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From: Ilya Leoshkevich <iii@linux.ibm.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>
Cc: bpf@vger.kernel.org, Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Ilya Leoshkevich <iii@linux.ibm.com>
Subject: [PATCH 5/5] s390/bpf: use bpf_skip() in bpf_jit_prologue()
Date: Fri, 17 Jul 2020 18:53:26 +0200	[thread overview]
Message-ID: <20200717165326.6786-6-iii@linux.ibm.com> (raw)
In-Reply-To: <20200717165326.6786-1-iii@linux.ibm.com>

Now that we have bpf_skip() for emitting nops, use it in
bpf_jit_prologue() in order to reduce code duplication.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 arch/s390/net/bpf_jit_comp.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index e68854ab27ae..be4b8532dd3c 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -520,10 +520,11 @@ static void bpf_jit_prologue(struct bpf_jit *jit, u32 stack_depth)
 		/* xc STK_OFF_TCCNT(4,%r15),STK_OFF_TCCNT(%r15) */
 		_EMIT6(0xd703f000 | STK_OFF_TCCNT, 0xf000 | STK_OFF_TCCNT);
 	} else {
-		/* j tail_call_start: NOP if no tail calls are used */
-		EMIT4_PCREL(0xa7f40000, 6);
-		/* bcr 0,%0 */
-		EMIT2(0x0700, 0, REG_0);
+		/*
+		 * There are no tail calls. Insert nops in order to have
+		 * tail_call_start at a predictable offset.
+		 */
+		bpf_skip(jit, 6);
 	}
 	/* Tail calls have to skip above initialization */
 	jit->tail_call_start = jit->prg;
-- 
2.25.4


  parent reply	other threads:[~2020-07-17 16:57 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-17 16:53 [PATCH 0/5] s390/bpf: fix lib/test_bpf.c failures Ilya Leoshkevich
2020-07-17 16:53 ` [PATCH 1/5] selftests: bpf: test_kmod.sh: fix running out of srctree Ilya Leoshkevich
2020-07-17 16:53 ` [PATCH 2/5] s390/bpf: fix sign extension in branch_ku Ilya Leoshkevich
2020-07-17 22:23   ` Seth Forshee
2020-07-17 16:53 ` [PATCH 3/5] s390/bpf: use brcl for jumping to exit_ip if necessary Ilya Leoshkevich
2020-07-17 16:53 ` [PATCH 4/5] s390/bpf: tolerate not converging code shrinking Ilya Leoshkevich
2020-07-17 16:53 ` Ilya Leoshkevich [this message]
2020-07-21 18:17 ` [PATCH 0/5] s390/bpf: fix lib/test_bpf.c failures Alexei Starovoitov

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