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bpf: Fix test verif_scale_strobemeta_subprogs failure due to llvm19 #6414

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bpf: Fix test verif_scale_strobemeta_subprogs failure due to llvm19 #6414

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Pull request for series with
subject: bpf: Fix test verif_scale_strobemeta_subprogs failure due to llvm19
version: 2
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=824191

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Upstream branch: e55dad1
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=824191
version: 2

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Upstream branch: a7170d8
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=824191
version: 2

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Upstream branch: a7170d8
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=824476
version: 3

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Upstream branch: 2e7f18a
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=824476
version: 3

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Upstream branch: a7170d8
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=824476
version: 3

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Upstream branch: 68bc61c
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=824476
version: 3

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Upstream branch: 68bc61c
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=824476
version: 3

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Upstream branch: 68bc61c
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=824476
version: 3

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Upstream branch: fc1c9e4
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=824476
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=824476 expired. Closing PR.

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Upstream branch: a4561f5
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=826182
version: 4

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Upstream branch: 57354f5
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=826182
version: 4

bpf: Fix test verif_scale_strobemeta_subprogs failure due to llvm19
1b44265 
With latest llvm19, I hit the following selftest failures with

  $ ./test_progs -j
  libbpf: prog 'on_event': BPF program load failed: Permission denied
  libbpf: prog 'on_event': -- BEGIN PROG LOAD LOG --
  combined stack size of 4 calls is 544. Too large
  verification time 1344153 usec
  stack depth 24+440+0+32
  processed 51008 insns (limit 1000000) max_states_per_insn 19 total_states 1467 peak_states 303 mark_read 146
  -- END PROG LOAD LOG --
  libbpf: prog 'on_event': failed to load: -13
  libbpf: failed to load object 'strobemeta_subprogs.bpf.o'
  scale_test:FAIL:expect_success unexpected error: -13 (errno 13)
  #498     verif_scale_strobemeta_subprogs:FAIL

The verifier complains too big of the combined stack size (544 bytes) which
exceeds the maximum stack limit 512. This is a regression from llvm19 ([1]).

In the above error log, the original stack depth is 24+440+0+32.
To satisfy interpreter's need, in verifier the stack depth is adjusted to
32+448+32+32=544 which exceeds 512, hence the error. The same adjusted
stack size is also used for jit case.

But the jitted codes could use smaller stack size.

  $ egrep -r stack_depth | grep round_up
  arm64/net/bpf_jit_comp.c:       ctx->stack_size = round_up(prog->aux->stack_depth, 16);
  loongarch/net/bpf_jit.c:        bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16);
  powerpc/net/bpf_jit_comp.c:     cgctx.stack_size = round_up(fp->aux->stack_depth, 16);
  riscv/net/bpf_jit_comp32.c:             round_up(ctx->prog->aux->stack_depth, STACK_ALIGN);
  riscv/net/bpf_jit_comp64.c:     bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16);
  s390/net/bpf_jit_comp.c:        u32 stack_depth = round_up(fp->aux->stack_depth, 8);
  sparc/net/bpf_jit_comp_64.c:            stack_needed += round_up(stack_depth, 16);
  x86/net/bpf_jit_comp.c:         EMIT3_off32(0x48, 0x81, 0xEC, round_up(stack_depth, 8));
  x86/net/bpf_jit_comp.c: int tcc_off = -4 - round_up(stack_depth, 8);
  x86/net/bpf_jit_comp.c:                     round_up(stack_depth, 8));
  x86/net/bpf_jit_comp.c: int tcc_off = -4 - round_up(stack_depth, 8);
  x86/net/bpf_jit_comp.c:         EMIT3_off32(0x48, 0x81, 0xC4, round_up(stack_depth, 8));

In the above, STACK_ALIGN in riscv/net/bpf_jit_comp32.c is defined as 16.
So stack is aligned in either 8 or 16, x86/s390 having 8-byte stack alignment and
the rest having 16-byte alignment.

This patch calculates total stack depth based on 16-byte alignment if jit is requested.
For the above failing case, the new stack size will be 32+448+0+32=512 and no verification
failure. llvm19 regression will be discussed separately in llvm upstream.

The verifier change caused three test failures as these tests compared messages
with stack size. More specifically,
  - test_global_funcs/global_func1: fail with interpreter mode and success with jit mode.
    Adjusted stack sizes so both jit and interpreter modes will fail.
  - async_stack_depth/{pseudo_call_check, async_call_root_check}: since jit and interpreter
    will calculate different stack sizes, the failure msg is adjusted to omit those
    specific stack size numbers.

  [1] https://lore.kernel.org/bpf/32bde0f0-1881-46c9-931a-673be566c61d@linux.dev/

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=826182 irrelevant now. Closing PR.

@kernel-patches-daemon-bpf kernel-patches-daemon-bpf bot deleted the series/824191=>bpf-next branch February 15, 2024 22:01
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