linux-kernel - linux PowerPC 85xx Address space query

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <abe8a1fd0906240345y3e50e8bck59e7c8682c81713e@mail.gmail.com>
Date:	Wed, 24 Jun 2009 16:15:41 +0530
From:	kernel mailz <kernelmailz@...glemail.com>
To:	linux-kernel@...r.kernel.org
Subject: linux PowerPC 85xx Address space query

Hi,

I am a newbie, trying to learn but have a few queries, nice if you could respond
For linux on 85xx systems...

(a) Kernel code runs in PR=0 AS=0 and PID=0, which user space
application run in PR=1 AS=0 and PID 1-255.
Is this correct.

(b) I am writing a small program where the application code opens
invokes a ioctl call and passes a buffer pointer ( say 0x10000 in user
space)
Now the driver code is using copy_from_user.
How this works internally ?

1. User code executes ioctl
2. interrupt goes to the kernel
3. ioctl handler in driver gets invoked
The buffer pointer still contains 0x10000.

How kernel code running in PR=0 accesses it and does the copy. I am
not able to see a address space switch in the asm code of
copy_tofrom_user.

Please respond

-TRX
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/