colin/u-boot
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

x86: Add 64-bit entries to the GDT

Browse Source 
At present it is not possible to execution 64-bit code without
installing an entire new Global Descriptor Table. This is inconvenient
since kvm does not seem to like switching into long mode with a new
table.

It isn't actually necessary, since we can just extend the existing
table. Add some new entries to this effect.

Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Simon Glass
2025-03-15 14:25:31 +00:00
committed by Tom Rini
parent 899ab6cd52
commit 66f0dcb07f
2 changed files with 7 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/cpu/i386/cpu.c
View File

@@ -160,6 +160,9 @@ void arch_setup_gd(gd_t *new_gd)
gdt_addr[X86_GDT_ENTRY_16BIT_FLAT_CS] = GDT_ENTRY(0x809b, 0, 0xfffff);
gdt_addr[X86_GDT_ENTRY_16BIT_FLAT_DS] = GDT_ENTRY(0x8093, 0, 0xfffff);
gdt_addr[X86_GDT_ENTRY_64BIT_CS] = GDT_ENTRY(0xaf9b, 0, 0xfffff);
gdt_addr[X86_GDT_ENTRY_64BIT_TS1] = GDT_ENTRY(0x8980, 0, 0xfffff);
gdt_addr[X86_GDT_ENTRY_64BIT_TS2] = 0;
load_gdt(gdt_addr, X86_GDT_NUM_ENTRIES);
load_ds(X86_GDT_ENTRY_32BIT_DS);

5
arch/x86/include/asm/processor.h
View File

@@ -18,7 +18,10 @@
#define X86_GDT_ENTRY_16BIT_DS 6
#define X86_GDT_ENTRY_16BIT_FLAT_CS 7
#define X86_GDT_ENTRY_16BIT_FLAT_DS 8
#define X86_GDT_NUM_ENTRIES 9
#define X86_GDT_ENTRY_64BIT_CS 9
#define X86_GDT_ENTRY_64BIT_TS1 10
#define X86_GDT_ENTRY_64BIT_TS2 11
#define X86_GDT_NUM_ENTRIES 12
#define X86_GDT_SIZE (X86_GDT_NUM_ENTRIES * X86_GDT_ENTRY_SIZE)