[Xen-devel] [PATCH v4 2/2] xen/PVH: Make GDT selectors PVH-specific

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

We don't need to share PVH GDT layout with other GDTs, especially
since we now have a PVH-speciific entry (for stack canary segment).

Define PVH's own selectors.

(As a side effect of this change we are also fixing improper
reference to __KERNEL_CS)

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
---
 arch/x86/xen/xen-pvh.S | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/arch/x86/xen/xen-pvh.S b/arch/x86/xen/xen-pvh.S
index 0169374..e7a5bf4 100644
--- a/arch/x86/xen/xen-pvh.S
+++ b/arch/x86/xen/xen-pvh.S
@@ -54,7 +54,11 @@
  * charge of setting up it's own stack, GDT and IDT.
  */
 
-#define PVH_GDT_ENTRY_CANARY   4
+#define PVH_GDT_ENTRY_CS       1
+#define PVH_GDT_ENTRY_DS       2
+#define PVH_GDT_ENTRY_CANARY   3
+#define PVH_CS_SEL             (PVH_GDT_ENTRY_CS * 8)
+#define PVH_DS_SEL             (PVH_GDT_ENTRY_DS * 8)
 #define PVH_CANARY_SEL         (PVH_GDT_ENTRY_CANARY * 8)
 
 ENTRY(pvh_start_xen)
@@ -62,7 +66,7 @@ ENTRY(pvh_start_xen)
 
        lgdt (_pa(gdt))
 
-       mov $(__BOOT_DS),%eax
+       mov $PVH_DS_SEL,%eax
        mov %eax,%ds
        mov %eax,%es
        mov %eax,%ss
@@ -96,7 +100,7 @@ ENTRY(pvh_start_xen)
        mov %eax, %cr0
 
        /* Jump to 64-bit mode. */
-       ljmp $__KERNEL_CS, $_pa(1f)
+       ljmp $PVH_CS_SEL, $_pa(1f)
 
        /* 64-bit entry point. */
        .code64
@@ -136,13 +140,13 @@ ENTRY(pvh_start_xen)
        or $(X86_CR0_PG | X86_CR0_PE), %eax
        mov %eax, %cr0
 
-       ljmp $__BOOT_CS, $1f
+       ljmp $PVH_CS_SEL, $1f
 1:
        call xen_prepare_pvh
        mov $_pa(pvh_bootparams), %esi
 
        /* startup_32 doesn't expect paging and PAE to be on. */
-       ljmp $__BOOT_CS, $_pa(2f)
+       ljmp $PVH_CS_SEL, $_pa(2f)
 2:
        mov %cr0, %eax
        and $~X86_CR0_PG, %eax
@@ -151,7 +155,7 @@ ENTRY(pvh_start_xen)
        and $~X86_CR4_PAE, %eax
        mov %eax, %cr4
 
-       ljmp $__BOOT_CS, $_pa(startup_32)
+       ljmp $PVH_CS_SEL, $_pa(startup_32)
 #endif
 END(pvh_start_xen)
 
@@ -163,13 +167,12 @@ gdt:
        .word 0
 gdt_start:
        .quad 0x0000000000000000            /* NULL descriptor */
-       .quad 0x0000000000000000            /* reserved */
 #ifdef CONFIG_X86_64
-       .quad GDT_ENTRY(0xa09a, 0, 0xfffff) /* __KERNEL_CS */
+       .quad GDT_ENTRY(0xa09a, 0, 0xfffff) /* PVH_CS_SEL */
 #else
-       .quad GDT_ENTRY(0xc09a, 0, 0xfffff) /* __KERNEL_CS */
+       .quad GDT_ENTRY(0xc09a, 0, 0xfffff) /* PVH_CS_SEL */
 #endif
-       .quad GDT_ENTRY(0xc092, 0, 0xfffff) /* __KERNEL_DS */
+       .quad GDT_ENTRY(0xc092, 0, 0xfffff) /* PVH_DS_SEL */
        .quad GDT_ENTRY(0x4090, 0, 0x18)    /* PVH_CANARY_SEL */
 gdt_end:
 
-- 
2.9.3


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel