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Date:      Sun, 22 Nov 2020 05:47:46 +0000 (UTC)
From:      Kyle Evans <kevans@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r367930 - in head/sys: kern sys
Message-ID:  <202011220547.0AM5lkOG078011@repo.freebsd.org>

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Author: kevans
Date: Sun Nov 22 05:47:45 2020
New Revision: 367930
URL: https://svnweb.freebsd.org/changeset/base/367930

Log:
  [2/2] _umtx_op: introduce 32-bit/i386 flags for operations
  
  This patch takes advantage of the consolidation that happened to provide two
  flags that can be used with the native _umtx_op(2): UMTX_OP___32BIT and
  UMTX_OP__I386.
  
  UMTX_OP__32BIT iindicates that we are being provided with 32-bit structures.
  Note that this flag alone indicates a 64bit time_t, since this is the
  majority case.
  
  UMTX_OP__I386 has been provided so that we can emulate i386 as well,
  regardless of whether the host is amd64 or not.
  
  Both imply a different set of copyops in sysumtx_op. freebsd32__umtx_op
  simply ignores the flags, since it's already doing a 32-bit operation and
  it's unlikely we'll be running an emulator under compat32. Future work
  could consider it, but the author sees little benefit.
  
  This will be used by qemu-bsd-user to pass on all _umtx_op calls to the
  native interface as long as the host/target endianness matches, effectively
  eliminating most if not all of the remaining unresolved deadlocks for most.
  
  This version changed a fair amount from what was under review, mostly in
  response to refactoring of the prereq reorganization and battle-testing
  it with qemu-bsd-user.  The main changes are as follows:
  
  1.) The i386 flag got renamed to omit '32BIT' since this is redundant.
  2.) The flags are now properly handled on 32-bit platforms to emulate other
      32-bit platforms.
  3.) Robust list handling was fixed, and the 32-bit functionality that was
      previously gated by COMPAT_FREEBSD32 is now unconditional.
  4.) Robust list handling was also improved, including the error reported
      when a process has already registered 32-bit ABI lists and also
      detecting if native robust lists have already been registered. Both
      scenarios now return EBUSY rather than EINVAL, because the input is
      technically valid but we're too busy with another ABI's lists.
  
  libsysdecode/kdump/truss support will go into review soon-ish, along with
  the associated manpage update.
  
  Reviewed by:	kib (earlier version)
  MFC after:	3 weeks

Modified:
  head/sys/kern/kern_umtx.c
  head/sys/sys/umtx.h

Modified: head/sys/kern/kern_umtx.c
==============================================================================
--- head/sys/kern/kern_umtx.c	Sun Nov 22 05:42:52 2020	(r367929)
+++ head/sys/kern/kern_umtx.c	Sun Nov 22 05:47:45 2020	(r367930)
@@ -75,8 +75,8 @@ __FBSDID("$FreeBSD$");
 #include <machine/atomic.h>
 #include <machine/cpu.h>
 
-#ifdef COMPAT_FREEBSD32
 #include <compat/freebsd32/freebsd32.h>
+#ifdef COMPAT_FREEBSD32
 #include <compat/freebsd32/freebsd32_proto.h>
 #endif
 
@@ -232,7 +232,6 @@ struct umtx_copyops {
 	const bool	compat32;
 };
 
-#ifdef COMPAT_FREEBSD32
 struct umtx_time32 {
 	struct	timespec32	_timeout;
 	uint32_t		_flags;
@@ -257,7 +256,6 @@ struct umutex32 {
 _Static_assert(sizeof(struct umutex) == sizeof(struct umutex32), "umutex32");
 _Static_assert(__offsetof(struct umutex, m_spare[0]) ==
     __offsetof(struct umutex32, m_spare[0]), "m_spare32");
-#endif
 
 int umtx_shm_vnobj_persistent = 0;
 SYSCTL_INT(_kern_ipc, OID_AUTO, umtx_vnode_persistent, CTLFLAG_RWTUN,
@@ -4167,6 +4165,15 @@ __umtx_op_robust_lists(struct thread *td, struct _umtx
 	struct umtx_robust_lists_params rb;
 	int error;
 
+	if (ops->compat32) {
+		if ((td->td_pflags2 & TDP2_COMPAT32RB) == 0 &&
+		    (td->td_rb_list != 0 || td->td_rbp_list != 0 ||
+		    td->td_rb_inact != 0))
+			return (EBUSY);
+	} else if ((td->td_pflags2 & TDP2_COMPAT32RB) != 0) {
+		return (EBUSY);
+	}
+
 	bzero(&rb, sizeof(rb));
 	error = ops->copyin_robust_lists(uap->uaddr1, uap->val, &rb);
 	if (error != 0)
@@ -4174,8 +4181,6 @@ __umtx_op_robust_lists(struct thread *td, struct _umtx
 
 	if (ops->compat32)
 		td->td_pflags2 |= TDP2_COMPAT32RB;
-	else if ((td->td_pflags2 & TDP2_COMPAT32RB) != 0)
-		return (EINVAL);
 
 	td->td_rb_list = rb.robust_list_offset;
 	td->td_rbp_list = rb.robust_priv_list_offset;
@@ -4183,11 +4188,70 @@ __umtx_op_robust_lists(struct thread *td, struct _umtx
 	return (0);
 }
 
-#ifdef COMPAT_FREEBSD32
+#if defined(__i386__) || defined(__amd64__)
+/*
+ * Provide the standard 32-bit definitions for x86, since native/compat32 use a
+ * 32-bit time_t there.  Other architectures just need the i386 definitions
+ * along with their standard compat32.
+ */
+struct timespecx32 {
+	int64_t			tv_sec;
+	int32_t			tv_nsec;
+};
+
+struct umtx_timex32 {
+	struct	timespecx32	_timeout;
+	uint32_t		_flags;
+	uint32_t		_clockid;
+};
+
+#ifndef __i386__
+#define	timespeci386	timespec32
+#define	umtx_timei386	umtx_time32
+#endif
+#else /* !__i386__ && !__amd64__ */
+/* 32-bit architectures can emulate i386, so define these almost everywhere. */
+struct timespeci386 {
+	int32_t			tv_sec;
+	int32_t			tv_nsec;
+};
+
+struct umtx_timei386 {
+	struct	timespeci386	_timeout;
+	uint32_t		_flags;
+	uint32_t		_clockid;
+};
+
+#if defined(__LP64__)
+#define	timespecx32	timespec32
+#define	umtx_timex32	umtx_time32
+#endif
+#endif
+
+static int
+umtx_copyin_robust_lists32(const void *uaddr, size_t size,
+    struct umtx_robust_lists_params *rbp)
+{
+	struct umtx_robust_lists_params_compat32 rb32;
+	int error;
+
+	if (size > sizeof(rb32))
+		return (EINVAL);
+	bzero(&rb32, sizeof(rb32));
+	error = copyin(uaddr, &rb32, size);
+	if (error != 0)
+		return (error);
+	CP(rb32, *rbp, robust_list_offset);
+	CP(rb32, *rbp, robust_priv_list_offset);
+	CP(rb32, *rbp, robust_inact_offset);
+	return (0);
+}
+
+#ifndef __i386__
 static inline int
-umtx_copyin_timeout32(const void *uaddr, struct timespec *tsp)
+umtx_copyin_timeouti386(const void *uaddr, struct timespec *tsp)
 {
-	struct timespec32 ts32;
+	struct timespeci386 ts32;
 	int error;
 
 	error = copyin(uaddr, &ts32, sizeof(ts32));
@@ -4205,9 +4269,9 @@ umtx_copyin_timeout32(const void *uaddr, struct timesp
 }
 
 static inline int
-umtx_copyin_umtx_time32(const void *uaddr, size_t size, struct _umtx_time *tp)
+umtx_copyin_umtx_timei386(const void *uaddr, size_t size, struct _umtx_time *tp)
 {
-	struct umtx_time32 t32;
+	struct umtx_timei386 t32;
 	int error;
 
 	t32._clockid = CLOCK_REALTIME;
@@ -4228,28 +4292,73 @@ umtx_copyin_umtx_time32(const void *uaddr, size_t size
 }
 
 static int
-umtx_copyin_robust_lists32(const void *uaddr, size_t size,
-    struct umtx_robust_lists_params *rbp)
+umtx_copyout_timeouti386(void *uaddr, size_t sz, struct timespec *tsp)
 {
-	struct umtx_robust_lists_params_compat32 rb32;
+	struct timespeci386 remain32 = {
+		.tv_sec = tsp->tv_sec,
+		.tv_nsec = tsp->tv_nsec,
+	};
+
+	/*
+	 * Should be guaranteed by the caller, sz == uaddr1 - sizeof(_umtx_time)
+	 * and we're only called if sz >= sizeof(timespec) as supplied in the
+	 * copyops.
+	 */
+	KASSERT(sz >= sizeof(remain32),
+	    ("umtx_copyops specifies incorrect sizes"));
+
+	return (copyout(&remain32, uaddr, sizeof(remain32)));
+}
+#endif /* !__i386__ */
+
+#if defined(__i386__) || defined(__LP64__)
+static inline int
+umtx_copyin_timeoutx32(const void *uaddr, struct timespec *tsp)
+{
+	struct timespecx32 ts32;
 	int error;
 
-	if (size > sizeof(rb32))
-		return (EINVAL);
-	bzero(&rb32, sizeof(rb32));
-	error = copyin(uaddr, &rb32, size);
+	error = copyin(uaddr, &ts32, sizeof(ts32));
+	if (error == 0) {
+		if (ts32.tv_sec < 0 ||
+		    ts32.tv_nsec >= 1000000000 ||
+		    ts32.tv_nsec < 0)
+			error = EINVAL;
+		else {
+			CP(ts32, *tsp, tv_sec);
+			CP(ts32, *tsp, tv_nsec);
+		}
+	}
+	return (error);
+}
+
+static inline int
+umtx_copyin_umtx_timex32(const void *uaddr, size_t size, struct _umtx_time *tp)
+{
+	struct umtx_timex32 t32;
+	int error;
+
+	t32._clockid = CLOCK_REALTIME;
+	t32._flags   = 0;
+	if (size <= sizeof(t32._timeout))
+		error = copyin(uaddr, &t32._timeout, sizeof(t32._timeout));
+	else
+		error = copyin(uaddr, &t32, sizeof(t32));
 	if (error != 0)
 		return (error);
-	CP(rb32, *rbp, robust_list_offset);
-	CP(rb32, *rbp, robust_priv_list_offset);
-	CP(rb32, *rbp, robust_inact_offset);
+	if (t32._timeout.tv_sec < 0 ||
+	    t32._timeout.tv_nsec >= 1000000000 || t32._timeout.tv_nsec < 0)
+		return (EINVAL);
+	TS_CP(t32, *tp, _timeout);
+	CP(t32, *tp, _flags);
+	CP(t32, *tp, _clockid);
 	return (0);
 }
 
 static int
-umtx_copyout_timeout32(void *uaddr, size_t sz, struct timespec *tsp)
+umtx_copyout_timeoutx32(void *uaddr, size_t sz, struct timespec *tsp)
 {
-	struct timespec32 remain32 = {
+	struct timespecx32 remain32 = {
 		.tv_sec = tsp->tv_sec,
 		.tv_nsec = tsp->tv_nsec,
 	};
@@ -4264,7 +4373,7 @@ umtx_copyout_timeout32(void *uaddr, size_t sz, struct 
 
 	return (copyout(&remain32, uaddr, sizeof(remain32)));
 }
-#endif /* COMPAT_FREEBSD32 */
+#endif /* __i386__ || __LP64__ */
 
 typedef int (*_umtx_op_func)(struct thread *td, struct _umtx_op_args *uap,
     const struct umtx_copyops *umtx_ops);
@@ -4313,25 +4422,48 @@ static const struct umtx_copyops umtx_native_ops = {
 	.umtx_time_sz = sizeof(struct _umtx_time),
 };
 
-#ifdef COMPAT_FREEBSD32
-const struct umtx_copyops umtx_native_ops32 = {
-	.copyin_timeout = umtx_copyin_timeout32,
-	.copyin_umtx_time = umtx_copyin_umtx_time32,
+#ifndef __i386__
+static const struct umtx_copyops umtx_native_opsi386 = {
+	.copyin_timeout = umtx_copyin_timeouti386,
+	.copyin_umtx_time = umtx_copyin_umtx_timei386,
 	.copyin_robust_lists = umtx_copyin_robust_lists32,
-	.copyout_timeout = umtx_copyout_timeout32,
-	.timespec_sz = sizeof(struct timespec32),
-	.umtx_time_sz = sizeof(struct umtx_time32),
+	.copyout_timeout = umtx_copyout_timeouti386,
+	.timespec_sz = sizeof(struct timespeci386),
+	.umtx_time_sz = sizeof(struct umtx_timei386),
 	.compat32 = true,
 };
 #endif
 
+#if defined(__i386__) || defined(__LP64__)
+/* i386 can emulate other 32-bit archs, too! */
+static const struct umtx_copyops umtx_native_opsx32 = {
+	.copyin_timeout = umtx_copyin_timeoutx32,
+	.copyin_umtx_time = umtx_copyin_umtx_timex32,
+	.copyin_robust_lists = umtx_copyin_robust_lists32,
+	.copyout_timeout = umtx_copyout_timeoutx32,
+	.timespec_sz = sizeof(struct timespecx32),
+	.umtx_time_sz = sizeof(struct umtx_timex32),
+	.compat32 = true,
+};
+
+#ifdef COMPAT_FREEBSD32
+#ifdef __amd64__
+#define	umtx_native_ops32	umtx_native_opsi386
+#else
+#define	umtx_native_ops32	umtx_native_opsx32
+#endif
+#endif /* COMPAT_FREEBSD32 */
+#endif /* __i386__ || __LP64__ */
+
+#define	UMTX_OP__FLAGS	(UMTX_OP__32BIT | UMTX_OP__I386)
+
 static int
 kern__umtx_op(struct thread *td, void *obj, int op, unsigned long val,
     void *uaddr1, void *uaddr2, const struct umtx_copyops *ops)
 {
 	struct _umtx_op_args uap = {
 		.obj = obj,
-		.op = op,
+		.op = op & ~UMTX_OP__FLAGS,
 		.val = val,
 		.uaddr1 = uaddr1,
 		.uaddr2 = uaddr2
@@ -4345,9 +4477,27 @@ kern__umtx_op(struct thread *td, void *obj, int op, un
 int
 sys__umtx_op(struct thread *td, struct _umtx_op_args *uap)
 {
+	static const struct umtx_copyops *umtx_ops;
 
+	umtx_ops = &umtx_native_ops;
+#ifdef __LP64__
+	if ((uap->op & (UMTX_OP__32BIT | UMTX_OP__I386)) != 0) {
+		if ((uap->op & UMTX_OP__I386) != 0)
+			umtx_ops = &umtx_native_opsi386;
+		else
+			umtx_ops = &umtx_native_opsx32;
+	}
+#elif !defined(__i386__)
+	/* We consider UMTX_OP__32BIT a nop on !i386 ILP32. */
+	if ((uap->op & UMTX_OP__I386) != 0)
+		umtx_ops = &umtx_native_opsi386;
+#else
+	/* Likewise, UMTX_OP__I386 is a nop on i386. */
+	if ((uap->op & UMTX_OP__32BIT) != 0)
+		umtx_ops = &umtx_native_opsx32;
+#endif
 	return (kern__umtx_op(td, uap->obj, uap->op, uap->val, uap->uaddr1,
-	    uap->uaddr2, &umtx_native_ops));
+	    uap->uaddr2, umtx_ops));
 }
 
 #ifdef COMPAT_FREEBSD32
@@ -4435,19 +4585,14 @@ static int
 umtx_read_uptr(struct thread *td, uintptr_t ptr, uintptr_t *res, bool compat32)
 {
 	u_long res1;
-#ifdef COMPAT_FREEBSD32
 	uint32_t res32;
-#endif
 	int error;
 
-#ifdef COMPAT_FREEBSD32
 	if (compat32) {
 		error = fueword32((void *)ptr, &res32);
 		if (error == 0)
 			res1 = res32;
-	} else
-#endif
-	{
+	} else {
 		error = fueword((void *)ptr, &res1);
 	}
 	if (error == 0)
@@ -4461,15 +4606,14 @@ static void
 umtx_read_rb_list(struct thread *td, struct umutex *m, uintptr_t *rb_list,
     bool compat32)
 {
-#ifdef COMPAT_FREEBSD32
 	struct umutex32 m32;
 
 	if (compat32) {
 		memcpy(&m32, m, sizeof(m32));
 		*rb_list = m32.m_rb_lnk;
-	} else
-#endif
+	} else {
 		*rb_list = m->m_rb_lnk;
+	}
 }
 
 static int

Modified: head/sys/sys/umtx.h
==============================================================================
--- head/sys/sys/umtx.h	Sun Nov 22 05:42:52 2020	(r367929)
+++ head/sys/sys/umtx.h	Sun Nov 22 05:47:45 2020	(r367930)
@@ -101,6 +101,13 @@
 #define	UMTX_OP_SHM		25
 #define	UMTX_OP_ROBUST_LISTS	26
 
+/*
+ * Flags for ops; the double-underbar convention must be maintained for future
+ * additions for the sake of libsysdecode.
+ */
+#define	UMTX_OP__I386		0x40000000
+#define	UMTX_OP__32BIT		0x80000000
+
 /* Flags for UMTX_OP_CV_WAIT */
 #define	CVWAIT_CHECK_UNPARKING	0x01
 #define	CVWAIT_ABSTIME		0x02



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