpf_mov r0, 1
4: goto 6
5: bpf_mov r0, 2
6: bpf_exit
The verifier will walk insns: 1, 2, 3, 4, 6
then it will pop the state recorded at insn#2 and will continue: 5, 6

This way it walks all possible paths through the program and checks all
possible values of registers. While doing so, it checks for:
- invalid instructions
- uninitialized register access
- uninitialized stack access
- misaligned stack access
- out of range stack access
- invalid calling convention
- instruction encoding is not using reserved fields

Kernel subsystem configures the verifier with two callbacks:

- bool (*is_valid_access)(int off, int size, enum bpf_access_type type);
  that provides information to the verifer which fields of 'ctx'
  are accessible (remember 'ctx' is the first argument to eBPF program)

- const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id);
  returns argument constraints of kernel helper functions that eBPF program
  may call, so that verifier can checks that R1-R5 types match the prototype

More details in Documentation/networking/filter.txt and in kernel/bpf/verifier.c
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

check that control flow graph of eBPF program is a directed acyclic graph

check_cfg() does:
- detect loops
- detect unreachable instructions
- check that program terminates with BPF_EXIT insn
- check that all branches are within program boundary
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

eBPF programs passed from userspace are using pseudo BPF_LD_IMM64 instructions
to refer to process-local map_fd. Scan the program for such instructions and
if FDs are valid, convert them to 'struct bpf_map' pointers which will be used
by verifier to check access to maps in bpf_map_lookup/update() calls.
If program passes verifier, convert pseudo BPF_LD_IMM64 into generic by dropping
BPF_PSEUDO_MAP_FD flag.

Note that eBPF interpreter is generic and knows nothing about pseudo insns.
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

add optional attributes for BPF_PROG_LOAD syscall:
union bpf_attr {
    struct {
	...
	__u32         log_level; /* verbosity level of eBPF verifier */
	__u32         log_size;  /* size of user buffer */
	__aligned_u64 log_buf;   /* user supplied 'char *buffer' */
    };
};

when log_level > 0 the verifier will return its verification log in the user
supplied buffer 'log_buf' which can be used by program author to analyze why
verifier rejected given program.

'Understanding eBPF verifier messages' section of Documentation/networking/filter.txt
provides several examples of these messages, like the program:

  BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
  BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
  BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
  BPF_LD_MAP_FD(BPF_REG_1, 0),
  BPF_CALL_FUNC(BPF_FUNC_map_lookup_elem),
  BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 1),
  BPF_ST_MEM(BPF_DW, BPF_REG_0, 4, 0),
  BPF_EXIT_INSN(),

will be rejected with the following multi-line message in log_buf:

  0: (7a) *(u64 *)(r10 -8) = 0
  1: (bf) r2 = r10
  2: (07) r2 += -8
  3: (b7) r1 = 0
  4: (85) call 1
  5: (15) if r0 == 0x0 goto pc+1
   R0=map_ptr R10=fp
  6: (7a) *(u64 *)(r0 +4) = 0
  misaligned access off 4 size 8

The format of the output can change at any time as verifier evolves.
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

this patch adds all of eBPF verfier documentation and empty bpf_check()

The end goal for the verifier is to statically check safety of the program.

Verifier will catch:
- loops
- out of range jumps
- unreachable instructions
- invalid instructions
- uninitialized register access
- uninitialized stack access
- misaligned stack access
- out of range stack access
- invalid calling convention

More details in Documentation/networking/filter.txt
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

in native eBPF programs userspace is using pseudo BPF_CALL instructions
which encode one of 'enum bpf_func_id' inside insn->imm field.
Verifier checks that program using correct function arguments to given func_id.
If all checks passed, kernel needs to fixup BPF_CALL->imm fields by
replacing func_id with in-kernel function pointer.
eBPF interpreter just calls the function.

In-kernel eBPF users continue to use generic BPF_CALL.
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

eBPF programs are similar to kernel modules. They are loaded by the user
process and automatically unloaded when process exits. Each eBPF program is
a safe run-to-completion set of instructions. eBPF verifier statically
determines that the program terminates and is safe to execute.

The following syscall wrapper can be used to load the program:
int bpf_prog_load(enum bpf_prog_type prog_type,
                  const struct bpf_insn *insns, int insn_cnt,
                  const char *license)
{
    union bpf_attr attr = {
        .prog_type = prog_type,
        .insns = ptr_to_u64(insns),
        .insn_cnt = insn_cnt,
        .license = ptr_to_u64(license),
    };

    return bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
}
where 'insns' is an array of eBPF instructions and 'license' is a string
that must be GPL compatible to call helper functions marked gpl_only

Upon succesful load the syscall returns prog_fd.
Use close(prog_fd) to unload the program.

User space tests and examples follow in the later patches
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

'maps' is a generic storage of different types for sharing data between kernel
and userspace.

The maps are accessed from user space via BPF syscall, which has commands:

- create a map with given type and attributes
  fd = bpf(BPF_MAP_CREATE, union bpf_attr *attr, u32 size)
  returns fd or negative error

- lookup key in a given map referenced by fd
  err = bpf(BPF_MAP_LOOKUP_ELEM, union bpf_attr *attr, u32 size)
  using attr->map_fd, attr->key, attr->value
  returns zero and stores found elem into value or negative error

- create or update key/value pair in a given map
  err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size)
  using attr->map_fd, attr->key, attr->value
  returns zero or negative error

- find and delete element by key in a given map
  err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size)
  using attr->map_fd, attr->key

- iterate map elements (based on input key return next_key)
  err = bpf(BPF_MAP_GET_NEXT_KEY, union bpf_attr *attr, u32 size)
  using attr->map_fd, attr->key, attr->next_key

- close(fd) deletes the map
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

done as separate commit to ease conflict resolution
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

BPF syscall is a multiplexor for a range of different operations on eBPF.
This patch introduces syscall with single command to create a map.
Next patch adds commands to access maps.

'maps' is a generic storage of different types for sharing data between kernel
and userspace.

Userspace example:
/* this syscall wrapper creates a map with given type and attributes
 * and returns map_fd on success.
 * use close(map_fd) to delete the map
 */
int bpf_create_map(enum bpf_map_type map_type, int key_size,
                   int value_size, int max_entries)
{
    union bpf_attr attr = {
        .map_type = map_type,
        .key_size = key_size,
        .value_size = value_size,
        .max_entries = max_entries
    };

    return bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
}

'union bpf_attr' is backwards compatible with future extensions.

More details in Documentation/networking/filter.txt and in manpage
Signed-off-by: NAlexei Starovoitov <ast@plumgrid.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

While using a MQ + NETEM setup, I had confirmation that the default
timer migration ( /proc/sys/kernel/timer_migration ) is killing us.

Installing this on a receiver side of a TCP_STREAM test, (NIC has 8 TX
queues) :

EST="est 1sec 4sec"
for ETH in eth1
do
 tc qd del dev $ETH root 2>/dev/null
 tc qd add dev $ETH root handle 1: mq
 tc qd add dev $ETH parent 1:1 $EST netem limit 70000 delay 6ms
 tc qd add dev $ETH parent 1:2 $EST netem limit 70000 delay 8ms
 tc qd add dev $ETH parent 1:3 $EST netem limit 70000 delay 10ms
 tc qd add dev $ETH parent 1:4 $EST netem limit 70000 delay 12ms
 tc qd add dev $ETH parent 1:5 $EST netem limit 70000 delay 14ms
 tc qd add dev $ETH parent 1:6 $EST netem limit 70000 delay 16ms
 tc qd add dev $ETH parent 1:7 $EST netem limit 80000 delay 18ms
 tc qd add dev $ETH parent 1:8 $EST netem limit 90000 delay 20ms
done

We can see that timers get migrated into a single cpu, presumably idle
at the time timers are set up.
Then all qdisc dequeues run from this cpu and huge lock contention
happens. This single cpu is stuck in softirq mode and cannot dequeue
fast enough.

    39.24%  [kernel]          [k] _raw_spin_lock
     2.65%  [kernel]          [k] netem_enqueue
     1.80%  [kernel]          [k] netem_dequeue
     1.63%  [kernel]          [k] copy_user_enhanced_fast_string
     1.45%  [kernel]          [k] _raw_spin_lock_bh

By pinning qdisc timers on the cpu running the qdisc, we respect proper
XPS setting and remove this lock contention.

     5.84%  [kernel]          [k] netem_enqueue
     4.83%  [kernel]          [k] _raw_spin_lock
     2.92%  [kernel]          [k] copy_user_enhanced_fast_string

Current Qdiscs that benefit from this change are :

	netem, cbq, fq, hfsc, tbf, htb.
Signed-off-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Tom Herbert says:

====================
net: Eliminate gso_send_check

gso_send_check presents a lot of complexity for what it is being used
for. It seems that there are only two cases where it might be effective:
TCP and UFO paths. In these cases, the gso_send_check function
initializes the TCP or UDP checksum respectively to the pseudo header
checksum so that the checksum computation is appropriately offloaded or
computed in the gso_segment functions. The gso_send_check functions
are only called from dev.c in skb_mac_gso_segment when ip_summed !=
CHECKSUM_PARTIAL (which seems very unlikely in TCP case). We can move
the logic of this into the respective gso_segment functions where the
checksum is initialized if ip_summed != CHECKSUM_PARTIAL.

With the above cases handled, gso_send_check is no longer needed, so
we can remove all uses of it and the fields in the offload callbacks.
With this change, ip_summed in the skb should be preserved though all
the layers of gso_segment calls.

In follow-on patches, we may be able to remove the check setup code in
tcp_gso_segment if we can guarantee that ip_summed will always be
CHECKSUM_PARTIAL (verify all paths and probably add an assert in
tcp_gro_segment).

Tested these patches by:
  - netperf TCP_STREAM test with GSO enabled
  - Forced ip_summed != CHECKSUM_PARTIAL with above
  - Ran UDP_RR with 10000 request size over GRE tunnel. This exercised
    UFO path.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The send_check logic was only interesting in cases of TCP offload and
UDP UFO where the checksum needed to be initialized to the pseudo
header checksum. Now we've moved that logic into the related
gso_segment functions so gso_send_check is no longer needed.
Signed-off-by: NTom Herbert <therbert@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In udp[46]_ufo_send_check the UDP checksum initialized to the pseudo
header checksum. We can move this logic into udp[46]_ufo_fragment.
After this change udp[64]_ufo_send_check is a no-op.
Signed-off-by: NTom Herbert <therbert@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In tcp_v[46]_gso_send_check the TCP checksum is initialized to the
pseudo header checksum using __tcp_v[46]_send_check. We can move this
logic into new tcp[46]_gso_segment functions to be done when
ip_summed != CHECKSUM_PARTIAL (ip_summed == CHECKSUM_PARTIAL should be
the common case, possibly always true when taking GSO path). After this
change tcp_v[46]_gso_send_check is no-op.
Signed-off-by: NTom Herbert <therbert@google.com>
Acked-by: NEric Dumazet <edumazet@google.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Beniamino Galvani says:

====================
net: stmmac glue layer for Amlogic Meson SoCs

the Ethernet controller available in Amlogic Meson6 and Meson8 SoCs is
a Synopsys DesignWare MAC IP core, already supported by the stmmac
driver.

These patches add a glue layer to the driver for the platform-specific
settings required by the Amlogic variant.

This has been tested on a Amlogic S802 device with the initial Meson
support submitted by Carlo Caione [1].

[1] http://lwn.net/Articles/612000/
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>