Björn Töpel says:

====================
This is a four patch series of various barrier, {READ, WRITE}_ONCE
cleanups in the AF_XDP socket code. More details can be found in the
corresponding commit message. Previous revisions: v1 [4] and v2 [5].

For an AF_XDP socket, most control plane operations are done under the
control mutex (struct xdp_sock, mutex), but there are some places
where members of the struct is read outside the control mutex. The
dev, queue_id members are set in bind() and cleared at cleanup. The
umem, fq, cq, tx, rx, and state member are all assigned in various
places, e.g. bind() and setsockopt(). When the members are assigned,
they are protected by the control mutex, but since they are read
outside the mutex, a WRITE_ONCE is required to avoid store-tearing on
the read-side.

Prior the state variable was introduced by Ilya, the dev member was
used to determine whether the socket was bound or not. However, when
dev was read, proper SMP barriers and READ_ONCE were missing. In order
to address the missing barriers and READ_ONCE, we start using the
state variable as a point of synchronization. The state member
read/write is paired with proper SMP barriers, and from this follows
that the members described above does not need READ_ONCE statements if
used in conjunction with state check.

To summarize: The members struct xdp_sock members dev, queue_id, umem,
fq, cq, tx, rx, and state were read lock-less, with incorrect barriers
and missing {READ, WRITE}_ONCE. After this series umem, fq, cq, tx,
rx, and state are read lock-less. When these members are updated,
WRITE_ONCE is used. When read, READ_ONCE are only used when read
outside the control mutex (e.g. mmap) or, not synchronized with the
state member (XSK_BOUND plus smp_rmb())

[1] https://lore.kernel.org/bpf/beef16bb-a09b-40f1-7dd0-c323b4b89b17@iogearbox.net/
[2] https://lwn.net/Articles/793253/
[3] https://github.com/google/ktsan/wiki/READ_ONCE-and-WRITE_ONCE
[4] https://lore.kernel.org/bpf/20190822091306.20581-1-bjorn.topel@gmail.com/
[5] https://lore.kernel.org/bpf/20190826061053.15996-1-bjorn.topel@gmail.com/

v2->v3:
  Minor restructure of commits.
  Improve cover and commit messages. (Daniel)
v1->v2:
  Removed redundant dev check. (Jonathan)
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

When accessing the members of an XDP socket, the control mutex should
be held. This commit fixes that.
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Fixes: a36b38aa ("xsk: add sock_diag interface for AF_XDP")
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Prior the state variable was introduced by Ilya, the dev member was
used to determine whether the socket was bound or not. However, when
dev was read, proper SMP barriers and READ_ONCE were missing. In order
to address the missing barriers and READ_ONCE, we start using the
state variable as a point of synchronization. The state member
read/write is paired with proper SMP barriers, and from this follows
that the members described above does not need READ_ONCE if used in
conjunction with state check.

In all syscalls and the xsk_rcv path we check if state is
XSK_BOUND. If that is the case we do a SMP read barrier, and this
implies that the dev, umem and all rings are correctly setup. Note
that no READ_ONCE are needed for these variable if used when state is
XSK_BOUND (plus the read barrier).

To summarize: The members struct xdp_sock members dev, queue_id, umem,
fq, cq, tx, rx, and state were read lock-less, with incorrect barriers
and missing {READ, WRITE}_ONCE. Now, umem, fq, cq, tx, rx, and state
are read lock-less. When these members are updated, WRITE_ONCE is
used. When read, READ_ONCE are only used when read outside the control
mutex (e.g. mmap) or, not synchronized with the state member
(XSK_BOUND plus smp_rmb())

Note that dev and queue_id do not need a WRITE_ONCE or READ_ONCE, due
to the introduce state synchronization (XSK_BOUND plus smp_rmb()).

Introducing the state check also fixes a race, found by syzcaller, in
xsk_poll() where umem could be accessed when stale.
Suggested-by: Hillf Danton <hdanton@sina.com>
Reported-by: syzbot+c82697e3043781e08802@syzkaller.appspotmail.com
Fixes: 77cd0d7b ("xsk: add support for need_wakeup flag in AF_XDP rings")
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

The umem member of struct xdp_sock is read outside of the control
mutex, in the mmap implementation, and needs a WRITE_ONCE to avoid
potential store-tearing.
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Fixes: 423f3832 ("xsk: add umem fill queue support and mmap")
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Use WRITE_ONCE when doing the store of tx, rx, fq, and cq, to avoid
potential store-tearing. These members are read outside of the control
mutex in the mmap implementation.
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Fixes: 37b07693 ("xsk: add missing write- and data-dependency barrier")
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Add two tests to check that stack slot marking during backtracking
doesn't trigger 'spi > allocated_stack' warning.
One test is using BPF_ST insn. Another is using BPF_STX.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Currently, we don't add headroom to the handle in ixgbe_zca_free,
ixgbe_alloc_buffer_slow_zc and ixgbe_alloc_buffer_zc. The addition of the
headroom to the handle was removed in
commit d8c3061e ("ixgbe: modify driver for handling offsets"), which
will break things when headroom isvnon-zero. This patch fixes this and uses
xsk_umem_adjust_offset to add it appropritely based on the mode being run.

Fixes: d8c3061e ("ixgbe: modify driver for handling offsets")
Reported-by: Bjorn Topel <bjorn.topel@intel.com>
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Currently, we don't add headroom to the handle in i40e_zca_free,
i40e_alloc_buffer_slow_zc and i40e_alloc_buffer_zc. The addition of the
headroom to the handle was removed in
commit 2f86c806 ("i40e: modify driver for handling offsets"), which
will break things when headroom is non-zero. This patch fixes this and uses
xsk_umem_adjust_offset to add it appropritely based on the mode being run.

Fixes: 2f86c806 ("i40e: modify driver for handling offsets")
Reported-by: Bjorn Topel <bjorn.topel@intel.com>
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Acked-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Ilya Leoshkevich says:

====================
Patch 1 is a preparatory commit, which introduces 64-bit endianness
conversion functions.

Patch 2 fixes reading the wrong byte of an int.

Patch 3 improves error reporting.

Patch 4 uses the new conversion functions to fix wrong endianness of
immediates.

v1->v2: Use bpf_ntohl and bpf_be64_to_cpu, drop __bpf_le64_to_cpu.
v2->v3: Split bpf_be64_to_cpu introduction into a separate patch.
        Use the new functions in test_lwt_seg6local.c and
	test_seg6_loop.c.
v3->v4: Improved commit message, split fixes that are not related to
        each other into separate patches.
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

A lot of test_sysctl sub-tests fail due to handling strings as a bunch
of immediate values in a little-endian-specific manner.

Fix by wrapping all immediates in bpf_ntohl and the new bpf_be64_to_cpu.

fixup_sysctl_value() dynamically writes an immediate, and thus should be
endianness-aware.  Implement this by simply memcpy()ing the raw
user-provided value, since testcase endianness and bpf program
endianness match.

Fixes: 1f5fa9ab ("selftests/bpf: Test BPF_CGROUP_SYSCTL")
Fixes: 9a1027e5 ("selftests/bpf: Test file_pos field in bpf_sysctl ctx")
Fixes: 6041c67f ("selftests/bpf: Test bpf_sysctl_get_name helper")
Fixes: 11ff34f7 ("selftests/bpf: Test sysctl_get_current_value helper")
Fixes: 786047dd ("selftests/bpf: Test bpf_sysctl_{get,set}_new_value helpers")
Fixes: 8549ddc8 ("selftests/bpf: Test bpf_strtol and bpf_strtoul helpers")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

When tests fail because sysctl() unexpectedly succeeds, they print an
inappropriate "Unexpected failure" message and a random errno. Zero
out errno before calling sysctl() and replace the message with
"Unexpected success".

Fixes: 1f5fa9ab ("selftests/bpf: Test BPF_CGROUP_SYSCTL")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

"ctx:write sysctl:write read ok" fails on s390 because it reads the
first byte of an int assuming it's the least-significant one, which
is not the case on big-endian arches. Since we are not testing narrow
accesses here (there is e.g. "ctx:file_pos sysctl:read read ok narrow"
for that), simply read the whole int.

Fixes: 1f5fa9ab ("selftests/bpf: Test BPF_CGROUP_SYSCTL")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

test_lwt_seg6local and test_seg6_loop use custom 64-bit endianness
conversion macros. Centralize their definitions in bpf_endian.h in order
to reduce code duplication. This will also be useful when bpf_endian.h
is promoted to an offical libbpf header.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Optimize modulo operation instruction generation by
using single MSUB instruction vs MUL followed by SUB
instruction scheme.
Signed-off-by: Jerin Jacob <jerinj@marvell.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This adds support for generating bpf line info for JITed programs
like commit 6f20c71d ("bpf: powerpc64: add JIT support for bpf
line info") does for powerpc, but it should pass the array starting
from 1. This fixes test_btf.
Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Copy-paste error from CHECK.

Fixes: d38835b7 ("selftests/bpf: test_progs: remove global fail/success counts")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

fseeko(.., 0, SEEK_SET) on a memstream just puts the buffer pointer
to the beginning so when we call fflush on it we get some garbage
log data from the previous test. Let's manually set terminating
byte to zero at the reported buffer size.

To show the issue consider the following snippet:

	stream = open_memstream (&buf, &len);

	fprintf(stream, "aaa");
	fflush(stream);
	printf("buf=%s, len=%zu\n", buf, len);
	fseeko(stream, 0, SEEK_SET);

	fprintf(stream, "b");
	fflush(stream);
	printf("buf=%s, len=%zu\n", buf, len);

Output:

	buf=aaa, len=3
	buf=baa, len=1

Fixes: 946152b3 ("selftests/bpf: test_progs: switch to open_memstream")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Kevin Laatz says:

====================
This patch set adds the ability to use unaligned chunks in the XDP umem.

Currently, all chunk addresses passed to the umem are masked to be chunk
size aligned (max is PAGE_SIZE). This limits where we can place chunks
within the umem as well as limiting the packet sizes that are supported.

The changes in this patch set removes these restrictions, allowing XDP to
be more flexible in where it can place a chunk within a umem. By relaxing
where the chunks can be placed, it allows us to use an arbitrary buffer
size and place that wherever we have a free address in the umem. These
changes add the ability to support arbitrary frame sizes up to 4k
(PAGE_SIZE) and make it easy to integrate with other existing frameworks
that have their own memory management systems, such as DPDK.
In DPDK, for example, there is already support for AF_XDP with zero-copy.
However, with this patch set the integration will be much more seamless.
You can find the DPDK AF_XDP driver at:
https://git.dpdk.org/dpdk/tree/drivers/net/af_xdp

Since we are now dealing with arbitrary frame sizes, we need also need to
update how we pass around addresses. Currently, the addresses can simply be
masked to 2k to get back to the original address. This becomes less trivial
when using frame sizes that are not a 'power of 2' size. This patch set
modifies the Rx/Tx descriptor format to use the upper 16-bits of the addr
field for an offset value, leaving the lower 48-bits for the address (this
leaves us with 256 Terabytes, which should be enough!). We only need to use
the upper 16-bits to store the offset when running in unaligned mode.
Rather than adding the offset (headroom etc) to the address, we will store
it in the upper 16-bits of the address field. This way, we can easily add
the offset to the address where we need it, using some bit manipulation and
addition, and we can also easily get the original address wherever we need
it (for example in i40e_zca_free) by simply masking to get the lower
48-bits of the address field.

The patch set was tested with the following set up:
  - Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz
  - Intel Corporation Ethernet Controller XXV710 for 25GbE SFP28 (rev 02)
  - Driver: i40e
  - Application: xdpsock with l2fwd (single interface)
  - Turbo disabled in BIOS

There are no changes to performance before and after these patches for SKB
mode and Copy mode. Zero-copy mode saw a performance degradation of ~1.5%.

This patch set has been applied against
commit 0bb52b0d ("tools: bpftool: add 'bpftool map freeze' subcommand")

Structure of the patch set:

Patch 1:
  - Remove unnecessary masking and headroom addition during zero-copy Rx
    buffer recycling in i40e. This change is required in order for the
    buffer recycling to work in the unaligned chunk mode.

Patch 2:
  - Remove unnecessary masking and headroom addition during
    zero-copy Rx buffer recycling in ixgbe. This change is required in
    order for the  buffer recycling to work in the unaligned chunk mode.

Patch 3:
  - Add infrastructure for unaligned chunks. Since we are dealing with
    unaligned chunks that could potentially cross a physical page boundary,
    we add checks to keep track of that information. We can later use this
    information to correctly handle buffers that are placed at an address
    where they cross a page boundary.  This patch also modifies the
    existing Rx and Tx functions to use the new descriptor format. To
    handle addresses correctly, we need to mask appropriately based on
    whether we are in aligned or unaligned mode.

Patch 4:
  - This patch updates the i40e driver to make use of the new descriptor
    format.

Patch 5:
  - This patch updates the ixgbe driver to make use of the new descriptor
    format.

Patch 6:
  - This patch updates the mlx5e driver to make use of the new descriptor
    format. These changes are required to handle the new descriptor format
    and for unaligned chunks support.

Patch 7:
  - This patch allows XSK frames smaller than page size in the mlx5e
    driver. Relax the requirements to the XSK frame size to allow it to be
    smaller than a page and even not a power of two. The current
    implementation can work in this mode, both with Striding RQ and without
    it.

Patch 8:
  - Add flags for umem configuration to libbpf. Since we increase the size
    of the struct by adding flags, we also need to add the ABI versioning
    in this patch.

Patch 9:
  - Modify xdpsock application to add a command line option for
    unaligned chunks

Patch 10:
  - Since we can now run the application in unaligned chunk mode, we need
    to make sure we recycle the buffers appropriately.

Patch 11:
  - Adds hugepage support to the xdpsock application

Patch 12:
  - Documentation update to include the unaligned chunk scenario. We need
    to explicitly state that the incoming addresses are only masked in the
    aligned chunk mode and not the unaligned chunk mode.

v2:
  - fixed checkpatch issues
  - fixed Rx buffer recycling for unaligned chunks in xdpsock
  - removed unused defines
  - fixed how chunk_size is calculated in xsk_diag.c
  - added some performance numbers to cover letter
  - modified descriptor format to make it easier to retrieve original
    address
  - removed patch adding off_t off to the zero copy allocator. This is no
    longer needed with the new descriptor format.

v3:
  - added patch for mlx5 driver changes needed for unaligned chunks
  - moved offset handling to new helper function
  - changed value used for the umem chunk_mask. Now using the new
    descriptor format to save us doing the calculations in a number of
    places meaning more of the code is left unchanged while adding
    unaligned chunk support.

v4:
  - reworked the next_pg_contig field in the xdp_umem_page struct. We now
    use the low 12 bits of the addr for flags rather than adding an extra
    field in the struct.
  - modified unaligned chunks flag define
  - fixed page_start calculation in __xsk_rcv_memcpy().
  - move offset handling to the xdp_umem_get_* functions
  - modified the len field in xdp_umem_reg struct. We now use 16 bits from
    this for the flags field.
  - fixed headroom addition to handle in the mlx5e driver
  - other minor changes based on review comments

v5:
  - Added ABI versioning in the libbpf patch
  - Removed bitfields in the xdp_umem_reg struct. Adding new flags field.
  - Added accessors for getting addr and offset.
  - Added helper function for adding the offset to the addr.
  - Fixed conflicts with 'bpf-af-xdp-wakeup' which was merged recently.
  - Fixed typo in mlx driver patch.
  - Moved libbpf patch to later in the set (7/11, just before the sample
    app changes)

v6:
  - Added support for XSK frames smaller than page in mlx5e driver (Maxim
    Mikityanskiy <maximmi@mellanox.com).
  - Fixed offset handling in xsk_generic_rcv.
  - Added check for base address in xskq_is_valid_addr_unaligned.
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

The addition of unaligned chunks mode, the documentation needs to be
updated to indicate that the incoming addr to the fill ring will only be
masked if the user application is run in the aligned chunk mode. This patch
also adds a line to explicitly indicate that the incoming addr will not be
masked if running the user application in the unaligned chunk mode.
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This patch modifies xdpsock to use mmap instead of posix_memalign. With
this change, we can use hugepages when running the application in unaligned
chunks mode. Using hugepages makes it more likely that we have physically
contiguous memory, which supports the unaligned chunk mode better.
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This patch adds buffer recycling support for unaligned buffers. Since we
don't mask the addr to 2k at umem_reg in unaligned mode, we need to make
sure we give back the correct (original) addr to the fill queue. We achieve
this using the new descriptor format and associated masks. The new format
uses the upper 16-bits for the offset and the lower 48-bits for the addr.
Since we have a field for the offset, we no longer need to modify the
actual address. As such, all we have to do to get back the original address
is mask for the lower 48 bits (i.e. strip the offset and we get the address
on it's own).
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This patch adds support for the unaligned chunks mode. The addition of the
unaligned chunks option will allow users to run the application with more
relaxed chunk placement in the XDP umem.

Unaligned chunks mode can be used with the '-u' or '--unaligned' command
line options.
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This patch adds a 'flags' field to the umem_config and umem_reg structs.
This will allow for more options to be added for configuring umems.

The first use for the flags field is to add a flag for unaligned chunks
mode. These flags can either be user-provided or filled with a default.

Since we change the size of the xsk_umem_config struct, we need to version
the ABI. This patch includes the ABI versioning for xsk_umem__create. The
Makefile was also updated to handle multiple function versions in
check-abi.
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Relax the requirements to the XSK frame size to allow it to be smaller
than a page and even not a power of two. The current implementation can
work in this mode, both with Striding RQ and without it.

The code that checks `mtu + headroom <= XSK frame size` is modified
accordingly. Any frame size between 2048 and PAGE_SIZE is accepted.

Functions that worked with pages only now work with XSK frames, even if
their size is different from PAGE_SIZE.

With XSK queues, regardless of the frame size, Striding RQ uses the
stride size of PAGE_SIZE, and UMR MTTs are posted using starting
addresses of frames, but PAGE_SIZE as page size. MTU guarantees that no
packet data will overlap with other frames. UMR MTT size is made equal
to the stride size of the RQ, because UMEM frames may come in random
order, and we need to handle them one by one. PAGE_SIZE is just a power
of two that is bigger than any allowed XSK frame size, and also it
doesn't require making additional changes to the code.
Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Reviewed-by: Saeed Mahameed <saeedm@mellanox.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

With the addition of the unaligned chunks option, we need to make sure we
handle the offsets accordingly based on the mode we are currently running
in. This patch modifies the driver to appropriately mask the address for
each case.
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

With the addition of the unaligned chunks option, we need to make sure we
handle the offsets accordingly based on the mode we are currently running
in. This patch modifies the driver to appropriately mask the address for
each case.
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

With the addition of the unaligned chunks option, we need to make sure we
handle the offsets accordingly based on the mode we are currently running
in. This patch modifies the driver to appropriately mask the address for
each case.
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Currently, addresses are chunk size aligned. This means, we are very
restricted in terms of where we can place chunk within the umem. For
example, if we have a chunk size of 2k, then our chunks can only be placed
at 0,2k,4k,6k,8k... and so on (ie. every 2k starting from 0).

This patch introduces the ability to use unaligned chunks. With these
changes, we are no longer bound to having to place chunks at a 2k (or
whatever your chunk size is) interval. Since we are no longer dealing with
aligned chunks, they can now cross page boundaries. Checks for page
contiguity have been added in order to keep track of which pages are
followed by a physically contiguous page.
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Currently, the dma, addr and handle are modified when we reuse Rx buffers
in zero-copy mode. However, this is not required as the inputs to the
function are copies, not the original values themselves. As we use the
copies within the function, we can use the original 'obi' values
directly without having to mask and add the headroom.
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Currently, the dma, addr and handle are modified when we reuse Rx buffers
in zero-copy mode. However, this is not required as the inputs to the
function are copies, not the original values themselves. As we use the
copies within the function, we can use the original 'old_bi' values
directly without having to mask and add the headroom.
Signed-off-by: Kevin Laatz <kevin.laatz@intel.com>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

This patch fix a spelling typo in test_offload.py
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

If a SYN cookie is not issued by tcp_v#_gen_syncookie, then the return
value will be exactly 0, rather than <= 0. Let's change the check to
reflect that, especially since mss is an unsigned value and cannot be
negative.

Fixes: 70d66244 ("bpf: add bpf_tcp_gen_syncookie helper")
Reported-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Petar Penkov <ppenkov@google.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Jakub Kicinski says:

====================
This set adds a small batching and cache mechanism to the driver.
Map dumps require two operations per element - get next, and
lookup. Each of those needs a round trip to the device, and on
a loaded system scheduling out and in of the dumping process.
This set makes the driver request a number of entries at the same
time, and if no operation which would modify the map happens
from the host side those entries are used to serve lookup
requests for up to 250us, at which point they are considered
stale.

This set has been measured to provide almost 4x dumping speed
improvement, Jaco says:

OLD dump times
    500 000 elements: 26.1s
  1 000 000 elements: 54.5s

NEW dump times
    500 000 elements: 7.6s
  1 000 000 elements: 16.5s
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Each get_next and lookup call requires a round trip to the device.
However, the device is capable of giving us a few entries back,
instead of just one.

In this patch we ask for a small yet reasonable number of entries
(4) on every get_next call, and on subsequent get_next/lookup calls
check this little cache for a hit. The cache is only kept for 250us,
and is invalidated on every operation which may modify the map
(e.g. delete or update call). Note that operations may be performed
simultaneously, so we have to keep track of operations in flight.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

If control channel MTU is too low to support map operations a warning
will be printed. This is not enough, we want to make sure probe fails
in such scenario, as this would clearly be a faulty configuration.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Quentin Monnet <quentin.monnet@netronome.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Quentin Monnet says:

====================
This set attempts to make it easier to build bpftool, in particular when
passing a specific output directory. This is a follow-up to the
conversation held last month by Lorenz, Ilya and Jakub [0].

The first patch is a minor fix to bpftool's Makefile, regarding the
retrieval of kernel version (which currently prints a non-relevant make
warning on some invocations).

Second patch improves the Makefile commands to support more "make"
invocations, or to fix building with custom output directory. On Jakub's
suggestion, a script is also added to BPF selftests in order to keep track
of the supported build variants.

Building bpftool with "make tools/bpf" from the top of the repository
generates files in "libbpf/" and "feature/" directories under tools/bpf/
and tools/bpf/bpftool/. The third patch ensures such directories are taken
care of on "make clean", and add them to the relevant .gitignore files.

At last, fourth patch is a sligthly modified version of Ilya's fix
regarding libbpf.a appearing twice on the linking command for bpftool.

[0] https://lore.kernel.org/bpf/CACAyw9-CWRHVH3TJ=Tke2x8YiLsH47sLCijdp=V+5M836R9aAA@mail.gmail.com/

v2:
- Return error from check script if one of the make invocations returns
  non-zero (even if binary is successfully produced).
- Run "make clean" from bpf/ and not only bpf/bpftool/ in that same script,
  when relevant.
- Add a patch to clean up generated "feature/" and "libbpf/" directories.
====================
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Lorenz Bauer <lmb@cloudflare.com>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

In bpftool's Makefile, $(LIBS) includes $(LIBBPF), therefore the library
is used twice in the linking command. No need to have $(LIBBPF) (from
$^) on that command, let's do with "$(OBJS) $(LIBS)" (but move $(LIBBPF)
_before_ the -l flags in $(LIBS)).
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

When building "tools/bpf" from the top of the Linux repository, the
build system passes a value for the $(OUTPUT) Makefile variable to
tools/bpf/Makefile and tools/bpf/bpftool/Makefile, which results in
generating "libbpf/" (for bpftool) and "feature/" (bpf and bpftool)
directories inside the tree.

This commit adds such directories to the relevant .gitignore files, and
edits the Makefiles to ensure they are removed on "make clean". The use
of "rm" is also made consistent throughout those Makefiles (relies on
the $(RM) variable, use "--" to prevent interpreting
$(OUTPUT)/$(DESTDIR) as options.

v2:
- New patch.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

There are a number of alternative "make" invocations that can be used to
compile bpftool. The following invocations are expected to work:

  - through the kbuild system, from the top of the repository
    (make tools/bpf)
  - by telling make to change to the bpftool directory
    (make -C tools/bpf/bpftool)
  - by building the BPF tools from tools/
    (cd tools && make bpf)
  - by running make from bpftool directory
    (cd tools/bpf/bpftool && make)

Additionally, setting the O or OUTPUT variables should tell the build
system to use a custom output path, for each of these alternatives.

The following patch fixes the following invocations:

  $ make tools/bpf
  $ make tools/bpf O=<dir>
  $ make -C tools/bpf/bpftool OUTPUT=<dir>
  $ make -C tools/bpf/bpftool O=<dir>
  $ cd tools/ && make bpf O=<dir>
  $ cd tools/bpf/bpftool && make OUTPUT=<dir>
  $ cd tools/bpf/bpftool && make O=<dir>

After this commit, the build still fails for two variants when passing
the OUTPUT variable:

  $ make tools/bpf OUTPUT=<dir>
  $ cd tools/ && make bpf OUTPUT=<dir>

In order to remember and check what make invocations are supposed to
work, and to document the ones which do not, a new script is added to
the BPF selftests. Note that some invocations require the kernel to be
configured, so the script skips them if no .config file is found.

v2:
- In make_and_clean(), set $ERROR to 1 when "make" returns non-zero,
  even if the binary was produced.
- Run "make clean" from the correct directory (bpf/ instead of bpftool/,
  when relevant).
Reported-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

Bpftool calls the toplevel Makefile to get the kernel version for the
sources it is built from. But when the utility is built from the top of
the kernel repository, it may dump the following error message for
certain architectures (including x86):

    $ make tools/bpf
    [...]
    make[3]: *** [checkbin] Error 1
    [...]

This does not prevent bpftool compilation, but may feel disconcerting.
The "checkbin" arch-dependent target is not supposed to be called for
target "kernelversion", which is a simple "echo" of the version number.

It turns out this is caused by the make invocation in tools/bpf/bpftool,
which attempts to find implicit rules to apply. Extract from debug
output:

    Reading makefiles...
    Reading makefile 'Makefile'...
    Reading makefile 'scripts/Kbuild.include' (search path) (no ~ expansion)...
    Reading makefile 'scripts/subarch.include' (search path) (no ~ expansion)...
    Reading makefile 'arch/x86/Makefile' (search path) (no ~ expansion)...
    Reading makefile 'scripts/Makefile.kcov' (search path) (no ~ expansion)...
    Reading makefile 'scripts/Makefile.gcc-plugins' (search path) (no ~ expansion)...
    Reading makefile 'scripts/Makefile.kasan' (search path) (no ~ expansion)...
    Reading makefile 'scripts/Makefile.extrawarn' (search path) (no ~ expansion)...
    Reading makefile 'scripts/Makefile.ubsan' (search path) (no ~ expansion)...
    Updating makefiles....
     Considering target file 'scripts/Makefile.ubsan'.
      Looking for an implicit rule for 'scripts/Makefile.ubsan'.
      Trying pattern rule with stem 'Makefile.ubsan'.
    [...]
      Trying pattern rule with stem 'Makefile.ubsan'.
      Trying implicit prerequisite 'scripts/Makefile.ubsan.o'.
      Looking for a rule with intermediate file 'scripts/Makefile.ubsan.o'.
       Avoiding implicit rule recursion.
       Trying pattern rule with stem 'Makefile.ubsan'.
       Trying rule prerequisite 'prepare'.
       Trying rule prerequisite 'FORCE'.
      Found an implicit rule for 'scripts/Makefile.ubsan'.
        Considering target file 'prepare'.
         File 'prepare' does not exist.
          Considering target file 'prepare0'.
           File 'prepare0' does not exist.
            Considering target file 'archprepare'.
             File 'archprepare' does not exist.
              Considering target file 'archheaders'.
               File 'archheaders' does not exist.
               Finished prerequisites of target file 'archheaders'.
              Must remake target 'archheaders'.
    Putting child 0x55976f4f6980 (archheaders) PID 31743 on the chain.

To avoid that, pass the -r and -R flags to eliminate the use of make
built-in rules (and while at it, built-in variables) when running
command "make kernelversion" from bpftool's Makefile.
Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>