linux-kernel - Re: [PATCH AUTOSEL 5.17 21/21] Revert "parisc: Fix patch code locking and flushing"

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Date:   Tue, 10 May 2022 17:49:31 +0200
From:   Helge Deller <deller@....de>
To:     Sasha Levin <sashal@...nel.org>, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Cc:     James.Bottomley@...senPartnership.com, dave.anglin@...l.net,
        linux-parisc@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 5.17 21/21] Revert "parisc: Fix patch code locking
 and flushing"

Hello Sascha,

please drop this patch from all your stable-series queues....
It shouldn't be backported.

Thanks,
Helge

On 5/10/22 17:43, Sasha Levin wrote:
> From: Helge Deller <deller@....de>
>
> [ Upstream commit 6c800d7f55fcd78e17deae5ae4374d8e73482c13 ]
>
> This reverts commit a9fe7fa7d874a536e0540469f314772c054a0323.
>
> Leads to segfaults on 32bit kernel.
>
> Signed-off-by: Helge Deller <deller@....de>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  arch/parisc/kernel/patch.c | 25 ++++++++++++++-----------
>  1 file changed, 14 insertions(+), 11 deletions(-)
>
> diff --git a/arch/parisc/kernel/patch.c b/arch/parisc/kernel/patch.c
> index e59574f65e64..80a0ab372802 100644
> --- a/arch/parisc/kernel/patch.c
> +++ b/arch/parisc/kernel/patch.c
> @@ -40,7 +40,10 @@ static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags,
>
>  	*need_unmap = 1;
>  	set_fixmap(fixmap, page_to_phys(page));
> -	raw_spin_lock_irqsave(&patch_lock, *flags);
> +	if (flags)
> +		raw_spin_lock_irqsave(&patch_lock, *flags);
> +	else
> +		__acquire(&patch_lock);
>
>  	return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
>  }
> @@ -49,7 +52,10 @@ static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
>  {
>  	clear_fixmap(fixmap);
>
> -	raw_spin_unlock_irqrestore(&patch_lock, *flags);
> +	if (flags)
> +		raw_spin_unlock_irqrestore(&patch_lock, *flags);
> +	else
> +		__release(&patch_lock);
>  }
>
>  void __kprobes __patch_text_multiple(void *addr, u32 *insn, unsigned int len)
> @@ -61,9 +67,8 @@ void __kprobes __patch_text_multiple(void *addr, u32 *insn, unsigned int len)
>  	int mapped;
>
>  	/* Make sure we don't have any aliases in cache */
> -	flush_kernel_dcache_range_asm(start, end);
> -	flush_kernel_icache_range_asm(start, end);
> -	flush_tlb_kernel_range(start, end);
> +	flush_kernel_vmap_range(addr, len);
> +	flush_icache_range(start, end);
>
>  	p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &flags, &mapped);
>
> @@ -76,10 +81,8 @@ void __kprobes __patch_text_multiple(void *addr, u32 *insn, unsigned int len)
>  			 * We're crossing a page boundary, so
>  			 * need to remap
>  			 */
> -			flush_kernel_dcache_range_asm((unsigned long)fixmap,
> -						      (unsigned long)p);
> -			flush_tlb_kernel_range((unsigned long)fixmap,
> -					       (unsigned long)p);
> +			flush_kernel_vmap_range((void *)fixmap,
> +						(p-fixmap) * sizeof(*p));
>  			if (mapped)
>  				patch_unmap(FIX_TEXT_POKE0, &flags);
>  			p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &flags,
> @@ -87,10 +90,10 @@ void __kprobes __patch_text_multiple(void *addr, u32 *insn, unsigned int len)
>  		}
>  	}
>
> -	flush_kernel_dcache_range_asm((unsigned long)fixmap, (unsigned long)p);
> -	flush_tlb_kernel_range((unsigned long)fixmap, (unsigned long)p);
> +	flush_kernel_vmap_range((void *)fixmap, (p-fixmap) * sizeof(*p));
>  	if (mapped)
>  		patch_unmap(FIX_TEXT_POKE0, &flags);
> +	flush_icache_range(start, end);
>  }
>
>  void __kprobes __patch_text(void *addr, u32 insn)