From owner-dev-commits-src-branches@freebsd.org Thu Aug 12 13:49:51 2021 Return-Path: Delivered-To: dev-commits-src-branches@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id A56D166C1FC; Thu, 12 Aug 2021 13:49:51 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4Glp333mZ4z4nMQ; Thu, 12 Aug 2021 13:49:51 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 6943E23BD5; Thu, 12 Aug 2021 13:49:51 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 17CDnp7f052496; Thu, 12 Aug 2021 13:49:51 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 17CDnp0n052495; Thu, 12 Aug 2021 13:49:51 GMT (envelope-from git) Date: Thu, 12 Aug 2021 13:49:51 GMT Message-Id: <202108121349.17CDnp0n052495@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Mark Johnston Subject: git: b8adacf39a5a - stable/13 - amd64: Set GS.base before calling init_secondary() on APs MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: markj X-Git-Repository: src X-Git-Refname: refs/heads/stable/13 X-Git-Reftype: branch X-Git-Commit: b8adacf39a5a968dabb36390bc51388553fb6ca9 Auto-Submitted: auto-generated X-BeenThere: dev-commits-src-branches@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Commits to the stable branches of the FreeBSD src repository List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 12 Aug 2021 13:49:51 -0000 The branch stable/13 has been updated by markj: URL: https://cgit.FreeBSD.org/src/commit/?id=b8adacf39a5a968dabb36390bc51388553fb6ca9 commit b8adacf39a5a968dabb36390bc51388553fb6ca9 Author: Mark Johnston AuthorDate: 2021-07-29 14:22:37 +0000 Commit: Mark Johnston CommitDate: 2021-08-12 13:43:21 +0000 amd64: Set GS.base before calling init_secondary() on APs KMSAN instrumentation requires thread-local storage to track initialization state for function parameters and return values. This buffer is accessed as part of each function prologue. It is provided by the KMSAN runtime, which looks up a pointer in the current thread's structure. When KMSAN is configured, init_secondary() is instrumented, but this means that GS.base must be initialized first, otherwise the runtime cannot safely access curthread. Work around this by loading GS.base before calling init_secondary(), so that the runtime can at least check curthread == NULL and return a pointer to some dummy storage. Note that init_secondary() still must reload GS.base after calling lgdt(), which loads a selector into %gs, which in turn clears the base register. Reviewed by: kib Sponsored by: The FreeBSD Foundation (cherry picked from commit 4b136ef259cefedc9b6404afc09138aeb8acbd91) --- sys/amd64/amd64/mp_machdep.c | 8 ++++---- sys/amd64/amd64/mpboot.S | 17 +++++++++++++++++ 2 files changed, 21 insertions(+), 4 deletions(-) diff --git a/sys/amd64/amd64/mp_machdep.c b/sys/amd64/amd64/mp_machdep.c index 74f1af919b66..41c082ff40e9 100644 --- a/sys/amd64/amd64/mp_machdep.c +++ b/sys/amd64/amd64/mp_machdep.c @@ -103,6 +103,7 @@ char *doublefault_stack; char *mce_stack; char *nmi_stack; char *dbg_stack; +void *bootpcpu; extern u_int mptramp_la57; @@ -273,10 +274,8 @@ init_secondary(void) /* Update microcode before doing anything else. */ ucode_load_ap(cpu); - /* Get per-cpu data and save */ - pc = &__pcpu[cpu]; - - /* prime data page for it to use */ + /* Initialize the PCPU area. */ + pc = bootpcpu; pcpu_init(pc, cpu, sizeof(struct pcpu)); dpcpu_init(dpcpu, cpu); pc->pc_apic_id = cpu_apic_ids[cpu]; @@ -495,6 +494,7 @@ native_start_all_aps(void) dpcpu = (void *)kmem_malloc_domainset(DOMAINSET_PREF(domain), DPCPU_SIZE, M_WAITOK | M_ZERO); + bootpcpu = &__pcpu[cpu]; bootSTK = (char *)bootstacks[cpu] + kstack_pages * PAGE_SIZE - 8; bootAP = cpu; diff --git a/sys/amd64/amd64/mpboot.S b/sys/amd64/amd64/mpboot.S index e525102b5d3d..afdcffa573a4 100644 --- a/sys/amd64/amd64/mpboot.S +++ b/sys/amd64/amd64/mpboot.S @@ -270,4 +270,21 @@ entry_64: 2: movq KPML5phys, %rax 3: movq %rax, %cr3 movq bootSTK, %rsp + + /* + * Initialize the segment register used for the PCPU area. The PCPU + * area will be initialized by init_secondary(), but it should be + * accessible before that to support sanitizer instrumentation which + * accesses per-CPU variables. + * + * Note that GS.base is loaded again in init_secondary(). This is not + * redundant: lgdt() loads a selector into %gs and this has the side + * effect of clearing GS.base. + */ + movl $MSR_GSBASE, %ecx + movq bootpcpu, %rax + movq %rax, %rdx + shrq $32, %rdx + wrmsr + jmp init_secondary