LoongArch: BPF: Remove duplicated flags check

The check for (BPF_TRAMP_F_ORIG_STACK | BPF_TRAMP_F_SHARE_IPMODIFY) is
duplicated in __arch_prepare_bpf_trampoline(). Remove it.

While at it, make sure stack_size and nargs are initialized once.

Cc: [email protected]
Tested-by: Vincent Li <[email protected]>
Signed-off-by: Hengqi Chen <[email protected]>
Signed-off-by: Huacai Chen <[email protected]>

Author: chenhengqi

arch/loongarch/net/bpf_jit.c

@@ -1451,7 +1451,7 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i
 					 void *func_addr, u32 flags)
 {
 	int i, ret, save_ret;
-	int stack_size = 0, nargs = 0;
+	int stack_size, nargs;
 	int retval_off, args_off, nargs_off, ip_off, run_ctx_off, sreg_off, tcc_ptr_off;
 	bool is_struct_ops = flags & BPF_TRAMP_F_INDIRECT;
 	void *orig_call = func_addr;
@@ -1460,9 +1460,6 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i
 	struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN];
 	u32 **branches = NULL;
 
-	if (flags & (BPF_TRAMP_F_ORIG_STACK | BPF_TRAMP_F_SHARE_IPMODIFY))
-		return -ENOTSUPP;
-
 	/*
 	 * FP + 8       [ RA to parent func ] return address to parent
 	 *                    function
@@ -1496,10 +1493,8 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i
 	if (flags & (BPF_TRAMP_F_ORIG_STACK | BPF_TRAMP_F_SHARE_IPMODIFY))
 		return -ENOTSUPP;
 
-	stack_size = 0;
-
 	/* Room of trampoline frame to store return address and frame pointer */
-	stack_size += 16;
+	stack_size = 16;
 
 	save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET);
 	if (save_ret)