From: Mark Rutland <mark.rutland@arm.com>
To: linux-kernel@vger.kernel.org
Cc: benh@kernel.crashing.org, boqun.feng@gmail.com, bp@alien8.de,
catalin.marinas@arm.com, dvyukov@google.com, efuller@redhat.com,
elver@google.com, ink@jurassic.park.msu.ru, joey.gouly@arm.com,
jonas@southpole.se, juri.lelli@redhat.com, linux@armlinux.org.uk,
luto@kernel.org, mark.rutland@arm.com, mattst88@gmail.com,
michal.simek@xilinx.com, mingo@redhat.com, mpe@ellerman.id.au,
npiggin@gmail.com, paulmck@kernel.org, paulus@samba.org,
peterz@infradead.org, rth@twiddle.net, shorne@gmail.com,
stefan.kristiansson@saunalahti.fi, tglx@linutronix.de,
vincent.guittot@linaro.org, will@kernel.org
Subject: [PATCHv7 11/11] x86: snapshot thread flags
Date: Wed, 17 Nov 2021 16:30:49 +0000 [thread overview]
Message-ID: <20211117163050.53986-12-mark.rutland@arm.com> (raw)
In-Reply-To: <20211117163050.53986-1-mark.rutland@arm.com>
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>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@redhat.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 e9ee8b526319..180d7a00cb66 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;
/*
--
2.11.0
next prev parent reply other threads:[~2021-11-17 16:32 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-17 16:30 [PATCHv7 00/11] thread_info: use helpers to snapshot thread flags Mark Rutland
2021-11-17 16:30 ` [PATCHv7 01/11] thread_info: add " Mark Rutland
2021-11-26 20:23 ` [tip: core/entry] thread_info: Add " tip-bot2 for Mark Rutland
2021-11-17 16:30 ` [PATCHv7 02/11] entry: " Mark Rutland
2021-11-26 20:22 ` [tip: core/entry] entry: Snapshot " tip-bot2 for Mark Rutland
2021-11-17 16:30 ` [PATCHv7 03/11] sched: snapshot " Mark Rutland
2021-11-26 20:22 ` [tip: core/entry] sched: Snapshot " tip-bot2 for Mark Rutland
2021-11-17 16:30 ` [PATCHv7 04/11] alpha: snapshot " Mark Rutland
2021-11-26 20:22 ` [tip: core/entry] alpha: Snapshot " tip-bot2 for Mark Rutland
2021-11-17 16:30 ` [PATCHv7 05/11] arm: snapshot " Mark Rutland
2021-11-26 20:22 ` [tip: core/entry] ARM: Snapshot " tip-bot2 for Mark Rutland
2021-11-17 16:30 ` [PATCHv7 06/11] arm64: snapshot " Mark Rutland
2021-11-26 20:22 ` [tip: core/entry] " tip-bot2 for Mark Rutland
2021-11-17 16:30 ` [PATCHv7 07/11] microblaze: " Mark Rutland
2021-11-26 20:22 ` [tip: core/entry] microblaze: Snapshot " tip-bot2 for Mark Rutland
2021-11-17 16:30 ` [PATCHv7 08/11] openrisc: snapshot " Mark Rutland
2021-11-26 20:22 ` [tip: core/entry] openrisc: Snapshot " tip-bot2 for Mark Rutland
2021-11-17 16:30 ` [PATCHv7 09/11] powerpc: avoid discarding flags in system_call_exception() Mark Rutland
2021-11-26 20:22 ` [tip: core/entry] powerpc: Avoid " tip-bot2 for Mark Rutland
2021-11-17 16:30 ` [PATCHv7 10/11] powerpc: snapshot thread flags Mark Rutland
2021-11-26 20:22 ` [tip: core/entry] powerpc: Snapshot " tip-bot2 for Mark Rutland
2021-11-17 16:30 ` Mark Rutland [this message]
2021-11-26 20:22 ` [tip: core/entry] x86: " tip-bot2 for Mark Rutland
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