Change in coreboot[master]: src/arch/x86/c_start.S: Add proper x86_64 code

[Patrick Rudolph (Code Review)]

Patrick Rudolph has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/59874 )

Change subject: src/arch/x86/c_start.S: Add proper x86_64 code
......................................................................

src/arch/x86/c_start.S: Add proper x86_64 code

Don't truncate upper bits in assemlby code and thus allow loading
of ramstage above 4GiB. Tested on qemu.

Change-Id: Ifc9b45f69d0b7534b2faacaad0d099cef2667478
Signed-off-by: Patrick Rudolph 
---
M src/arch/x86/c_start.S
1 file changed, 35 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/74/59874/1

diff --git a/src/arch/x86/c_start.S b/src/arch/x86/c_start.S
index 9e718fc..c979e81 100644
--- a/src/arch/x86/c_start.S
+++ b/src/arch/x86/c_start.S
@@ -62,6 +62,24 @@
    leal	_stack, %edi
 #endif

+#if ENV_X86_64
+	/** poison the stack. Code should not count on the
+	 * stack being full of zeros. This stack poisoning
+	 * recently uncovered a bug in the broadcast SIPI
+	 * code.
+	 */
+	movabs	$_estack, %rcx
+	sub	%rdi, %rcx
+	shr	$3, %rcx   /* it is 64 bit aligned, right? */
+	movq	$0xDEADBEEFDEADBEEF, %rax
+	rep
+	stosq
+
+	/* Set new stack with enforced alignment. */
+	movabs	$_estack, %rsp
+	movq	$(~(CONFIG_STACK_SIZE-1)), %rax
+	and	%rax, %rsp
+#else
    /** poison the stack. Code should not count on the
     * stack being full of zeros. This stack poisoning
     * recently uncovered a bug in the broadcast SIPI
@@ -77,13 +95,23 @@
    /* Set new stack with enforced alignment. */
    movl	$_estack, %esp
    andl	$(~(CONFIG_STACK_SIZE-1)), %esp
-
+#endif
    push_cpu_info

#if CONFIG(CPU_INFO_V2)
    /* Allocate the per_cpu_segment_data on the stack */
    push_per_cpu_segment_data

+#if ENV_X86_64
+	/*
+	 * Update the BSP's per_cpu_segment_descriptor to point to the
+	 * per_cpu_segment_data that was allocated on the stack.
+	 */
+	set_segment_descriptor_base $per_cpu_segment_descriptors, %esp
+
+	movabs	per_cpu_segment_selector, %rax
+	mov	%eax, %gs
+#else
    /*
     * Update the BSP's per_cpu_segment_descriptor to point to the
     * per_cpu_segment_data that was allocated on the stack.
@@ -93,6 +121,7 @@
    mov	per_cpu_segment_selector, %eax
    mov	%eax, %gs
 #endif
+#endif

/*
     *	Now we are finished. Memory is up, data is copied and
@@ -101,7 +130,12 @@
     */
    post_code(POST_PRE_HARDWAREMAIN)	/* post 6e */

+#if ENV_X86_64
+	movq	$0xFFFFFFFFFFFFFFF0, %rax
+	and	%rax, %rsp
+#else
    andl	$0xFFFFFFF0, %esp
+#endif

#if CONFIG(ASAN_IN_RAMSTAGE)
    call asan_init