Leon Hwang says:

====================
bpf, xdp: Add tracepoint to xdp attaching failure

This series introduces a new tracepoint in bpf_xdp_link_attach(). By
this tracepoint, error message will be captured when error happens in
dev_xdp_attach(), e.g. invalid attaching flags.

v4 -> v5:
* Initialise the extack variable.
* Fix code style issue of variable declaration lines.

v3 -> v4:
* Fix selftest-crashed issue.
====================

Link: https://lore.kernel.org/r/20230801142621.7925-1-hffilwlqm@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Add a test case for the tracepoint of xdp attaching failure by bpf
tracepoint when attach XDP to a device with invalid flags option.

The bpf tracepoint retrieves error message from the tracepoint, and
then put the error message to a perf buffer. The testing code receives
error message from perf buffer, and then ASSERT "Invalid XDP flags for
BPF link attachment".
Signed-off-by: Leon Hwang <hffilwlqm@gmail.com>
Link: https://lore.kernel.org/r/20230801142621.7925-3-hffilwlqm@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

When error happens in dev_xdp_attach(), it should have a way to tell
users the error message like the netlink approach.

To avoid breaking uapi, adding a tracepoint in bpf_xdp_link_attach() is
an appropriate way to notify users the error message.

Hence, bpf libraries are able to retrieve the error message by this
tracepoint, and then report the error message to users.
Signed-off-by: Leon Hwang <hffilwlqm@gmail.com>
Link: https://lore.kernel.org/r/20230801142621.7925-2-hffilwlqm@gmail.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

commit bdeeed34 ("libbpf: fix offsetof() and container_of() to work with CO-RE")

...was backported to stable trees such as 5.15. The problem is that with older
LLVM/clang (14/15) - which is often used for older kernels - we see compilation
failures in BPF selftests now:

In file included from progs/test_cls_redirect_subprogs.c:2:
progs/test_cls_redirect.c:90:2: error: static assertion expression is not an integral constant expression
        sizeof(flow_ports_t) !=
        ^~~~~~~~~~~~~~~~~~~~~~~
progs/test_cls_redirect.c:91:3: note: cast that performs the conversions of a reinterpret_cast is not allowed in a constant expression
                offsetofend(struct bpf_sock_tuple, ipv4.dport) -
                ^
progs/test_cls_redirect.c:32:3: note: expanded from macro 'offsetofend'
        (offsetof(TYPE, MEMBER) + sizeof((((TYPE *)0)->MEMBER)))
         ^
tools/testing/selftests/bpf/tools/include/bpf/bpf_helpers.h:86:33: note: expanded from macro 'offsetof'
                                 ^
In file included from progs/test_cls_redirect_subprogs.c:2:
progs/test_cls_redirect.c:95:2: error: static assertion expression is not an integral constant expression
        sizeof(flow_ports_t) !=
        ^~~~~~~~~~~~~~~~~~~~~~~
progs/test_cls_redirect.c:96:3: note: cast that performs the conversions of a reinterpret_cast is not allowed in a constant expression
                offsetofend(struct bpf_sock_tuple, ipv6.dport) -
                ^
progs/test_cls_redirect.c:32:3: note: expanded from macro 'offsetofend'
        (offsetof(TYPE, MEMBER) + sizeof((((TYPE *)0)->MEMBER)))
         ^
tools/testing/selftests/bpf/tools/include/bpf/bpf_helpers.h:86:33: note: expanded from macro 'offsetof'
                                 ^
2 errors generated.
make: *** [Makefile:594: tools/testing/selftests/bpf/test_cls_redirect_subprogs.bpf.o] Error 1

The problem is the new offsetof() does not play nice with static asserts.
Given that the context is a static assert (and CO-RE relocation is not
needed at compile time), offsetof() usage can be replaced by restoring
the original offsetof() definition as __builtin_offsetof().

Fixes: bdeeed34 ("libbpf: fix offsetof() and container_of() to work with CO-RE")
Reported-by: Colm Harrington <colm.harrington@oracle.com>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Tested-by: Yipeng Zou <zouyipeng@huawei.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230802073906.3197480-1-alan.maguire@oracle.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

bpf_probe_read_kernel() has a __weak definition in core.c and another
definition with an incompatible prototype in kernel/trace/bpf_trace.c,
when CONFIG_BPF_EVENTS is enabled.

Since the two are incompatible, there cannot be a shared declaration in
a header file, but the lack of a prototype causes a W=1 warning:

kernel/bpf/core.c:1638:12: error: no previous prototype for 'bpf_probe_read_kernel' [-Werror=missing-prototypes]

On 32-bit architectures, the local prototype

u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr)

passes arguments in other registers as the one in bpf_trace.c

BPF_CALL_3(bpf_probe_read_kernel, void *, dst, u32, size,
            const void *, unsafe_ptr)

which uses 64-bit arguments in pairs of registers.

As both versions of the function are fairly simple and only really
differ in one line, just move them into a header file as an inline
function that does not add any overhead for the bpf_trace.c callers
and actually avoids a function call for the other one.

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/ac25cb0f-b804-1649-3afb-1dc6138c2716@iogearbox.net/Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230801111449.185301-1-arnd@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Commit 6724a76c ("riscv: ftrace: Reduce the detour code size to
half") optimizes the detour code size of kernel functions to half with
T0 register and the upcoming DYNAMIC_FTRACE_WITH_DIRECT_CALLS of riscv
is based on this optimization, we need to adapt riscv bpf trampoline
based on this. One thing to do is to reduce detour code size of bpf
programs, and the second is to deal with the return address after the
execution of bpf trampoline. Meanwhile, we need to construct the frame
of parent function, otherwise we will miss one layer when unwinding.
The related tests have passed.
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20230721100627.2630326-1-pulehui@huaweicloud.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Capitalize ABI (acronym) and fix spelling of "destination".

Fixes: 70681949 ("libbpf: Improve usability of libbpf Makefile")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org
Cc: Xin Liu <liuxin350@huawei.com>
Link: https://lore.kernel.org/r/20230722065236.17010-1-rdunlap@infradead.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

bpf tracepoint program uses struct trace_event_raw_sys_enter as
argument where trace_entry is the first field. Use the same instead
of unsigned long long since if it's amended (for example by RT
patch) it accesses data with wrong offset.
Signed-off-by: Yauheni Kaliuta <ykaliuta@redhat.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230801075222.7717-1-ykaliuta@redhat.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Hou Tao says:

====================
Patchset "Simplify xdp_do_redirect_map()/xdp_do_flush_map() and XDP
maps" [0] changed per-map flush list to global per-cpu flush list
for cpumap, devmap and xskmap, but it forgot to remove these unused
fields from cpumap and devmap. So just remove these unused fields.

Comments and suggestions are always welcome.

[0]: https://lore.kernel.org/bpf/20191219061006.21980-1-bjorn.topel@gmail.com
====================
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

Commit 96360004 ("xdp: Make devmap flush_list common for all map
instances") removes the use of bpf_dtab_netdev::dtab in bq_enqueue(),
so just remove dtab from bpf_dtab_netdev.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://lore.kernel.org/r/20230728014942.892272-3-houtao@huaweicloud.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

Since commit cdfafe98 ("xdp: Make cpumap flush_list common for all
map instances"), cmap is no longer used, so just remove it.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230728014942.892272-2-houtao@huaweicloud.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

Before, we were getting this warning:

  net/netfilter/nf_bpf_link.c:32:1: warning: 'get_proto_defrag_hook' defined but not used [-Wunused-function]

Guard the definition with CONFIG_NF_DEFRAG_IPV[4|6].

Fixes: 91721c2d ("netfilter: bpf: Support BPF_F_NETFILTER_IP_DEFRAG in netfilter link")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202307291213.fZ0zDmoG-lkp@intel.com/Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/b128b6489f0066db32c4772ae4aaee1480495929.1690840454.git.dxu@dxuuu.xyzSigned-off-by: Alexei Starovoitov <ast@kernel.org>

syzbot reported an array-index-out-of-bounds when printing out bpf
insns. Further investigation shows the insn is illegal but
is printed out due to log level 1 or 2 before actual insn verification
in do_check().

This particular illegal insn is a MOVSX insn with offset value 2.
The legal offset value for MOVSX should be 8, 16 and 32.
The disasm sign-extension-size array index is calculated as
 (insn->off / 8) - 1
and offset value 2 gives an out-of-bound index -1.

Tighten the checking for MOVSX insn in disasm.c to avoid
array-index-out-of-bounds issue.

Reported-by: syzbot+3758842a6c01012aa73b@syzkaller.appspotmail.com
Fixes: f835bb62 ("bpf: Add kernel/bpftool asm support for new instructions")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230731204534.1975311-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

There are already INDIRECT_CALLABLE_DECLARE in the hashtable
headers, no need to declare them again.

Fixes: 0f495f76 ("net: remove duplicate reuseport_lookup functions")
Suggested-by: Martin Lau <martin.lau@linux.dev>
Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20230731-indir-call-v1-1-4cd0aeaee64f@isovalent.comSigned-off-by: Martin KaFai Lau <martin.lau@kernel.org>

Two issues are fixed:
  1. Malformed table due to newly-introduced BPF_MOVSX
  2. Missing reference link for ``Sign-extension load operations``

Fixes: 245d4c40 ("docs/bpf: Add documentation for new instructions")
Cc: bpf@ietf.org
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202307291840.Cqhj7uox-lkp@intel.com/Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230730004251.381307-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Daniel Xu says:

====================
Support defragmenting IPv(4|6) packets in BPF

=== Context ===

In the context of a middlebox, fragmented packets are tricky to handle.
The full 5-tuple of a packet is often only available in the first
fragment which makes enforcing consistent policy difficult. There are
really only two stateless options, neither of which are very nice:

1. Enforce policy on first fragment and accept all subsequent fragments.
   This works but may let in certain attacks or allow data exfiltration.

2. Enforce policy on first fragment and drop all subsequent fragments.
   This does not really work b/c some protocols may rely on
   fragmentation. For example, DNS may rely on oversized UDP packets for
   large responses.

So stateful tracking is the only sane option. RFC 8900 [0] calls this
out as well in section 6.3:

    Middleboxes [...] should process IP fragments in a manner that is
    consistent with [RFC0791] and [RFC8200]. In many cases, middleboxes
    must maintain state in order to achieve this goal.

=== BPF related bits ===

Policy has traditionally been enforced from XDP/TC hooks. Both hooks
run before kernel reassembly facilities. However, with the new
BPF_PROG_TYPE_NETFILTER, we can rather easily hook into existing
netfilter reassembly infra.

The basic idea is we bump a refcnt on the netfilter defrag module and
then run the bpf prog after the defrag module runs. This allows bpf
progs to transparently see full, reassembled packets. The nice thing
about this is that progs don't have to carry around logic to detect
fragments.

=== Changelog ===

Changes from v5:

* Fix defrag disable codepaths

Changes from v4:

* Refactor module handling code to not sleep in rcu_read_lock()
* Also unify the v4 and v6 hook structs so they can share codepaths
* Fixed some checkpatch.pl formatting warnings

Changes from v3:

* Correctly initialize `addrlen` stack var for recvmsg()

Changes from v2:

* module_put() if ->enable() fails
* Fix CI build errors

Changes from v1:

* Drop bpf_program__attach_netfilter() patches
* static -> static const where appropriate
* Fix callback assignment order during registration
* Only request_module() if callbacks are missing
* Fix retval when modprobe fails in userspace
* Fix v6 defrag module name (nf_defrag_ipv6_hooks -> nf_defrag_ipv6)
* Simplify priority checking code
* Add warning if module doesn't assign callbacks in the future
* Take refcnt on module while defrag link is active

[0]: https://datatracker.ietf.org/doc/html/rfc8900
====================

Link: https://lore.kernel.org/r/cover.1689970773.git.dxu@dxuuu.xyzSigned-off-by: Alexei Starovoitov <ast@kernel.org>

These selftests tests 2 major scenarios: the BPF based defragmentation
can successfully be done and that packet pointers are invalidated after
calls to the kfunc. The logic is similar for both ipv4 and ipv6.

In the first scenario, we create a UDP client and UDP echo server. The
the server side is fairly straightforward: we attach the prog and simply
echo back the message.

The on the client side, we send fragmented packets to and expect the
reassembled message back from the server.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/33e40fdfddf43be93f2cb259303f132f46750953.1689970773.git.dxu@dxuuu.xyzSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Extend connect_to_fd_opts() to take optional type and protocol
parameters for the client socket. These parameters are useful when
opening a raw socket to send IP fragments.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/9067db539efdfd608aa86a2b143c521337c111fc.1689970773.git.dxu@dxuuu.xyzSigned-off-by: Alexei Starovoitov <ast@kernel.org>

For connectionless protocols or raw sockets we do not want to actually
connect() to the server.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/525c13d66dac2d640a1db922546842c051c6f2e6.1689970773.git.dxu@dxuuu.xyzSigned-off-by: Alexei Starovoitov <ast@kernel.org>

This commit adds support for enabling IP defrag using pre-existing
netfilter defrag support. Basically all the flag does is bump a refcnt
while the link the active. Checks are also added to ensure the prog
requesting defrag support is run _after_ netfilter defrag hooks.

We also take care to avoid any issues w.r.t. module unloading -- while
defrag is active on a link, the module is prevented from unloading.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Reviewed-by: Florian Westphal <fw@strlen.de>
Link: https://lore.kernel.org/r/5cff26f97e55161b7d56b09ddcf5f8888a5add1d.1689970773.git.dxu@dxuuu.xyzSigned-off-by: Alexei Starovoitov <ast@kernel.org>

We want to be able to enable/disable IP packet defrag from core
bpf/netfilter code. In other words, execute code from core that could
possibly be built as a module.

To help avoid symbol resolution errors, use glue hooks that the modules
will register callbacks with during module init.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Reviewed-by: Florian Westphal <fw@strlen.de>
Link: https://lore.kernel.org/r/f6a8824052441b72afe5285acedbd634bd3384c1.1689970773.git.dxu@dxuuu.xyzSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Improve documentation for cpu=v4 instructions based on
David's suggestions.

Cc: bpf@ietf.org
Suggested-by: David Vernet <void@manifault.com>
Acked-by: David Vernet <void@manifault.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728225105.919595-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

In internal testing of test_maps, we sometimes observed failures like:
  test_maps: test_maps.c:173: void test_hashmap_percpu(unsigned int, void *):
    Assertion `bpf_map_update_elem(fd, &key, value, BPF_ANY) == 0' failed.
where the errno is ENOMEM. After some troubleshooting and enabling
the warnings, we saw:
  [   91.304708] percpu: allocation failed, size=8 align=8 atomic=1, atomic alloc failed, no space left
  [   91.304716] CPU: 51 PID: 24145 Comm: test_maps Kdump: loaded Tainted: G                 N 6.1.38-smp-DEV #7
  [   91.304719] Hardware name: Google Astoria/astoria, BIOS 0.20230627.0-0 06/27/2023
  [   91.304721] Call Trace:
  [   91.304724]  <TASK>
  [   91.304730]  [<ffffffffa7ef83b9>] dump_stack_lvl+0x59/0x88
  [   91.304737]  [<ffffffffa7ef83f8>] dump_stack+0x10/0x18
  [   91.304738]  [<ffffffffa75caa0c>] pcpu_alloc+0x6fc/0x870
  [   91.304741]  [<ffffffffa75ca302>] __alloc_percpu_gfp+0x12/0x20
  [   91.304743]  [<ffffffffa756785e>] alloc_bulk+0xde/0x1e0
  [   91.304746]  [<ffffffffa7566c02>] bpf_mem_alloc_init+0xd2/0x2f0
  [   91.304747]  [<ffffffffa7547c69>] htab_map_alloc+0x479/0x650
  [   91.304750]  [<ffffffffa751d6e0>] map_create+0x140/0x2e0
  [   91.304752]  [<ffffffffa751d413>] __sys_bpf+0x5a3/0x6c0
  [   91.304753]  [<ffffffffa751c3ec>] __x64_sys_bpf+0x1c/0x30
  [   91.304754]  [<ffffffffa7ef847a>] do_syscall_64+0x5a/0x80
  [   91.304756]  [<ffffffffa800009b>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

This makes sense, because in atomic context, percpu allocation would
not create new chunks; it would only create in non-atomic contexts.
And if during prefill all precpu chunks are full, -ENOMEM would
happen immediately upon next unit_alloc.

Prefill phase does not actually run in atomic context, so we can
use this fact to allocate non-atomically with GFP_KERNEL instead
of GFP_NOWAIT. This avoids the immediate -ENOMEM.

GFP_NOWAIT has to be used in unit_alloc when bpf program runs
in atomic context. Even if bpf program runs in non-atomic context,
in most cases, rcu read lock is enabled for the program so
GFP_NOWAIT is still needed. This is often also the case for
BPF_MAP_UPDATE_ELEM syscalls.
Signed-off-by: YiFei Zhu <zhuyifei@google.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20230728043359.3324347-1-zhuyifei@google.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Currently, test_progs-cpuv4 is generated with clang build kernel
when bpf cpu=v4 is supported by the clang compiler.
Let us enable test_progs-cpuv4 for gcc build kernel as well.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728055745.2285202-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

The kernel test robot reported compilation warnings when -Wparentheses is
added to KBUILD_CFLAGS with gcc compiler. The following is the error message:

  .../bpf-next/kernel/bpf/verifier.c: In function ‘coerce_reg_to_size_sx’:
  .../bpf-next/kernel/bpf/verifier.c:5901:14:
    error: suggest parentheses around comparison in operand of ‘==’ [-Werror=parentheses]
    if (s64_max >= 0 == s64_min >= 0) {
        ~~~~~~~~^~~~
  .../bpf-next/kernel/bpf/verifier.c: In function ‘coerce_subreg_to_size_sx’:
  .../bpf-next/kernel/bpf/verifier.c:5965:14:
    error: suggest parentheses around comparison in operand of ‘==’ [-Werror=parentheses]
    if (s32_min >= 0 == s32_max >= 0) {
        ~~~~~~~~^~~~

To fix the issue, add proper parentheses for the above '>=' condition
to silence the warning/error.

I tried a few clang compilers like clang16 and clang18 and they do not emit
such warnings with -Wparentheses.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202307281133.wi0c4SqG-lkp@intel.com/Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230728055740.2284534-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Yonghong Song says:

====================
bpf: Support new insns from cpu v4

In previous discussion ([1]), it is agreed that we should introduce
cpu version 4 (llvm flag -mcpu=v4) which contains some instructions
which can simplify code, make code easier to understand, fix the
existing problem, or simply for feature completeness. More specifically,
the following new insns are proposed:
  . sign extended load
  . sign extended mov
  . bswap
  . signed div/mod
  . ja with 32-bit offset

This patch set added kernel support for insns proposed in [1] except
BPF_ST which already has full kernel support. Beside the above proposed
insns, LLVM will generate BPF_ST insn as well under -mcpu=v4.
The llvm patch ([2]) has been merged into llvm-project 'main' branch.

The patchset implements interpreter, jit and verifier support for these new
insns.

For this patch set, I tested cpu v2/v3/v4 and the selftests are all passed.
I also tested selftests introduced in this patch set with additional changes
beside normal jit testing (bpf_jit_enable = 1 and bpf_jit_harden = 0)
  - bpf_jit_enable = 0
  - bpf_jit_enable = 1 and bpf_jit_harden = 1
and both testing passed.

  [1] https://lore.kernel.org/bpf/4bfe98be-5333-1c7e-2f6d-42486c8ec039@meta.com/
  [2] https://reviews.llvm.org/D144829

Changelogs:
  v4 -> v5:
   . for v4, patch 8/17 missed in mailing list and patchwork, so resend.
   . rebase on top of master
  v3 -> v4:
   . some minor asm syntax adjustment based on llvm change.
   . add clang version and target arch guard for new tests
     so they can still compile with old llvm compilers.
   . some changes to the bpf doc.
  v2 -> v3:
   . add missed disasm change from v2.
   . handle signed load of ctx fields properly.
   . fix some interpreter sdiv/smod error when bpf_jit_enable = 0.
   . fix some verifier range bounding errors.
   . add more C tests.
  RFCv1 -> v2:
   . add more verifier supports for signed extend load and mov insns.
   . rename some insn names to be more consistent with intel practice.
   . add cpuv4 test runner for test progs.
   . add more unit and C tests.
   . add documentation.
====================

Link: https://lore.kernel.org/r/20230728011143.3710005-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Add documentation in instruction-set.rst for new instruction encoding
and their corresponding operations. Also removed the question
related to 'no BPF_SDIV' in bpf_design_QA.rst since we have
BPF_SDIV insn now.

Cc: bpf@ietf.org
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011342.3724411-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

The following ldsx cases are tested:
  - signed readonly map value
  - read/write map value
  - probed memory
  - not-narrowed ctx field access
  - narrowed ctx field access.

Without previous proper verifier/git handling, the test will fail.

If cpuv4 is not supported either by compiler or by jit,
the test will be skipped.

  # ./test_progs -t ldsx_insn
  #113/1   ldsx_insn/map_val and probed_memory:SKIP
  #113/2   ldsx_insn/ctx_member_sign_ext:SKIP
  #113/3   ldsx_insn/ctx_member_narrow_sign_ext:SKIP
  #113     ldsx_insn:SKIP
  Summary: 1/0 PASSED, 3 SKIPPED, 0 FAILED
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011336.3723434-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Add unit tests for gotol insn.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011329.3721881-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Add unit tests for sdiv/smod insns.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011321.3720500-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Add unit tests for bswap insns.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011314.3720109-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Add unit tests for movsx insns.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011309.3719295-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Add unit tests for new ldsx insns. The test includes sign-extension
with a single value or with a value range.

If cpuv4 is not supported due to
  (1) older compiler, e.g., less than clang version 18, or
  (2) test runner test_progs and test_progs-no_alu32 which tests
      cpu v2 and v3, or
  (3) non-x86_64 arch not supporting new insns in jit yet,
a dummy program is added with below output:
  #318/1   verifier_ldsx/cpuv4 is not supported by compiler or jit, use a dummy test:OK
  #318     verifier_ldsx:OK
to indicate the test passed with a dummy test instead of actually
testing cpuv4. I am using a dummy prog to avoid changing the
verifier testing infrastructure. Once clang 18 is widely available
and other architectures support cpuv4, at least for CI run,
the dummy program can be removed.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011304.3719139-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Similar to no-alu32 runner, if clang compiler supports -mcpu=v4,
a cpuv4 runner is created to test bpf programs compiled with
-mcpu=v4.

The following are some num-of-insn statistics for each newer
instructions based on existing selftests, excluding subsequent
cpuv4 insn specific tests.

   insn pattern                # of instructions
   reg = (s8)reg               4
   reg = (s16)reg              4
   reg = (s32)reg              144
   reg = *(s8 *)(reg + off)    13
   reg = *(s16 *)(reg + off)   14
   reg = *(s32 *)(reg + off)   15215
   reg = bswap16 reg           142
   reg = bswap32 reg           38
   reg = bswap64 reg           14
   reg s/= reg                 0
   reg s%= reg                 0
   gotol <offset>              58

Note that in llvm -mcpu=v4 implementation, the compiler is a little
bit conservative about generating 'gotol' insn (32-bit branch offset)
as it didn't precise count the number of insns (e.g., some insns are
debug insns, etc.). Compared to old 'goto' insn, newer 'gotol' insn
should have comparable verification states to 'goto' insn.

With current patch set, all selftests passed with -mcpu=v4
when running test_progs-cpuv4 binary. The -mcpu=v3 and -mcpu=v2 run
are also successful.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011250.3718252-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

The following test_verifier subtest failed due to
new encoding for BSWAP.

  $ ./test_verifier
  ...
  #99/u invalid 64-bit BPF_END FAIL
  Unexpected success to load!
  verification time 215 usec
  stack depth 0
  processed 3 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0
  #99/p invalid 64-bit BPF_END FAIL
  Unexpected success to load!
  verification time 198 usec
  stack depth 0
  processed 3 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0

Tighten the test so it still reports a failure.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011244.3717464-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Add asm support for new instructions so kernel verifier and bpftool
xlated insn dumps can have proper asm syntax for new instructions.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Add interpreter/jit/verifier support for 32bit offset jmp instruction.
If a conditional jmp instruction needs more than 16bit offset,
it can be simulated with a conditional jmp + a 32bit jmp insn.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011231.3716103-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Handle new insns properly in bpf_jit_blind_insn() function.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011225.3715812-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

Add interpreter/jit support for new signed div/mod insns.
The new signed div/mod instructions are encoded with
unsigned div/mod instructions plus insn->off == 1.
Also add basic verifier support to ensure new insns get
accepted.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011219.3714605-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>

The existing 'be' and 'le' insns will do conditional bswap
depends on host endianness. This patch implements
unconditional bswap insns.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011213.3712808-1-yonghong.song@linux.devSigned-off-by: Alexei Starovoitov <ast@kernel.org>