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From: Ilya Leoshkevich <iii@linux.ibm.com>
To: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org, Heiko Carstens <hca@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Ilya Leoshkevich <iii@linux.ibm.com>
Subject: [PATCH bpf-next 04/10] s390/bpf: Land on the next JITed instruction after exception
Date: Thu, 27 Jun 2024 11:07:07 +0200	[thread overview]
Message-ID: <20240627090900.20017-5-iii@linux.ibm.com> (raw)
In-Reply-To: <20240627090900.20017-1-iii@linux.ibm.com>

Currently we land on the nop, which is unnecessary: we can just as well
begin executing the next instruction. Furthermore, the upcoming arena
support for the loop-based BPF_XCHG implementation will require landing
on an instruction that comes after the loop.

So land on the next JITed instruction, which covers both cases.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 arch/s390/net/bpf_jit_comp.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 582fa3830772..ecd53f8f0602 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -747,10 +747,11 @@ static int bpf_jit_probe_post(struct bpf_jit *jit, struct bpf_prog *fp,
 			return -1;
 		ex->insn = delta;
 		/*
-		 * Always land on the nop. Note that extable infrastructure
-		 * ignores fixup field, it is handled by ex_handler_bpf().
+		 * Land on the current instruction. Note that the extable
+		 * infrastructure ignores the fixup field; it is handled by
+		 * ex_handler_bpf().
 		 */
-		delta = jit->prg_buf + probe->nop_prg - (u8 *)&ex->fixup;
+		delta = jit->prg_buf + jit->prg - (u8 *)&ex->fixup;
 		if (WARN_ON_ONCE(delta < INT_MIN || delta > INT_MAX))
 			/* JIT bug - landing pad and extable must be close. */
 			return -1;
-- 
2.45.2


  parent reply	other threads:[~2024-06-27  9:09 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-06-27  9:07 [PATCH bpf-next 00/10] s390/bpf: Implement arena Ilya Leoshkevich
2024-06-27  9:07 ` [PATCH bpf-next 01/10] s390/bpf: Factor out emitting probe nops Ilya Leoshkevich
2024-06-27  9:07 ` [PATCH bpf-next 02/10] s390/bpf: Get rid of get_probe_mem_regno() Ilya Leoshkevich
2024-06-27  9:07 ` [PATCH bpf-next 03/10] s390/bpf: Introduce pre- and post- probe functions Ilya Leoshkevich
2024-06-27  9:07 ` Ilya Leoshkevich [this message]
2024-06-27  9:07 ` [PATCH bpf-next 05/10] s390/bpf: Support BPF_PROBE_MEM32 Ilya Leoshkevich
2024-06-27  9:07 ` [PATCH bpf-next 06/10] s390/bpf: Support address space cast instruction Ilya Leoshkevich
2024-06-27  9:07 ` [PATCH bpf-next 07/10] s390/bpf: Enable arena Ilya Leoshkevich
2024-06-27  9:07 ` [PATCH bpf-next 08/10] s390/bpf: Support arena atomics Ilya Leoshkevich
2024-06-28  0:43   ` Alexei Starovoitov
2024-06-28  9:09     ` Ilya Leoshkevich
2024-06-27  9:07 ` [PATCH bpf-next 09/10] selftests/bpf: Add UAF tests for " Ilya Leoshkevich
2024-06-28  0:45   ` Alexei Starovoitov
2024-06-28  9:13     ` Ilya Leoshkevich
2024-07-03  2:10   ` kernel test robot
2024-06-27  9:07 ` [PATCH bpf-next 10/10] selftests/bpf: Remove arena tests from DENYLIST.s390x Ilya Leoshkevich

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