To: Roland McGrath <roland@redhat.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86-64 kprobes: handle %RIP-relative addressing mode
References: <200503130954.j2D9sgjB028594@magilla.sf.frob.com>
From: Andi Kleen <ak@muc.de>
Date: Sun, 13 Mar 2005 17:37:46 +0100
In-Reply-To: <200503130954.j2D9sgjB028594@magilla.sf.frob.com> (Roland
 McGrath's message of "Sun, 13 Mar 2005 01:54:42 -0800")
Message-ID: <m18y4ry011.fsf@muc.de>
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Roland McGrath <roland@redhat.com> writes:

> The existing x86-64 kprobes implementation doesn't cope with the
> %RIP-relative addressing mode.  Kprobes work by single-stepping a copy of

Thanks for fixing that long standing bug. 

> +	static const unsigned char onebyte_has_modrm[256] = {

Can you turn these two arrays into a bitmap please? 

> +	 * This basically replicates __vmalloc, except that it uses a

This shouldn't be opencoded here. Instead make a utility function
like vmalloc_range() that takes a start and end address and
make the module allocation use it too.

Also you should fix up asm-x86_64/page.h and Documentation/x86_64/mm.txt
with the new fixed allocation.

> +	 * range of addresses starting a MODULE_END.  This also
> +	 * allocates a single page of address space with no following
> +	 * guard page (__get_vm_area always adds PAGE_SIZE to the size,
> +	 * so by passing zero we get the one page).  We set up all the

I think Andrea has just changed that and the patch went into
mainline. Be careful with merging.

-Andi
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