From: Mark Rutland mark.rutland@arm.com
mainline inclusion from mainline-v5.17-rc1 commit dca99fb643a2e9bc2e67a0f626b09d4f177f0f09 category: performance bugzilla: https://gitee.com/openeuler/kernel/issues/IA5WFA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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Some thread flags can be set remotely, and so even when IRQs are disabled, the flags can change under our feet. Generally this is unlikely to cause a problem in practice, but it is somewhat unsound, and KCSAN will legitimately warn that there is a data race.
To avoid such issues, a snapshot of the flags has to be taken prior to using them. Some places already use READ_ONCE() for that, others do not.
Convert them all to the new flag accessor helpers.
Signed-off-by: Mark Rutland mark.rutland@arm.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Thomas Gleixner tglx@linutronix.de Acked-by: Paul E. McKenney paulmck@kernel.org Link: https://lore.kernel.org/r/20211129130653.2037928-12-mark.rutland@arm.com
Conflict: arch/x86/mm/tlb.c
Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- arch/x86/kernel/process.c | 8 ++++---- arch/x86/kernel/process.h | 4 ++-- arch/x86/mm/tlb.c | 2 +- 3 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index e0c04a26a176..f9343b826651 100755 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -370,7 +370,7 @@ void arch_setup_new_exec(void) clear_thread_flag(TIF_SSBD); task_clear_spec_ssb_disable(current); task_clear_spec_ssb_noexec(current); - speculation_ctrl_update(task_thread_info(current)->flags); + speculation_ctrl_update(read_thread_flags()); } }
@@ -622,7 +622,7 @@ static unsigned long speculation_ctrl_update_tif(struct task_struct *tsk) clear_tsk_thread_flag(tsk, TIF_SPEC_IB); } /* Return the updated threadinfo flags*/ - return task_thread_info(tsk)->flags; + return read_task_thread_flags(tsk); }
void speculation_ctrl_update(unsigned long tif) @@ -658,8 +658,8 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p) { unsigned long tifp, tifn;
- tifn = READ_ONCE(task_thread_info(next_p)->flags); - tifp = READ_ONCE(task_thread_info(prev_p)->flags); + tifn = read_task_thread_flags(next_p); + tifp = read_task_thread_flags(prev_p);
switch_to_bitmap(tifp);
diff --git a/arch/x86/kernel/process.h b/arch/x86/kernel/process.h index 1d0797b2338a..76b547b83232 100644 --- a/arch/x86/kernel/process.h +++ b/arch/x86/kernel/process.h @@ -13,8 +13,8 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p); static inline void switch_to_extra(struct task_struct *prev, struct task_struct *next) { - unsigned long next_tif = task_thread_info(next)->flags; - unsigned long prev_tif = task_thread_info(prev)->flags; + unsigned long next_tif = read_task_thread_flags(next); + unsigned long prev_tif = read_task_thread_flags(prev);
if (IS_ENABLED(CONFIG_SMP)) { /* diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index f4b162f273f5..86a66efa26dc 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -318,7 +318,7 @@ void switch_mm(struct mm_struct *prev, struct mm_struct *next,
static unsigned long mm_mangle_tif_spec_ib(struct task_struct *next) { - unsigned long next_tif = task_thread_info(next)->flags; + unsigned long next_tif = read_task_thread_flags(next); unsigned long ibpb = (next_tif >> TIF_SPEC_IB) & LAST_USER_MM_IBPB;
return (unsigned long)next->mm | ibpb;