From: Simon Glass <sjg@chromium.org>
Date: Thu, 4 May 2023 22:50:59 +0000 (-0600)
Subject: x86: Simplify cpu_jump_to_64bit_uboot()
X-Git-Url: http://git.dujemihanovic.xyz/img/%7B%7B%20%28.OutputFormats.Get?a=commitdiff_plain;h=4cb3b9f01ed8bdbd49627b977e91fc05472837cc;p=u-boot.git

x86: Simplify cpu_jump_to_64bit_uboot()

This copies the cpu_call64() function to memory address and then jumps to
it. This seems to work correctly even when called from SPL, which is
running from SPI flash.

Drop the copy as it is not needed.

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

diff --git a/arch/x86/cpu/i386/cpu.c b/arch/x86/cpu/i386/cpu.c
index c7f6c5a013..91cd5d7c9e 100644
--- a/arch/x86/cpu/i386/cpu.c
+++ b/arch/x86/cpu/i386/cpu.c
@@ -572,6 +572,7 @@ int cpu_has_64bit(void)
 		has_long_mode();
 }
 
+/* Base address for page tables used for 64-bit mode */
 #define PAGETABLE_BASE		0x80000
 #define PAGETABLE_SIZE		(6 * 4096)
 
@@ -614,43 +615,20 @@ int cpu_jump_to_64bit(ulong setup_base, ulong target)
 }
 
 /*
- * Jump from SPL to U-Boot
+ * cpu_jump_to_64bit_uboot() - Jump from SPL to U-Boot
  *
- * This function is work-in-progress with many issues to resolve.
- *
- * It works by setting up several regions:
- *   ptr      - a place to put the code that jumps into 64-bit mode
- *   gdt      - a place to put the global descriptor table
- *   pgtable  - a place to put the page tables
- *
- * The cpu_call64() code is copied from ROM and then manually patched so that
- * it has the correct GDT address in RAM. U-Boot is copied from ROM into
- * its pre-relocation address. Then we jump to the cpu_call64() code in RAM,
- * which changes to 64-bit mode and starts U-Boot.
+ * It works by setting up page tables and calling the code to enter 64-bit long
+ * mode
  */
 int cpu_jump_to_64bit_uboot(ulong target)
 {
-	typedef void (*func_t)(ulong pgtable, ulong setup_base, ulong target);
 	uint32_t *pgtable;
-	func_t func;
-	char *ptr;
 
 	pgtable = (uint32_t *)PAGETABLE_BASE;
-
 	build_pagetable(pgtable);
 
-	extern long call64_stub_size;
-	ptr = malloc(call64_stub_size);
-	if (!ptr) {
-		printf("Failed to allocate the cpu_call64 stub\n");
-		return -ENOMEM;
-	}
-	memcpy(ptr, cpu_call64, call64_stub_size);
-
-	func = (func_t)ptr;
-
 	/* Jump to U-Boot */
-	func((ulong)pgtable, 0, (ulong)target);
+	cpu_call64(PAGETABLE_BASE, 0, (ulong)target);
 
 	return -EFAULT;
 }