x86: Support booting a 64-bit kernel from 64-bit U-Boot

Add the missing code to handle this. For a 64-bit kernel the entry
address is 0x200 bytes after the normal entry.

Rename the parameter to boot_linux_kernel() accordingly. Update the
comments to indicate that these are addresses, not pointers.

Signed-off-by: Simon Glass <sjg@chromium.org>

3 files changed, 36 insertions, 16 deletions

diff --git a/arch/x86/include/asm/bootm.h b/arch/x86/include/asm/bootm.h
index 109f686f740..3b641783b9c 100644
--- a/arch/x86/include/asm/bootm.h
+++ b/arch/x86/include/asm/bootm.h
@@ -14,14 +14,14 @@ void bootm_announce_and_cleanup(void);
  * This boots a kernel image, either 32-bit or 64-bit. It will also work with
  * a self-extracting kernel, if you set @image_64bit to false.
  *
- * @setup_base:		Pointer to the setup.bin information for the kernel
- * @load_address:	Pointer to the start of the kernel image
- * @image_64bit:	true if the image is a raw 64-bit kernel, false if it
- *			is raw 32-bit or any type of self-extracting kernel
- *			such as a bzImage.
+ * @setup_base:		Address of the setup.bin information for the kernel
+ * @entry:		Address of the kernel entry point
+ * @image_64bit:	true if the image is a raw 64-bit kernel, or a kernel
+ * which supports booting in 64-bit mode; false if it is raw 32-bit or any type
+ * of self-extracting kernel such as a bzImage.
  * Return: -ve error code. This function does not return if the kernel was
  * booted successfully.
  */
-int boot_linux_kernel(ulong setup_base, ulong load_address, bool image_64bit);
+int boot_linux_kernel(ulong setup_base, ulong entry, bool image_64bit);
 
 #endif
diff --git a/arch/x86/lib/bootm.c b/arch/x86/lib/bootm.c
index 873e2bc176f..9beb376bb9c 100644
--- a/arch/x86/lib/bootm.c
+++ b/arch/x86/lib/bootm.c
@@ -149,7 +149,7 @@ error:
 	return 1;
 }
 
-int boot_linux_kernel(ulong setup_base, ulong load_address, bool image_64bit)
+int boot_linux_kernel(ulong setup_base, ulong entry, bool image_64bit)
 {
 	bootm_announce_and_cleanup();
 
@@ -161,14 +161,23 @@ int boot_linux_kernel(ulong setup_base, ulong load_address, bool image_64bit)
 			puts("Cannot boot 64-bit kernel on 32-bit machine\n");
 			return -EFAULT;
 		}
-		/* At present 64-bit U-Boot does not support booting a
+		/*
+		 * At present 64-bit U-Boot only supports booting a 64-bit
 		 * kernel.
-		 * TODO(sjg@chromium.org): Support booting both 32-bit and
-		 * 64-bit kernels from 64-bit U-Boot.
+		 *
+		 * TODO(sjg@chromium.org): Support booting 32-bit kernels from
+		 * 64-bit U-Boot
 		 */
-#if !CONFIG_IS_ENABLED(X86_64)
-		return cpu_jump_to_64bit(setup_base, load_address);
-#endif
+		if (CONFIG_IS_ENABLED(X86_64)) {
+			typedef void (*h_func)(ulong zero, ulong setup);
+			h_func func;
+
+			/* jump to Linux with rdi=0, rsi=setup_base */
+			func = (h_func)entry;
+			func(0, setup_base);
+		} else {
+			return cpu_jump_to_64bit(setup_base, entry);
+		}
 	} else {
 		/*
 		* Set %ebx, %ebp, and %edi to 0, %esi to point to the
@@ -190,7 +199,7 @@ int boot_linux_kernel(ulong setup_base, ulong load_address, bool image_64bit)
 		"movl $0, %%ebp\n"
 		"cli\n"
 		"jmp *%[kernel_entry]\n"
-		:: [kernel_entry]"a"(load_address),
+		:: [kernel_entry]"a"(entry),
 		[boot_params] "S"(setup_base),
 		"b"(0), "D"(0)
 		);
diff --git a/arch/x86/lib/zimage.c b/arch/x86/lib/zimage.c
index a6d9151c324..e5ea5129c1e 100644
--- a/arch/x86/lib/zimage.c
+++ b/arch/x86/lib/zimage.c
@@ -504,13 +504,24 @@ static int do_zboot_info(struct cmd_tbl *cmdtp, int flag, int argc,
 static int do_zboot_go(struct cmd_tbl *cmdtp, int flag, int argc,
 		       char *const argv[])
 {
+	struct boot_params *params = state.base_ptr;
+	struct setup_header *hdr = &params->hdr;
+	bool image_64bit;
+	ulong entry;
 	int ret;
 
 	disable_interrupts();
 
+	entry = state.load_address;
+	image_64bit = false;
+	if (IS_ENABLED(CONFIG_X86_RUN_64BIT) &&
+	    (hdr->xloadflags & XLF_KERNEL_64)) {
+		entry += 0x200;
+		image_64bit = true;
+	}
+
 	/* we assume that the kernel is in place */
-	ret = boot_linux_kernel((ulong)state.base_ptr, state.load_address,
-				false);
+	ret = boot_linux_kernel((ulong)state.base_ptr, entry, image_64bit);
 	printf("Kernel returned! (err=%d)\n", ret);
 
 	return CMD_RET_FAILURE;