1 files changed, 42 insertions, 0 deletions

diff --git a/arch/x86/kernel/trampoline.c b/arch/x86/kernel/trampoline.c
new file mode 100644
index 00000000000..a91ae7709b4
--- /dev/null
+++ b/arch/x86/kernel/trampoline.c
@@ -0,0 +1,42 @@
+#include <linux/io.h>
+#include <linux/memblock.h>
+
+#include <asm/trampoline.h>
+#include <asm/cacheflush.h>
+#include <asm/pgtable.h>
+
+unsigned char *x86_trampoline_base;
+
+void __init setup_trampolines(void)
+{
+        phys_addr_t mem;
+        size_t size = PAGE_ALIGN(x86_trampoline_end - x86_trampoline_start);
+
+        /* Has to be in very low memory so we can execute real-mode AP code. */
+        mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
+        if (mem == MEMBLOCK_ERROR)
+                panic("Cannot allocate trampoline\n");
+
+        x86_trampoline_base = __va(mem);
+        memblock_x86_reserve_range(mem, mem + size, "TRAMPOLINE");
+
+        printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
+               x86_trampoline_base, (unsigned long long)mem, size);
+
+        memcpy(x86_trampoline_base, x86_trampoline_start, size);
+}
+
+/*
+ * setup_trampolines() gets called very early, to guarantee the
+ * availability of low memory.  This is before the proper kernel page
+ * tables are set up, so we cannot set page permissions in that
+ * function.  Thus, we use an arch_initcall instead.
+ */
+static int __init configure_trampolines(void)
+{
+        size_t size = PAGE_ALIGN(x86_trampoline_end - x86_trampoline_start);
+
+        set_memory_x((unsigned long)x86_trampoline_base, size >> PAGE_SHIFT);
+        return 0;
+}
+arch_initcall(configure_trampolines);