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Mon, 8 Jun 2026 18:14:56 +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, japo@linux.ibm.com (Jan Polensky) Subject: [PATCH v6 2/6] s390/jump_label: Implement ARCH_STATIC_BRANCH_JUMP_ASM and ARCH_STATIC_BRANCH_ASM macros Date: Mon, 8 Jun 2026 20:14:47 +0200 Message-ID: <20260608181451.3734956-3-japo@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260608181451.3734956-1-japo@linux.ibm.com> References: <20260608181451.3734956-1-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-ORIG-GUID: Z3M_4wLGPtWh2W7wz7I_5icdE_MykGZ5 X-Proofpoint-GUID: VZPn9GfBXmu1Frxf4b_1GwIyAWZHWZ-E X-Authority-Analysis: v=2.4 cv=ZbEt8MVA c=1 sm=1 tr=0 ts=6a2706a6 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=FelO9ux0wxsA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=_2yia0w1AAAA:8 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=1XWaLZrsAAAA:8 a=V3UG4Yqg79Bxd1UTefQA:9 a=4yAS8WwzZ1jAEY03B-5r:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjA4MDE3MCBTYWx0ZWRfXwa0ysiCFKzxP dJ+1/0ZQ3DZ9MG3gIUmPIB9rpOSuYTFRAf8nbD0zhexdkok5teXkqFDOh4VQY8sQ6zEyL9pcwlK m7++oET3mV/dcKBlYSdlkptiX/eM1QZJSIzaQy7WhCprjHFws1Cto5mBq9M9BRoV998zY93CPxP ojG/sMwTAkWbLTPCQg97bjln3tI0aKI32sCxP+EdMlOjOlF0/9upvlTZOnKgFBtoZDGXr5LjjBm V9mFGxaoj27xldSAuUInshVC3TFwHVsGOdvgWP0QQO+bKmQayYaMti2A1UgpszHl4RaFgbEXTn+ HrisxQ8cBOBwH7x9reKyDzSr1hjB/CWy/4ek8D/0bWTqqzN6YOkpRBl+QrhKSqDWsN1f9TZ2vBP XknotTCcA3Rl2Xc/ZqP1QQL65dqYFs+Jclhp46UR0/R4JSBKpVJ/ruALWR1COUKUj2svMTcJ+Ny S0zU37ZgqvbOUhna+5Q== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-08_04,2026-06-05_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 impostorscore=0 malwarescore=0 lowpriorityscore=0 clxscore=1015 adultscore=0 spamscore=0 priorityscore=1501 bulkscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2606080170 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. Acked-by: Gary Guo Acked-by: Miguel Ojeda Acked-by: Heiko Carstens Reviewed-by: Alice Ryhl 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; -- 2.53.0