All of lore.kernel.org
 help / color / mirror / Atom feed
From: Will Deacon <will@kernel.org>
To: Muchun Song <songmuchun@bytedance.com>
Cc: catalin.marinas@arm.com, akpm@linux-foundation.org,
	anshuman.khandual@arm.com, aneesh.kumar@linux.ibm.com,
	steven.price@arm.com, lengxujun2007@126.com, arnd@arndb.de,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, smuchun@gmail.com,
	duanxiongchun@bytedance.com, Qian Cai <quic_qiancai@quicinc.com>
Subject: Re: [PATCH] arm64: mm: fix pmd_leaf()
Date: Mon, 4 Apr 2022 10:19:58 +0100	[thread overview]
Message-ID: <20220404091957.GA22790@willie-the-truck> (raw)
In-Reply-To: <20220403024928.4125-1-songmuchun@bytedance.com>

On Sun, Apr 03, 2022 at 10:49:28AM +0800, Muchun Song wrote:
> The pmd_leaf() is used to test a leaf mapped PMD, however, it misses
> the PROT_NONE mapped PMD on arm64.  Fix it.  A real world issue [1]
> caused by this was reported by Qian Cai.
> 
> Link: https://patchwork.kernel.org/comment/24798260/ [1]
> Fixes: 8aa82df3c123 ("arm64: mm: add p?d_leaf() definitions")
> Reported-by: Qian Cai <quic_qiancai@quicinc.com>
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> ---
>  arch/arm64/include/asm/pgtable.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 94e147e5456c..09eaae46a19b 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -535,7 +535,7 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
>  				 PMD_TYPE_TABLE)
>  #define pmd_sect(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
>  				 PMD_TYPE_SECT)
> -#define pmd_leaf(pmd)		pmd_sect(pmd)
> +#define pmd_leaf(pmd)		(pmd_present(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT))
>  #define pmd_bad(pmd)		(!pmd_table(pmd))
>  
>  #define pmd_leaf_size(pmd)	(pmd_cont(pmd) ? CONT_PMD_SIZE : PMD_SIZE)

A bunch of the users of pmd_leaf() already check pmd_present() -- is it
documented that we need to handle this check inside the macro? afaict x86
doesn't do this either.

Will

WARNING: multiple messages have this Message-ID (diff)
From: Will Deacon <will@kernel.org>
To: Muchun Song <songmuchun@bytedance.com>
Cc: catalin.marinas@arm.com, akpm@linux-foundation.org,
	anshuman.khandual@arm.com, aneesh.kumar@linux.ibm.com,
	steven.price@arm.com, lengxujun2007@126.com, arnd@arndb.de,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, smuchun@gmail.com,
	duanxiongchun@bytedance.com, Qian Cai <quic_qiancai@quicinc.com>
Subject: Re: [PATCH] arm64: mm: fix pmd_leaf()
Date: Mon, 4 Apr 2022 10:19:58 +0100	[thread overview]
Message-ID: <20220404091957.GA22790@willie-the-truck> (raw)
In-Reply-To: <20220403024928.4125-1-songmuchun@bytedance.com>

On Sun, Apr 03, 2022 at 10:49:28AM +0800, Muchun Song wrote:
> The pmd_leaf() is used to test a leaf mapped PMD, however, it misses
> the PROT_NONE mapped PMD on arm64.  Fix it.  A real world issue [1]
> caused by this was reported by Qian Cai.
> 
> Link: https://patchwork.kernel.org/comment/24798260/ [1]
> Fixes: 8aa82df3c123 ("arm64: mm: add p?d_leaf() definitions")
> Reported-by: Qian Cai <quic_qiancai@quicinc.com>
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>
> ---
>  arch/arm64/include/asm/pgtable.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index 94e147e5456c..09eaae46a19b 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -535,7 +535,7 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
>  				 PMD_TYPE_TABLE)
>  #define pmd_sect(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
>  				 PMD_TYPE_SECT)
> -#define pmd_leaf(pmd)		pmd_sect(pmd)
> +#define pmd_leaf(pmd)		(pmd_present(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT))
>  #define pmd_bad(pmd)		(!pmd_table(pmd))
>  
>  #define pmd_leaf_size(pmd)	(pmd_cont(pmd) ? CONT_PMD_SIZE : PMD_SIZE)

A bunch of the users of pmd_leaf() already check pmd_present() -- is it
documented that we need to handle this check inside the macro? afaict x86
doesn't do this either.

Will

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2022-04-04  9:20 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-03  2:49 [PATCH] arm64: mm: fix pmd_leaf() Muchun Song
2022-04-03  2:49 ` Muchun Song
2022-04-04  9:19 ` Will Deacon [this message]
2022-04-04  9:19   ` Will Deacon
2022-04-04 10:51   ` Steven Price
2022-04-04 10:51     ` Steven Price
2022-04-04 11:40   ` Muchun Song
2022-04-04 11:40     ` Muchun Song
2022-04-04 14:10     ` Aneesh Kumar K V
2022-04-04 14:10       ` Aneesh Kumar K V
2022-04-04 15:24       ` Muchun Song
2022-04-04 15:24         ` Muchun Song

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220404091957.GA22790@willie-the-truck \
    --to=will@kernel.org \
    --cc=akpm@linux-foundation.org \
    --cc=aneesh.kumar@linux.ibm.com \
    --cc=anshuman.khandual@arm.com \
    --cc=arnd@arndb.de \
    --cc=catalin.marinas@arm.com \
    --cc=duanxiongchun@bytedance.com \
    --cc=lengxujun2007@126.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=quic_qiancai@quicinc.com \
    --cc=smuchun@gmail.com \
    --cc=songmuchun@bytedance.com \
    --cc=steven.price@arm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.