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Commit afb94c9e authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Jiri Kosina
Browse files

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: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Acked-by: default avatarAndy Lutomirski <luto@kernel.org>
Reviewed-by: default avatarPetr Mladek <pmladek@suse.com>
Reviewed-by: default avatarMiroslav Benes <mbenes@suse.cz>
Reviewed-by: default avatarKamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Acked-by: Ingo Molnar <mingo@kernel.org>        # for the x86 changes
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 46c5a011

arch/x86/entry/common.c

+6 −3
Original line number Diff line number Diff line
@@ -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();

arch/x86/include/asm/thread_info.h

+3 −1
Original line number Diff line number Diff line
@@ -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							\