riscv, bpf: Fix incorrect runtime stats

When __bpf_prog_enter() returns zero, the s1 register is not set to zero, resulting in incorrect runtime stats. Fix it by setting s1 immediately upon the return of __bpf_prog_enter(). Fixes: 49b5e77 ("riscv, bpf: Add bpf trampoline support for RV64") Signed-off-by: Xu Kuohai <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]> Reviewed-by: Pu Lehui <[email protected]> Acked-by: Björn Töpel <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
kvm-riscv · Apr 16, 2024 · 10541b3 · 10541b3
1 parent dc7d744
commit 10541b3
Showing 1 changed file with 3 additions and 3 deletions.
diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
@@ -722,16 +722,16 @@ static int invoke_bpf_prog(struct bpf_tramp_link *l, int args_off, int retval_of
 	if (ret)
 		return ret;
 
+	/* store prog start time */
+	emit_mv(RV_REG_S1, RV_REG_A0, ctx);
+
 	/* if (__bpf_prog_enter(prog) == 0)
 	 *	goto skip_exec_of_prog;
 	 */
 	branch_off = ctx->ninsns;
 	/* nop reserved for conditional jump */
 	emit(rv_nop(), ctx);
 
-	/* store prog start time */
-	emit_mv(RV_REG_S1, RV_REG_A0, ctx);
-
 	/* arg1: &args_off */
 	emit_addi(RV_REG_A0, RV_REG_FP, -args_off, ctx);
 	if (!p->jited)