From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] ARM: mm: Provide better fault message for permission fault
Date: Mon, 26 Sep 2022 11:13:51 +0100 [thread overview]
Message-ID: <YzF7X2PBdps2MaG/@shell.armlinux.org.uk> (raw)
In-Reply-To: <20220919103845.100809-1-wangkefeng.wang@huawei.com>
On Mon, Sep 19, 2022 at 06:38:45PM +0800, Kefeng Wang wrote:
> If there is a permission fault in __do_kernel_fault(), we only
> print the generic "paging request" message which don't show
> read, write or excute information, let's provide better fault
> message for them.
I don't like this change. With CPUs that do not have the ability to
relocate the vectors to 0xffff0000, the vectors live at address 0,
so NULL pointer dereferences can produce permission faults.
I would much rather we did something similar to what x86 does:
pr_alert("#PF: %s %s in %s mode\n",
(error_code & X86_PF_USER) ? "user" : "supervisor",
(error_code & X86_PF_INSTR) ? "instruction fetch" :
(error_code & X86_PF_WRITE) ? "write access" :
"read access",
user_mode(regs) ? "user" : "kernel");
As we already print whether we're in user or kernel mode in the
register dump, there's no need to repeat that. I think we just
need an extra line to decode the FSR PF and write bits.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-09-26 10:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-19 10:38 [PATCH v2] ARM: mm: Provide better fault message for permission fault Kefeng Wang
2022-09-26 10:13 ` Russell King (Oracle) [this message]
2022-09-26 13:26 ` Kefeng Wang
2022-09-26 14:15 ` Russell King (Oracle)
2022-09-27 6:21 ` [PATCH v3] ARM: mm: Provide better message when kernel fault Kefeng Wang
2022-10-10 11:24 ` Kefeng Wang
2022-10-10 15:55 ` Russell King (Oracle)
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=YzF7X2PBdps2MaG/@shell.armlinux.org.uk \
--to=linux@armlinux.org.uk \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=wangkefeng.wang@huawei.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).