linux-kernel - Re: [PATCH 2/5] riscv: misaligned: enable IRQs while handling misaligned accesses

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Message-ID: <f834a4dd-8c76-4246-9923-600979b1d983@ghiti.fr>
Date: Mon, 21 Apr 2025 09:13:23 +0200
From: Alexandre Ghiti <alex@...ti.fr>
To: Clément Léger <cleger@...osinc.com>,
 "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
 open list <linux-kernel@...r.kernel.org>,
 "open list:RISC-V ARCHITECTURE" <linux-riscv@...ts.infradead.org>,
 "open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@...r.kernel.org>
Cc: Jonathan Corbet <corbet@....net>, Paul Walmsley
 <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>,
 Albert Ou <aou@...s.berkeley.edu>, Shuah Khan <shuah@...nel.org>,
 Andrew Jones <ajones@...tanamicro.com>,
 Samuel Holland <samuel.holland@...ive.com>
Subject: Re: [PATCH 2/5] riscv: misaligned: enable IRQs while handling
 misaligned accesses

On 14/04/2025 14:34, Clément Léger wrote:
> We can safely reenable IRQs if they were enabled in the previous
> context. This allows to access user memory that could potentially
> trigger a page fault.
>
> Fixes: b686ecdeacf6 ("riscv: misaligned: Restrict user access to kernel memory")
> Signed-off-by: Clément Léger <cleger@...osinc.com>
> ---
>   arch/riscv/kernel/traps.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
>
> diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
> index 55d9f3450398..3eecc2addc41 100644
> --- a/arch/riscv/kernel/traps.c
> +++ b/arch/riscv/kernel/traps.c
> @@ -206,6 +206,11 @@ enum misaligned_access_type {
>   static void do_trap_misaligned(struct pt_regs *regs, enum misaligned_access_type type)
>   {
>   	irqentry_state_t state = irqentry_enter(regs);
> +	bool enable_irqs = !regs_irqs_disabled(regs);
> +
> +	/* Enable interrupts if they were enabled in the interrupted context. */
> +	if (enable_irqs)
> +		local_irq_enable();
>   
>   	if (type ==  MISALIGNED_LOAD) {
>   		if (handle_misaligned_load(regs))
> @@ -217,6 +222,9 @@ static void do_trap_misaligned(struct pt_regs *regs, enum misaligned_access_type
>   				      "Oops - store (or AMO) address misaligned");
>   	}
>   
> +	if (enable_irqs)
> +		local_irq_disable();
> +
>   	irqentry_exit(regs, state);
>   }
>   


Reviewed-by: Alexandre Ghiti <alexghiti@...osinc.com>

Thanks,

Alex