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authorRusty Russell <rusty@rustcorp.com.au>2007-10-22 11:03:36 +1000
committerRusty Russell <rusty@rustcorp.com.au>2007-10-23 15:49:54 +1000
commit47436aa4ad054c1c7c8231618e86ebd9305308dc (patch)
treea9ba6e0521f9116442144a86e781a3164ec86094 /drivers/lguest/x86
parentc18acd73ffc209def08003a1927473096f66c5ad (diff)
Boot with virtual == physical to get closer to native Linux.
1) This allows us to get alot closer to booting bzImages. 2) It means we don't have to know page_offset. 3) The Guest needs to modify the boot pagetables to create the PAGE_OFFSET mapping before jumping to C code. 4) guest_pa() walks the page tables rather than using page_offset. 5) We don't use page_offset to figure out whether to emulate: it was always kinda quesationable, and won't work for instructions done before remapping (bzImage unpacking in particular). 6) We still want the kernel address for tlb flushing: have the initial hypercall give us that, too. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/lguest/x86')
-rw-r--r--drivers/lguest/x86/core.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c
index a125109446dc..39f64c95de18 100644
--- a/drivers/lguest/x86/core.c
+++ b/drivers/lguest/x86/core.c
@@ -216,9 +216,10 @@ static int emulate_insn(struct lguest *lg)
* guest_pa just subtracts the Guest's page_offset. */
unsigned long physaddr = guest_pa(lg, lg->regs->eip);
- /* The guest_pa() function only works for Guest kernel addresses, but
- * that's all we're trying to do anyway. */
- if (lg->regs->eip < lg->page_offset)
+ /* This must be the Guest kernel trying to do something, not userspace!
+ * The bottom two bits of the CS segment register are the privilege
+ * level. */
+ if ((lg->regs->cs & 3) != GUEST_PL)
return 0;
/* Decoding x86 instructions is icky. */