From: Mark Rutland <mark.rutland@arm.com>
To: Laura Abbott <labbott@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Will Deacon <will.deacon@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCHv3 6/6] arm64: Add support for CONFIG_DEBUG_VIRTUAL
Date: Fri, 18 Nov 2016 19:05:31 +0000 [thread overview]
Message-ID: <20161118190531.GJ1197@leverpostej> (raw)
In-Reply-To: <16e4b3da-c552-252d-108a-0681b71b12ef@redhat.com>
On Fri, Nov 18, 2016 at 10:42:56AM -0800, Laura Abbott wrote:
> On 11/18/2016 09:53 AM, Mark Rutland wrote:
> > On Thu, Nov 17, 2016 at 05:16:56PM -0800, Laura Abbott wrote:
> >> +#define __virt_to_phys_nodebug(x) ({ \
> >> phys_addr_t __x = (phys_addr_t)(x); \
> >> - __x & BIT(VA_BITS - 1) ? (__x & ~PAGE_OFFSET) + PHYS_OFFSET : \
> >> - (__x - kimage_voffset); })
> >> + ((__x & ~PAGE_OFFSET) + PHYS_OFFSET); \
> >> +})
> >
> > Given the KASAN failure, and the strong possibility that there's even
> > more stuff lurking in common code, I think we should retain the logic to
> > handle kernel image addresses for the timebeing (as x86 does). Once
> > we've merged DEBUG_VIRTUAL, it will be easier to track those down.
>
> Agreed. I might see about adding another option DEBUG_STRICT_VIRTUAL
> for catching bad __pa vs __pa_symbol usage and keep DEBUG_VIRTUAL for
> catching addresses that will work in neither case.
I think it makes sense for DEBUG_VIRTUAL to do both, so long as the
default behaviour (and fallback after a WARN for virt_to_phys()) matches
what we currently do. We'll get useful diagnostics, but a graceful
fallback.
I think the helpers I suggested below do that? Or have I misunderstood,
and you mean something stricter (e.g. checking whether a lm address is
is backed by something)?
> > phys_addr_t __virt_to_phys(unsigned long x)
> > {
> > WARN(!__is_lm_address(x),
> > "virt_to_phys() used for non-linear address: %pK\n",
> > (void*)x);
> >
> > return __virt_to_phys_nodebug(x);
> > }
> > EXPORT_SYMBOL(__virt_to_phys);
> > phys_addr_t __phys_addr_symbol(unsigned long x)
> > {
> > /*
> > * This is bounds checking against the kernel image only.
> > * __pa_symbol should only be used on kernel symbol addresses.
> > */
> > VIRTUAL_BUG_ON(x < (unsigned long) KERNEL_START ||
> > x > (unsigned long) KERNEL_END);
> >
> > return __pa_symbol_nodebug(x);
> > }
> > EXPORT_SYMBOL(__phys_addr_symbol);
Thanks,
Mark.
next prev parent reply other threads:[~2016-11-18 19:06 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-18 1:16 [PATCHv3 0/6] CONFIG_DEBUG_VIRTUAL for arm64 Laura Abbott
2016-11-18 1:16 ` [PATCHv3 1/6] lib/Kconfig.debug: Add ARCH_HAS_DEBUG_VIRTUAL Laura Abbott
2016-11-18 8:25 ` Ingo Molnar
2016-11-18 1:16 ` [PATCHv3 2/6] mm/cma: Cleanup highmem check Laura Abbott
2016-11-18 1:16 ` [PATCHv3 3/6] arm64: Move some macros under #ifndef __ASSEMBLY__ Laura Abbott
2016-11-18 1:16 ` [PATCHv3 4/6] arm64: Add cast for virt_to_pfn Laura Abbott
2016-11-18 1:16 ` [PATCHv3 5/6] arm64: Use __pa_symbol for kernel symbols Laura Abbott
2016-11-18 14:35 ` Mark Rutland
2016-11-18 16:46 ` Mark Rutland
2016-11-21 17:40 ` Laura Abbott
2016-11-23 9:48 ` Mark Rutland
2016-11-18 1:16 ` [PATCHv3 6/6] arm64: Add support for CONFIG_DEBUG_VIRTUAL Laura Abbott
2016-11-18 17:53 ` Mark Rutland
2016-11-18 18:42 ` Laura Abbott
2016-11-18 19:05 ` Mark Rutland [this message]
2016-11-18 19:17 ` Laura Abbott
2016-11-18 18:25 ` Mark Rutland
2016-11-18 17:57 ` [PATCHv3 0/6] CONFIG_DEBUG_VIRTUAL for arm64 Mark Rutland
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