Changeset d242cb6 in mainline

Timestamp:

2013-05-13T22:34:28Z (11 years ago)

Author:

Martin Decky <martin@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

6e8ed225

Parents:

959d2ec

Message:

make sure we configure two distinct segment descriptors and set the read bit on the code segment before switching back to real-mode for VESA/VBE
this fixes execution on the latest (3.9.1) Linux KVM with real-mode x86 code emulation that is particularly picky about the code segment permission bits

Location:

kernel/arch

Files:

• amd64/include/arch/pm.h (modified) (1 diff)
• amd64/src/pm.c (modified) (1 diff)
• ia32/include/arch/pm.h (modified) (2 diffs)
• ia32/src/boot/vesa_real.inc (modified) (3 diffs)
• ia32/src/pm.c (modified) (1 diff)

kernel/arch/amd64/include/arch/pm.h

@@ -57 +57 @@
 #ifdef CONFIG_FB
 
-#define VESA_INIT_DES      8
 #define VESA_INIT_SEGMENT  0x8000
+#define VESA_INIT_CODE_DES      8
+#define VESA_INIT_DATA_DES      9
 
 #undef GDT_ITEMS
-#define GDT_ITEMS  9
+#define GDT_ITEMS  10
 
 #endif /* CONFIG_FB */

kernel/arch/amd64/src/pm.c

@@ -112 +112 @@
         /* VESA Init descriptor */
 #ifdef CONFIG_FB
-        {
-                0xffff, 0, VESA_INIT_SEGMENT >> 12, AR_PRESENT | AR_CODE | DPL_KERNEL,
-                    0xf, 0, 0, 0, 0, 0
-        }
+        { 0xffff, 0, VESA_INIT_SEGMENT >> 12, AR_PRESENT | AR_CODE | AR_READABLE | DPL_KERNEL, 0xf, 0, 0, 0, 0, 0 },
+        { 0xffff, 0, VESA_INIT_SEGMENT >> 12, AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_KERNEL, 0xf, 0, 0, 0, 0, 0 }
 #endif
 };

kernel/arch/ia32/include/arch/pm.h

@@ -50 +50 @@
 
 #define VESA_INIT_SEGMENT  0x8000
-#define VESA_INIT_DES      7
+#define VESA_INIT_CODE_DES      7
+#define VESA_INIT_DATA_DES      8
 #define KTEXT32_DES        KTEXT_DES
 
 #undef GDT_ITEMS
-#define GDT_ITEMS  8
+#define GDT_ITEMS  9
 
 #endif /* CONFIG_FB */
@@ -67 +68 @@
 #define AR_CODE       (3 << 3)
 #define AR_WRITABLE   (1 << 1)
+#define AR_READABLE   (1 << 1)
 #define AR_INTERRUPT  (0xe)
 #define AR_TRAP       (0xf)

kernel/arch/ia32/src/boot/vesa_real.inc

@@ -31 +31 @@
 vesa_init:
         lidtl vesa_idtr
-        jmp $GDT_SELECTOR(VESA_INIT_DES), $vesa_init_real - vesa_init
+        
+        mov $GDT_SELECTOR(VESA_INIT_DATA_DES), %bx
+        
+        mov %bx, %es
+        mov %bx, %fs
+        mov %bx, %gs
+        mov %bx, %ds
+        mov %bx, %ss
+        
+        jmp $GDT_SELECTOR(VESA_INIT_CODE_DES), $vesa_init_real - vesa_init
 
 vesa_idtr:
@@ -39 +48 @@
 .code16
 vesa_init_real:
-        
         mov %cr0, %eax
         and $~1, %eax
@@ -45 +53 @@
         
         jmp $VESA_INIT_SEGMENT, $vesa_init_real2 - vesa_init
-        
+
 vesa_init_real2:
         mov $VESA_INIT_SEGMENT, %bx

kernel/arch/ia32/src/pm.c

@@ -75 +75 @@
         /* VESA Init descriptor */
 #ifdef CONFIG_FB
-        { 0xffff, 0, VESA_INIT_SEGMENT >> 12, AR_PRESENT | AR_CODE | DPL_KERNEL, 0xf, 0, 0, 0, 0, 0 }
+        { 0xffff, 0, VESA_INIT_SEGMENT >> 12, AR_PRESENT | AR_CODE | AR_READABLE | DPL_KERNEL, 0xf, 0, 0, 0, 0, 0 },
+        { 0xffff, 0, VESA_INIT_SEGMENT >> 12, AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_KERNEL, 0xf, 0, 0, 0, 0, 0 }
 #endif
 };