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| author | Mark Rutland <mark.rutland@arm.com> | 2021-11-29 13:06:53 +0000 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2021-12-01 00:06:43 +0100 |
| commit | dca99fb643a2e9bc2e67a0f626b09d4f177f0f09 (patch) | |
| tree | 55747d41170b37c93cd762186cc7210e19c82ce8 | |
| parent | 7ad639840acf2800b5f387c495795f995a67a329 (diff) | |
| download | linux-dca99fb643a2e9bc2e67a0f626b09d4f177f0f09.tar.gz linux-dca99fb643a2e9bc2e67a0f626b09d4f177f0f09.tar.bz2 linux-dca99fb643a2e9bc2e67a0f626b09d4f177f0f09.zip | |
x86: Snapshot thread flags
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
| -rw-r--r-- | arch/x86/kernel/process.c | 8 | ||||
| -rw-r--r-- | arch/x86/kernel/process.h | 4 | ||||
| -rw-r--r-- | 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 04143a653a8a..5d481038fe0b 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -365,7 +365,7 @@ 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()); } } @@ -617,7 +617,7 @@ 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) @@ -653,8 +653,8 @@ 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 59ba2968af1b..92bb03b9ceb5 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -361,7 +361,7 @@ static void l1d_flush_evaluate(unsigned long prev_mm, unsigned long next_mm, static unsigned long mm_mangle_tif_spec_bits(struct task_struct *next) { - unsigned long next_tif = task_thread_info(next)->flags; + unsigned long next_tif = read_task_thread_flags(next); unsigned long spec_bits = (next_tif >> TIF_SPEC_IB) & LAST_USER_MM_SPEC_MASK; /* |