From: Andrew Cooper <andrew.cooper3@citrix.com>
To: xen-devel@lists.xen.org
Subject: Re: The entry of Xen's exception handler
Date: Tue, 2 Oct 2012 22:23:05 +0100 [thread overview]
Message-ID: <506B5B39.4010205@citrix.com> (raw)
In-Reply-To: <CAJJWZczK3+KWcuk8yvjr6AXtkBkPgzUTrnqp0+FhQcf=s00e_A@mail.gmail.com>
On 02/10/2012 21:51, Xinxin Jin wrote:
> Hi, I am trying to understand the exception handler of Xen. In
> xen/arch/x86/x86_64/entry.S, the entry of the page fault handler is :
>
> ENTRY(page_fault)
> movl $TRAP_page_fault,4(%rsp)
> jmp handle_exception
>
> Here I did not get why to put the exception vector ($TRAP_page_fault)
> to stack before calling handle_exception?
This is so every single exception fills in its cpu_user_regs with the
correct trap, so the C code an distinguish if its needs to. (See
current.h for the structures which get filled in)
~Andrew
>
> Thanks,
>
> --
> Xinxin
>
next prev parent reply other threads:[~2012-10-02 21:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-02 20:51 The entry of Xen's exception handler Xinxin Jin
2012-10-02 21:23 ` Andrew Cooper [this message]
2012-10-02 21:30 ` Keir Fraser
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