[Xen-devel] [PATCH v2 2/4] x86/page: Remove bifurcated PAGE_HYPERVISOR constant

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Despite being vaguely aware, the difference between PAGE_HYPERVISOR in ASM and
C code has nevertheless caused several bugs I should have known better about,
and contributed to review confusion.

There are exactly 4 uses of these constants in asm code (and one is shortly
going to disappear).

Instead of creating the constants which behave differently between ASM and C
code, expose all the constants and use non-ambiguous non-NX ones in ASM.
Adjust the hiding to just _PAGE_NX, which contains a C ternary expression.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>

v2:
 * Hide _PAGE_NX
---
 xen/arch/x86/boot/head.S          |  2 +-
 xen/arch/x86/boot/x86_64.S        |  6 +++---
 xen/include/asm-x86/page.h        |  4 ++++
 xen/include/asm-x86/x86_64/page.h | 17 +++++------------
 4 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index d246e374f1..563bb19056 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -674,7 +674,7 @@ trampoline_setup:
          * the transition into long mode), using 2M superpages.
          */
         lea     sym_esi(start),%ebx
-        lea     
(1<<L2_PAGETABLE_SHIFT)*7+(PAGE_HYPERVISOR|_PAGE_PSE)(%ebx),%eax
+        lea     
(1<<L2_PAGETABLE_SHIFT)*7+(PAGE_HYPERVISOR_RWX|_PAGE_PSE)(%ebx),%eax
         shr     $(L2_PAGETABLE_SHIFT-3),%ebx
         mov     $8,%ecx
 1:      mov     %eax,sym_fs(l2_bootmap)-8(%ebx,%ecx,8)
diff --git a/xen/arch/x86/boot/x86_64.S b/xen/arch/x86/boot/x86_64.S
index af62850589..662c8b7ead 100644
--- a/xen/arch/x86/boot/x86_64.S
+++ b/xen/arch/x86/boot/x86_64.S
@@ -56,9 +56,9 @@ l1_identmap:
         .rept L1_PAGETABLE_ENTRIES
         /* VGA hole (0xa0000-0xc0000) should be mapped UC-. */
         .if pfn >= 0xa0 && pfn < 0xc0
-        .quad (pfn << PAGE_SHIFT) | PAGE_HYPERVISOR_UCMINUS | MAP_SMALL_PAGES
+        .quad (pfn << PAGE_SHIFT) | __PAGE_HYPERVISOR_UCMINUS | _PAGE_GLOBAL | 
MAP_SMALL_PAGES
         .else
-        .quad (pfn << PAGE_SHIFT) | PAGE_HYPERVISOR | MAP_SMALL_PAGES
+        .quad (pfn << PAGE_SHIFT) | PAGE_HYPERVISOR_RWX | MAP_SMALL_PAGES
         .endif
         pfn = pfn + 1
         .endr
@@ -89,7 +89,7 @@ GLOBAL(l2_xenmap)
         .quad 0
         idx = 1
         .rept 7
-        .quad sym_offs(__image_base__) + (idx << L2_PAGETABLE_SHIFT) + 
(PAGE_HYPERVISOR | _PAGE_PSE)
+        .quad sym_offs(__image_base__) + (idx << L2_PAGETABLE_SHIFT) + 
(PAGE_HYPERVISOR_RWX | _PAGE_PSE)
         idx = idx + 1
         .endr
         .fill L2_PAGETABLE_ENTRIES - 8, 8, 0
diff --git a/xen/include/asm-x86/page.h b/xen/include/asm-x86/page.h
index 05a8b1efa6..a3c76a403b 100644
--- a/xen/include/asm-x86/page.h
+++ b/xen/include/asm-x86/page.h
@@ -316,7 +316,11 @@ void efi_update_l4_pgtable(unsigned int l4idx, 
l4_pgentry_t);
 #define _PAGE_AVAIL    _AC(0xE00,U)
 #define _PAGE_PSE_PAT  _AC(0x1000,U)
 #define _PAGE_AVAIL_HIGH (_AC(0x7ff, U) << 12)
+
+#ifndef __ASSEMBLY__
+/* Dependency on NX being available can't be expressed. */
 #define _PAGE_NX       (cpu_has_nx ? _PAGE_NX_BIT : 0)
+#endif
 
 #define PAGE_CACHE_ATTRS (_PAGE_PAT | _PAGE_PCD | _PAGE_PWT)
 
diff --git a/xen/include/asm-x86/x86_64/page.h 
b/xen/include/asm-x86/x86_64/page.h
index 4fe0205553..9876634881 100644
--- a/xen/include/asm-x86/x86_64/page.h
+++ b/xen/include/asm-x86/x86_64/page.h
@@ -172,18 +172,11 @@ static inline intpte_t put_pte_flags(unsigned int x)
 #define PAGE_HYPERVISOR_RX      (__PAGE_HYPERVISOR_RX      | _PAGE_GLOBAL)
 #define PAGE_HYPERVISOR_RWX     (__PAGE_HYPERVISOR         | _PAGE_GLOBAL)
 
-#ifdef __ASSEMBLY__
-/* Dependency on NX being available can't be expressed. */
-# define PAGE_HYPERVISOR         PAGE_HYPERVISOR_RWX
-# define PAGE_HYPERVISOR_UCMINUS (__PAGE_HYPERVISOR_UCMINUS | _PAGE_GLOBAL)
-# define PAGE_HYPERVISOR_UC      (__PAGE_HYPERVISOR_UC      | _PAGE_GLOBAL)
-#else
-# define PAGE_HYPERVISOR         PAGE_HYPERVISOR_RW
-# define PAGE_HYPERVISOR_UCMINUS (__PAGE_HYPERVISOR_UCMINUS | \
-                                  _PAGE_GLOBAL | _PAGE_NX)
-# define PAGE_HYPERVISOR_UC      (__PAGE_HYPERVISOR_UC | \
-                                  _PAGE_GLOBAL | _PAGE_NX)
-#endif
+#define PAGE_HYPERVISOR         PAGE_HYPERVISOR_RW
+#define PAGE_HYPERVISOR_UCMINUS (__PAGE_HYPERVISOR_UCMINUS | \
+                                 _PAGE_GLOBAL | _PAGE_NX)
+#define PAGE_HYPERVISOR_UC      (__PAGE_HYPERVISOR_UC | \
+                                 _PAGE_GLOBAL | _PAGE_NX)
 
 #endif /* __X86_64_PAGE_H__ */
 
-- 
2.11.0


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