riscv, bpf: fix reads of thread_info.cpu

[PATCH 2/2] riscv, bpf: use lw when reading int cpu in bpf_get_smp_processor_id

Posted by Radim Krčmář 1 month, 3 weeks ago

emit_ld is wrong, because thread_info.cpu is 32-bit, not xlen-bit wide.
The struct currently has a hole after cpu, so little endian accesses
seemed fine.

Fixes: 2ddec2c80b44 ("riscv, bpf: inline bpf_get_smp_processor_id()")
Cc: <stable@vger.kernel.org>
Signed-off-by: Radim Krčmář <rkrcmar@ventanamicro.com>
---
 arch/riscv/net/bpf_jit_comp64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
index 6e1554d89681..9883a55d61b5 100644
--- a/arch/riscv/net/bpf_jit_comp64.c
+++ b/arch/riscv/net/bpf_jit_comp64.c
@@ -1763,7 +1763,7 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
 		 */
 		if (insn->src_reg == 0 && insn->imm == BPF_FUNC_get_smp_processor_id) {
 			/* Load current CPU number in R0 */
-			emit_ld(bpf_to_rv_reg(BPF_REG_0, ctx), offsetof(struct thread_info, cpu),
+			emit_lw(bpf_to_rv_reg(BPF_REG_0, ctx), offsetof(struct thread_info, cpu),
 				RV_REG_TP, ctx);
 			break;
 		}
-- 
2.50.0

Re: [PATCH 2/2] riscv, bpf: use lw when reading int cpu in bpf_get_smp_processor_id

Posted by Pu Lehui 1 month, 2 weeks ago


On 2025/8/12 17:02, Radim Krčmář wrote:
> emit_ld is wrong, because thread_info.cpu is 32-bit, not xlen-bit wide.
> The struct currently has a hole after cpu, so little endian accesses
> seemed fine.
> 
> Fixes: 2ddec2c80b44 ("riscv, bpf: inline bpf_get_smp_processor_id()")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Radim Krčmář <rkrcmar@ventanamicro.com>
> ---
>   arch/riscv/net/bpf_jit_comp64.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
> index 6e1554d89681..9883a55d61b5 100644
> --- a/arch/riscv/net/bpf_jit_comp64.c
> +++ b/arch/riscv/net/bpf_jit_comp64.c
> @@ -1763,7 +1763,7 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>   		 */
>   		if (insn->src_reg == 0 && insn->imm == BPF_FUNC_get_smp_processor_id) {
>   			/* Load current CPU number in R0 */
> -			emit_ld(bpf_to_rv_reg(BPF_REG_0, ctx), offsetof(struct thread_info, cpu),
> +			emit_lw(bpf_to_rv_reg(BPF_REG_0, ctx), offsetof(struct thread_info, cpu),
>   				RV_REG_TP, ctx);
>   			break;
>   		}

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

[PATCH 1/2] riscv, bpf: use lw when reading int cpu in BPF_MOV64_PERCPU_REG
[PATCH 2/2] riscv, bpf: use lw when reading int cpu in bpf_get_smp_processor_id