diff options
| author | Rusty Russell <rusty@rustcorp.com.au> | 2007-10-22 11:03:36 +1000 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2007-10-23 15:49:54 +1000 |
| commit | 47436aa4ad054c1c7c8231618e86ebd9305308dc (patch) | |
| tree | a9ba6e0521f9116442144a86e781a3164ec86094 /drivers/lguest/interrupts_and_traps.c | |
| parent | c18acd73ffc209def08003a1927473096f66c5ad (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/interrupts_and_traps.c')
| -rw-r--r-- | drivers/lguest/interrupts_and_traps.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c index a57d757eab6..3271c0031a1 100644 --- a/drivers/lguest/interrupts_and_traps.c +++ b/drivers/lguest/interrupts_and_traps.c @@ -62,8 +62,9 @@ static void push_guest_stack(struct lguest *lg, unsigned long *gstack, u32 val) * it). */ static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err) { - unsigned long gstack; + unsigned long gstack, origstack; u32 eflags, ss, irq_enable; + unsigned long virtstack; /* There are two cases for interrupts: one where the Guest is already * in the kernel, and a more complex one where the Guest is in @@ -71,8 +72,10 @@ static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err) if ((lg->regs->ss&0x3) != GUEST_PL) { /* The Guest told us their kernel stack with the SET_STACK * hypercall: both the virtual address and the segment */ - gstack = guest_pa(lg, lg->esp1); + virtstack = lg->esp1; ss = lg->ss1; + + origstack = gstack = guest_pa(lg, virtstack); /* We push the old stack segment and pointer onto the new * stack: when the Guest does an "iret" back from the interrupt * handler the CPU will notice they're dropping privilege @@ -81,8 +84,10 @@ static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err) push_guest_stack(lg, &gstack, lg->regs->esp); } else { /* We're staying on the same Guest (kernel) stack. */ - gstack = guest_pa(lg, lg->regs->esp); + virtstack = lg->regs->esp; ss = lg->regs->ss; + + origstack = gstack = guest_pa(lg, virtstack); } /* Remember that we never let the Guest actually disable interrupts, so @@ -108,7 +113,7 @@ static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err) /* Now we've pushed all the old state, we change the stack, the code * segment and the address to execute. */ lg->regs->ss = ss; - lg->regs->esp = gstack + lg->page_offset; + lg->regs->esp = virtstack + (gstack - origstack); lg->regs->cs = (__KERNEL_CS|GUEST_PL); lg->regs->eip = idt_address(lo, hi); |