created a test directory to hold test guest OSes

[palacios.git] / test / geekos_test_vm / src / geekos / segment.c

diff --git a/test/geekos_test_vm/src/geekos/segment.c b/test/geekos_test_vm/src/geekos/segment.c
new file mode 100644 (file)
index 0000000..4e83db0
--- /dev/null
+++ b/test/geekos_test_vm/src/geekos/segment.c
@@ -0,0 +1,138 @@
+/*
+ * General data structures and routines for segmentation
+ * Copyright (c) 2001, David H. Hovemeyer <daveho@cs.umd.edu>
+ * $Revision: 1.1 $
+ * 
+ * This is free software.  You are permitted to use,
+ * redistribute, and modify it as specified in the file "COPYING".
+ */
+
+/*
+ * Source: _Protected Mode Software Architecture_ by Tom Shanley,
+ * ISBN 020155447X.
+ */
+
+#include <geekos/kassert.h>
+#include <geekos/string.h>
+#include <geekos/tss.h>
+#include <geekos/segment.h>
+
+static __inline__ void Set_Size_And_Base_Pages(
+    struct Segment_Descriptor* desc,
+    ulong_t baseAddr,
+    ulong_t numPages
+)
+{
+    /*
+     * There are 20 bits in the size fields of a segment descriptor.
+     * The maximum possible value is thus 0xFFFFF, which in terms of
+     * pages is one page less than 4GB.  So, I conclude that the
+     * number of pages in the segment is one greater than the
+     * value specified in the descriptor.
+     */
+    KASSERT(numPages > 0);
+    numPages -= 1;
+
+    desc->sizeLow     = numPages & 0xFFFF;
+    desc->sizeHigh    = (numPages >> 16) & 0x0F;
+    desc->baseLow     = baseAddr & 0xFFFFFF;
+    desc->baseHigh    = (baseAddr >> 24) & 0xFF;
+    desc->granularity = 1;  /* size in pages */
+}
+
+static __inline__ void Set_Size_And_Base_Bytes(
+    struct Segment_Descriptor* desc,
+    ulong_t baseAddr,
+    ulong_t numBytes
+)
+{
+    desc->sizeLow     = numBytes & 0xFFFF;
+    desc->sizeHigh    = (numBytes >> 16) & 0x0F;
+    desc->baseLow     = baseAddr & 0xFFFFFF;
+    desc->baseHigh    = (baseAddr >> 24) & 0xFF;
+    desc->granularity = 0;  /* size in bytes */
+}
+
+/*
+ * Initialize an unused segment descriptor.
+ */
+void Init_Null_Segment_Descriptor(struct Segment_Descriptor* desc)
+{
+    memset(desc, '\0', sizeof(*desc));
+}
+
+/*
+ * Initialize a code segment descriptor.
+ */
+void Init_Code_Segment_Descriptor(
+    struct Segment_Descriptor* desc,
+    ulong_t baseAddr,
+    ulong_t numPages,
+    int privilegeLevel
+)
+{
+    KASSERT(privilegeLevel >= 0 && privilegeLevel <= 3);
+
+    Set_Size_And_Base_Pages(desc, baseAddr, numPages);
+    desc->type     = 0x0A;   /* 1010b: code, !conforming, readable, !accessed */
+    desc->system   = 1;
+    desc->dpl      = privilegeLevel;
+    desc->present  = 1;
+    desc->reserved = 0;
+    desc->dbBit    = 1;  /* 32 bit code segment */
+}
+
+/*
+ * Initialize a data segment descriptor.
+ */
+void Init_Data_Segment_Descriptor(
+    struct Segment_Descriptor* desc,
+    ulong_t baseAddr,
+    ulong_t numPages,
+    int privilegeLevel
+)
+{
+    KASSERT(privilegeLevel >= 0 && privilegeLevel <= 3);
+
+    Set_Size_And_Base_Pages(desc, baseAddr, numPages);
+    desc->type     = 0x02;  /* 0010b: data, expand-up, writable, !accessed */
+    desc->system   = 1;
+    desc->dpl      = privilegeLevel;
+    desc->present  = 1;
+    desc->reserved = 0;
+    desc->dbBit    = 1;  /* 32 bit operands */
+}
+
+/*
+ * Initialize a TSS descriptor.
+ */
+void Init_TSS_Descriptor(struct Segment_Descriptor* desc, struct TSS* theTSS)
+{
+    Set_Size_And_Base_Bytes(desc, (ulong_t) theTSS, sizeof(struct TSS));
+    desc->type     = 0x09;  /* 1001b: 32 bit, !busy */
+    desc->system   = 0;
+    desc->dpl      = 0;
+    desc->present  = 1;
+    desc->reserved = 0;
+    desc->dbBit    = 0;  /* must be 0 in TSS */
+}
+
+/*
+ * Initialize an LDT (Local Descriptor Table) descriptor.
+ */
+void Init_LDT_Descriptor(
+    struct Segment_Descriptor* desc,
+    struct Segment_Descriptor theLDT[],
+    int numEntries
+)
+{
+    Set_Size_And_Base_Bytes(
+       desc, (ulong_t) theLDT, sizeof(struct Segment_Descriptor) * numEntries);
+
+    desc->type     = 0x02;  /* 0010b */
+    desc->system   = 0;
+    desc->dpl      = 0;
+    desc->present  = 1;
+    desc->reserved = 0;
+    desc->dbBit    = 0;
+}