bpf, arm64: Fix BTI type used for freplace attached functions
[ Upstream commit a3f25d61 ] When running an freplace attached bpf program on an arm64 system w were seeing the following issue: Unhandled 64-bit el1h sync exception on CPU47, ESR 0x0000000036000003 -- BTI After a bit of work to track it down I determined that what appeared to be happening is that the 'bti c' at the start of the program was somehow being reached after a 'br' instruction. Further digging pointed me toward the fact that the function was attached via freplace. This in turn led me to build_plt which I believe is invoking the long jump which is triggering this error. To resolve it we can replace the 'bti c' with 'bti jc' and add a comment explaining why this has to be modified as such. Fixes: b2ad54e1 ("bpf, arm64: Implement bpf_arch_text_poke() for arm64") Signed-off-by:Alexander Duyck <alexanderduyck@fb.com> Acked-by:
Xu Kuohai <xukuohai@huawei.com> Link: https://lore.kernel.org/r/168926677665.316237.9953845318337455525.stgit@ahduyck-xeon-server.home.arpa Signed-off-by:
Alexei Starovoitov <ast@kernel.org> Signed-off-by:
Sasha Levin <sashal@kernel.org>
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8620c53c
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