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Thu, 21 May 2026 17:03:06 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav03.fra02v.mail.ibm.com (Postfix) with ESMTP; Thu, 21 May 2026 17:03:06 +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 v3 2/4] s390/jump_label: Implement ARCH_STATIC_BRANCH_JUMP_ASM and ARCH_STATIC_BRANCH_ASM macros Date: Thu, 21 May 2026 18:56:20 +0200 Message-ID: <20260521165622.279953-3-japo@linux.ibm.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260521165622.279953-1-japo@linux.ibm.com> References: <20260521165622.279953-1-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: AW1haW4tMjYwNTIxMDE2NyBTYWx0ZWRfXzSqVnFNsqhae b4ZWmSo9N0ziZ3S0WaOTGDHvH5J4UCEKjkrDqcvzXlfSMfPwC4rhXDPXPXrphNlO1IImtz3kAfA 91FU2kVE04KakKRYLsJCp0NG3f8QZq+dVOMqfi3fjR+5h+IQhbDeHw+U4re0MBlq7vJ1Qc0jPK3 K1Kx+5DXbEn85pcuJohsrfKG6tfJQCY9v1MeIktKTdN7st6IAvw61igKc3AqpR2D9lBFZZ7Tsds a9Q+MC8lxT+xce7VwrjtTdXJ3Kyw7jEM73LOiHNAUaZADNM7vsZ4SjsCplaBTmPHylRRpD1F7gQ 8kaGtU1XMRzkuwjzj28W9qdSLw8/chcPCygtYz0bDwPnX+Ub3Bc/zXcxYQtBh3mBd4E/5N1QAkQ BmilUjPB2z6WLt8Qr7s4dUj0iAgfN/3EfRPXbY4J5AlqoW/LxPdAqUglZQVwgM2c7MVpoPK1xk6 6bdxL59YmPY2tsgWznw== X-Authority-Analysis: v=2.4 cv=Np/htcdJ c=1 sm=1 tr=0 ts=6a0f3acf cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=V3UG4Yqg79Bxd1UTefQA:9 X-Proofpoint-ORIG-GUID: naEMPCAJ6jT6aKL8qZ3s_q27tnm5EGS2 X-Proofpoint-GUID: h5r23O5umdIL6LXx7k1ozNaieTJcSXyS 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=2026-05-21_03,2026-05-18_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 spamscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 lowpriorityscore=0 suspectscore=0 adultscore=0 phishscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605210167 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..0e28c90dc242 100644 --- a/arch/s390/include/asm/jump_label.h +++ b/arch/s390/include/asm/jump_label.h @@ -19,19 +19,29 @@ #define JUMP_LABEL_STATIC_KEY_CONSTRAINT "jdd" #endif +#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" + /* * We use a brcl 0, instruction for jump labels so it * can be easily distinguished from a hotpatch generated instruction. */ +#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