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- Add a set of thread_info.flags accessors which snapshot it before

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accesing it in order to prevent any potential data races, and convert
 all users to those new accessors
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Merge tag 'core_entry_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull thread_info flag accessor helper updates from Borislav Petkov:
 "Add a set of thread_info.flags accessors which snapshot it before
  accesing it in order to prevent any potential data races, and convert
  all users to those new accessors"

* tag 'core_entry_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  powerpc: Snapshot thread flags
  powerpc: Avoid discarding flags in system_call_exception()
  openrisc: Snapshot thread flags
  microblaze: Snapshot thread flags
  arm64: Snapshot thread flags
  ARM: Snapshot thread flags
  alpha: Snapshot thread flags
  sched: Snapshot thread flags
  entry: Snapshot thread flags
  x86: Snapshot thread flags
  thread_info: Add helpers to snapshot thread flags
This commit is contained in:
Linus Torvalds 2022-01-10 11:34:10 -08:00
commit 48a60bdb2b
19 changed files with 46 additions and 34 deletions
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2
include/linux/entry-kvm.h
View file

@ -75,7 +75,7 @@ static inline void xfer_to_guest_mode_prepare(void)
*/
static inline bool __xfer_to_guest_mode_work_pending(void)
{
unsigned long ti_work = READ_ONCE(current_thread_info()->flags);
unsigned long ti_work = read_thread_flags();
return !!(ti_work & XFER_TO_GUEST_MODE_WORK);
}

14
include/linux/thread_info.h
View file

@ -118,6 +118,15 @@ static inline int test_ti_thread_flag(struct thread_info *ti, int flag)
return test_bit(flag, (unsigned long *)&ti->flags);
}
/*
* This may be used in noinstr code, and needs to be __always_inline to prevent
* inadvertent instrumentation.
*/
static __always_inline unsigned long read_ti_thread_flags(struct thread_info *ti)
{
return READ_ONCE(ti->flags);
}
#define set_thread_flag(flag) \
set_ti_thread_flag(current_thread_info(), flag)
#define clear_thread_flag(flag) \
@ -130,6 +139,11 @@ static inline int test_ti_thread_flag(struct thread_info *ti, int flag)
test_and_clear_ti_thread_flag(current_thread_info(), flag)
#define test_thread_flag(flag) \
test_ti_thread_flag(current_thread_info(), flag)
#define read_thread_flags() \
read_ti_thread_flags(current_thread_info())
#define read_task_thread_flags(t) \
read_ti_thread_flags(task_thread_info(t))
#ifdef CONFIG_GENERIC_ENTRY
#define set_syscall_work(fl) \