From: Wang Nan <wangnan0@huawei.com>
To: Vaibhav Bedia <vaibhav.bedia@gmail.com>
Cc: kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org, linux-mm@kvack.org,
Eric Biederman <ebiederm@xmission.com>,
Geng Hui <hui.geng@huawei.com>,
Russell King <rmk+kernel@arm.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Linux ARM Kernel List <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 2/3] ARM: kexec: copying code to ioremapped area
Date: Wed, 22 Jan 2014 21:03:54 +0800 [thread overview]
Message-ID: <52DFC1BA.8030001@huawei.com> (raw)
In-Reply-To: <CANacCWz2DdLvns9htszpwWnASrYGXQt+tHMsw4aBbjoyw-DmeQ@mail.gmail.com>
On 2014/1/22 20:56, Vaibhav Bedia wrote:
> On Wed, Jan 22, 2014 at 6:25 AM, Wang Nan <wangnan0@huawei.com <mailto:wangnan0@huawei.com>> wrote:
>
> ARM's kdump is actually corrupted (at least for omap4460), mainly because of
> cache problem: flush_icache_range can't reliably ensure the copied data
> correctly goes into RAM. After mmu turned off and jump to the trampoline, kexec
> always failed due to random undef instructions.
>
> This patch use ioremap to make sure the destnation of all memcpy() is
> uncachable memory, including copying of target kernel and trampoline.
>
>
> AFAIK ioremap on RAM in forbidden in ARM and device memory that ioremap()
> ends up creating is not meant for executable code.
>
> Doesn't this trigger the WARN_ON() in _arm_ioremap_pfn_caller)?
This patch is depend on the previous one:
ARM: Premit ioremap() to map reserved pages
However, Russell is opposed to it.
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WARNING: multiple messages have this Message-ID (diff)
From: wangnan0@huawei.com (Wang Nan)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/3] ARM: kexec: copying code to ioremapped area
Date: Wed, 22 Jan 2014 21:03:54 +0800 [thread overview]
Message-ID: <52DFC1BA.8030001@huawei.com> (raw)
In-Reply-To: <CANacCWz2DdLvns9htszpwWnASrYGXQt+tHMsw4aBbjoyw-DmeQ@mail.gmail.com>
On 2014/1/22 20:56, Vaibhav Bedia wrote:
> On Wed, Jan 22, 2014 at 6:25 AM, Wang Nan <wangnan0 at huawei.com <mailto:wangnan0@huawei.com>> wrote:
>
> ARM's kdump is actually corrupted (at least for omap4460), mainly because of
> cache problem: flush_icache_range can't reliably ensure the copied data
> correctly goes into RAM. After mmu turned off and jump to the trampoline, kexec
> always failed due to random undef instructions.
>
> This patch use ioremap to make sure the destnation of all memcpy() is
> uncachable memory, including copying of target kernel and trampoline.
>
>
> AFAIK ioremap on RAM in forbidden in ARM and device memory that ioremap()
> ends up creating is not meant for executable code.
>
> Doesn't this trigger the WARN_ON() in _arm_ioremap_pfn_caller)?
This patch is depend on the previous one:
ARM: Premit ioremap() to map reserved pages
However, Russell is opposed to it.
WARNING: multiple messages have this Message-ID (diff)
From: Wang Nan <wangnan0@huawei.com>
To: Vaibhav Bedia <vaibhav.bedia@gmail.com>
Cc: kexec@lists.infradead.org, stable@vger.kernel.org,
linux-kernel@vger.kernel.org, Geng Hui <hui.geng@huawei.com>,
linux-mm@kvack.org, Eric Biederman <ebiederm@xmission.com>,
Russell King <rmk+kernel@arm.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Linux ARM Kernel List <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 2/3] ARM: kexec: copying code to ioremapped area
Date: Wed, 22 Jan 2014 21:03:54 +0800 [thread overview]
Message-ID: <52DFC1BA.8030001@huawei.com> (raw)
In-Reply-To: <CANacCWz2DdLvns9htszpwWnASrYGXQt+tHMsw4aBbjoyw-DmeQ@mail.gmail.com>
On 2014/1/22 20:56, Vaibhav Bedia wrote:
> On Wed, Jan 22, 2014 at 6:25 AM, Wang Nan <wangnan0@huawei.com <mailto:wangnan0@huawei.com>> wrote:
>
> ARM's kdump is actually corrupted (at least for omap4460), mainly because of
> cache problem: flush_icache_range can't reliably ensure the copied data
> correctly goes into RAM. After mmu turned off and jump to the trampoline, kexec
> always failed due to random undef instructions.
>
> This patch use ioremap to make sure the destnation of all memcpy() is
> uncachable memory, including copying of target kernel and trampoline.
>
>
> AFAIK ioremap on RAM in forbidden in ARM and device memory that ioremap()
> ends up creating is not meant for executable code.
>
> Doesn't this trigger the WARN_ON() in _arm_ioremap_pfn_caller)?
This patch is depend on the previous one:
ARM: Premit ioremap() to map reserved pages
However, Russell is opposed to it.
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WARNING: multiple messages have this Message-ID (diff)
From: Wang Nan <wangnan0@huawei.com>
To: Vaibhav Bedia <vaibhav.bedia@gmail.com>
Cc: <kexec@lists.infradead.org>, <stable@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, Geng Hui <hui.geng@huawei.com>,
<linux-mm@kvack.org>, Eric Biederman <ebiederm@xmission.com>,
Russell King <rmk+kernel@arm.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Linux ARM Kernel List <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 2/3] ARM: kexec: copying code to ioremapped area
Date: Wed, 22 Jan 2014 21:03:54 +0800 [thread overview]
Message-ID: <52DFC1BA.8030001@huawei.com> (raw)
In-Reply-To: <CANacCWz2DdLvns9htszpwWnASrYGXQt+tHMsw4aBbjoyw-DmeQ@mail.gmail.com>
On 2014/1/22 20:56, Vaibhav Bedia wrote:
> On Wed, Jan 22, 2014 at 6:25 AM, Wang Nan <wangnan0@huawei.com <mailto:wangnan0@huawei.com>> wrote:
>
> ARM's kdump is actually corrupted (at least for omap4460), mainly because of
> cache problem: flush_icache_range can't reliably ensure the copied data
> correctly goes into RAM. After mmu turned off and jump to the trampoline, kexec
> always failed due to random undef instructions.
>
> This patch use ioremap to make sure the destnation of all memcpy() is
> uncachable memory, including copying of target kernel and trampoline.
>
>
> AFAIK ioremap on RAM in forbidden in ARM and device memory that ioremap()
> ends up creating is not meant for executable code.
>
> Doesn't this trigger the WARN_ON() in _arm_ioremap_pfn_caller)?
This patch is depend on the previous one:
ARM: Premit ioremap() to map reserved pages
However, Russell is opposed to it.
next prev parent reply other threads:[~2014-01-22 13:03 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-22 11:25 [PATCH 0/3] Bugfix for kdump on arm Wang Nan
2014-01-22 11:25 ` Wang Nan
2014-01-22 11:25 ` Wang Nan
2014-01-22 11:25 ` Wang Nan
2014-01-22 11:25 ` [PATCH 1/3] ARM: Premit ioremap() to map reserved pages Wang Nan
2014-01-22 11:25 ` Wang Nan
2014-01-22 11:25 ` Wang Nan
2014-01-22 11:25 ` Wang Nan
2014-01-22 11:38 ` Will Deacon
2014-01-22 11:38 ` Will Deacon
2014-01-22 11:38 ` Will Deacon
2014-01-22 11:38 ` Will Deacon
2014-01-22 11:42 ` Russell King - ARM Linux
2014-01-22 11:42 ` Russell King - ARM Linux
2014-01-22 11:42 ` Russell King - ARM Linux
2014-01-22 11:42 ` Russell King - ARM Linux
2014-01-22 11:55 ` Wang Nan
2014-01-22 11:55 ` Wang Nan
2014-01-22 11:55 ` Wang Nan
2014-01-22 11:55 ` Wang Nan
2014-01-22 11:25 ` [PATCH 2/3] ARM: kexec: copying code to ioremapped area Wang Nan
2014-01-22 11:25 ` Wang Nan
2014-01-22 11:25 ` Wang Nan
2014-01-22 11:25 ` Wang Nan
2014-01-22 12:56 ` Vaibhav Bedia
2014-01-22 13:03 ` Wang Nan [this message]
2014-01-22 13:03 ` Wang Nan
2014-01-22 13:03 ` Wang Nan
2014-01-22 13:03 ` Wang Nan
2014-01-22 13:27 ` Russell King - ARM Linux
2014-01-22 13:27 ` Russell King - ARM Linux
2014-01-22 13:27 ` Russell King - ARM Linux
2014-01-22 13:27 ` Russell King - ARM Linux
2014-01-23 2:16 ` Wang Nan
2014-01-23 2:16 ` Wang Nan
2014-01-23 2:16 ` Wang Nan
2014-01-23 2:16 ` Wang Nan
2014-01-22 11:25 ` [PATCH 3/3] ARM: allow kernel to be loaded in middle of phymem Wang Nan
2014-01-22 11:25 ` Wang Nan
2014-01-22 11:25 ` Wang Nan
2014-01-22 11:25 ` Wang Nan
2014-01-23 19:15 ` Nicolas Pitre
2014-01-23 19:15 ` Nicolas Pitre
2014-01-23 19:15 ` Nicolas Pitre
2014-01-23 19:15 ` Nicolas Pitre
2014-01-23 19:31 ` Russell King - ARM Linux
2014-01-23 19:31 ` Russell King - ARM Linux
2014-01-23 19:31 ` Russell King - ARM Linux
2014-01-23 19:31 ` Russell King - ARM Linux
2014-01-23 20:01 ` Nicolas Pitre
2014-01-23 20:01 ` Nicolas Pitre
2014-01-23 20:01 ` Nicolas Pitre
2014-01-23 20:01 ` Nicolas Pitre
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