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From: Greg KH <gregkh@suse.de>
To: linux-kernel@vger.kernel.org, stable@kernel.org
Cc: Justin Forbes <jmforbes@linuxtx.org>,
	Zwane Mwaikambo <zwane@arm.linux.org.uk>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Randy Dunlap <rdunlap@xenotime.net>,
	Dave Jones <davej@redhat.com>,
	Chuck Wolber <chuckw@quantumlinux.com>,
	Chris Wedgwood <reviews@ml.cw.f00f.org>,
	Michael Krufky <mkrufky@linuxtv.org>,
	Chuck Ebbert <cebbert@redhat.com>,
	torvalds@linux-foundation.org, akpm@linux-foundation.org,
	alan@lxorguk.ukuu.org.uk, Greg KH <greg@kroah.com>,
	uml-devel <user-mode-linux-devel@lists.sourceforge.net>,
	Jeff Dike <jdike@addtoit.com>
Subject: [patch 31/31] UML - arch_prctl should set thread fs
Date: Mon, 19 Mar 2007 14:41:24 -0700	[thread overview]
Message-ID: <20070319214124.GG9261@kroah.com> (raw)
In-Reply-To: <20070319213647.GB9261@kroah.com>

[-- Attachment #1: uml-arch_prctl-should-set-thread-fs.patch --]
[-- Type: text/plain, Size: 7241 bytes --]

-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Jeff Dike <jdike@addtoit.com>

x86_64 needs some TLS fixes.  What was missing was remembering the child
thread id during clone and stuffing it into the child during each context
switch.

The %fs value is stored separately in the thread structure since the host
controls what effect it has on the actual register file.  The host also needs
to store it in its own thread struct, so we need the value kept outside the
register file.

arch_prctl_skas was fixed to call PTRACE_ARCH_PRCTL appropriately.  There is
some saving and restoring of registers in the ARCH_SET_* cases so that the
correct set of registers are changed on the host and restored to the process
when it runs again.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 arch/um/include/os.h                 |    2 
 arch/um/os-Linux/sys-x86_64/Makefile |    2 
 arch/um/os-Linux/sys-x86_64/prctl.c  |   12 +++++
 arch/um/sys-x86_64/syscalls.c        |   76 ++++++++++++++++++++++++++---------
 arch/um/sys-x86_64/tls.c             |   11 +++--
 include/asm-um/processor-x86_64.h    |    6 +-
 include/asm-um/ptrace-x86_64.h       |    6 --
 7 files changed, 86 insertions(+), 29 deletions(-)

--- a/arch/um/include/os.h
+++ b/arch/um/include/os.h
@@ -341,4 +341,6 @@ extern void maybe_sigio_broken(int fd, i
 extern void sig_handler_common_skas(int sig, void *sc_ptr);
 extern void user_signal(int sig, union uml_pt_regs *regs, int pid);
 
+extern int os_arch_prctl(int pid, int code, unsigned long *addr);
+
 #endif
--- a/arch/um/os-Linux/sys-x86_64/Makefile
+++ b/arch/um/os-Linux/sys-x86_64/Makefile
@@ -3,7 +3,7 @@
 # Licensed under the GPL
 #
 
-obj-$(CONFIG_MODE_SKAS) = registers.o signal.o
+obj-$(CONFIG_MODE_SKAS) = registers.o prctl.o signal.o
 
 USER_OBJS := $(obj-y)
 
--- /dev/null
+++ b/arch/um/os-Linux/sys-x86_64/prctl.c
@@ -0,0 +1,12 @@
+/*
+ * Copyright (C) 2007 Jeff Dike (jdike@{addtoit.com,linux.intel.com})
+ * Licensed under the GPL
+ */
+
+#include <sys/ptrace.h>
+#include <linux/ptrace.h>
+
+int os_arch_prctl(int pid, int code, unsigned long *addr)
+{
+	return ptrace(PTRACE_ARCH_PRCTL, pid, (unsigned long) addr, code);
+}
--- a/arch/um/sys-x86_64/syscalls.c
+++ b/arch/um/sys-x86_64/syscalls.c
@@ -16,6 +16,7 @@
 #include "asm/prctl.h" /* XXX This should get the constants from libc */
 #include "choose-mode.h"
 #include "kern.h"
+#include "os.h"
 
 asmlinkage long sys_uname64(struct new_utsname __user * name)
 {
@@ -58,40 +59,70 @@ static long arch_prctl_tt(int code, unsi
 
 #ifdef CONFIG_MODE_SKAS
 
-/* XXX: Must also call arch_prctl in the host, beside saving the segment bases! */
-static long arch_prctl_skas(int code, unsigned long addr)
+static long arch_prctl_skas(int code, unsigned long __user *addr)
 {
-	long ret = 0;
+	unsigned long *ptr = addr, tmp;
+	long ret;
+	int pid = current->mm->context.skas.id.u.pid;
+
+	/*
+	 * With ARCH_SET_FS (and ARCH_SET_GS is treated similarly to
+	 * be safe), we need to call arch_prctl on the host because
+	 * setting %fs may result in something else happening (like a
+	 * GDT being set instead).  So, we let the host fiddle the
+	 * registers and restore them afterwards.
+	 *
+	 * So, the saved registers are stored to the process (this
+	 * needed because a stub may have been the last thing to run),
+	 * arch_prctl is run on the host, then the registers are read
+	 * back.
+	 */
+	switch(code){
+	case ARCH_SET_FS:
+	case ARCH_SET_GS:
+		restore_registers(pid, &current->thread.regs.regs);
+		break;
+	case ARCH_GET_FS:
+	case ARCH_GET_GS:
+		/*
+		 * With these two, we read to a local pointer and
+		 * put_user it to the userspace pointer that we were
+		 * given.  If addr isn't valid (because it hasn't been
+		 * faulted in or is just bogus), we want put_user to
+		 * fault it in (or return -EFAULT) instead of having
+		 * the host return -EFAULT.
+		 */
+		ptr = &tmp;
+	}
+
+	ret = os_arch_prctl(pid, code, ptr);
+	if(ret)
+		return ret;
 
 	switch(code){
 	case ARCH_SET_FS:
-		current->thread.regs.regs.skas.regs[FS_BASE / sizeof(unsigned long)] = addr;
+		current->thread.arch.fs = (unsigned long) ptr;
+		save_registers(pid, &current->thread.regs.regs);
 		break;
 	case ARCH_SET_GS:
-		current->thread.regs.regs.skas.regs[GS_BASE / sizeof(unsigned long)] = addr;
+		save_registers(pid, &current->thread.regs.regs);
 		break;
 	case ARCH_GET_FS:
-		ret = put_user(current->thread.regs.regs.skas.
-				regs[FS_BASE / sizeof(unsigned long)],
-				(unsigned long __user *)addr);
-	        break;
+		ret = put_user(tmp, addr);
+		break;
 	case ARCH_GET_GS:
-		ret = put_user(current->thread.regs.regs.skas.
-				regs[GS_BASE / sizeof(unsigned long)],
-				(unsigned long __user *)addr);
-	        break;
-	default:
-		ret = -EINVAL;
+		ret = put_user(tmp, addr);
 		break;
 	}
 
-	return(ret);
+	return ret;
 }
 #endif
 
 long sys_arch_prctl(int code, unsigned long addr)
 {
-	return(CHOOSE_MODE_PROC(arch_prctl_tt, arch_prctl_skas, code, addr));
+	return CHOOSE_MODE_PROC(arch_prctl_tt, arch_prctl_skas, code,
+				(unsigned long __user *) addr);
 }
 
 long sys_clone(unsigned long clone_flags, unsigned long newsp,
@@ -105,5 +136,14 @@ long sys_clone(unsigned long clone_flags
 	ret = do_fork(clone_flags, newsp, &current->thread.regs, 0, parent_tid,
 		      child_tid);
 	current->thread.forking = 0;
-	return(ret);
+	return ret;
 }
+
+void arch_switch_to_skas(struct task_struct *from, struct task_struct *to)
+{
+	if((to->thread.arch.fs == 0) || (to->mm == NULL))
+		return;
+
+	arch_prctl_skas(ARCH_SET_FS, (void __user *) to->thread.arch.fs);
+}
+
--- a/arch/um/sys-x86_64/tls.c
+++ b/arch/um/sys-x86_64/tls.c
@@ -1,14 +1,17 @@
 #include "linux/sched.h"
 
-void debug_arch_force_load_TLS(void)
-{
-}
-
 void clear_flushed_tls(struct task_struct *task)
 {
 }
 
 int arch_copy_tls(struct task_struct *t)
 {
+	/*
+	 * If CLONE_SETTLS is set, we need to save the thread id
+	 * (which is argument 5, child_tid, of clone) so it can be set
+	 * during context switches.
+	 */
+	t->thread.arch.fs = t->thread.regs.regs.skas.regs[R8 / sizeof(long)];
+
         return 0;
 }
--- a/include/asm-um/processor-x86_64.h
+++ b/include/asm-um/processor-x86_64.h
@@ -13,6 +13,7 @@
 struct arch_thread {
         unsigned long debugregs[8];
         int debugregs_seq;
+	unsigned long fs;
         struct faultinfo faultinfo;
 };
 
@@ -25,8 +26,9 @@ extern inline void rep_nop(void)
 #define cpu_relax()   rep_nop()
 
 #define INIT_ARCH_THREAD { .debugregs  		= { [ 0 ... 7 ] = 0 }, \
-                           .debugregs_seq	= 0, \
-                           .faultinfo		= { 0, 0, 0 } }
+			   .debugregs_seq	= 0,			       \
+			   .fs			= 0, \
+			   .faultinfo		= { 0, 0, 0 } }
 
 static inline void arch_flush_thread(struct arch_thread *thread)
 {
--- a/include/asm-um/ptrace-x86_64.h
+++ b/include/asm-um/ptrace-x86_64.h
@@ -81,9 +81,7 @@ static inline void arch_switch_to_tt(str
 {
 }
 
-static inline void arch_switch_to_skas(struct task_struct *from,
-                                       struct task_struct *to)
-{
-}
+extern void arch_switch_to_skas(struct task_struct *from,
+				struct task_struct *to);
 
 #endif

-- 

  parent reply	other threads:[~2007-03-19 21:44 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20070319213047.710101653@mini.kroah.org>
2007-03-19 21:36 ` [patch 00/31] 2.6.20-stable review Greg KH
2007-03-19 21:37   ` [patch 01/31] Fix another NULL pointer deref in ipv6_sockglue.c Greg KH
2007-03-19 21:37   ` [patch 02/31] Fix rtm_to_ifaddr() error return Greg KH
2007-03-19 21:37   ` [patch 03/31] Fix user copy length in ipv6_sockglue.c Greg KH
2007-03-19 22:01     ` Chris Wright
2007-03-19 22:51       ` David Miller
2007-03-20  4:05       ` Greg KH
2007-03-19 21:37   ` [patch 04/31] gdth: fix oops in gdth_copy_cmd() Greg KH
2007-03-19 21:37   ` [patch 05/31] NetLabel: Verify sensitivity level has a valid CIPSO mapping Greg KH
2007-03-19 21:38   ` [patch 06/31] NETFILTER: nfnetlink_log: fix reference counting Greg KH
2007-03-19 21:38   ` [patch 07/31] IA64: fix NULL pointer in ia64/irq_chip-mask/unmask function Greg KH
2007-03-19 21:38   ` [patch 08/31] adjust legacy IDE resource setting (v2) Greg KH
2007-03-19 21:38   ` [patch 09/31] mm: fix madvise infinine loop Greg KH
2007-03-19 21:38   ` [patch 10/31] EHCI: add delay to bus_resume before accessing ports Greg KH
2007-03-19 21:38   ` [patch 11/31] initialise pi_lock if CONFIG_RT_MUTEXES=N Greg KH
2007-03-19 21:38   ` [patch 12/31] futex: PI state locking fix Greg KH
2007-03-19 21:39   ` [patch 13/31] nfs: nfs_getattr() cant call nfs_sync_mapping_range() for non-regular files Greg KH
2007-03-19 21:39   ` [patch 14/31] hrtimer: prevent overrun DoS in hrtimer_forward() Greg KH
2007-03-19 21:39   ` [patch 15/31] fix MTIME_SEC_MAX on 32-bit Greg KH
2007-03-19 21:39   ` [patch 16/31] fix read past end of array in md/linear.c Greg KH
2007-03-19 21:39   ` [patch 17/31] r8169: fix a race between PCI probe and dev_open Greg KH
2007-03-19 21:39   ` [patch 18/31] Fix extraneous IPSEC larval SA creation Greg KH
2007-03-19 21:39   ` [patch 19/31] : Fix GFP_KERNEL with preemption disabled in fib_trie Greg KH
2007-03-19 21:40   ` [patch 20/31] Fix ipv6 flow label inheritance Greg KH
2007-03-19 21:40   ` [patch 21/31] Copy over mac_len when cloning an skb Greg KH
2007-03-19 21:40   ` [patch 22/31] Fix sparc64 hugepage bugs Greg KH
2007-03-19 21:40   ` [patch 23/31] Fix page allocation debugging on sparc64 Greg KH
2007-03-19 21:40   ` [patch 24/31] IrDA: irttp_dup spin_lock initialisation Greg KH
2007-03-19 21:40   ` [patch 25/31] Input: i8042 - really suppress ACK/NAK during panic blink Greg KH
2007-03-19 21:40   ` [patch 26/31] hda-intel - Fix codec probe with ATI controllers Greg KH
2007-03-19 21:40   ` [patch 27/31] oom fix: prevent oom from killing a process with children/sibling unkillable Greg KH
2007-03-19 21:41   ` [patch 28/31] dio: invalidate clean pages before dio write Greg KH
2007-03-19 21:41   ` [patch 29/31] Input: i8042 - fix AUX IRQ delivery check Greg KH
2007-03-19 21:48     ` Dmitry Torokhov
2007-03-19 21:55       ` Chuck Ebbert
2007-03-20  4:18       ` [stable] " Greg KH
2007-03-19 21:41   ` [patch 30/31] fix deadlock in audit_log_task_context() Greg KH
2007-03-19 21:41   ` Greg KH [this message]
2007-03-19 21:43   ` [patch 00/31] 2.6.20-stable review Greg KH
2007-03-20  5:15   ` Gene Heskett
2007-03-20 15:52     ` Greg KH
2007-03-20 19:59       ` Gene Heskett
2007-03-20 20:12         ` Michael Krufky
2007-03-21  2:56           ` Gene Heskett
2007-03-21  3:04           ` Gene Heskett
2007-03-21  3:39             ` Greg KH
2007-03-21  3:53               ` Gene Heskett
2007-03-25 16:30                 ` Adrian Bunk

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