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, elver@google.com,
ink@jurassic.park.msu.ru, jonas@southpole.se,
juri.lelli@redhat.com, linux@armlinux.org.uk, luto@kernel.org,
mark.rutland@arm.com, mattst88@gmail.com, mingo@redhat.com,
monstr@monstr.eu, mpe@ellerman.id.au, 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: [RFC PATCH 10/10] x86: snapshot thread flags
Date: Wed, 9 Jun 2021 13:20:01 +0100 [thread overview]
Message-ID: <20210609122001.18277-11-mark.rutland@arm.com> (raw)
In-Reply-To: <20210609122001.18277-1-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, we should snapshot the flags prior to using them.
Let's use the new helpers to do so on x86.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/kernel/process.c | 8 ++++----
arch/x86/kernel/process.h | 6 +++---
arch/x86/mm/tlb.c | 2 +-
3 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 5e1f38179f49..d1c4a93c6e26 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -332,7 +332,7 @@ 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());
}
}
@@ -584,7 +584,7 @@ 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)
@@ -620,8 +620,8 @@ 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..0b1be8685b49 100644
--- a/arch/x86/kernel/process.h
+++ b/arch/x86/kernel/process.h
@@ -13,9 +13,9 @@ 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)) {
/*
* Avoid __switch_to_xtra() invocation when conditional
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 78804680e923..fcc5e22050d4 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;
--
2.11.0
next prev parent reply other threads:[~2021-06-09 12:20 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-09 12:19 [RFC PATCH 00/10] thread_info: use helpers to snapshot thread flags Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 01/10] thread_info: add " Mark Rutland
2021-06-10 9:01 ` Marco Elver
2021-06-11 9:17 ` Mark Rutland
2021-06-19 22:28 ` Thomas Gleixner
2021-06-21 8:29 ` Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 02/10] entry: " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 03/10] sched: " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 04/10] alpha: " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 05/10] arm: " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 06/10] arm64: read " Mark Rutland
2021-06-16 22:07 ` kernel test robot
2021-06-09 12:19 ` [RFC PATCH 07/10] microblaze: snapshot " Mark Rutland
2021-06-09 12:19 ` [RFC PATCH 08/10] openrisc: " Mark Rutland
2021-06-10 19:14 ` Stafford Horne
2021-06-09 12:20 ` [RFC PATCH 09/10] powerpc: " Mark Rutland
2021-06-15 13:18 ` Michael Ellerman
2021-06-21 8:46 ` Mark Rutland
2021-06-09 12:20 ` Mark Rutland [this message]
2021-06-19 22:30 ` [RFC PATCH 10/10] x86: " Thomas Gleixner
2021-06-21 8:35 ` Mark Rutland
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210609122001.18277-11-mark.rutland@arm.com \
--to=mark.rutland@arm.com \
--cc=benh@kernel.crashing.org \
--cc=boqun.feng@gmail.com \
--cc=bp@alien8.de \
--cc=catalin.marinas@arm.com \
--cc=dvyukov@google.com \
--cc=elver@google.com \
--cc=ink@jurassic.park.msu.ru \
--cc=jonas@southpole.se \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux@armlinux.org.uk \
--cc=luto@kernel.org \
--cc=mattst88@gmail.com \
--cc=mingo@redhat.com \
--cc=monstr@monstr.eu \
--cc=mpe@ellerman.id.au \
--cc=paulmck@kernel.org \
--cc=paulus@samba.org \
--cc=peterz@infradead.org \
--cc=rth@twiddle.net \
--cc=shorne@gmail.com \
--cc=stefan.kristiansson@saunalahti.fi \
--cc=tglx@linutronix.de \
--cc=vincent.guittot@linaro.org \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.