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[82.27.106.168]) by smtp.gmail.com with ESMTPSA id i13-20020adff30d000000b0021e4982270asm2078759wro.13.2022.07.21.06.41.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 21 Jul 2022 06:41:41 -0700 (PDT) Date: Thu, 21 Jul 2022 14:41:15 +0100 From: Jean-Philippe Brucker To: Xu Kuohai Cc: bpf@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Alexei Starovoitov , Andrii Nakryiko , Catalin Marinas , Daniel Borkmann , Hao Luo , Jakub Sitnicki , Jiri Olsa , John Fastabend , Jon Hunter , KP Singh , Martin KaFai Lau , Song Liu , Stanislav Fomichev , Will Deacon , Yonghong Song , Zi Shen Lim Subject: Re: [PATCH bpf-next] bpf, arm64: Fix compile error in dummy_tramp() Message-ID: References: <20220721121319.2999259-1-xukuohai@huaweicloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220721121319.2999259-1-xukuohai@huaweicloud.com> Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Jul 21, 2022 at 08:13:19AM -0400, Xu Kuohai wrote: > From: Xu Kuohai > > dummy_tramp() uses "lr" to refer to the x30 register, but some assembler > does not recognize "lr" and reports a build failure: > > /tmp/cc52xO0c.s: Assembler messages: > /tmp/cc52xO0c.s:8: Error: operand 1 should be an integer register -- `mov lr,x9' > /tmp/cc52xO0c.s:7: Error: undefined symbol lr used as an immediate value > make[2]: *** [scripts/Makefile.build:250: arch/arm64/net/bpf_jit_comp.o] Error 1 > make[1]: *** [scripts/Makefile.build:525: arch/arm64/net] Error 2 > > So replace "lr" with "x30" to fix it. > > Fixes: b2ad54e1533e ("bpf, arm64: Implement bpf_arch_text_poke() for arm64") > Reported-by: Jon Hunter > Tested-by: Jon Hunter > Signed-off-by: Xu Kuohai Right, it looks like the lr alias was only added to binutils 2.30, and Linux supports 2.23+ Reviewed-by: Jean-Philippe Brucker > --- > arch/arm64/net/bpf_jit_comp.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c > index dcc572b7d4da..7ca8779ae34f 100644 > --- a/arch/arm64/net/bpf_jit_comp.c > +++ b/arch/arm64/net/bpf_jit_comp.c > @@ -610,8 +610,8 @@ asm ( > #if IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) > " bti j\n" /* dummy_tramp is called via "br x10" */ > #endif > -" mov x10, lr\n" > -" mov lr, x9\n" > +" mov x10, x30\n" > +" mov x30, x9\n" > " ret x10\n" > " .size dummy_tramp, .-dummy_tramp\n" > " .popsection\n" > -- > 2.30.2 >