From: suthambhara nagaraj <suthambhara@gmail.com>
To: "Hanson, Jonathan M" <jonathan.m.hanson@intel.com>
Cc: main kernel <linux-kernel@vger.kernel.org>
Subject: Re: Getting a process' EIP address (and other registers)
Date: Wed, 13 Oct 2004 10:26:04 +0530 [thread overview]
Message-ID: <46561a7904101221564f0ef523@mail.gmail.com> (raw)
In-Reply-To: <C863B68032DED14E8EBA9F71EB8FE4C204FB456A@azsmsx406>
Why don't you use the pt_regs structure to restore the EIP
value stored during SAVE_ALL. Add a line in sys_ioctl to access the SAVE_ALL
stored values (EIP).This would then be simple pointer arithmetic.
I hope I havae answered you.
Regards
Suthambhara
On Tue, 12 Oct 2004 21:10:13 -0700, Hanson, Jonathan M
<jonathan.m.hanson@intel.com> wrote:
> I have written a 2.4 kernel module that is triggered upon an
> IOCTL from a user application. Once triggered the kernel module dumps
> out the contents of the system memory and the x86 CPU architecture state
> to separate files.
> I'm writing to the list because my method for getting registers
> from the user process before it entered the kernel is producing
> incorrect results. I've looked all through the kernel code and searched
> all over the web for an answer to this specific question and found
> nothing relevant.
> In my research how to do this I've found that the stack pointer
> for the user process before it entered the kernel is stored in
> current->thread.esp0. From there the registers for the user process are
> stored at offsets from that location (for example, EIP is supposed to be
> 0x28 unsigned char bytes from esp0). I have code to get the EIP as
> follows:
>
> unsigned char *stack_address, *eip;
>
> stack_address = (unsigned char *)(current->thread.esp0);
> eip = stack_address + 0x28;
> printk("eip = %08lx\n", *(unsigned long *)eip);
>
> Like I mentioned this is producing incorrect results. How do I access
> the user process' general purpose registers contents as they were before
> the kernel was entered (or correct my code above if I'm accessing
> something wrong)?
> Thanks in advance for any help offered.
> -
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next prev parent reply other threads:[~2004-10-13 4:56 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-10-13 4:10 Getting a process' EIP address (and other registers) Hanson, Jonathan M
2004-10-13 4:20 ` Hua Zhong
2004-10-13 4:56 ` suthambhara nagaraj [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-10-13 18:15 Hanson, Jonathan M
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