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bb5bad6a78
Implement the struct_ops arena argument conversion on arm64. save_args() receives the arena base from bpf_tramp_arena_base() and consults the btf_func_model argument flags as it copies each native argument into the BPF ctx, routing a marked argument through x10 with the low half of the base materialized once into x11: sub w10, wsrc, w11 /* truncate and clear the upper 32 bits */ str x10, [sp, #slot] A nullable argument tests the full 64-bit kernel pointer first: mov x10, xsrc cbz x10, 1f sub w10, w10, w11 1: str x10, [sp, #slot] The 32-bit subtraction is sufficient since (u32)(kaddr - base) == (u32)kaddr - (u32)base, and it clears the upper half as the JITs require of arena pointer registers. Stack-passed arguments already reload through x10, so only the subtraction (and the NULL test) is inserted there. The register loop now walks arguments rather than registers so that the per-argument flags line up with the slots a multi-slot argument occupies; the sequence of stores is otherwise unchanged. bpf_tramp_arena_base() returns a base only for a single-program struct_ops indirect trampoline, so a tracing trampoline emits exactly what it did before and never touches x11. The size probe reruns the same emission with the same model and nodes, so the image size matches by construction. Conversion must never reach the original function, which takes kernel addresses. That holds because BPF_TRAMP_F_INDIRECT is incompatible with BPF_TRAMP_F_CALL_ORIG, so pass 0 rather than the base to the call-origin save_args() and assert the flag combination the same way x86 does, rather than leaving the invariant to a comment. With both the kfunc and struct_ops directions implemented, flip bpf_jit_supports_arena_args() on for arm64 and drop the x86-64-only qualifier from the kfunc documentation. Signed-off-by: Puranjay Mohan <puranjay@kernel.org> Reviewed-by: Xu Kuohai <xukuohai@huawei.com> Link: https://lore.kernel.org/bpf/20260813190356.335181-5-puranjay@kernel.org Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> |
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| admin-guide | ||
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| cdrom | ||
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| .gitignore | ||
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| atomic_bitops.txt | ||
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| conf.py | ||
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| memory-barriers.txt | ||
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| subsystem-apis.rst | ||