From: John Fastabend <john.fastabend@gmail.com>
Date: Tue, 11 Aug 2020 15:05:33 -0700
Subject: bpf, selftests: Add tests for sock_ops load with r9, r8.r7 registers
Patch-mainline: v5.9-rc2
Git-commit: 8e0c1517565f06027b68caf2875620ddf6914eee
References: bsc#1177028
Loads in sock_ops case when using high registers requires extra logic to
ensure the correct temporary value is used. We need to ensure the temp
register does not use either the src_reg or dst_reg. Lets add an asm
test to force the logic is triggered.
The xlated code is here,
30: (7b) *(u64 *)(r9 +32) = r7
31: (61) r7 = *(u32 *)(r9 +28)
32: (15) if r7 == 0x0 goto pc+2
33: (79) r7 = *(u64 *)(r9 +0)
34: (63) *(u32 *)(r7 +916) = r8
35: (79) r7 = *(u64 *)(r9 +32)
Notice r9 and r8 are not used for temp registers and r7 is chosen.
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/159718353345.4728.8805043614257933227.stgit@john-Precision-5820-Tower
Acked-by: Gary Lin <glin@suse.com>
---
tools/testing/selftests/bpf/progs/test_tcpbpf_kern.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/tools/testing/selftests/bpf/progs/test_tcpbpf_kern.c
+++ b/tools/testing/selftests/bpf/progs/test_tcpbpf_kern.c
@@ -75,6 +75,13 @@ int bpf_testcb(struct bpf_sock_ops *skop
: [skops] "r"(skops)
:);
+ asm volatile (
+ "r9 = %[skops];\n"
+ "r8 = *(u32 *)(r9 +164);\n"
+ "*(u32 *)(r9 +164) = r8;\n"
+ :: [skops] "r"(skops)
+ : "r9", "r8");
+
op = (int) skops->op;
update_event_map(op);