From owner-svn-src-all@freebsd.org Thu Jun 13 16:33:56 2019 Return-Path: Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id C2F5515B7741; Thu, 13 Jun 2019 16:33:56 +0000 (UTC) (envelope-from markj@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) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 63C698C937; Thu, 13 Jun 2019 16:33:56 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 227552F00; Thu, 13 Jun 2019 16:33:56 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x5DGXunR002812; Thu, 13 Jun 2019 16:33:56 GMT (envelope-from markj@FreeBSD.org) Received: (from markj@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x5DGXtI3002809; Thu, 13 Jun 2019 16:33:55 GMT (envelope-from markj@FreeBSD.org) Message-Id: <201906131633.x5DGXtI3002809@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: markj set sender to markj@FreeBSD.org using -f From: Mark Johnston Date: Thu, 13 Jun 2019 16:33:55 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org Subject: svn commit: r349016 - in stable/12/sys: amd64/amd64 cddl/contrib/opensolaris/uts/common/dtrace i386/i386 X-SVN-Group: stable-12 X-SVN-Commit-Author: markj X-SVN-Commit-Paths: in stable/12/sys: amd64/amd64 cddl/contrib/opensolaris/uts/common/dtrace i386/i386 X-SVN-Commit-Revision: 349016 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 63C698C937 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.97 / 15.00]; local_wl_from(0.00)[FreeBSD.org]; NEURAL_HAM_MEDIUM(-1.00)[-0.997,0]; NEURAL_HAM_SHORT(-0.97)[-0.973,0]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; ASN(0.00)[asn:11403, ipnet:2610:1c1:1::/48, country:US] X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 13 Jun 2019 16:33:57 -0000 Author: markj Date: Thu Jun 13 16:33:55 2019 New Revision: 349016 URL: https://svnweb.freebsd.org/changeset/base/349016 Log: MFC r348742: Fix a race between fasttrap and the user breakpoint handler. Modified: stable/12/sys/amd64/amd64/trap.c stable/12/sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c stable/12/sys/i386/i386/trap.c Directory Properties: stable/12/ (props changed) Modified: stable/12/sys/amd64/amd64/trap.c ============================================================================== --- stable/12/sys/amd64/amd64/trap.c Thu Jun 13 16:33:01 2019 (r349015) +++ stable/12/sys/amd64/amd64/trap.c Thu Jun 13 16:33:55 2019 (r349016) @@ -113,6 +113,10 @@ void dblfault_handler(struct trapframe *frame); static int trap_pfault(struct trapframe *, int); static void trap_fatal(struct trapframe *, vm_offset_t); +#ifdef KDTRACE_HOOKS +static bool trap_user_dtrace(struct trapframe *, + int (**hook)(struct trapframe *)); +#endif #define MAX_TRAP_MSG 32 static char *trap_msg[] = { @@ -284,11 +288,11 @@ trap(struct trapframe *frame) break; case T_BPTFLT: /* bpt instruction fault */ - enable_intr(); #ifdef KDTRACE_HOOKS - if (dtrace_pid_probe_ptr != NULL && - dtrace_pid_probe_ptr(frame) == 0) + if (trap_user_dtrace(frame, &dtrace_pid_probe_ptr)) return; +#else + enable_intr(); #endif signo = SIGTRAP; ucode = TRAP_BRKPT; @@ -425,9 +429,7 @@ trap(struct trapframe *frame) break; #ifdef KDTRACE_HOOKS case T_DTRACE_RET: - enable_intr(); - if (dtrace_return_probe_ptr != NULL) - dtrace_return_probe_ptr(frame); + (void)trap_user_dtrace(frame, &dtrace_return_probe_ptr); return; #endif } @@ -947,6 +949,25 @@ trap_fatal(frame, eva) else panic("unknown/reserved trap"); } + +#ifdef KDTRACE_HOOKS +/* + * Invoke a userspace DTrace hook. The hook pointer is cleared when no + * userspace probes are enabled, so we must synchronize with DTrace to ensure + * that a trapping thread is able to call the hook before it is cleared. + */ +static bool +trap_user_dtrace(struct trapframe *frame, int (**hookp)(struct trapframe *)) +{ + int (*hook)(struct trapframe *); + + hook = (int (*)(struct trapframe *))atomic_load_ptr(hookp); + enable_intr(); + if (hook != NULL) + return ((hook)(frame) == 0); + return (false); +} +#endif /* * Double fault handler. Called when a fault occurs while writing Modified: stable/12/sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c ============================================================================== --- stable/12/sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c Thu Jun 13 16:33:01 2019 (r349015) +++ stable/12/sys/cddl/contrib/opensolaris/uts/common/dtrace/fasttrap.c Thu Jun 13 16:33:55 2019 (r349016) @@ -1125,31 +1125,17 @@ fasttrap_enable_callbacks(void) static void fasttrap_disable_callbacks(void) { -#ifdef illumos - ASSERT(MUTEX_HELD(&cpu_lock)); -#endif - - mutex_enter(&fasttrap_count_mtx); ASSERT(fasttrap_pid_count > 0); fasttrap_pid_count--; if (fasttrap_pid_count == 0) { -#ifdef illumos - cpu_t *cur, *cpu = CPU; - - for (cur = cpu->cpu_next_onln; cur != cpu; - cur = cur->cpu_next_onln) { - rw_enter(&cur->cpu_ft_lock, RW_WRITER); - } -#endif + /* + * Synchronize with the breakpoint handler, which is careful to + * enable interrupts only after loading the hook pointer. + */ + dtrace_sync(); dtrace_pid_probe_ptr = NULL; dtrace_return_probe_ptr = NULL; -#ifdef illumos - for (cur = cpu->cpu_next_onln; cur != cpu; - cur = cur->cpu_next_onln) { - rw_exit(&cur->cpu_ft_lock); - } -#endif } mutex_exit(&fasttrap_count_mtx); } Modified: stable/12/sys/i386/i386/trap.c ============================================================================== --- stable/12/sys/i386/i386/trap.c Thu Jun 13 16:33:01 2019 (r349015) +++ stable/12/sys/i386/i386/trap.c Thu Jun 13 16:33:55 2019 (r349016) @@ -116,6 +116,10 @@ void syscall(struct trapframe *frame); static int trap_pfault(struct trapframe *, int, vm_offset_t); static void trap_fatal(struct trapframe *, vm_offset_t); +#ifdef KDTRACE_HOOKS +static bool trap_user_dtrace(struct trapframe *, + int (**hook)(struct trapframe *)); +#endif void dblfault_handler(void); extern inthand_t IDTVEC(bpt), IDTVEC(dbg), IDTVEC(int0x80_syscall); @@ -321,11 +325,11 @@ trap(struct trapframe *frame) break; case T_BPTFLT: /* bpt instruction fault */ - enable_intr(); #ifdef KDTRACE_HOOKS - if (dtrace_pid_probe_ptr != NULL && - dtrace_pid_probe_ptr(frame) == 0) + if (trap_user_dtrace(frame, &dtrace_pid_probe_ptr)) return; +#else + enable_intr(); #endif signo = SIGTRAP; ucode = TRAP_BRKPT; @@ -503,9 +507,7 @@ user_trctrap_out: break; #ifdef KDTRACE_HOOKS case T_DTRACE_RET: - enable_intr(); - if (dtrace_return_probe_ptr != NULL) - dtrace_return_probe_ptr(frame); + (void)trap_user_dtrace(frame, &dtrace_return_probe_ptr); return; #endif } @@ -993,6 +995,25 @@ trap_fatal(frame, eva) else panic("unknown/reserved trap"); } + +#ifdef KDTRACE_HOOKS +/* + * Invoke a userspace DTrace hook. The hook pointer is cleared when no + * userspace probes are enabled, so we must synchronize with DTrace to ensure + * that a trapping thread is able to call the hook before it is cleared. + */ +static bool +trap_user_dtrace(struct trapframe *frame, int (**hookp)(struct trapframe *)) +{ + int (*hook)(struct trapframe *); + + hook = (int (*)(struct trapframe *))atomic_load_ptr(hookp); + enable_intr(); + if (hook != NULL) + return ((hook)(frame) == 0); + return (false); +} +#endif /* * Double fault handler. Called when a fault occurs while writing