From: Amit Kachhap <amit.kachhap@arm.com>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-kernel@vger.kernel.org,
Vincenzo Frascino <Vincenzo.Frascino@arm.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
kexec <kexec@lists.infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Young <dyoung@redhat.com>, Baoquan He <bhe@redhat.com>,
Vivek Goyal <vgoyal@redhat.com>, x86 <x86@kernel.org>
Subject: Re: [RFC PATCH 01/14] fs/proc/vmcore: Update read_from_oldmem() for user pointer
Date: Tue, 7 Dec 2021 12:41:52 +0530 [thread overview]
Message-ID: <08e4e9d8-2c42-115a-f440-d7f44fb19280@arm.com> (raw)
In-Reply-To: <20211206140451.GA4936@lst.de>
On 12/6/21 7:34 PM, Christoph Hellwig wrote:
> On Fri, Dec 03, 2021 at 04:12:18PM +0530, Amit Daniel Kachhap wrote:
>> + return read_from_oldmem_to_kernel(buf, count, ppos,
>> + cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT));
>
> Overly long line.
>
>> +ssize_t read_from_oldmem(char __user *ubuf, char *kbuf, size_t count,
>> + u64 *ppos, bool encrypted)
>> {
>> unsigned long pfn, offset;
>> size_t nr_bytes;
>> @@ -156,19 +163,27 @@ ssize_t read_from_oldmem(char *buf, size_t count,
>> /* If pfn is not ram, return zeros for sparse dump files */
>> if (!pfn_is_ram(pfn)) {
>> tmp = 0;
>> - if (!userbuf)
>> - memset(buf, 0, nr_bytes);
>> - else if (clear_user(buf, nr_bytes))
>> + if (kbuf)
>> + memset(kbuf, 0, nr_bytes);
>> + else if (clear_user(ubuf, nr_bytes))
>> tmp = -EFAULT;
>
> This looks like a huge mess. What speak against using an iov_iter
> here?
iov_iter seems to be a reasonable way. As a start I thought of adding
minimal changes.
>
next prev parent reply other threads:[~2021-12-07 7:12 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-03 10:42 [RFC PATCH 00/14] fs/proc/vmcore: Remove unnecessary user pointer conversions Amit Daniel Kachhap
2021-12-03 10:42 ` [RFC PATCH 01/14] fs/proc/vmcore: Update read_from_oldmem() for user pointer Amit Daniel Kachhap
2021-12-06 14:04 ` Christoph Hellwig
2021-12-06 14:17 ` Matthew Wilcox
2021-12-06 14:54 ` Christoph Hellwig
2021-12-06 15:07 ` Matthew Wilcox
2021-12-07 11:15 ` Christoph Hellwig
2021-12-07 7:11 ` Amit Kachhap [this message]
2021-12-03 10:42 ` [RFC PATCH 02/14] fs/proc/vmcore: Update copy_oldmem_page_encrypted() for user buffer Amit Daniel Kachhap
2021-12-03 10:42 ` [RFC PATCH 03/14] fs/proc/vmcore: Update copy_oldmem_page() " Amit Daniel Kachhap
2021-12-03 10:42 ` [RFC PATCH 04/14] x86/crash_dump_64: Use the new interface copy_oldmem_page_buf Amit Daniel Kachhap
2021-12-03 10:42 ` [RFC PATCH 05/14] x86/crash_dump_32: " Amit Daniel Kachhap
2021-12-03 10:42 ` [RFC PATCH 06/14] arm64/crash_dump: " Amit Daniel Kachhap
2021-12-03 10:42 ` [RFC PATCH 07/14] arm/crash_dump: " Amit Daniel Kachhap
2021-12-03 10:42 ` [RFC PATCH 08/14] mips/crash_dump: " Amit Daniel Kachhap
2021-12-03 10:42 ` [RFC PATCH 09/14] sh/crash_dump: " Amit Daniel Kachhap
2021-12-03 10:42 ` [RFC PATCH 10/14] riscv/crash_dump: " Amit Daniel Kachhap
2021-12-03 10:42 ` [RFC PATCH 11/14] powerpc/crash_dump: " Amit Daniel Kachhap
2021-12-03 10:42 ` [RFC PATCH 12/14] ia64/crash_dump: " Amit Daniel Kachhap
2021-12-03 10:42 ` [RFC PATCH 13/14] s390/crash_dump: " Amit Daniel Kachhap
2021-12-03 10:42 ` [RFC PATCH 14/14] fs/proc/vmcore: Remove the unused old interface copy_oldmem_page Amit Daniel Kachhap
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