[lkml]   [2002]   [Aug]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 1 / ...] i386 dynamic fixup/self modifying code

> This patch implements a system that modifies the kernel code at runtime
> depending on CPU features and SMPness.


> This patch requires the is_smp() patch I posted earlier and also
> requires the new CPU selection code and the code that actually uses
> both.
> This code already exists, but needs a few adjustments so it may not
> arrive immediately.
> The code is invoked in the following ways:
> * Undefined exception handler: this is used to replace
> unsupported instructions with supported ones. Used for invlpg
> -> flushall, prefetchnta -> prefetch -> nop, *fence -> lock
> addl 0, (%esp), movntq -> movq
> * Int3 handler: this is used when a 1 byte opcode is desired.
> This is controlled by a config option so that debuggers and
> kprobe won't break. Used for lock/nop and APIC write

Why not do *everything* using int3 handler? It should simplify your code.

Hooking on 'unknown instruction' should not be really neccessary if you
replace all invlpgs (etc) with 0xcc...
> Unfortunately with this patch executing invalid code will cause the
> processor to enter an infinite exception loop rather than panic. Fixing
> this is not trivial for SMP+preempt so it's not done at the moment.

Using 0xcc for everything should fix that, right?

Philips Velo 1: 1"x4"x8", 300gram, 60, 12MB, 40bogomips, linux, mutt,
details at

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:28    [W:0.084 / U:0.060 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site