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authorMark Rutland <mark.rutland@arm.com>2021-11-29 13:06:53 +0000
committerThomas Gleixner <tglx@linutronix.de>2021-12-01 00:06:43 +0100
commitdca99fb643a2e9bc2e67a0f626b09d4f177f0f09 (patch)
tree55747d41170b37c93cd762186cc7210e19c82ce8
parent7ad639840acf2800b5f387c495795f995a67a329 (diff)
downloadlinux-dca99fb643a2e9bc2e67a0f626b09d4f177f0f09.tar.bz2
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.c8
-rw-r--r--arch/x86/kernel/process.h4
-rw-r--r--arch/x86/mm/tlb.c2
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;
/*