x86/boot: Defer setup_real_mode() to early_initcall time

There's no need to run setup_real_mode() as early as we run it.
Defer it to the same early_initcall that sets up the page
permissions for the real mode code.

This should be a code size reduction.  More importantly, it give us
a longer window in which we can allocate the real mode trampoline.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Matt Fleming <mfleming@suse.de>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/fd62f0da4f79357695e9bf3e365623736b05f119.1470821230.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h
index 9c6b890d5e7a0733ed7e92f1d3f1b1aa81bd349f..8d6777724ba42977912f5f0435b750dd451a95f8 100644 (file)
--- a/arch/x86/include/asm/realmode.h
+++ b/arch/x86/include/asm/realmode.h
@@ -59,6 +59,5 @@ extern unsigned char secondary_startup_64[];
 #endif
 
 void reserve_real_mode(void);
-void setup_real_mode(void);
 
 #endif /* _ARCH_X86_REALMODE_H */

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 95c8c9c7dd6d17587e412cb8f7fc567f9f4eb745..0fa60f5f5a1641dc8eb2c82968dbadd650ed6e37 100644 (file)
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1141,8 +1141,6 @@ void __init setup_arch(char **cmdline_p)
                /* A CPU has %cr4 if and only if it has CPUID. */
                mmu_cr4_features = __read_cr4();
 
-       setup_real_mode();
-
        memblock_set_current_limit(get_max_mapped());
 
        /*

diff --git a/arch/x86/realmode/init.c b/arch/x86/realmode/init.c
index c5bdc4e473e7d52a2fbc670702acf39b6cadc38b..747b71e8f5479da20da86d2952ea9884ad18f088 100644 (file)
--- a/arch/x86/realmode/init.c
+++ b/arch/x86/realmode/init.c
@@ -30,7 +30,7 @@ void __init reserve_real_mode(void)
               base, (unsigned long long)mem, size);
 }
 
-void __init setup_real_mode(void)
+static void __init setup_real_mode(void)
 {
        u16 real_mode_seg;
        const u32 *rel;
@@ -101,7 +101,7 @@ void __init setup_real_mode(void)
  * need to mark it executable at do_pre_smp_initcalls() at least,
  * thus run it as a early_initcall().
  */
-static int __init set_real_mode_permissions(void)
+static void __init set_real_mode_permissions(void)
 {
        unsigned char *base = (unsigned char *) real_mode_header;
        size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
@@ -120,7 +120,16 @@ static int __init set_real_mode_permissions(void)
        set_memory_nx((unsigned long) base, size >> PAGE_SHIFT);
        set_memory_ro((unsigned long) base, ro_size >> PAGE_SHIFT);
        set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
+}
+
+static int __init init_real_mode(void)
+{
+       if (!real_mode_header)
+               panic("Real mode trampoline was not allocated");
+
+       setup_real_mode();
+       set_real_mode_permissions();
 
        return 0;
 }
-early_initcall(set_real_mode_permissions);
+early_initcall(init_real_mode);