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authorDanny Holman <dholman@gymli.xyz>2021-01-24 21:10:57 -0600
committerDanny Holman <dholman@gymli.xyz>2021-01-24 21:10:57 -0600
commita4534660fecb1b571c24ad82e67bc6c2fb814cb9 (patch)
tree149984cb0e9a32765e63df0f696091817c2b6dd5 /arch/i386/include
parentdd6656f7132d1727a055035ca94945fa4fbaae58 (diff)
x86: reorganize the i386 directory
Add structure to the internals of the x86 directory. Signed-off-by: Danny Holman <dholman@gymli.xyz>
Diffstat (limited to 'arch/i386/include')
-rw-r--r--arch/i386/include/gdt.h69
1 files changed, 69 insertions, 0 deletions
diff --git a/arch/i386/include/gdt.h b/arch/i386/include/gdt.h
new file mode 100644
index 0000000..4ffa155
--- /dev/null
+++ b/arch/i386/include/gdt.h
@@ -0,0 +1,69 @@
+#ifndef GDT_H
+#define GDT_H
+
+#include <stdint.h>
+
+#define SEG_DESCTYPE(x) ((x) << 0x04)
+#define SEG_PRES(x) ((x) << 0x07)
+#define SEG_SAVL(x) ((x) << 0x0C)
+#define SEG_LONG(x) ((x) << 0x0D)
+#define SEG_SIZE(x) ((x) << 0x0E)
+#define SEG_GRAN(x) ((x) << 0x0F)
+#define SEG_PRIV(x) (((x) & 0x03) << 0x05)
+
+#define SEG_DATA_RD 0x00
+#define SEG_DATA_RDA 0x01
+#define SEG_DATA_RDWR 0x02
+#define SEG_DATA_RDWRA 0x03
+#define SEG_DATA_RDEXPD 0x04
+#define SEG_DATA_RDEXPDA 0x05
+#define SEG_DATA_RDWREXD 0x06
+#define SEG_DATA_RDWREXDA 0x07
+#define SEG_CODE_EX 0x08
+#define SEG_CODE_EXA 0x09
+#define SEG_CODE_EXRD 0x0A
+#define SEG_CODE_EXRDA 0x0B
+#define SEG_CODE_EXC 0x0C
+#define SEG_CODE_EXCA 0x0D
+#define SEG_CODE_EXRDC 0x0E
+#define SEG_CODE_EXRDCA 0x0F
+
+#define GDT_CODE_PL0 SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \
+ SEG_LONG(0) | SEG_SIZE(1) | SEG_GRAN(1) | \
+ SEG_PRIV(0) | SEG_CODE_EXRD
+
+#define GDT_DATA_PL0 SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \
+ SEG_LONG(0) | SEG_SIZE(1) | SEG_GRAN(1) | \
+ SEG_PRIV(0) | SEG_CODE_RDWR
+
+#define GDT_CODE_PL3 SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \
+ SEG_LONG(0) | SEG_SIZE(1) | SEG_GRAN(1) | \
+ SEG_PRIV(3) | SEG_DATA_EXRD
+
+#define GDT_DATA_PL3 SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \
+ SEG_LONG(0) | SEG_SIZE(1) | SEG_GRAN(1) | \
+ SEG_PRIV(3) | SEG_DATA_RDWR
+
+struct gdt {
+ uint16_t size;
+ uint32_t offset;
+} __attribute__((packed));
+
+void flush_gdt(void);
+
+uint64_t create_descriptor(uint32_t base, uint32_t limit, uint16_t flag) {
+ uint64_t descriptor;
+
+ descriptor = limit & 0x000F0000;
+ descriptor |= (flag << 8) & 0x00F0FF00;
+ descriptor |= (base >> 16) & 0x000000FF;
+ descriptor |= base & 0xFF000000;
+
+ descriptor <<= 32;
+ descriptor |= base << 16;
+ descriptor |= limit & 0x0000FFFF;
+
+ return descriptor;
+}
+
+#endif