x86, realmode: Relocator for realmode code
Implements relocator for real mode code that is called
as part of setup_arch(). Processes segment relocations
and linear relocations. Real-mode code is relocated to
a free hole below 1 MB.
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-4-git-send-email-jarkko.sakkinen@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
diff --git a/arch/x86/kernel/realmode.c b/arch/x86/kernel/realmode.c
new file mode 100644
index 0000000..7415c42
--- /dev/null
+++ b/arch/x86/kernel/realmode.c
@@ -0,0 +1,79 @@
+#include <linux/io.h>
+#include <linux/memblock.h>
+
+#include <asm/cacheflush.h>
+#include <asm/pgtable.h>
+#include <asm/realmode.h>
+
+unsigned char *real_mode_base;
+struct real_mode_header real_mode_header;
+
+void __init setup_real_mode(void)
+{
+ phys_addr_t mem;
+ u16 real_mode_seg;
+ u32 *rel;
+ u32 count;
+ u32 *ptr;
+ u16 *seg;
+ int i;
+
+ struct real_mode_header *header =
+ (struct real_mode_header *) real_mode_blob;
+
+ size_t size = PAGE_ALIGN(header->end);
+
+ /* 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)
+ panic("Cannot allocate trampoline\n");
+
+ real_mode_base = __va(mem);
+ memblock_reserve(mem, size);
+
+ printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
+ real_mode_base, (unsigned long long)mem, size);
+
+ memcpy(real_mode_base, real_mode_blob, size);
+
+ real_mode_seg = __pa(real_mode_base) >> 4;
+ rel = (u32 *) real_mode_relocs;
+
+ /* 16-bit segment relocations. */
+ count = rel[0];
+ rel = &rel[1];
+ for (i = 0; i < count; i++) {
+ seg = (u16 *) (real_mode_base + rel[i]);
+ *seg = real_mode_seg;
+ }
+
+ /* 32-bit linear relocations. */
+ count = rel[i];
+ rel = &rel[i + 1];
+ for (i = 0; i < count; i++) {
+ ptr = (u32 *) (real_mode_base + rel[i]);
+ *ptr += __pa(real_mode_base);
+ }
+
+ /* Copied header will contain relocated physical addresses. */
+ memcpy(&real_mode_header, real_mode_base,
+ sizeof(struct real_mode_header));
+}
+
+/*
+ * set_real_mode_permissions() 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 set_real_mode_permissions(void)
+{
+ size_t all_size =
+ PAGE_ALIGN(real_mode_header.end) -
+ __pa(real_mode_base);
+
+ set_memory_x((unsigned long) real_mode_base, all_size >> PAGE_SHIFT);
+ return 0;
+}
+
+arch_initcall(set_real_mode_permissions);