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ftrace/alternatives: Introducing *_text_reserved functions

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Introducing *_text_reserved functions for checking the text
address range is partially reserved or not. This patch provides
checking routines for x86 smp alternatives and dynamic ftrace.
Since both functions modify fixed pieces of kernel text, they
should reserve and protect those from other dynamic text
modifier, like kprobes.

This will also be extended when introducing other subsystems
which modify fixed pieces of kernel text. Dynamic text modifiers
should avoid those.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: systemtap <systemtap@sources.redhat.com>
Cc: DLE <dle-develop@lists.sourceforge.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: przemyslaw@pawelczyk.it
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Jason Baron <jbaron@redhat.com>
LKML-Reference: <20100202214911.4694.16587.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Masami Hiramatsu
2010-02-02 16:49:11 -05:00
committed by Ingo Molnar
parent 615d0ebbc7
commit 2cfa19780d
4 changed files with 42 additions and 0 deletions
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16
arch/x86/kernel/alternative.c
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@@ -390,6 +390,22 @@ void alternatives_smp_switch(int smp)
mutex_unlock(&smp_alt);
}
/* Return 1 if the address range is reserved for smp-alternatives */
int alternatives_text_reserved(void *start, void *end)
{
struct smp_alt_module *mod;
u8 **ptr;
list_for_each_entry(mod, &smp_alt_modules, next) {
if (mod->text > end || mod->text_end < start)
continue;
for (ptr = mod->locks; ptr < mod->locks_end; ptr++)
if (start <= *ptr && end >= *ptr)
return 1;
}
return 0;
}
#endif
#ifdef CONFIG_PARAVIRT