LoongArch: BPF: Enable trampoline-based tracing for module functions

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commit 26138762d9 upstream.

Remove the previous restrictions that blocked the tracing of kernel
module functions. Fix the issue that previously caused kernel lockups
when attempting to trace module functions.

Before entering the trampoline code, the return address register ra
shall store the address of the next assembly instruction after the
'bl trampoline' instruction, which is the traced function address, and
the register t0 shall store the parent function return address. Refine
the trampoline return logic to ensure that register data remains correct
when returning to both the traced function and the parent function.

Before this patch was applied, the module_attach test in selftests/bpf
encountered a deadlock issue. This was caused by an incorrect jump
address after the trampoline execution, which resulted in an infinite
loop within the module function.

Cc: stable@vger.kernel.org
Fixes: 677e6123e3 ("LoongArch: BPF: Disable trampoline for kernel module function trace")
Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Chenghao Duan 2025-12-31 15:19:21 +08:00 • committed by Greg Kroah-Hartman

parent 8b3c00c060

commit 85fdef3dcc

1 changed files with 11 additions and 9 deletions

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arch/loongarch/net/bpf_jit.c

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