[PATCH[ Export __PAGE_KERNEL_EXEC for modules (vmmon)

[PATCH[ Export __PAGE_KERNEL_EXEC for modules (vmmon)

[Petr Vandrovec]

Hello Ingo,
  recently support for NX on i386 arrived to 2.6.x kernel, and I have
some problems building code which uses vmap since then - PAGE_KERNEL_EXEC
expands to __PAGE_KERNEL_EXEC, and this one is not accessible to modules.

  Or should I just use __pgprot(__PAGE_KERNEL & ~_PAGE_NX) or
__pgprot(_PAGE_KERNEL_EXEC) instead as pgprot argument to vmap?
						Thanks,
							Petr Vandrovec



--- linux/arch/i386/kernel/i386_ksyms.c	2004-10-27 22:55:58.000000000 +0200
+++ linux/arch/i386/kernel/i386_ksyms.c	2004-10-28 23:59:22.000000000 +0200
@@ -179,6 +179,7 @@
 #endif
 
 EXPORT_SYMBOL(__PAGE_KERNEL);
+EXPORT_SYMBOL(__PAGE_KERNEL_EXEC);
 
 #ifdef CONFIG_HIGHMEM
 EXPORT_SYMBOL(kmap);

Re: [PATCH[ Export __PAGE_KERNEL_EXEC for modules (vmmon)

[Arjan van de Ven]

On Fri, 2004-10-29 at 00:11 +0200, Petr Vandrovec wrote:
> Hello Ingo,
>   recently support for NX on i386 arrived to 2.6.x kernel, and I have
> some problems building code which uses vmap since then - PAGE_KERNEL_EXEC

why are you vmap'ing *executable* kernel memory?
That sounds very wrong.... very very wrong. The module loader needs it,
sure, but that's not modular. What on earth are you doing ????

Re: [PATCH[ Export __PAGE_KERNEL_EXEC for modules (vmmon)

[Petr Vandrovec]

On Fri, Oct 29, 2004 at 11:03:41AM +0200, Arjan van de Ven wrote:
> On Fri, 2004-10-29 at 00:11 +0200, Petr Vandrovec wrote:
> > Hello Ingo,
> >   recently support for NX on i386 arrived to 2.6.x kernel, and I have
> > some problems building code which uses vmap since then - PAGE_KERNEL_EXEC
> 
> why are you vmap'ing *executable* kernel memory?
> That sounds very wrong.... very very wrong. The module loader needs it,
> sure, but that's not modular. What on earth are you doing ????

Due to rule that not everything should be in kernel, userspace
picks one of codes needed to switch processor from currently used
mode  & address space to mode VMware needs (ia32 => long, long => ia32, 
PAE <=> non-PAE + cr3 + gdt + idt) maps it into kernel space, and then run 
it as needed.  And for running it it must be executable.

OK, I think that I understand message.  __pgprot(__PAGE_KERNEL & ~_PAGE_NX)
is my friend.
						Petr Vandrovec

Re: [PATCH[ Export __PAGE_KERNEL_EXEC for modules (vmmon)

[Arjan van de Ven]

On Fri, 2004-10-29 at 13:38 +0200, Petr Vandrovec wrote:
> ????
> 
> Due to rule that not everything should be in kernel, userspace
> picks one of codes needed to switch processor from currently used
> mode  & address space to mode VMware needs (ia32 => long, long => ia32, 
> PAE <=> non-PAE + cr3 + gdt + idt) maps it into kernel space, and then run 
> it as needed.  And for running it it must be executable.

so effectively vmware has it's own module loader. quite interesting ;)

Re: [PATCH[ Export __PAGE_KERNEL_EXEC for modules (vmmon)

[Christoph Hellwig]

On Fri, Oct 29, 2004 at 12:11:48AM +0200, Petr Vandrovec wrote:
> Hello Ingo,
>   recently support for NX on i386 arrived to 2.6.x kernel, and I have
> some problems building code which uses vmap since then - PAGE_KERNEL_EXEC
> expands to __PAGE_KERNEL_EXEC, and this one is not accessible to modules.

The right thing is not to mark kernel virtual memory executable from
modules at all.