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The llvm patch [1] enabled opaque pointer which caused selftest 'exhandler' failure. ... ; work = task->task_works; 7: (79) r1 = *(u64 *)(r6 +2120) ; R1_w=ptr_callback_head(off=0,imm=0) R6_w=ptr_task_struct(off=0,imm=0) ; func = work->func; 8: (79) r2 = *(u64 *)(r1 +8) ; R1_w=ptr_callback_head(off=0,imm=0) R2_w=scalar() ; if (!work && !func) 9: (4f) r1 |= r2 math between ptr_ pointer and register with unbounded min value is not allowed below is insn 10 and 11 10: (55) if r1 != 0 goto +5 11: (18) r1 = 0 ll ... In llvm, the code generation of 'r1 |= r2' happened in codegen selectiondag phase due to difference of opaque pointer vs. non-opaque pointer. Without [1], the related code looks like: r2 = *(u64 *)(r6 + 2120) r1 = *(u64 *)(r2 + 8) if r2 != 0 goto +6 <LBB0_4> if r1 != 0 goto +5 <LBB0_4> r1 = 0 ll ... I haven't found a good way in llvm to fix this issue. So let us workaround the problem first so bpf CI won't be blocked. [1] https://reviews.llvm.org/D123300 Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20220419050900.3136024-1-yhs@fb.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.