x86: Don't copy the cpu_call64() function to a hardcoded address

Before jumping to 64-bit U-Boot proper, SPL copies the cpu_call64()
function to a hardcoded address 0x3000000. This can have potential
conflicts with application usage. Switch the destination address
to be allocated from the heap to avoid such risk.

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

diff --git a/arch/x86/cpu/i386/call64.S b/arch/x86/cpu/i386/call64.S
index 8f86728d42d5a1abe4bac6089ae63abcc9183e3b..275063c4af8c17fb78074003478daf0ef892da2c 100644 (file)
--- a/arch/x86/cpu/i386/call64.S
+++ b/arch/x86/cpu/i386/call64.S
@@ -79,6 +79,10 @@ lret_target:
        mov     %eax, %eax              /* Clear bits 63:32 */
        jmp     *%eax                   /* Jump to the 64-bit target */
 
+.globl call64_stub_size
+call64_stub_size:
+       .long   . - cpu_call64
+
        .data
        .align  16
        .globl  gdt64

diff --git a/arch/x86/cpu/i386/cpu.c b/arch/x86/cpu/i386/cpu.c
index af42431f45e4c68eedc2e659c3513116e1f224a1..e4b551452d655edac81008f89ad18a0e82820a96 100644 (file)
--- a/arch/x86/cpu/i386/cpu.c
+++ b/arch/x86/cpu/i386/cpu.c
@@ -523,18 +523,23 @@ 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);
 
-       /* TODO(sjg@chromium.org): Find a better place for this */
-       char *ptr = (char *)0x3000000;
+       extern long call64_stub_size;
+       ptr = malloc(call64_stub_size);
+       if (!ptr) {
+               printf("Failed to allocate the cpu_call64 stub\n");
+               return -ENOMEM;
+       }
        char *gdt = (char *)0x3100000;
 
        extern char gdt64[];
 
-       memcpy(ptr, cpu_call64, 0x1000);
+       memcpy(ptr, cpu_call64, call64_stub_size);
        memcpy(gdt, gdt64, 0x100);
 
        /*