x86: Use the existing GDT in the ROM for 64-bit U-Boot proper

It is unnecessary to use a RAM version GDT for 64-bit U-Boot proper.
In fact we can just use the ROM version directly, which not only
eliminates the risk of being overwritten by application, but also
removes the complexity of patching the cpu_call64().

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

diff --git a/arch/x86/cpu/i386/cpu.c b/arch/x86/cpu/i386/cpu.c
index e4b551452d655edac81008f89ad18a0e82820a96..3bde44ebf53ff83d725d5920117e5fbeb77dd557 100644 (file)
--- a/arch/x86/cpu/i386/cpu.c
+++ b/arch/x86/cpu/i386/cpu.c
@@ -535,23 +535,9 @@ int cpu_jump_to_64bit_uboot(ulong target)
                printf("Failed to allocate the cpu_call64 stub\n");
                return -ENOMEM;
        }
-       char *gdt = (char *)0x3100000;
-
-       extern char gdt64[];
-
        memcpy(ptr, cpu_call64, call64_stub_size);
-       memcpy(gdt, gdt64, 0x100);
 
-       /*
-        * TODO(sjg@chromium.org): This manually inserts the pointers into
-        * the code. Tidy this up to avoid this.
-        */
        func = (func_t)ptr;
-       ulong ofs = (ulong)cpu_call64 - (ulong)ptr;
-       *(ulong *)(ptr + 7) = (ulong)gdt;
-       *(ulong *)(ptr + 0xc) = (ulong)gdt + 2;
-       *(ulong *)(ptr + 0x13) = (ulong)gdt;
-       *(ulong *)(ptr + 0x117 - 0xd4) -= ofs;
 
        /*
         * Copy U-Boot from ROM