netdev - [PATCH v9 bpf-next 06/17] tools: bpf: sync uapi header bpf.h

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Message-Id: <1558736728-7229-7-git-send-email-jiong.wang@netronome.com>
Date:   Fri, 24 May 2019 23:25:17 +0100
From:   Jiong Wang <jiong.wang@...ronome.com>
To:     alexei.starovoitov@...il.com, daniel@...earbox.net
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org,
        oss-drivers@...ronome.com, davem@...emloft.net,
        paul.burton@...s.com, udknight@...il.com, zlim.lnx@...il.com,
        illusionist.neo@...il.com, naveen.n.rao@...ux.ibm.com,
        sandipan@...ux.ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, jakub.kicinski@...ronome.com,
        Jiong Wang <jiong.wang@...ronome.com>
Subject: [PATCH v9 bpf-next 06/17] tools: bpf: sync uapi header bpf.h

Sync new bpf prog load flag "BPF_F_TEST_RND_HI32" to tools/.

Signed-off-by: Jiong Wang <jiong.wang@...ronome.com>
---
 tools/include/uapi/linux/bpf.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 68d4470..7c6aef2 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -260,6 +260,24 @@ enum bpf_attach_type {
  */
 #define BPF_F_ANY_ALIGNMENT	(1U << 1)
 
+/* BPF_F_TEST_RND_HI32 is used in BPF_PROG_LOAD command for testing purpose.
+ * Verifier does sub-register def/use analysis and identifies instructions whose
+ * def only matters for low 32-bit, high 32-bit is never referenced later
+ * through implicit zero extension. Therefore verifier notifies JIT back-ends
+ * that it is safe to ignore clearing high 32-bit for these instructions. This
+ * saves some back-ends a lot of code-gen. However such optimization is not
+ * necessary on some arches, for example x86_64, arm64 etc, whose JIT back-ends
+ * hence hasn't used verifier's analysis result. But, we really want to have a
+ * way to be able to verify the correctness of the described optimization on
+ * x86_64 on which testsuites are frequently exercised.
+ *
+ * So, this flag is introduced. Once it is set, verifier will randomize high
+ * 32-bit for those instructions who has been identified as safe to ignore them.
+ * Then, if verifier is not doing correct analysis, such randomization will
+ * regress tests to expose bugs.
+ */
+#define BPF_F_TEST_RND_HI32	(1U << 2)
+
 /* When BPF ldimm64's insn[0].src_reg != 0 then this can have
  * two extensions:
  *
-- 
2.7.4