Benjamin Herrenschmidt <b...@kernel.crashing.org> wrote on 06/10/2009 00:37:28:
>
> On Tue, 2009-10-06 at 00:31 +0200, Joakim Tjernlund wrote:
> >
> > regs or regs->nip is NULL? Either one does not make sense
> > In any case it might be a secondary problem as DAR is NULL already
> > when you
> > enter the page fault.
> > >
> > > insn = *((unsigned long *)regs->nip);
> > > c000e110: 80 a9 00 00 lwz r5,0(r9)
> > >
> > > fails.
> >
> > hmm, I wonder if you managed to invalidate the a kernel TLB?
> > Are you using pinned kernel TLBs?
>
> You should not dereference a user address like that. Use get_user !
So how does this look? Does it change anything?
It should as the previous way was way off :(
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index c33c6de..08a392f 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -153,7 +153,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned
long address,
#ifdef DEBUG_DCBX
const char *istr = NULL;
- insn = *((unsigned long *)regs->nip);
+ __get_user(insn, (unsigned long __user *)regs->nip);
if (((insn >> (31-5)) & 0x3f) == 31) {
if (((insn >> 1) & 0x3ff) == 1014) /* dcbz ? 0x3f6 */
istr = "dcbz";
@@ -178,11 +178,12 @@ int __kprobes do_page_fault(struct pt_regs *regs,
unsigned long address,
ra, rb, dar);
is_write = 0;
}
-
+#if 0
if (trap == 0x300 && address != dar) {
__asm__ ("mtdar %0" : : "r" (dar));
return 0;
}
+#endif
}
}
#endif
@@ -191,7 +192,7 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned
long address,
/* This is from a dcbX or icbi insn gone bad, these
* insn do not set DAR so we have to do it here instead
*/
- insn = *((unsigned long *)regs->nip);
+ __get_user(insn, (unsigned long __user *)regs->nip);
ra = (insn >> (31-15)) & 0x1f; /* Reg RA */
rb = (insn >> (31-20)) & 0x1f; /* Reg RB */
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