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Mon, 25 May 2026 23:18:11 -0700 (PDT) Received: from sw08.internal.sifive.com ([4.53.31.132]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-30452461cb5sm14062504eec.31.2026.05.25.23.18.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 May 2026 23:18:11 -0700 (PDT) From: Jesse Huang To: libc-alpha@sourceware.org Cc: andrew@sifive.com, darius@bluespec.com, debug@rivosinc.com, jeffreyalaw@gmail.com, kito.cheng@sifive.com, palmer@dabbelt.com, Jesse Huang Subject: [PATCH v4 16/17] riscv/cfi: Add __INDIRECT_RETURN attribute to swapcontext Date: Mon, 25 May 2026 23:17:02 -0700 Message-Id: <20260526061703.2188042-17-jesse.huang@sifive.com> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20260526061703.2188042-1-jesse.huang@sifive.com> References: <20260526061703.2188042-1-jesse.huang@sifive.com> MIME-Version: 1.0 X-Spam-Status: No, score=-13.2 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_BLOCKED, SPF_HELO_NONE, SPF_PASS, TXREP, URIBL_BLOCKED shortcircuit=no autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libc-alpha-bounces~patchwork=sourceware.org@sourceware.org --- sysdeps/riscv/bits/indirect-return.h | 36 ++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) create mode 100644 sysdeps/riscv/bits/indirect-return.h diff --git a/sysdeps/riscv/bits/indirect-return.h b/sysdeps/riscv/bits/indirect-return.h new file mode 100644 index 0000000000..1d8f658cc8 --- /dev/null +++ b/sysdeps/riscv/bits/indirect-return.h @@ -0,0 +1,36 @@ +/* Definition of __INDIRECT_RETURN. RISC-V version. + Copyright (C) 2026 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#ifndef _UCONTEXT_H +# error "Never include directly; use instead." +#endif + +/* __INDIRECT_RETURN indicates that swapcontext may return via + an indirect branch. This happens when GCS is enabled, so + add the attribute if available, otherwise returns_twice has + a similar effect, but it prevents some code transformations + that can cause build failures in some rare cases so it is + only used when GCS is enabled. */ +#if __glibc_has_attribute (__indirect_return__) +# define __INDIRECT_RETURN __attribute__ ((__indirect_return__)) +#elif __glibc_has_attribute (__returns_twice__) \ + && defined __ARM_FEATURE_GCS_DEFAULT +# define __INDIRECT_RETURN __attribute__ ((__returns_twice__)) +#else +# define __INDIRECT_RETURN +#endif