x86: fsp: Load GDT before calling FspInitEntry

[u-boot] / arch / x86 / cpu / cpu.c

diff --git a/arch/x86/cpu/cpu.c b/arch/x86/cpu/cpu.c
index bb4a110c0072e0d96b8efee2b58069233de7fdad..b6c585a28f572f980bc14802a904daf98ce8cb49 100644 (file)
--- a/arch/x86/cpu/cpu.c
+++ b/arch/x86/cpu/cpu.c
@@ -164,6 +164,26 @@ void setup_gdt(gd_t *id, u64 *gdt_addr)
        load_fs(X86_GDT_ENTRY_32BIT_FS);
 }
 
+#ifdef CONFIG_HAVE_FSP
+/*
+ * Setup FSP execution environment GDT
+ *
+ * Per Intel FSP external architecture specification, before calling any FSP
+ * APIs, we need make sure the system is in flat 32-bit mode and both the code
+ * and data selectors should have full 4GB access range. Here we reuse the one
+ * we used in arch/x86/cpu/start16.S, and reload the segement registers.
+ */
+void setup_fsp_gdt(void)
+{
+       load_gdt((const u64 *)(gdt_rom + CONFIG_RESET_SEG_START), 4);
+       load_ds(X86_GDT_ENTRY_32BIT_DS);
+       load_ss(X86_GDT_ENTRY_32BIT_DS);
+       load_es(X86_GDT_ENTRY_32BIT_DS);
+       load_fs(X86_GDT_ENTRY_32BIT_DS);
+       load_gs(X86_GDT_ENTRY_32BIT_DS);
+}
+#endif
+
 int __weak x86_cleanup_before_linux(void)
 {
 #ifdef CONFIG_BOOTSTAGE_STASH