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Message-Id: <1173410210.32234.76.camel@localhost.localdomain>
Date: Fri, 09 Mar 2007 14:16:50 +1100
From: Rusty Russell <rusty@...tcorp.com.au>
To: Andrew Morton <akpm@...l.org>
Cc: Andi Kleen <ak@....de>,
lkml - Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH 4/9] lguest: cleanup: clean up regs save/restore
We previously put "cr3" in the guest regs restored and saved: the
guest cannot change cr3, so saving it it silly. Hand it across to the
host<->guest switcher in ebx.
While we're there, only save the host registers we need to; tell GCC
we clobber everything we can.
Finally, and trap 2 (NMI) doesn't supply a error code (we don't handle
NMI yet, but the test is wrong, so fix it before I get confused).
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
diff -r 6efda2f8ac22 arch/i386/lguest/core.c
--- a/arch/i386/lguest/core.c Thu Mar 08 16:25:07 2007 +1100
+++ b/arch/i386/lguest/core.c Thu Mar 08 16:51:17 2007 +1100
@@ -260,11 +260,11 @@ static void run_guest_once(struct lguest
{
unsigned int clobber;
- /* Put eflags on stack, lcall does rest. */
+ /* Put eflags on stack, lcall does rest: suitable for iret return. */
asm volatile("pushf; lcall *lguest_entry"
- : "=a"(clobber), "=d"(clobber)
- : "0"(lg->state), "1"(get_idt_table())
- : "memory");
+ : "=a"(clobber), "=d"(clobber), "=b"(clobber)
+ : "0"(lg->state), "1"(get_idt_table()), "2"(lg->cr3)
+ : "memory", "%ecx", "%edi", "%esi");
}
int run_guest(struct lguest *lg, char *__user user)
diff -r 6efda2f8ac22 arch/i386/lguest/hypervisor.S
--- a/arch/i386/lguest/hypervisor.S Thu Mar 08 16:25:07 2007 +1100
+++ b/arch/i386/lguest/hypervisor.S Thu Mar 08 16:52:56 2007 +1100
@@ -4,26 +4,17 @@
#include <asm/asm-offsets.h>
#include "lg.h"
-#define SAVE_REGS \
- /* Save old guest/host state */ \
- pushl %es; \
- pushl %ds; \
- pushl %fs; \
- pushl %eax; \
- pushl %gs; \
- pushl %ebp; \
- pushl %edi; \
- pushl %esi; \
- pushl %edx; \
- pushl %ecx; \
- pushl %ebx; \
-
.text
ENTRY(_start) /* ld complains unless _start is defined. */
-/* %eax contains ptr to target guest state, %edx contains host idt. */
+/* %eax contains ptr to target guest state, %edx contains host idt.
+ %ebx contains cr3 value. All normal registers can be clobbered! */
switch_to_guest:
- pushl %ss
- SAVE_REGS
+ pushl %es
+ pushl %ds
+ pushl %fs
+ pushl %gs
+ pushl %edx
+ pushl %ebp
/* Save old stack, switch to guest's stack. */
movl %esp, LGUEST_STATE_host_stackptr(%eax)
movl %eax, %esp
@@ -33,17 +24,16 @@ switch_to_guest:
lgdt LGUEST_STATE_gdt(%eax)
lidt LGUEST_STATE_idt(%eax)
/* Save page table top. */
- movl %cr3, %ebx
- movl %ebx, LGUEST_STATE_host_pgdir(%eax)
+ movl %cr3, %ecx
+ movl %ecx, LGUEST_STATE_host_pgdir(%eax)
/* Set host's TSS to available (clear byte 5 bit 2). */
- movl (LGUEST_STATE_host_gdt+2)(%eax), %ebx
- andb $0xFD, (GDT_ENTRY_TSS*8 + 5)(%ebx)
+ movl (LGUEST_STATE_host_gdt+2)(%eax), %ecx
+ andb $0xFD, (GDT_ENTRY_TSS*8 + 5)(%ecx)
/* Switch to guest page tables */
- popl %ebx
movl %ebx, %cr3
/* Switch to guest's TSS. */
- movl $(GDT_ENTRY_TSS*8), %ebx
- ltr %bx
+ movl $(GDT_ENTRY_TSS*8), %edx
+ ltr %dx
/* Restore guest regs */
popl %ebx
popl %ecx
@@ -66,10 +56,18 @@ switch_to_guest:
iret
#define SWITCH_TO_HOST \
- SAVE_REGS; \
- /* Save old pgdir */ \
- movl %cr3, %eax; \
+ /* Save guest state */ \
+ pushl %es; \
+ pushl %ds; \
+ pushl %fs; \
pushl %eax; \
+ pushl %gs; \
+ pushl %ebp; \
+ pushl %edi; \
+ pushl %esi; \
+ pushl %edx; \
+ pushl %ecx; \
+ pushl %ebx; \
/* Load lguest ds segment for convenience. */ \
movl $(LGUEST_DS), %eax; \
movl %eax, %ds; \
@@ -88,21 +86,15 @@ switch_to_guest:
/* Switch to host's stack. */ \
movl LGUEST_STATE_host_stackptr(%eax), %esp; \
/* Switch to host's TSS */ \
- movl $(GDT_ENTRY_TSS*8), %eax; \
- ltr %ax; \
+ movl $(GDT_ENTRY_TSS*8), %ebx; \
+ ltr %bx; \
/* Restore host regs */ \
- popl %ebx; \
- popl %ecx; \
+ popl %ebp; \
popl %edx; \
- popl %esi; \
- popl %edi; \
- popl %ebp; \
popl %gs; \
- popl %eax; \
popl %fs; \
popl %ds; \
- popl %es; \
- popl %ss
+ popl %es
/* Return to run_guest_once. */
return_to_host:
@@ -135,7 +127,7 @@ deliver_to_host_with_errcode:
.macro IRQ_STUB N TARGET
.data; .long 1f; .text; 1:
/* Make an error number for most traps, which don't have one. */
- .if (\N <> 2) && (\N <> 8) && (\N < 10 || \N > 14) && (\N <> 17)
+ .if (\N <> 8) && (\N < 10 || \N > 14) && (\N <> 17)
pushl $0
.endif
pushl $\N
diff -r 6efda2f8ac22 arch/i386/lguest/lg.h
--- a/arch/i386/lguest/lg.h Thu Mar 08 16:25:07 2007 +1100
+++ b/arch/i386/lguest/lg.h Thu Mar 08 16:51:17 2007 +1100
@@ -24,7 +24,6 @@ struct lguest_regs
struct lguest_regs
{
/* Manually saved part. */
- u32 cr3;
u32 ebx, ecx, edx;
u32 esi, edi, ebp;
u32 gs;
@@ -81,6 +80,7 @@ struct lguest
u32 pfn_limit;
u32 page_offset;
u32 cr2;
+ u32 cr3;
int timer_on;
int halted;
int ts;
diff -r 6efda2f8ac22 arch/i386/lguest/lguest_user.c
--- a/arch/i386/lguest/lguest_user.c Thu Mar 08 16:25:07 2007 +1100
+++ b/arch/i386/lguest/lguest_user.c Thu Mar 08 16:51:17 2007 +1100
@@ -4,7 +4,7 @@
#include <linux/fs.h>
#include "lg.h"
-static struct lguest_state *setup_guest_state(unsigned int num, void *pgdir,
+static struct lguest_state *setup_guest_state(unsigned int num,
unsigned long start)
{
struct lguest_state *guest = &__lguest_states()[num];
@@ -38,7 +38,6 @@ static struct lguest_state *setup_guest_
/* Write out stack in format lguest expects, so we can switch to it. */
regs = &guest->regs;
- regs->cr3 = __pa(pgdir);
regs->eax = regs->ebx = regs->ecx = regs->edx = regs->esp = 0;
regs->edi = LGUEST_MAGIC_EDI;
regs->ebp = LGUEST_MAGIC_EBP;
@@ -149,7 +148,7 @@ static int initialize(struct file *file,
if (err)
goto free_trap_page;
- lg->state = setup_guest_state(i, lg->pgdirs[lg->pgdidx].pgdir,args[2]);
+ lg->state = setup_guest_state(i, args[2]);
if (!lg->state) {
err = -ENOEXEC;
goto release_pgtable;
diff -r 6efda2f8ac22 arch/i386/lguest/page_tables.c
--- a/arch/i386/lguest/page_tables.c Thu Mar 08 16:25:07 2007 +1100
+++ b/arch/i386/lguest/page_tables.c Thu Mar 08 16:51:17 2007 +1100
@@ -223,7 +223,7 @@ void guest_new_pagetable(struct lguest *
if (newpgdir == ARRAY_SIZE(lg->pgdirs))
newpgdir = new_pgdir(lg, pgtable);
lg->pgdidx = newpgdir;
- lg->state->regs.cr3 = __pa(lg->pgdirs[lg->pgdidx].pgdir);
+ lg->cr3 = __pa(lg->pgdirs[lg->pgdidx].pgdir);
pin_stack_pages(lg);
}
@@ -296,6 +296,7 @@ int init_guest_pagetable(struct lguest *
lg->pgdirs[lg->pgdidx].pgdir = (u32*)get_zeroed_page(GFP_KERNEL);
if (!lg->pgdirs[lg->pgdidx].pgdir)
return -ENOMEM;
+ lg->cr3 = __pa(lg->pgdirs[lg->pgdidx].pgdir);
return 0;
}
-
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