[PATCH v2 0/1] riscv: bpf: Fix uninitialized symbol 'retval_off'

[PATCH v2 0/1] riscv: bpf: Fix uninitialized symbol 'retval_off'

[Chenghao Duan]

v2:
Adjust the commit log

URL for version v1:
https://lore.kernel.org/all/20250820062520.846720-1-duanchenghao@kylinos.cn/

Chenghao Duan (1):
  riscv: bpf: Fix uninitialized symbol 'retval_off'

 arch/riscv/net/bpf_jit_comp64.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

-- 
2.25.1

[PATCH v2 1/1] riscv: bpf: Fix uninitialized symbol 'retval_off'

[Chenghao Duan]

In the __arch_prepare_bpf_trampoline() function, retval_off is only
meaningful when save_ret is true, so the current logic is correct.
However, in the original logic, retval_off is only initialized under
certain conditions; for example, in the fmod_ret logic, the compiler is
not aware that the flags of the fmod_ret program (prog) have set
BPF_TRAMP_F_CALL_ORIG, which results in an uninitialized symbol
compilation warning.

So initialize retval_off unconditionally to fix it.

Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
---
 arch/riscv/net/bpf_jit_comp64.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index 9883a55d61b5..8475a8ab5715 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -1079,10 +1079,9 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
 	stack_size += 16;
 
 	save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET);
-	if (save_ret) {
+	if (save_ret)
 		stack_size += 16; /* Save both A5 (BPF R0) and A0 */
-		retval_off = stack_size;
-	}
+	retval_off = stack_size;
 
 	stack_size += nr_arg_slots * 8;
 	args_off = stack_size;
-- 
2.25.1

Re: [PATCH v2 1/1] riscv: bpf: Fix uninitialized symbol 'retval_off'

[Pu Lehui]

On 2025/9/22 14:22, Chenghao Duan wrote:
> In the __arch_prepare_bpf_trampoline() function, retval_off is only
> meaningful when save_ret is true, so the current logic is correct.
> However, in the original logic, retval_off is only initialized under
> certain conditions; for example, in the fmod_ret logic, the compiler is
> not aware that the flags of the fmod_ret program (prog) have set
> BPF_TRAMP_F_CALL_ORIG, which results in an uninitialized symbol
> compilation warning.
> 
> So initialize retval_off unconditionally to fix it.
> 
> Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
> ---
>   arch/riscv/net/bpf_jit_comp64.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
> index 9883a55d61b5..8475a8ab5715 100644
> --- a/arch/riscv/net/bpf_jit_comp64.c
> +++ b/arch/riscv/net/bpf_jit_comp64.c
> @@ -1079,10 +1079,9 @@ static int __arch_prepare_bpf_trampoline(struct bpf_tramp_image *im,
>   	stack_size += 16;
>   
>   	save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET);
> -	if (save_ret) {
> +	if (save_ret)
>   		stack_size += 16; /* Save both A5 (BPF R0) and A0 */
> -		retval_off = stack_size;
> -	}
> +	retval_off = stack_size;
>   
>   	stack_size += nr_arg_slots * 8;
>   	args_off = stack_size;

Reviewed-by: Pu Lehui <pulehui@huawei.com>

Re: [PATCH v2 0/1] riscv: bpf: Fix uninitialized symbol 'retval_off'

[patchwork-bot+linux-riscv]

Hello:

This patch was applied to riscv/linux.git (for-next)
by Alexei Starovoitov <ast@kernel.org>:

On Mon, 22 Sep 2025 14:22:43 +0800 you wrote:
> v2:
> Adjust the commit log
> 
> URL for version v1:
> https://lore.kernel.org/all/20250820062520.846720-1-duanchenghao@kylinos.cn/
> 
> Chenghao Duan (1):
>   riscv: bpf: Fix uninitialized symbol 'retval_off'
> 
> [...]

Here is the summary with links:
  - [v2,1/1] riscv: bpf: Fix uninitialized symbol 'retval_off'
    https://git.kernel.org/riscv/c/d0bf7cd5df18

You are awesome, thank you!
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