x86: change static allocation of trampoline area

Impact: fix trampoline sizing bug, save space

While debugging a suspend-to-RAM related issue it occured to me that
if the trampoline code had grown past 4 KB, we would have been
allocating too little memory for it, since the 4 KB size of the
trampoline is hardcoded into arch/x86/kernel/e820.c .  Change that
by making the kernel compute the trampoline size and allocate as much
memory as necessary.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/trampoline.h

@@ -3,6 +3,7 @@
 
 #ifndef __ASSEMBLY__
 
+#ifdef CONFIG_X86_TRAMPOLINE
 /*
  * Trampoline 80x86 program as an array.
  */
@@ -13,8 +14,14 @@ extern unsigned char *trampoline_base;
 extern unsigned long init_rsp;
 extern unsigned long initial_code;
 
+#define TRAMPOLINE_SIZE roundup(trampoline_end - trampoline_data, PAGE_SIZE)
 #define TRAMPOLINE_BASE 0x6000
+
 extern unsigned long setup_trampoline(void);
+extern void __init reserve_trampoline_memory(void);
+#else
+static inline void reserve_trampoline_memory(void) {};
+#endif /* CONFIG_X86_TRAMPOLINE */
 
 #endif /* __ASSEMBLY__ */
 

arch/x86/kernel/e820.c

@@ -677,22 +677,6 @@ struct early_res {
 };
 static struct early_res early_res[MAX_EARLY_RES] __initdata = {
 	{ 0, PAGE_SIZE, "BIOS data page" },	/* BIOS data page */
-#if defined(CONFIG_X86_64) && defined(CONFIG_X86_TRAMPOLINE)
-	{ TRAMPOLINE_BASE, TRAMPOLINE_BASE + 2 * PAGE_SIZE, "TRAMPOLINE" },
-#endif
-#if defined(CONFIG_X86_32) && defined(CONFIG_SMP)
-	/*
-	 * But first pinch a few for the stack/trampoline stuff
-	 * FIXME: Don't need the extra page at 4K, but need to fix
-	 * trampoline before removing it. (see the GDT stuff)
-	 */
-	{ PAGE_SIZE, PAGE_SIZE + PAGE_SIZE, "EX TRAMPOLINE" },
-	/*
-	 * Has to be in very low memory so we can execute
-	 * real-mode AP code.
-	 */
-	{ TRAMPOLINE_BASE, TRAMPOLINE_BASE + PAGE_SIZE, "TRAMPOLINE" },
-#endif
 	{}
 };
 

arch/x86/kernel/head32.c

@@ -12,9 +12,12 @@
 #include <asm/sections.h>
 #include <asm/e820.h>
 #include <asm/bios_ebda.h>
+#include <asm/trampoline.h>
 
 void __init i386_start_kernel(void)
 {
+	reserve_trampoline_memory();
+
 	reserve_early(__pa_symbol(&_text), __pa_symbol(&_end), "TEXT DATA BSS");
 
 #ifdef CONFIG_BLK_DEV_INITRD

arch/x86/kernel/head64.c

@@ -24,6 +24,7 @@
 #include <asm/kdebug.h>
 #include <asm/e820.h>
 #include <asm/bios_ebda.h>
+#include <asm/trampoline.h>
 
 /* boot cpu pda */
 static struct x8664_pda _boot_cpu_pda __read_mostly;
@@ -120,6 +121,8 @@ void __init x86_64_start_reservations(char *real_mode_data)
 {
 	copy_bootdata(__va(real_mode_data));
 
+	reserve_trampoline_memory();
+
 	reserve_early(__pa_symbol(&_text), __pa_symbol(&_end), "TEXT DATA BSS");
 
 #ifdef CONFIG_BLK_DEV_INITRD

arch/x86/kernel/trampoline.c

 #include <linux/io.h>
 
 #include <asm/trampoline.h>
+#include <asm/e820.h>
 
 /* ready for x86_64 and x86 */
 unsigned char *trampoline_base = __va(TRAMPOLINE_BASE);
 
+void __init reserve_trampoline_memory(void)
+{
+#ifdef CONFIG_X86_32
+	/*
+	 * But first pinch a few for the stack/trampoline stuff
+	 * FIXME: Don't need the extra page at 4K, but need to fix
+	 * trampoline before removing it. (see the GDT stuff)
+	 */
+	reserve_early(PAGE_SIZE, PAGE_SIZE + PAGE_SIZE, "EX TRAMPOLINE");
+#endif
+	/* Has to be in very low memory so we can execute real-mode AP code. */
+	reserve_early(TRAMPOLINE_BASE, TRAMPOLINE_BASE + TRAMPOLINE_SIZE,
+			"TRAMPOLINE");
+}
+
 /*
  * Currently trivial. Write the real->protected mode
  * bootstrap into the page concerned. The caller
@@ -12,7 +28,6 @@ unsigned char *trampoline_base = __va(TRAMPOLINE_BASE);
  */
 unsigned long setup_trampoline(void)
 {
-	memcpy(trampoline_base, trampoline_data,
-	       trampoline_end - trampoline_data);
+	memcpy(trampoline_base, trampoline_data, TRAMPOLINE_SIZE);
 	return virt_to_phys(trampoline_base);
 }