livepatch/x86: add TIF_PATCH_PENDING thread flag

Add the TIF_PATCH_PENDING thread flag to enable the new livepatch
per-task consistency model for x86_64.  The bit getting set indicates
the thread has a pending patch which needs to be applied when the thread
exits the kernel.

The bit is placed in the _TIF_ALLWORK_MASK macro, which results in
exit_to_usermode_loop() calling klp_update_patch_state() when it's set.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>        # for the x86 changes
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 370c42c7f04683d7eced851b22d59b18a792af4b..cdefcfdd9e63effa6a06660adf013c4fe96ea853 100644 (file)
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -22,6 +22,7 @@
 #include <linux/context_tracking.h>
 #include <linux/user-return-notifier.h>
 #include <linux/uprobes.h>
+#include <linux/livepatch.h>
 
 #include <asm/desc.h>
 #include <asm/traps.h>
@@ -130,14 +131,13 @@ static long syscall_trace_enter(struct pt_regs *regs)
 
 #define EXIT_TO_USERMODE_LOOP_FLAGS                            \
        (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE |   \
-        _TIF_NEED_RESCHED | _TIF_USER_RETURN_NOTIFY)
+        _TIF_NEED_RESCHED | _TIF_USER_RETURN_NOTIFY | _TIF_PATCH_PENDING)
 
 static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags)
 {
        /*
         * In order to return to user mode, we need to have IRQs off with
-        * none of _TIF_SIGPENDING, _TIF_NOTIFY_RESUME, _TIF_USER_RETURN_NOTIFY,
-        * _TIF_UPROBE, or _TIF_NEED_RESCHED set.  Several of these flags
+        * none of EXIT_TO_USERMODE_LOOP_FLAGS set.  Several of these flags
         * can be set at any time on preemptable kernels if we have IRQs on,
         * so we need to loop.  Disabling preemption wouldn't help: doing the
         * work to clear some of the flags can sleep.
@@ -164,6 +164,9 @@ static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags)
                if (cached_flags & _TIF_USER_RETURN_NOTIFY)
                        fire_user_return_notifiers();
 
+               if (cached_flags & _TIF_PATCH_PENDING)
+                       klp_update_patch_state(current);
+
                /* Disable IRQs and retry */
                local_irq_disable();
 

diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 207d0d981287256d46c303bda63715e2e4cd9998..83372dc439435ea389a0c2aaae5fe38bbc84409f 100644 (file)
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -84,6 +84,7 @@ struct thread_info {
 #define TIF_SECCOMP            8       /* secure computing */
 #define TIF_USER_RETURN_NOTIFY 11      /* notify kernel of userspace return */
 #define TIF_UPROBE             12      /* breakpointed or singlestepping */
+#define TIF_PATCH_PENDING      13      /* pending live patching update */
 #define TIF_NOTSC              16      /* TSC is not accessible in userland */
 #define TIF_IA32               17      /* IA32 compatibility process */
 #define TIF_NOHZ               19      /* in adaptive nohz mode */
@@ -107,6 +108,7 @@ struct thread_info {
 #define _TIF_SECCOMP           (1 << TIF_SECCOMP)
 #define _TIF_USER_RETURN_NOTIFY        (1 << TIF_USER_RETURN_NOTIFY)
 #define _TIF_UPROBE            (1 << TIF_UPROBE)
+#define _TIF_PATCH_PENDING     (1 << TIF_PATCH_PENDING)
 #define _TIF_NOTSC             (1 << TIF_NOTSC)
 #define _TIF_IA32              (1 << TIF_IA32)
 #define _TIF_NOHZ              (1 << TIF_NOHZ)
@@ -133,7 +135,7 @@ struct thread_info {
        (_TIF_SYSCALL_TRACE | _TIF_NOTIFY_RESUME | _TIF_SIGPENDING |    \
         _TIF_NEED_RESCHED | _TIF_SINGLESTEP | _TIF_SYSCALL_EMU |       \
         _TIF_SYSCALL_AUDIT | _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE |   \
-        _TIF_NOHZ | _TIF_SYSCALL_TRACEPOINT)
+        _TIF_PATCH_PENDING | _TIF_NOHZ | _TIF_SYSCALL_TRACEPOINT)
 
 /* flags to check in __switch_to() */
 #define _TIF_WORK_CTXSW                                                        \