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Tue, 12 May 2026 10:59:32 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 12 May 2026 10:59:32 +0000 (GMT) From: Jan Polensky To: hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, ojeda@kernel.org, peterz@infradead.org, jpoimboe@kernel.org, jbaron@akamai.com, aliceryhl@google.com Cc: borntraeger@linux.ibm.com, svens@linux.ibm.com, boqun@kernel.org, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, a.hindborg@kernel.org, tmgross@umich.edu, dakr@kernel.org, rostedt@goodmis.org, ardb@kernel.org, linux-s390@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/4] s390/jump_label: Implement ARCH_STATIC_BRANCH_JUMP_ASM and ARCH_STATIC_BRANCH_ASM macros Date: Tue, 12 May 2026 12:59:18 +0200 Message-ID: <20260512105920.2426293-3-japo@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260512105920.2426293-1-japo@linux.ibm.com> References: <20260512105920.2426293-1-japo@linux.ibm.com> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTEyMDEwOSBTYWx0ZWRfX5VGOT+5AQOSJ r/JZuDJEtjEUL7gVxfdBj3pVPjvqrQnFsE87nnsYQBYcCFZrxV30uZZDLlMS8cll6lcAYqTa73t gtlvdH54/1EzVJwQG9YfnmcMm3wsFxeOqw2l35xYRS5thi/SKfPokWHXIxRpkD1GsZzJyPqsCxV KKViQGyR1xXW39smTYVNnXrtPsikEYBOqeOSPB6h3UVPq08jAx2t2/IAikhxZJDUXSRlWI49JoU OkW+MW86cK7auCbZR/m6hGQqYRxyDdYYUVv9Q4LbllYxO/W7jry6M/iCvDhiW8ygNzIXY6RmskS Dmq2srVzC/jF3OEfGz+U4mN4ZsMA036Nj8oqKvBv+rdM7JHPCFqRoZhQUXHkA6Jx/gQHqm3aUJw 69P/4Mh/k8w4OZSQ6HpSBg32Fya2seo6iKS6N2gx/mz2g9jQj/x4aWYYthfPLH4pISp23Ug8zE5 UaDQUfPeBEjD4DxnEEw== X-Proofpoint-ORIG-GUID: 6PnBxjdJk1ULrfNypeM2w_JOA-zW5YEu X-Authority-Analysis: v=2.4 cv=Jc6Ma0KV c=1 sm=1 tr=0 ts=6a03081a cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=V3UG4Yqg79Bxd1UTefQA:9 X-Proofpoint-GUID: xIXG0wP7jiv_mrMKjiup93jc8FKiVNYV X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-11_05,2026-05-08_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 priorityscore=1501 malwarescore=0 bulkscore=0 clxscore=1015 phishscore=0 adultscore=0 lowpriorityscore=0 suspectscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605050000 definitions=main-2605120109 Rust static branch support needs the s390 jump label instruction sequence and __jump_table emission in a reusable form. The current implementation embeds the sequence directly in the C asm goto blocks, which cannot be shared with Rust. Introduce ARCH_STATIC_BRANCH_ASM and ARCH_STATIC_BRANCH_JUMP_ASM to describe the brcl sequences for the likely-false and likely-true cases and to emit the same __jump_table entries as before. Switch the existing C helpers to use the new macros to avoid duplication without changing the generated code. Signed-off-by: Jan Polensky --- arch/s390/include/asm/jump_label.h | 33 +++++++++++++++++------------- 1 file changed, 19 insertions(+), 14 deletions(-) diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h index d9cbc18f6b2e..1f0114150786 100644 --- a/arch/s390/include/asm/jump_label.h +++ b/arch/s390/include/asm/jump_label.h @@ -23,15 +23,25 @@ * We use a brcl 0, instruction for jump labels so it * can be easily distinguished from a hotpatch generated instruction. */ +#define ARCH_JUMP_TABLE_ENTRY(key, label, local_label) \ + ".pushsection __jump_table,\"aw\"\n" \ + ".balign 8\n" \ + ".long " local_label "-.," label "-.\n" \ + ".quad " key "-.\n" \ + ".popsection\n" + +#define ARCH_STATIC_BRANCH_ASM(key, label) \ + "0: brcl 0," label "\n" \ + ARCH_JUMP_TABLE_ENTRY(key, label, "0b") + +#define ARCH_STATIC_BRANCH_JUMP_ASM(key, label) \ + "0: brcl 15," label "\n" \ + ARCH_JUMP_TABLE_ENTRY(key, label, "0b") + static __always_inline bool arch_static_branch(struct static_key *key, bool branch) { - asm goto("0: brcl 0,%l[label]\n" - ".pushsection __jump_table,\"aw\"\n" - ".balign 8\n" - ".long 0b-.,%l[label]-.\n" - ".quad %0+%1-.\n" - ".popsection\n" - : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label); + asm goto(ARCH_STATIC_BRANCH_ASM("%0+%1", "%l[label]") + : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label); return false; label: return true; @@ -39,13 +49,8 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch) { - asm goto("0: brcl 15,%l[label]\n" - ".pushsection __jump_table,\"aw\"\n" - ".balign 8\n" - ".long 0b-.,%l[label]-.\n" - ".quad %0+%1-.\n" - ".popsection\n" - : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label); + asm goto(ARCH_STATIC_BRANCH_JUMP_ASM("%0+%1", "%l[label]") + : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label); return false; label: return true; -- 2.51.0