linux-kernel - Re: [PATCH 4.4 078/131] PM / Hibernate: Call flush_icache

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Message-ID: <20190401203918.GA26671@amd>
Date:   Mon, 1 Apr 2019 22:39:18 +0200
From:   Pavel Machek <pavel@....cz>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        James Morse <james.morse@....com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.4 078/131] PM / Hibernate: Call flush_icache_range() on
 pages restored in-place

On Mon 2019-04-01 19:02:28, Greg Kroah-Hartman wrote:
> 4.4-stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> [ Upstream commit f6cf0545ec697ddc278b7457b7d0c0d86a2ea88e ]
> 
> Some architectures require code written to memory as if it were data to be
> 'cleaned' from any data caches before the processor can fetch them as new
> instructions.
> 
> During resume from hibernate, the snapshot code copies some pages directly,
> meaning these architectures do not get a chance to perform their cache
> maintenance. Modify the read and decompress code to call
> flush_icache_range() on all pages that are restored, so that the restored
> in-place pages are guaranteed to be executable on these architectures.
> 
> Signed-off-by: James Morse <james.morse@....com>
> Acked-by: Pavel Machek <pavel@....cz>
> Acked-by: Rafael J. Wysocki <rjw@...ysocki.net>
> Acked-by: Catalin Marinas <catalin.marinas@....com>
> [will: make clean_pages_on_* static and remove initialisers]
> Signed-off-by: Will Deacon <will.deacon@....com>
> Signed-off-by: Sasha Levin <sashal@...nel.org>

I don't think this is suitable for stable.

Catalin: Are there platforms that a) need this and b) support
hibernation in 4.4.X?

Thanks
								Pavel

> @@ -36,6 +36,14 @@
>  
>  #define HIBERNATE_SIG	"S1SUSPEND"
>  
> +/*
> + * When reading an {un,}compressed image, we may restore pages in place,
> + * in which case some architectures need these pages cleaning before they
> + * can be executed. We don't know which pages these may be, so clean the lot.
> + */
> +static bool clean_pages_on_read;
> +static bool clean_pages_on_decompress;
> +
>  /*
>   *	The swap map is a data structure used for keeping track of each page
>   *	written to a swap partition.  It consists of many swap_map_page
> @@ -241,6 +249,9 @@ static void hib_end_io(struct bio *bio)
>  
>  	if (bio_data_dir(bio) == WRITE)
>  		put_page(page);
> +	else if (clean_pages_on_read)
> +		flush_icache_range((unsigned long)page_address(page),
> +				   (unsigned long)page_address(page) + PAGE_SIZE);
>  
>  	if (bio->bi_error && !hb->error)
>  		hb->error = bio->bi_error;
> @@ -1049,6 +1060,7 @@ static int load_image(struct swap_map_handle *handle,
>  
>  	hib_init_batch(&hb);
>  
> +	clean_pages_on_read = true;
>  	printk(KERN_INFO "PM: Loading image data pages (%u pages)...\n",
>  		nr_to_read);
>  	m = nr_to_read / 10;
> @@ -1124,6 +1136,10 @@ static int lzo_decompress_threadfn(void *data)
>  		d->unc_len = LZO_UNC_SIZE;
>  		d->ret = lzo1x_decompress_safe(d->cmp + LZO_HEADER, d->cmp_len,
>  		                               d->unc, &d->unc_len);
> +		if (clean_pages_on_decompress)
> +			flush_icache_range((unsigned long)d->unc,
> +					   (unsigned long)d->unc + d->unc_len);
> +
>  		atomic_set(&d->stop, 1);
>  		wake_up(&d->done);
>  	}
> @@ -1189,6 +1205,8 @@ static int load_image_lzo(struct swap_map_handle *handle,
>  	}
>  	memset(crc, 0, offsetof(struct crc_data, go));
>  
> +	clean_pages_on_decompress = true;
> +
>  	/*
>  	 * Start the decompression threads.
>  	 */

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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