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[bpf-next] bpf, arm64: Fix compile error in dummy_tramp()

Message ID 20220721121319.2999259-1-xukuohai@huaweicloud.com (mailing list archive)
State Accepted
Commit 339ed900b3079b6ea21df55f368b1ccba17cd5e6
Delegated to: BPF
Headers show
Series [bpf-next] bpf, arm64: Fix compile error in dummy_tramp() | expand

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Commit Message

Xu Kuohai July 21, 2022, 12:13 p.m. UTC
From: Xu Kuohai <xukuohai@huawei.com>

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 <jonathanh@nvidia.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
---
 arch/arm64/net/bpf_jit_comp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Jiri Olsa July 21, 2022, 12:45 p.m. UTC | #1
On Thu, Jul 21, 2022 at 08:13:19AM -0400, Xu Kuohai wrote:
> From: Xu Kuohai <xukuohai@huawei.com>
> 
> 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 <jonathanh@nvidia.com>
> Tested-by: Jon Hunter <jonathanh@nvidia.com>
> Signed-off-by: Xu Kuohai <xukuohai@huawei.com>

Jean-Philippe, could you please take a look?

thanks,
jirka

> ---
>  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
>
Jean-Philippe Brucker July 21, 2022, 1:41 p.m. UTC | #2
On Thu, Jul 21, 2022 at 08:13:19AM -0400, Xu Kuohai wrote:
> From: Xu Kuohai <xukuohai@huawei.com>
> 
> 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 <jonathanh@nvidia.com>
> Tested-by: Jon Hunter <jonathanh@nvidia.com>
> Signed-off-by: Xu Kuohai <xukuohai@huawei.com>

Right, it looks like the lr alias was only added to binutils 2.30, and
Linux supports 2.23+

Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>

> ---
>  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
>
patchwork-bot+netdevbpf@kernel.org July 21, 2022, 10:30 p.m. UTC | #3
Hello:

This patch was applied to bpf/bpf-next.git (master)
by Daniel Borkmann <daniel@iogearbox.net>:

On Thu, 21 Jul 2022 08:13:19 -0400 you wrote:
> From: Xu Kuohai <xukuohai@huawei.com>
> 
> 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
> 
> [...]

Here is the summary with links:
  - [bpf-next] bpf, arm64: Fix compile error in dummy_tramp()
    https://git.kernel.org/bpf/bpf-next/c/339ed900b307

You are awesome, thank you!
diff mbox series

Patch

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"