Re: [PATCH v3 04/15] livepatch/x86: add TIF_PATCH_PENDING thread flag

[Kamalesh Babulal]

On Thursday 08 December 2016 11:38 PM, Josh Poimboeuf wrote:

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 


Reviewed-by: Kamalesh Babulal 

--
cheers,
Kamalesh.

Re: [PATCH v3 04/15] livepatch/x86: add TIF_PATCH_PENDING thread flag

[Miroslav Benes]

On Thu, 8 Dec 2016, Josh Poimboeuf wrote:

> 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 

Reviewed-by: Miroslav Benes 

Miroslav

Re: [PATCH v3 04/15] livepatch/x86: add TIF_PATCH_PENDING thread flag

[Petr Mladek]

On Thu 2016-12-08 12:08:29, Josh Poimboeuf wrote:
> 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 

Reviewed-by: Petr Mladek 

Best Regards,
Petr

Re: [PATCH v3 04/15] livepatch/x86: add TIF_PATCH_PENDING thread flag

[Andy Lutomirski]

On Thu, Dec 8, 2016 at 10:08 AM, Josh Poimboeuf  wrote:
> 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 

Acked-by: Andy Lutomirski 

[PATCH v3 04/15] livepatch/x86: add TIF_PATCH_PENDING thread flag

[Josh Poimboeuf]

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 
---
 arch/x86/entry/common.c| 9 ++---
 arch/x86/include/asm/thread_info.h | 4 +++-
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index bdd9cc5..16a51a5 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -21,6 +21,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include 
 #include 
@@ -129,14 +130,13 @@ 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.
@@ -163,6 +163,9 @@ 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 1fe6043..79f4d6a 100644
--- 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_SECCOMP8   /* 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_SINGLESTEP | _TIF_NEED_RESCHED | _TIF_SYSCALL_EMU |   \
 _TIF_SYSCALL_AUDIT | _TIF_USER_RETURN_NOTIFY | _TIF_UPROBE |   \
-_TIF_SYSCALL_TRACEPOINT | _TIF_NOHZ)
+_TIF_SYSCALL_TRACEPOINT | _TIF_NOHZ | _TIF_PATCH_PENDING)
 
 /* flags to check in __switch_to() */
 #define _TIF_WORK_CTXSW
\
-- 
2.7.4