From e378cd498204095196f8e66d277b2f45c84a5348 Mon Sep 17 00:00:00 2001
From: Jiri Slaby <jslaby@suse.cz>
Date: Apr 20 2023 11:00:23 +0000
Subject: LoongArch, bpf: Fix jit to skip speculation barrier opcode

(bsc#1012628).

---

diff --git a/patches.kernel.org/6.2.12-043-LoongArch-bpf-Fix-jit-to-skip-speculation-barr.patch b/patches.kernel.org/6.2.12-043-LoongArch-bpf-Fix-jit-to-skip-speculation-barr.patch
new file mode 100644
index 0000000..1a7d222
--- /dev/null
+++ b/patches.kernel.org/6.2.12-043-LoongArch-bpf-Fix-jit-to-skip-speculation-barr.patch
@@ -0,0 +1,75 @@
+From: George Guo <guodongtai@kylinos.cn>
+Date: Tue, 28 Mar 2023 15:13:35 +0800
+Subject: [PATCH] LoongArch, bpf: Fix jit to skip speculation barrier opcode
+References: bsc#1012628
+Patch-mainline: 6.2.12
+Git-commit: a6f6a95f25803500079513780d11a911ce551d76
+
+[ Upstream commit a6f6a95f25803500079513780d11a911ce551d76 ]
+
+Just skip the opcode(BPF_ST | BPF_NOSPEC) in the BPF JIT instead of
+failing to JIT the entire program, given LoongArch currently has no
+couterpart of a speculation barrier instruction. To verify the issue,
+use the ltp testcase as shown below.
+
+Also, Wang says:
+
+  I can confirm there's currently no speculation barrier equivalent
+  on LonogArch. (Loongson says there are builtin mitigations for
+  Spectre-V1 and V2 on their chips, and AFAIK efforts to port the
+  exploits to mips/LoongArch have all failed a few years ago.)
+
+Without this patch:
+
+  $ ./bpf_prog02
+  [...]
+  bpf_common.c:123: TBROK: Failed verification: ??? (524)
+  [...]
+  Summary:
+  passed   0
+  failed   0
+  broken   1
+  skipped  0
+  warnings 0
+
+With this patch:
+
+  $ ./bpf_prog02
+  [...]
+  Summary:
+  passed   0
+  failed   0
+  broken   0
+  skipped  0
+  warnings 0
+
+Fixes: 5dc615520c4d ("LoongArch: Add BPF JIT support")
+Signed-off-by: George Guo <guodongtai@kylinos.cn>
+Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
+Acked-by: WANG Xuerui <git@xen0n.name>
+Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
+Link: https://lore.kernel.org/bpf/20230328071335.2664966-1-guodongtai@kylinos.cn
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+Signed-off-by: Jiri Slaby <jslaby@suse.cz>
+---
+ arch/loongarch/net/bpf_jit.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c
+index 288003a9..d586df48 100644
+--- a/arch/loongarch/net/bpf_jit.c
++++ b/arch/loongarch/net/bpf_jit.c
+@@ -1022,6 +1022,10 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, bool ext
+ 		emit_atomic(insn, ctx);
+ 		break;
+ 
++	/* Speculation barrier */
++	case BPF_ST | BPF_NOSPEC:
++		break;
++
+ 	default:
+ 		pr_err("bpf_jit: unknown opcode %02x\n", code);
+ 		return -EINVAL;
+-- 
+2.35.3
+
diff --git a/series.conf b/series.conf
index 932551f..10dfcb9 100644
--- a/series.conf
+++ b/series.conf
@@ -2270,6 +2270,7 @@
 	patches.kernel.org/6.2.12-040-clk-rs9-Fix-suspend-resume.patch
 	patches.kernel.org/6.2.12-041-RDMA-cma-Allow-UD-qp_type-to-join-multicast-on.patch
 	patches.kernel.org/6.2.12-042-bpf-tcp-Use-sock_gen_put-instead-of-sock_put-i.patch
+	patches.kernel.org/6.2.12-043-LoongArch-bpf-Fix-jit-to-skip-speculation-barr.patch
 
 	########################################################
 	# Build fixes that apply to the vanilla kernel too.