From: Mark Rutland <mark.rutland@arm.com>
To: linux-kernel@vger.kernel.org
Cc: 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, paulmck@kernel.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: [PATCH v2 6/9] arm64: read thread flags
Date: Mon, 21 Jun 2021 10:05:58 +0100 [thread overview]
Message-ID: <20210621090602.16883-7-mark.rutland@arm.com> (raw)
In-Reply-To: <20210621090602.16883-1-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>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
---
arch/arm64/kernel/ptrace.c | 4 ++--
arch/arm64/kernel/signal.c | 2 +-
arch/arm64/kernel/syscall.c | 4 ++--
3 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index eb2f73939b7b..a6103b997664 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -1834,7 +1834,7 @@ static void tracehook_report_syscall(struct pt_regs *regs,
int syscall_trace_enter(struct pt_regs *regs)
{
- unsigned long flags = READ_ONCE(current_thread_info()->flags);
+ unsigned long flags = read_thread_flags();
if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) {
tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
@@ -1857,7 +1857,7 @@ int syscall_trace_enter(struct pt_regs *regs)
void syscall_trace_exit(struct pt_regs *regs)
{
- unsigned long flags = READ_ONCE(current_thread_info()->flags);
+ unsigned long flags = read_thread_flags();
audit_syscall_exit(regs);
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 6237486ff6bb..97acad72ec01 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -945,7 +945,7 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
}
local_daif_mask();
- thread_flags = READ_ONCE(current_thread_info()->flags);
+ thread_flags = read_thread_flags();
} while (thread_flags & _TIF_WORK_MASK);
}
diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
index 263d6c1a525f..badf1789dc3d 100644
--- a/arch/arm64/kernel/syscall.c
+++ b/arch/arm64/kernel/syscall.c
@@ -84,7 +84,7 @@ void syscall_trace_exit(struct pt_regs *regs);
static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
const syscall_fn_t syscall_table[])
{
- unsigned long flags = current_thread_info()->flags;
+ unsigned long flags = read_thread_flags();
regs->orig_x0 = regs->regs[0];
regs->syscallno = scno;
@@ -151,7 +151,7 @@ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
*/
if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
local_daif_mask();
- flags = current_thread_info()->flags;
+ flags = read_thread_flags();
if (!has_syscall_work(flags) && !(flags & _TIF_SINGLESTEP))
return;
local_daif_restore(DAIF_PROCCTX);
--
2.11.0
next prev parent reply other threads:[~2021-06-21 9:06 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-21 9:05 [PATCH v2 0/9] thread_info: use helpers to snapshot thread flags Mark Rutland
2021-06-21 9:05 ` [PATCH v2 1/9] thread_info: add " Mark Rutland
2021-06-21 9:05 ` [PATCH v2 2/9] entry: " Mark Rutland
2021-06-21 9:05 ` [PATCH v2 3/9] sched: " Mark Rutland
2021-06-21 9:05 ` [PATCH v2 4/9] alpha: " Mark Rutland
2021-06-21 9:05 ` [PATCH v2 5/9] arm: " Mark Rutland
2021-06-21 9:05 ` Mark Rutland [this message]
2021-06-21 9:05 ` [PATCH v2 6/9] arm64: " Mark Rutland
2021-06-21 9:06 ` [PATCH v2 7/9] microblaze: " Mark Rutland
2021-06-21 9:06 ` [PATCH v2 8/9] openrisc: " Mark Rutland
2021-06-21 9:06 ` [PATCH v2 9/9] x86: " Mark Rutland
2021-06-21 17:54 ` [PATCH v2 0/9] thread_info: use helpers to " Will Deacon
2021-06-22 14:45 ` Mark Rutland
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