3 files changed, 42 insertions, 17 deletions
diff --git a/src/arch/x86/c_start.S b/src/arch/x86/c_start.S
index 02a9b8933a..5b7052ef58 100644
--- a/src/arch/x86/c_start.S
+++ b/src/arch/x86/c_start.S
@@ -1,6 +1,5 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
-#include <cpu/x86/cpu_info.S.inc>
 #include <cpu/x86/post_code.h>
 #include <arch/ram_segs.h>
 
@@ -78,21 +77,6 @@ _start:
 	movl	$_estack, %esp
 	andl	$(~(CONFIG_STACK_SIZE-1)), %esp
 
-	push_cpu_info
-
-	/* Allocate the per_cpu_segment_data on the stack */
-	push_per_cpu_segment_data
-
-	/*
-	 * 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
-
-	mov	$per_cpu_segment_selector, %eax
-	movl	(%eax), %eax
-	mov	%eax, %gs
-
 	/*
 	 *	Now we are finished. Memory is up, data is copied and
 	 *	bss is cleared.   Now we call the main routine and
diff --git a/src/arch/x86/cpu.c b/src/arch/x86/cpu.c
index f4cb83a4dd..6a8ddefa14 100644
--- a/src/arch/x86/cpu.c
+++ b/src/arch/x86/cpu.c
@@ -6,6 +6,7 @@
 #include <cpu/cpu.h>
 #include <post.h>
 #include <string.h>
+#include <cpu/x86/gdt.h>
 #include <cpu/x86/mp.h>
 #include <cpu/x86/lapic.h>
 #include <cpu/x86/tsc.h>
@@ -340,3 +341,41 @@ int cpu_index(void)
 	}
 	return -1;
 }
+
+/* cpu_info() looks at address 0 at the base of %gs for a pointer to struct cpu_info */
+static struct per_cpu_segment_data segment_data[CONFIG_MAX_CPUS];
+static struct cpu_info cpu_infos[CONFIG_MAX_CPUS];
+
+enum cb_err set_cpu_info(unsigned int index, struct device *cpu)
+{
+	if (index >= ARRAY_SIZE(cpu_infos))
+		return CB_ERR;
+
+	if (!cpu)
+		return CB_ERR;
+
+	const struct cpu_info info = { .cpu = cpu, .index = index};
+	cpu_infos[index] = info;
+	segment_data[index].cpu_info = &cpu_infos[index];
+
+	struct segment_descriptor {
+		uint16_t segment_limit_0_15;
+		uint16_t base_address_0_15;
+		uint8_t base_address_16_23;
+		uint8_t attrs[2];
+		uint8_t base_address_24_31;
+	} *segment_descriptor = (void *)&per_cpu_segment_descriptors;
+
+	segment_descriptor[index].base_address_0_15 = (uintptr_t)&segment_data[index] & 0xffff;
+	segment_descriptor[index].base_address_16_23 = ((uintptr_t)&segment_data[index] >> 16) & 0xff;
+	segment_descriptor[index].base_address_24_31 = ((uintptr_t)&segment_data[index] >> 24) & 0xff;
+
+	const unsigned int cpu_segment = per_cpu_segment_selector + (index << 3);
+
+	__asm__ __volatile__ ("mov %0, %%gs\n"
+		:
+		: "r" (cpu_segment)
+		: );
+
+	return CB_SUCCESS;
+}
diff --git a/src/arch/x86/include/arch/cpu.h b/src/arch/x86/include/arch/cpu.h
index 0087a795ec..c7c6b4e074 100644
--- a/src/arch/x86/include/arch/cpu.h
+++ b/src/arch/x86/include/arch/cpu.h
@@ -147,11 +147,13 @@ struct per_cpu_segment_data {
 	struct cpu_info *cpu_info;
 };
 
+enum cb_err set_cpu_info(unsigned int index, struct device *cpu);
+
 static inline struct cpu_info *cpu_info(void)
 {
 	struct cpu_info *ci = NULL;
 
-	__asm__("mov %%gs:%c[offset], %[ci]"
+	__asm__ __volatile__("mov %%gs:%c[offset], %[ci]"
 		: [ci] "=r" (ci)
 		: [offset] "i" (offsetof(struct per_cpu_segment_data, cpu_info))
 	);