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 10/11] powerpc: snapshot thread flags
Date: Wed, 17 Nov 2021 16:30:48 +0000 [thread overview]
Message-ID: <20211117163050.53986-11-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>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
---
arch/powerpc/kernel/interrupt.c | 13 ++++++-------
arch/powerpc/kernel/ptrace/ptrace.c | 3 +--
2 files changed, 7 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
index 1c821b76c2d1..ff25888ffc25 100644
--- a/arch/powerpc/kernel/interrupt.c
+++ b/arch/powerpc/kernel/interrupt.c
@@ -181,7 +181,7 @@ notrace long system_call_exception(long r3, long r4, long r5,
local_irq_enable();
- if (unlikely(current_thread_info()->flags & _TIF_SYSCALL_DOTRACE)) {
+ if (unlikely(read_thread_flags() & _TIF_SYSCALL_DOTRACE)) {
if (unlikely(trap_is_unsupported_scv(regs))) {
/* Unsupported scv vector */
_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
@@ -343,7 +343,7 @@ interrupt_exit_user_prepare_main(unsigned long ret, struct pt_regs *regs)
unsigned long ti_flags;
again:
- ti_flags = READ_ONCE(current_thread_info()->flags);
+ ti_flags = read_thread_flags();
while (unlikely(ti_flags & (_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM))) {
local_irq_enable();
if (ti_flags & _TIF_NEED_RESCHED) {
@@ -359,7 +359,7 @@ interrupt_exit_user_prepare_main(unsigned long ret, struct pt_regs *regs)
do_notify_resume(regs, ti_flags);
}
local_irq_disable();
- ti_flags = READ_ONCE(current_thread_info()->flags);
+ ti_flags = read_thread_flags();
}
if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && IS_ENABLED(CONFIG_PPC_FPU)) {
@@ -437,7 +437,7 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
/* Check whether the syscall is issued inside a restartable sequence */
rseq_syscall(regs);
- ti_flags = current_thread_info()->flags;
+ ti_flags = read_thread_flags();
if (unlikely(r3 >= (unsigned long)-MAX_ERRNO) && is_not_scv) {
if (likely(!(ti_flags & (_TIF_NOERROR | _TIF_RESTOREALL)))) {
@@ -532,8 +532,7 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs)
unsigned long flags;
unsigned long ret = 0;
unsigned long kuap;
- bool stack_store = current_thread_info()->flags &
- _TIF_EMULATE_STACK_STORE;
+ bool stack_store = read_thread_flags() & _TIF_EMULATE_STACK_STORE;
if (regs_is_unrecoverable(regs))
unrecoverable_exception(regs);
@@ -554,7 +553,7 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs)
again:
if (IS_ENABLED(CONFIG_PREEMPT)) {
/* Return to preemptible kernel context */
- if (unlikely(current_thread_info()->flags & _TIF_NEED_RESCHED)) {
+ if (unlikely(read_thread_flags() & _TIF_NEED_RESCHED)) {
if (preempt_count() == 0)
preempt_schedule_irq();
}
diff --git a/arch/powerpc/kernel/ptrace/ptrace.c b/arch/powerpc/kernel/ptrace/ptrace.c
index 7c7093c17c45..c43f77e2ac31 100644
--- a/arch/powerpc/kernel/ptrace/ptrace.c
+++ b/arch/powerpc/kernel/ptrace/ptrace.c
@@ -260,8 +260,7 @@ long do_syscall_trace_enter(struct pt_regs *regs)
{
u32 flags;
- flags = READ_ONCE(current_thread_info()->flags) &
- (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE);
+ flags = read_thread_flags() & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE);
if (flags) {
int rc = tracehook_report_syscall_entry(regs);
--
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 ` Mark Rutland [this message]
2021-11-26 20:22 ` [tip: core/entry] powerpc: Snapshot thread flags tip-bot2 for Mark Rutland
2021-11-17 16:30 ` [PATCHv7 11/11] x86: snapshot " Mark Rutland
2021-11-26 20:22 ` [tip: core/entry] x86: Snapshot " tip-bot2 for Mark Rutland
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