From: "Nicholas Piggin" <npiggin@gmail•com>
To: "Rohan McLure" <rmclure@linux•ibm.com>, <linuxppc-dev@lists•ozlabs.org>
Cc: arnd@arndb•de
Subject: Re: [PATCH 05/12] powerpc: Mark [h]ssr_valid accesses in check_return_regs_valid
Date: Tue, 09 May 2023 12:17:10 +1000 [thread overview]
Message-ID: <CSHDWLEP2SLB.1Y2YHOLFT2H41@wheely> (raw)
In-Reply-To: <20230508020120.218494-6-rmclure@linux.ibm.com>
On Mon May 8, 2023 at 12:01 PM AEST, Rohan McLure wrote:
> Checks to see if the [H]SRR registers have been clobbered by (soft)
> NMI interrupts imply the possibility for a data race on the
> [h]srr_valid entries in the PACA. Annotate accesses to these fields with
> READ_ONCE, removing the need for the barrier.
>
> The diagnostic can use plain-access reads and writes, but annotate with
> data_race.
Reviewed-by: Nicholas Piggin <npiggin@gmail•com>
>
> Signed-off-by: Rohan McLure <rmclure@linux•ibm.com>
> Reported-by: Michael Ellerman <mpe@ellerman•id.au>
> ---
> arch/powerpc/include/asm/ptrace.h | 4 ++--
> arch/powerpc/kernel/interrupt.c | 14 ++++++--------
> 2 files changed, 8 insertions(+), 10 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h
> index 0eb90a013346..9db8b16567e2 100644
> --- a/arch/powerpc/include/asm/ptrace.h
> +++ b/arch/powerpc/include/asm/ptrace.h
> @@ -180,8 +180,8 @@ void do_syscall_trace_leave(struct pt_regs *regs);
> static inline void set_return_regs_changed(void)
> {
> #ifdef CONFIG_PPC_BOOK3S_64
> - local_paca->hsrr_valid = 0;
> - local_paca->srr_valid = 0;
> + WRITE_ONCE(local_paca->hsrr_valid, 0);
> + WRITE_ONCE(local_paca->srr_valid, 0);
> #endif
> }
>
> diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
> index e34c72285b4e..1f033f11b871 100644
> --- a/arch/powerpc/kernel/interrupt.c
> +++ b/arch/powerpc/kernel/interrupt.c
> @@ -125,7 +125,7 @@ static notrace void check_return_regs_valid(struct pt_regs *regs)
> case 0x1600:
> case 0x1800:
> validp = &local_paca->hsrr_valid;
> - if (!*validp)
> + if (!READ_ONCE(*validp))
> return;
>
> srr0 = mfspr(SPRN_HSRR0);
> @@ -135,7 +135,7 @@ static notrace void check_return_regs_valid(struct pt_regs *regs)
> break;
> default:
> validp = &local_paca->srr_valid;
> - if (!*validp)
> + if (!READ_ONCE(*validp))
> return;
>
> srr0 = mfspr(SPRN_SRR0);
> @@ -161,19 +161,17 @@ static notrace void check_return_regs_valid(struct pt_regs *regs)
> * such things will get caught most of the time, statistically
> * enough to be able to get a warning out.
> */
> - barrier();
> -
> - if (!*validp)
> + if (!READ_ONCE(*validp))
> return;
>
> - if (!warned) {
> - warned = true;
> + if (!data_race(warned)) {
> + data_race(warned = true);
> printk("%sSRR0 was: %lx should be: %lx\n", h, srr0, regs->nip);
> printk("%sSRR1 was: %lx should be: %lx\n", h, srr1, regs->msr);
> show_regs(regs);
> }
>
> - *validp = 0; /* fixup */
> + WRITE_ONCE(*validp, 0); /* fixup */
> #endif
> }
>
> --
> 2.37.2
next prev parent reply other threads:[~2023-05-09 2:18 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-08 2:01 [PATCH 00/12] powerpc: KCSAN fix warnings and mark accesses Rohan McLure
2023-05-08 2:01 ` [PATCH 01/12] powerpc: qspinlock: Fix qnode->locked value interpretation Rohan McLure
2023-05-09 2:01 ` Nicholas Piggin
2023-05-09 4:26 ` Rohan McLure
2023-05-08 2:01 ` [PATCH 02/12] powerpc: qspinlock: Mark accesses to qnode lock checks Rohan McLure
2023-05-09 2:02 ` Nicholas Piggin
2023-05-08 2:01 ` [PATCH 03/12] powerpc: qspinlock: Enforce qnode writes prior to publishing to queue Rohan McLure
2023-05-09 2:04 ` Nicholas Piggin
2023-05-09 5:26 ` Rohan McLure
2023-05-09 6:45 ` Nicholas Piggin
2023-05-08 2:01 ` [PATCH 04/12] asm-generic/mmiowb: Mark accesses to fix KCSAN warnings Rohan McLure
2023-05-08 6:30 ` Arnd Bergmann
2023-05-08 15:44 ` [PATCH 4/12] " Gautam Menghani
2023-05-09 2:16 ` [PATCH 04/12] " Nicholas Piggin
2023-05-08 2:01 ` [PATCH 05/12] powerpc: Mark [h]ssr_valid accesses in check_return_regs_valid Rohan McLure
2023-05-09 2:17 ` Nicholas Piggin [this message]
2023-05-08 2:01 ` [PATCH 06/12] powerpc: Mark accesses to power_save callback in arch_cpu_idle Rohan McLure
2023-05-09 2:21 ` Nicholas Piggin
2023-05-08 2:01 ` [PATCH 07/12] powerpc: powernv: Fix KCSAN datarace warnings on idle_state contention Rohan McLure
2023-05-09 2:26 ` Nicholas Piggin
2023-05-10 2:00 ` Rohan McLure
2023-05-08 2:01 ` [PATCH 08/12] powerpc: Annotate accesses to ipi message flags Rohan McLure
2023-05-09 2:28 ` Nicholas Piggin
2023-05-08 2:01 ` [PATCH 09/12] powerpc: Mark writes registering ipi to host cpu through kvm Rohan McLure
2023-05-09 2:30 ` Nicholas Piggin
2023-05-08 2:01 ` [PATCH 10/12] powerpc: powernv: Annotate data races in opal events Rohan McLure
2023-05-09 2:31 ` Nicholas Piggin
2023-05-08 2:01 ` [PATCH 11/12] powerpc: powernv: Annotate asynchronous access to opal tokens Rohan McLure
2023-05-08 2:01 ` [PATCH 12/12] powerpc: Mark asynchronous accesses to irq_data Rohan McLure
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