linux-stable.git/tools/testing, branch v5.10.83 Linux kernel stable tree selftests/x86/iopl: Adjust to the faked iopl CLI/STI usage 2021-11-21T12:46:37+00:00 Borislav Petkov bp@suse.de 2021-10-29T17:27:32+00:00 0685efd9840f7d017ea7cef1f49aa746329fa73d commit a72fdfd21e01c626273ddcf5ab740d4caef4be54 upstream. Commit in Fixes changed the iopl emulation to not #GP on CLI and STI because it would break some insane luserspace tools which would toggle interrupts. The corresponding selftest would rely on the fact that executing CLI/STI would trigger a #GP and thus detect it this way but since that #GP is not happening anymore, the detection is now wrong too. Extend the test to actually look at the IF flag and whether executing those insns had any effect on it. The STI detection needs to have the fact that interrupts were previously disabled, passed in so do that from the previous CLI test, i.e., STI test needs to follow a previous CLI one for it to make sense. Fixes: b968e84b509d ("x86/iopl: Fake iopl(3) CLI/STI usage") Suggested-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20211030083939.13073-1-bp@alien8.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a72fdfd21e01c626273ddcf5ab740d4caef4be54 upstream.

Commit in Fixes changed the iopl emulation to not #GP on CLI and STI
because it would break some insane luserspace tools which would toggle
interrupts.

The corresponding selftest would rely on the fact that executing CLI/STI
would trigger a #GP and thus detect it this way but since that #GP is
not happening anymore, the detection is now wrong too.

Extend the test to actually look at the IF flag and whether executing
those insns had any effect on it. The STI detection needs to have the
fact that interrupts were previously disabled, passed in so do that from
the previous CLI test, i.e., STI test needs to follow a previous CLI one
for it to make sense.

Fixes: b968e84b509d ("x86/iopl: Fake iopl(3) CLI/STI usage")
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20211030083939.13073-1-bp@alien8.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
selftests/bpf: Fix also no-alu32 strobemeta selftest 2021-11-18T13:04:32+00:00 Andrii Nakryiko andrii@kernel.org 2021-11-01T23:01:18+00:00 5be42b203f2c4b72205b4ecd72c0558dfdb3a552 commit a20eac0af02810669e187cb623bc904908c423af upstream. Previous fix aded bpf_clamp_umax() helper use to re-validate boundaries. While that works correctly, it introduces more branches, which blows up past 1 million instructions in no-alu32 variant of strobemeta selftests. Switching len variable from u32 to u64 also fixes the issue and reduces the number of validated instructions, so use that instead. Fix this patch and bpf_clamp_umax() removed, both alu32 and no-alu32 selftests pass. Fixes: 0133c20480b1 ("selftests/bpf: Fix strobemeta selftest regression") Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211101230118.1273019-1-andrii@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a20eac0af02810669e187cb623bc904908c423af upstream.

Previous fix aded bpf_clamp_umax() helper use to re-validate boundaries.
While that works correctly, it introduces more branches, which blows up
past 1 million instructions in no-alu32 variant of strobemeta selftests.

Switching len variable from u32 to u64 also fixes the issue and reduces
the number of validated instructions, so use that instead. Fix this
patch and bpf_clamp_umax() removed, both alu32 and no-alu32 selftests
pass.

Fixes: 0133c20480b1 ("selftests/bpf: Fix strobemeta selftest regression")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211101230118.1273019-1-andrii@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
selftests/net: udpgso_bench_rx: fix port argument 2021-11-18T13:04:28+00:00 Willem de Bruijn willemb@google.com 2021-11-11T11:57:17+00:00 ee79560cb768ef56d91452868d01888e97373ccb [ Upstream commit d336509cb9d03970911878bb77f0497f64fda061 ] The below commit added optional support for passing a bind address. It configures the sockaddr bind arguments before parsing options and reconfigures on options -b and -4. This broke support for passing port (-p) on its own. Configure sockaddr after parsing all arguments. Fixes: 3327a9c46352 ("selftests: add functionals test for UDP GRO") Reported-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit d336509cb9d03970911878bb77f0497f64fda061 ]

The below commit added optional support for passing a bind address.
It configures the sockaddr bind arguments before parsing options and
reconfigures on options -b and -4.

This broke support for passing port (-p) on its own.

Configure sockaddr after parsing all arguments.

Fixes: 3327a9c46352 ("selftests: add functionals test for UDP GRO")
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
bpf: Fix propagation of bounds from 64-bit min/max into 32-bit and var_off. 2021-11-18T13:04:13+00:00 Alexei Starovoitov ast@kernel.org 2021-11-01T22:21:51+00:00 84dde8c8c9335213f091977eb1e935f3f38da71c [ Upstream commit b9979db8340154526d9ab38a1883d6f6ba9b6d47 ] Before this fix: 166: (b5) if r2 <= 0x1 goto pc+22 from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0xffffffff)) After this fix: 166: (b5) if r2 <= 0x1 goto pc+22 from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0x1)) While processing BPF_JLE the reg_set_min_max() would set true_reg->umax_value = 1 and call __reg_combine_64_into_32(true_reg). Without the fix it would not pass the condition: if (__reg64_bound_u32(reg->umin_value) && __reg64_bound_u32(reg->umax_value)) since umin_value == 0 at this point. Before commit 10bf4e83167c the umin was incorrectly ingored. The commit 10bf4e83167c fixed the correctness issue, but pessimized propagation of 64-bit min max into 32-bit min max and corresponding var_off. Fixes: 10bf4e83167c ("bpf: Fix propagation of 32 bit unsigned bounds from 64 bit bounds") Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20211101222153.78759-1-alexei.starovoitov@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit b9979db8340154526d9ab38a1883d6f6ba9b6d47 ]

Before this fix:
166: (b5) if r2 <= 0x1 goto pc+22
from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0xffffffff))

After this fix:
166: (b5) if r2 <= 0x1 goto pc+22
from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0x1))

While processing BPF_JLE the reg_set_min_max() would set true_reg->umax_value = 1
and call __reg_combine_64_into_32(true_reg).

Without the fix it would not pass the condition:
if (__reg64_bound_u32(reg->umin_value) && __reg64_bound_u32(reg->umax_value))

since umin_value == 0 at this point.
Before commit 10bf4e83167c the umin was incorrectly ingored.
The commit 10bf4e83167c fixed the correctness issue, but pessimized
propagation of 64-bit min max into 32-bit min max and corresponding var_off.

Fixes: 10bf4e83167c ("bpf: Fix propagation of 32 bit unsigned bounds from 64 bit bounds")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211101222153.78759-1-alexei.starovoitov@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
selftests/bpf: Fix fclose/pclose mismatch in test_progs 2021-11-18T13:04:13+00:00 Andrea Righi andrea.righi@canonical.com 2021-10-26T14:34:09+00:00 8f3d88139df8c59f6a5e087f12d58a1ff3f3f531 [ Upstream commit f48ad69097fe79d1de13c4d8fef556d4c11c5e68 ] Make sure to use pclose() to properly close the pipe opened by popen(). Fixes: 81f77fd0deeb ("bpf: add selftest for stackmap with BPF_F_STACK_BUILD_ID") Signed-off-by: Andrea Righi <andrea.righi@canonical.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Shuah Khan <skhan@linuxfoundation.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20211026143409.42666-1-andrea.righi@canonical.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit f48ad69097fe79d1de13c4d8fef556d4c11c5e68 ]

Make sure to use pclose() to properly close the pipe opened by popen().

Fixes: 81f77fd0deeb ("bpf: add selftest for stackmap with BPF_F_STACK_BUILD_ID")
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20211026143409.42666-1-andrea.righi@canonical.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
selftests/bpf: Fix fd cleanup in sk_lookup test 2021-11-18T13:04:12+00:00 Kumar Kartikeya Dwivedi memxor@gmail.com 2021-10-28T06:35:00+00:00 b17f424f88bad19282fc607ac654e88b51d03796 [ Upstream commit c3fc706e94f5653def2783ffcd809a38676b7551 ] Similar to the fix in commit: e31eec77e4ab ("bpf: selftests: Fix fd cleanup in get_branch_snapshot") We use designated initializer to set fds to -1 without breaking on future changes to MAX_SERVER constant denoting the array size. The particular close(0) occurs on non-reuseport tests, so it can be seen with -n 115/{2,3} but not 115/4. This can cause problems with future tests if they depend on BTF fd never being acquired as fd 0, breaking internal libbpf assumptions. Fixes: 0ab5539f8584 ("selftests/bpf: Tests for BPF_SK_LOOKUP attach point") Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20211028063501.2239335-8-memxor@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit c3fc706e94f5653def2783ffcd809a38676b7551 ]

Similar to the fix in commit:
e31eec77e4ab ("bpf: selftests: Fix fd cleanup in get_branch_snapshot")

We use designated initializer to set fds to -1 without breaking on
future changes to MAX_SERVER constant denoting the array size.

The particular close(0) occurs on non-reuseport tests, so it can be seen
with -n 115/{2,3} but not 115/4. This can cause problems with future
tests if they depend on BTF fd never being acquired as fd 0, breaking
internal libbpf assumptions.

Fixes: 0ab5539f8584 ("selftests/bpf: Tests for BPF_SK_LOOKUP attach point")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211028063501.2239335-8-memxor@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
selftests: bpf: Convert sk_lookup ctx access tests to PROG_TEST_RUN 2021-11-18T13:04:12+00:00 Lorenz Bauer lmb@cloudflare.com 2021-03-03T10:18:14+00:00 2989a396b891911cafd42465bd35622f5e797013 [ Upstream commit 509b2937bce90089fd2785db9f27951a3d850c34 ] Convert the selftests for sk_lookup narrow context access to use PROG_TEST_RUN instead of creating actual sockets. This ensures that ctx is populated correctly when using PROG_TEST_RUN. Assert concrete values since we now control remote_ip and remote_port. Signed-off-by: Lorenz Bauer <lmb@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210303101816.36774-4-lmb@cloudflare.com Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 509b2937bce90089fd2785db9f27951a3d850c34 ]

Convert the selftests for sk_lookup narrow context access to use
PROG_TEST_RUN instead of creating actual sockets. This ensures that
ctx is populated correctly when using PROG_TEST_RUN.

Assert concrete values since we now control remote_ip and remote_port.

Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210303101816.36774-4-lmb@cloudflare.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
KVM: selftests: Fix nested SVM tests when built with clang 2021-11-18T13:04:10+00:00 Jim Mattson jmattson@google.com 2021-09-30T00:36:49+00:00 7cd4af996cd296f36676416fc1618b3df6fbc985 [ Upstream commit ed290e1c20da19fa100a3e0f421aa31b65984960 ] Though gcc conveniently compiles a simple memset to "rep stos," clang prefers to call the libc version of memset. If a test is dynamically linked, the libc memset isn't available in L1 (nor is the PLT or the GOT, for that matter). Even if the test is statically linked, the libc memset may choose to use some CPU features, like AVX, which may not be enabled in L1. Note that __builtin_memset doesn't solve the problem, because (a) the compiler is free to call memset anyway, and (b) __builtin_memset may also choose to use features like AVX, which may not be available in L1. To avoid a myriad of problems, use an explicit "rep stos" to clear the VMCB in generic_svm_setup(), which is called both from L0 and L1. Reported-by: Ricardo Koller <ricarkol@google.com> Signed-off-by: Jim Mattson <jmattson@google.com> Fixes: 20ba262f8631a ("selftests: KVM: AMD Nested test infrastructure") Message-Id: <20210930003649.4026553-1-jmattson@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit ed290e1c20da19fa100a3e0f421aa31b65984960 ]

Though gcc conveniently compiles a simple memset to "rep stos," clang
prefers to call the libc version of memset. If a test is dynamically
linked, the libc memset isn't available in L1 (nor is the PLT or the
GOT, for that matter). Even if the test is statically linked, the libc
memset may choose to use some CPU features, like AVX, which may not be
enabled in L1. Note that __builtin_memset doesn't solve the problem,
because (a) the compiler is free to call memset anyway, and (b)
__builtin_memset may also choose to use features like AVX, which may
not be available in L1.

To avoid a myriad of problems, use an explicit "rep stos" to clear the
VMCB in generic_svm_setup(), which is called both from L0 and L1.

Reported-by: Ricardo Koller <ricarkol@google.com>
Signed-off-by: Jim Mattson <jmattson@google.com>
Fixes: 20ba262f8631a ("selftests: KVM: AMD Nested test infrastructure")
Message-Id: <20210930003649.4026553-1-jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
KVM: selftests: Add operand to vmsave/vmload/vmrun in svm.c 2021-11-18T13:04:10+00:00 Ricardo Koller ricarkol@google.com 2021-02-10T03:17:19+00:00 293fa72d62e46bc5f8044be7204869efad4b4d0c [ Upstream commit 47bc726fe8d1910872dc3d7e7ec70f8b9e6043b7 ] Building the KVM selftests with LLVM's integrated assembler fails with: $ CFLAGS=-fintegrated-as make -C tools/testing/selftests/kvm CC=clang lib/x86_64/svm.c:77:16: error: too few operands for instruction asm volatile ("vmsave\n\t" : : "a" (vmcb_gpa) : "memory"); ^ <inline asm>:1:2: note: instantiated into assembly here vmsave ^ lib/x86_64/svm.c:134:3: error: too few operands for instruction "vmload\n\t" ^ <inline asm>:1:2: note: instantiated into assembly here vmload ^ This is because LLVM IAS does not currently support calling vmsave, vmload, or vmload without an explicit %rax operand. Add an explicit operand to vmsave, vmload, and vmrum in svm.c. Fixing this was suggested by Sean Christopherson. Tested: building without this error in clang 11. The following patch (not queued yet) needs to be applied to solve the other remaining error: "selftests: kvm: remove reassignment of non-absolute variables". Suggested-by: Sean Christopherson <seanjc@google.com> Link: https://lore.kernel.org/kvm/X+Df2oQczVBmwEzi@google.com/ Reviewed-by: Jim Mattson <jmattson@google.com> Signed-off-by: Ricardo Koller <ricarkol@google.com> Message-Id: <20210210031719.769837-1-ricarkol@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 47bc726fe8d1910872dc3d7e7ec70f8b9e6043b7 ]

Building the KVM selftests with LLVM's integrated assembler fails with:

  $ CFLAGS=-fintegrated-as make -C tools/testing/selftests/kvm CC=clang
  lib/x86_64/svm.c:77:16: error: too few operands for instruction
          asm volatile ("vmsave\n\t" : : "a" (vmcb_gpa) : "memory");
                        ^
  <inline asm>:1:2: note: instantiated into assembly here
          vmsave
          ^
  lib/x86_64/svm.c:134:3: error: too few operands for instruction
                  "vmload\n\t"
                  ^
  <inline asm>:1:2: note: instantiated into assembly here
          vmload
          ^
This is because LLVM IAS does not currently support calling vmsave,
vmload, or vmload without an explicit %rax operand.

Add an explicit operand to vmsave, vmload, and vmrum in svm.c. Fixing
this was suggested by Sean Christopherson.

Tested: building without this error in clang 11. The following patch
(not queued yet) needs to be applied to solve the other remaining error:
"selftests: kvm: remove reassignment of non-absolute variables".

Suggested-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/kvm/X+Df2oQczVBmwEzi@google.com/
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Ricardo Koller <ricarkol@google.com>
Message-Id: <20210210031719.769837-1-ricarkol@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
selftests/bpf: Fix strobemeta selftest regression 2021-11-18T13:04:01+00:00 Andrii Nakryiko andrii@kernel.org 2021-10-29T18:29:07+00:00 19337ed10e7e7d36b017b40d08eece6ab428d3af [ Upstream commit 0133c20480b14820d43c37c0e9502da4bffcad3a ] After most recent nightly Clang update strobemeta selftests started failing with the following error (relevant portion of assembly included): 1624: (85) call bpf_probe_read_user_str#114 1625: (bf) r1 = r0 1626: (18) r2 = 0xfffffffe 1628: (5f) r1 &= r2 1629: (55) if r1 != 0x0 goto pc+7 1630: (07) r9 += 104 1631: (6b) *(u16 *)(r9 +0) = r0 1632: (67) r0 <<= 32 1633: (77) r0 >>= 32 1634: (79) r1 = *(u64 *)(r10 -456) 1635: (0f) r1 += r0 1636: (7b) *(u64 *)(r10 -456) = r1 1637: (79) r1 = *(u64 *)(r10 -368) 1638: (c5) if r1 s< 0x1 goto pc+778 1639: (bf) r6 = r8 1640: (0f) r6 += r7 1641: (b4) w1 = 0 1642: (6b) *(u16 *)(r6 +108) = r1 1643: (79) r3 = *(u64 *)(r10 -352) 1644: (79) r9 = *(u64 *)(r10 -456) 1645: (bf) r1 = r9 1646: (b4) w2 = 1 1647: (85) call bpf_probe_read_user_str#114 R1 unbounded memory access, make sure to bounds check any such access In the above code r0 and r1 are implicitly related. Clang knows that, but verifier isn't able to infer this relationship. Yonghong Song narrowed down this "regression" in code generation to a recent Clang optimization change ([0]), which for BPF target generates code pattern that BPF verifier can't handle and loses track of register boundaries. This patch works around the issue by adding an BPF assembly-based helper that helps to prove to the verifier that upper bound of the register is a given constant by controlling the exact share of generated BPF instruction sequence. This fixes the immediate issue for strobemeta selftest. [0] https://github.com/llvm/llvm-project/commit/acabad9ff6bf13e00305d9d8621ee8eafc1f8b08 Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/bpf/20211029182907.166910-1-andrii@kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 0133c20480b14820d43c37c0e9502da4bffcad3a ]

After most recent nightly Clang update strobemeta selftests started
failing with the following error (relevant portion of assembly included):

  1624: (85) call bpf_probe_read_user_str#114
  1625: (bf) r1 = r0
  1626: (18) r2 = 0xfffffffe
  1628: (5f) r1 &= r2
  1629: (55) if r1 != 0x0 goto pc+7
  1630: (07) r9 += 104
  1631: (6b) *(u16 *)(r9 +0) = r0
  1632: (67) r0 <<= 32
  1633: (77) r0 >>= 32
  1634: (79) r1 = *(u64 *)(r10 -456)
  1635: (0f) r1 += r0
  1636: (7b) *(u64 *)(r10 -456) = r1
  1637: (79) r1 = *(u64 *)(r10 -368)
  1638: (c5) if r1 s< 0x1 goto pc+778
  1639: (bf) r6 = r8
  1640: (0f) r6 += r7
  1641: (b4) w1 = 0
  1642: (6b) *(u16 *)(r6 +108) = r1
  1643: (79) r3 = *(u64 *)(r10 -352)
  1644: (79) r9 = *(u64 *)(r10 -456)
  1645: (bf) r1 = r9
  1646: (b4) w2 = 1
  1647: (85) call bpf_probe_read_user_str#114

  R1 unbounded memory access, make sure to bounds check any such access

In the above code r0 and r1 are implicitly related. Clang knows that,
but verifier isn't able to infer this relationship.

Yonghong Song narrowed down this "regression" in code generation to
a recent Clang optimization change ([0]), which for BPF target generates
code pattern that BPF verifier can't handle and loses track of register
boundaries.

This patch works around the issue by adding an BPF assembly-based helper
that helps to prove to the verifier that upper bound of the register is
a given constant by controlling the exact share of generated BPF
instruction sequence. This fixes the immediate issue for strobemeta
selftest.

  [0] https://github.com/llvm/llvm-project/commit/acabad9ff6bf13e00305d9d8621ee8eafc1f8b08

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211029182907.166910-1-andrii@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>