x86, trampoline: Common infrastructure for low memory trampolines

Common infrastructure for low memory trampolines.  This code installs
the trampolines permanently in low memory very early.  It also permits
multiple pieces of code to be used for this purpose.

This code also introduces a standard infrastructure for computing
symbol addresses in the trampoline code.

The only change to the actual SMP trampolines themselves is that the
64-bit trampoline has been made reusable -- the previous version would
overwrite the code with a status variable; this moves the status
variable to a separate location.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
LKML-Reference: <4D5DFBE4.7090104@intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Matthieu Castet <castet.matthieu@free.fr>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>

1 files changed, 22 insertions, 20 deletions

diff --git a/arch/x86/kernel/trampoline.c b/arch/x86/kernel/trampoline.c
index a375616..a91ae77 100644
--- a/arch/x86/kernel/trampoline.c
+++ b/arch/x86/kernel/trampoline.c
@@ -2,39 +2,41 @@
 #include <linux/memblock.h>
 
 #include <asm/trampoline.h>
+#include <asm/cacheflush.h>
 #include <asm/pgtable.h>
 
-#if defined(CONFIG_X86_64) && defined(CONFIG_ACPI_SLEEP)
-#define __trampinit
-#define __trampinitdata
-#else
-#define __trampinit __cpuinit
-#define __trampinitdata __cpuinitdata
-#endif
+unsigned char *x86_trampoline_base;
 
-/* ready for x86_64 and x86 */
-unsigned char *__trampinitdata trampoline_base;
-
-void __init reserve_trampoline_memory(void)
+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, TRAMPOLINE_SIZE, PAGE_SIZE);
+	mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
 	if (mem == MEMBLOCK_ERROR)
 		panic("Cannot allocate trampoline\n");
 
-	trampoline_base = __va(mem);
-	memblock_x86_reserve_range(mem, mem + TRAMPOLINE_SIZE, "TRAMPOLINE");
+	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);
 }
 
 /*
- * Currently trivial. Write the real->protected mode
- * bootstrap into the page concerned. The caller
- * has made sure it's suitably aligned.
+ * 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.
  */
-unsigned long __trampinit setup_trampoline(void)
+static int __init configure_trampolines(void)
 {
-	memcpy(trampoline_base, trampoline_data, TRAMPOLINE_SIZE);
-	return virt_to_phys(trampoline_base);
+	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);