arch/x86: Prepare EFI support

As for Multiboot, let prep_c be aware of EFI boot.
In the futur, EFI will pass an argument to it.

Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>

arch/x86/Kconfig

@@ -479,6 +479,14 @@ config X86_KPTI
 	  user thread interrupts and system calls, and significant footprint
 	  increase for additional page tables and trampoline stacks.
 
+config X86_EFI
+	bool "EFI"
+	default y
+	depends on BUILD_OUTPUT_EFI
+	help
+	  Enable EFI support. This means you build your image with zefi
+	  support. See arch/x86/zefi/README.txt for more information.
+
 source "arch/x86/core/Kconfig.ia32"
 source "arch/x86/core/Kconfig.intel64"
 

arch/x86/core/CMakeLists.txt

@@ -14,6 +14,7 @@ zephyr_library_sources_ifdef(CONFIG_X86_MEMMAP memmap.c)
 zephyr_library_sources_ifdef(CONFIG_PCIE pcie.c)
 zephyr_library_sources_ifdef(CONFIG_REBOOT_RST_CNT reboot_rst_cnt.c)
 zephyr_library_sources_ifdef(CONFIG_MULTIBOOT_INFO multiboot.c)
+zephyr_library_sources_ifdef(CONFIG_X86_EFI efi.c)
 zephyr_library_sources_ifdef(CONFIG_ACPI acpi.c)
 zephyr_library_sources_ifdef(CONFIG_X86_MMU x86_mmu.c)
 zephyr_library_sources_ifdef(CONFIG_USERSPACE userspace.c)

arch/x86/core/efi.c

@@ -0,0 +1,10 @@
+/*
+ * Copyright (c) 2020 Intel Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+void efi_init(void)
+{
+	/* Do Nothing atm */
+}

arch/x86/core/intel64/locore.S

@@ -5,6 +5,7 @@
 
 #include <toolchain.h>
 #include <arch/x86/multiboot.h>
+#include <arch/x86/efi.h>
 #include <sys/util.h>
 #include <arch/x86/msr.h>
 #include <kernel_arch_data.h>
@@ -289,8 +290,14 @@ __start64:
 	outb %al, $0x21
 	outb %al, $0xA1
 
-	/* Far call into the Zephyr code segment */
-	movq $x86_cpuboot, %rbp
+	movq $x86_cpu_boot_arg, %rbp
+	/* Inserting boot type */
+	movq $EFI_BOOT_TYPE, __x86_boot_arg_t_boot_type_OFFSET(%rbp)
+	/* and EFI boot arg (if any) */
+	movq %rbx, __x86_boot_arg_t_arg_OFFSET(%rbp)
+
+	movq $x86_cpuboot, %rbp		/* BSP is always logical CPU id 0 */
+
 	mov jmpdesc, %rax
 	jmp *%rax
 jmpdesc:

arch/x86/core/prep_c.c

@@ -8,6 +8,7 @@
 #include <kernel_internal.h>
 #include <arch/x86/acpi.h>
 #include <arch/x86/multiboot.h>
+#include <arch/x86/efi.h>
 #include <x86_mmu.h>
 
 extern FUNC_NORETURN void z_cstart(void);
@@ -43,10 +44,12 @@ FUNC_NORETURN void z_x86_prep_c(void *arg)
 	x86_64_irq_init();
 #endif
 
-
 if (IS_ENABLED(CONFIG_MULTIBOOT_INFO) &&
     cpu_arg->boot_type == MULTIBOOT_BOOT_TYPE) {
 	z_multiboot_init((struct multiboot_info *)cpu_arg->arg);
+} else if (IS_ENABLED(CONFIG_X86_EFI) &&
+	   cpu_arg->boot_type == EFI_BOOT_TYPE) {
+		efi_init();
 } else {
 	ARG_UNUSED(cpu_arg);
 }

arch/x86/zefi/zefi.c

@@ -123,7 +123,8 @@ uintptr_t __abi efi_entry(void *img_handle, struct efi_system_table *sys_tab)
 	for (volatile int i = 0; i < 50000000; i++) {
 	}
 
-	__asm__ volatile("cli; jmp *%0" :: "r"(code));
+	__asm__ volatile("cli; movq %0, %%rbx; jmp *%1"
+			 :: "r"(NULL), "r"(code) : "rbx");
 
 	return 0;
 }

include/arch/x86/efi.h

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2020 Intel Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_ARCH_X86_INCLUDE_EFI_H_
+#define ZEPHYR_ARCH_X86_INCLUDE_EFI_H_
+
+/* Boot type value (see prep_c.c) */
+#define EFI_BOOT_TYPE 2
+
+#ifndef _ASMLANGUAGE
+
+#if defined(CONFIG_X86_EFI)
+
+/** @brief Initialize usage of EFI gathered information
+ */
+void efi_init(void);
+
+#else /* CONFIG_X86_EFI */
+
+#define efi_init(...)
+
+#endif /* CONFIG_X86_EFI */
+
+#endif /* _ASMLANGUAGE */
+
+#endif /* ZEPHYR_ARCH_X86_INCLUDE_EFI_H_ */