From: Jan Kiszka <jan.kiszka@web.de>
To: Alex Ghiti <alex@ghiti.fr>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
linux-riscv@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/3] riscv: Fix crash when flushing executable ioremap regions
Date: Sun, 16 Feb 2020 17:05:55 +0100 [thread overview]
Message-ID: <b63e5945-0e31-940f-5ff7-6754ef5c034f@web.de> (raw)
In-Reply-To: <e721c440-2baf-d962-62ef-41a4f3b1333b@ghiti.fr>
On 16.02.20 15:41, Alex Ghiti wrote:
> Hi Jan,
>
> On 2/15/20 6:49 AM, Jan Kiszka wrote:
>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>
>> Those are not backed by page structs, and pte_page is returning an
>> invalid pointer.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> =2D--
>> arch/riscv/mm/cacheflush.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c
>> index 8930ab7278e6..9ee2c1a387cc 100644
>> =2D-- a/arch/riscv/mm/cacheflush.c
>> +++ b/arch/riscv/mm/cacheflush.c
>> @@ -84,7 +84,8 @@ void flush_icache_pte(pte_t pte)
>> {
>> struct page *page =3D pte_page(pte);
>>
>> - if (!test_and_set_bit(PG_dcache_clean, &page->flags))
>> + if (!pfn_valid(pte_pfn(pte)) ||
>> + !test_and_set_bit(PG_dcache_clean, &page->flags))
>> flush_icache_all();
>> }
>> #endif /* CONFIG_MMU */
>> =2D-
>> 2.16.4
>>
>>
>
> When did you encounter such a situation ? i.e. executable code that is
> not backed by struct page ?
>
> Riscv uses the generic implementation of ioremap and the way
> _PAGE_IOREMAP is defined does not allow to map executable memory region
> using ioremap, so I'm interested to understand how we end up in
> flush_icache_pte for an executable region not backed by any struct page.
You can create executable mappings of memory that Linux does not
initially consider as RAM via ioremap_prot or ioremap_page_range. We are
using that in Jailhouse to load the hypervisor code into reserved memory
that is ioremapped for the purpose. Works fine on x86, arm and arm64.
Jan
next prev parent reply other threads:[~2020-02-16 16:06 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-15 11:49 [PATCH v2 0/3] riscv: mem= support, ioremap exec fix Jan Kiszka
2020-02-15 11:49 ` [PATCH v2 1/3] riscv: Add support for mem= Jan Kiszka
2020-02-15 13:40 ` Anup Patel
2020-02-15 13:44 ` Nikolay Borisov
2020-02-15 14:23 ` Jan Kiszka
2020-02-15 11:49 ` [PATCH v2 2/3] riscv: End kernel region search in setup_bootmem earlier Jan Kiszka
2020-02-16 14:42 ` Alex Ghiti
2020-02-16 16:06 ` Jan Kiszka
2020-02-16 19:57 ` Alex Ghiti
2020-02-15 11:49 ` [PATCH v2 3/3] riscv: Fix crash when flushing executable ioremap regions Jan Kiszka
2020-02-16 14:41 ` Alex Ghiti
2020-02-16 16:05 ` Jan Kiszka [this message]
2020-02-16 19:56 ` Alex Ghiti
2020-02-20 5:49 ` Alex Ghiti
2020-02-20 6:38 ` Jan Kiszka
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