From patchwork Mon May 29 19:14:14 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mathieu Desnoyers X-Patchwork-Id: 70263 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id C7AFF385624C for ; Mon, 29 May 2023 19:14:47 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org C7AFF385624C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1685387687; bh=hJbpA9guhgays83tJxGgreV4AGGG41TCjU0IDqP0kz0=; h=To:Cc:Subject:Date:In-Reply-To:References:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From:Reply-To:From; b=ia8m+maqYFKSmRkXYVhq3BVDy2XptoP+Dh8qtpyeSZI1f0Bl603CPm0SiYPaKN3+D pOFSpY+dqoKfH7rRL6C8gQJeH9NvGV9shVPFvzCgLpkeT8kYh1RLqV2+bGWyEBYxO7 yajlE1v54YecNjXoiqiozmBrE5UE8DMvt7z4soWs= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from smtpout.efficios.com (smtpout.efficios.com [167.114.26.122]) by sourceware.org (Postfix) with ESMTPS id A1B633858C00 for ; Mon, 29 May 2023 19:14:23 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org A1B633858C00 Received: from localhost.localdomain (192-222-143-198.qc.cable.ebox.net [192.222.143.198]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4QVQFB4ZFyz165P; Mon, 29 May 2023 15:14:22 -0400 (EDT) To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , "Paul E . McKenney" , Boqun Feng , "H . Peter Anvin" , Paul Turner , linux-api@vger.kernel.org, Christian Brauner , Florian Weimer , David.Laight@ACULAB.COM, carlos@redhat.com, Peter Oskolkov , Alexander Mikhalitsyn , Chris Kennelly , Ingo Molnar , Darren Hart , Davidlohr Bueso , =?utf-8?q?Andr=C3=A9_Almeida?= , libc-alpha@sourceware.org, Steven Rostedt , Jonathan Corbet , Noah Goldstein , Daniel Colascione , longman@redhat.com, Mathieu Desnoyers Subject: [RFC PATCH v2 2/4] selftests/rseq: Add sched_state rseq field and getter Date: Mon, 29 May 2023 15:14:14 -0400 Message-Id: <20230529191416.53955-3-mathieu.desnoyers@efficios.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230529191416.53955-1-mathieu.desnoyers@efficios.com> References: <20230529191416.53955-1-mathieu.desnoyers@efficios.com> MIME-Version: 1.0 X-Spam-Status: No, score=-11.8 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Mathieu Desnoyers via Libc-alpha From: Mathieu Desnoyers Reply-To: Mathieu Desnoyers Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Extend struct rseq in the rseq selftests to include the sched_state field. Implement a getter function for this field. Signed-off-by: Mathieu Desnoyers --- tools/testing/selftests/rseq/rseq-abi.h | 42 +++++++++++++++++++++++++ tools/testing/selftests/rseq/rseq.c | 13 ++++++++ tools/testing/selftests/rseq/rseq.h | 5 +++ 3 files changed, 60 insertions(+) diff --git a/tools/testing/selftests/rseq/rseq-abi.h b/tools/testing/selftests/rseq/rseq-abi.h index fb4ec8a75dd4..1092d6750386 100644 --- a/tools/testing/selftests/rseq/rseq-abi.h +++ b/tools/testing/selftests/rseq/rseq-abi.h @@ -37,6 +37,13 @@ enum rseq_abi_cs_flags { (1U << RSEQ_ABI_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT), }; +enum rseq_abi_sched_state_flags { + /* + * Task is currently running on a CPU if bit is set. + */ + RSEQ_ABI_SCHED_STATE_FLAG_ON_CPU = (1U << 0), +}; + /* * struct rseq_abi_cs is aligned on 4 * 8 bytes to ensure it is always * contained within a single cache-line. It is usually declared as @@ -53,6 +60,32 @@ struct rseq_abi_cs { __u64 abort_ip; } __attribute__((aligned(4 * sizeof(__u64)))); +/* + * rseq_abi_sched_state should be aligned on the cache line size. + */ +struct rseq_abi_sched_state { + /* + * Version of this structure. Populated by the kernel, read by + * user-space. + */ + __u32 version; + /* + * The state is updated by the kernel. Read by user-space with + * single-copy atomicity semantics. This field can be read by any + * userspace thread. Aligned on 32-bit, and ideally on cache line size. + * Contains a bitmask of enum rseq_abi_sched_state_flags. This field is + * provided as a hint by the scheduler, and requires that the page + * holding this state is faulted-in for the state update to be + * performed by the scheduler. + */ + __u32 state; + /* + * Thread ID associated with the thread registering this structure. + * Initialized by user-space before registration. + */ + __u32 tid; +}; + /* * struct rseq_abi is aligned on 4 * 8 bytes to ensure it is always * contained within a single cache-line. @@ -164,6 +197,15 @@ struct rseq_abi { */ __u32 mm_cid; + __u32 padding1; + + /* + * Restartable sequences sched_state_ptr field. Initialized by + * userspace to the address at which the struct rseq_abi_sched_state is + * located. Read by the kernel on rseq registration. + */ + __u64 sched_state_ptr; + /* * Flexible array member at end of structure, after last feature field. */ diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c index 4e4aa006004c..76925b116054 100644 --- a/tools/testing/selftests/rseq/rseq.c +++ b/tools/testing/selftests/rseq/rseq.c @@ -62,17 +62,28 @@ static int rseq_reg_success; /* At least one rseq registration has succeded. */ /* Allocate a large area for the TLS. */ #define RSEQ_THREAD_AREA_ALLOC_SIZE 1024 +/* Approximation of cacheline size. */ +#define CACHELINE_SIZE 128 + /* Original struct rseq feature size is 20 bytes. */ #define ORIG_RSEQ_FEATURE_SIZE 20 /* Original struct rseq allocation size is 32 bytes. */ #define ORIG_RSEQ_ALLOC_SIZE 32 +static +__thread struct rseq_abi_sched_state __rseq_abi_sched_state __attribute__((tls_model("initial-exec"), aligned(CACHELINE_SIZE))); + static __thread struct rseq_abi __rseq_abi __attribute__((tls_model("initial-exec"), aligned(RSEQ_THREAD_AREA_ALLOC_SIZE))) = { .cpu_id = RSEQ_ABI_CPU_ID_UNINITIALIZED, }; +static pid_t rseq_gettid(void) +{ + return syscall(__NR_gettid); +} + static int sys_rseq(struct rseq_abi *rseq_abi, uint32_t rseq_len, int flags, uint32_t sig) { @@ -109,6 +120,8 @@ int rseq_register_current_thread(void) /* Treat libc's ownership as a successful registration. */ return 0; } + __rseq_abi_sched_state.tid = rseq_gettid(); + __rseq_abi.sched_state_ptr = (uint64_t)(unsigned long)&__rseq_abi_sched_state; rc = sys_rseq(&__rseq_abi, rseq_size, 0, RSEQ_SIG); if (rc) { if (RSEQ_READ_ONCE(rseq_reg_success)) { diff --git a/tools/testing/selftests/rseq/rseq.h b/tools/testing/selftests/rseq/rseq.h index d7364ea4d201..4c14ef3f581f 100644 --- a/tools/testing/selftests/rseq/rseq.h +++ b/tools/testing/selftests/rseq/rseq.h @@ -236,6 +236,11 @@ static inline void rseq_prepare_unload(void) rseq_clear_rseq_cs(); } +static inline struct rseq_abi_sched_state *rseq_get_sched_state(struct rseq_abi *rseq) +{ + return (struct rseq_abi_sched_state *)(unsigned long)rseq->sched_state_ptr; +} + static inline __attribute__((always_inline)) int rseq_cmpeqv_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode, intptr_t *v, intptr_t expect,