x86: fix x86-32 early fixmap initialization.

pageexec@freemail.hu writes:

> i've just noticed that the chunk in i386/kernel/head.S ended up in a
> weird place, namely, it's not going to be executed as it's just after
> a 'jmp 3f' and before startup_32_smp, probably not what you intended.
> on a sidenote, the whole thing can be done in a single insn, like:
>
> movl $(swapper_pg_pmd - __PAGE_OFFSET + 0x067), (swapper_pg_dir -
> __PAGE_OFFSET+ 4092)

Thanks for the reminder I thought we had fixed this problem a while ago.

Needed to get fixed virtual address for USB debug and earlycon with mmio.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 374b7ec..ac0637a 100644 (file)
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -193,6 +193,12 @@ default_entry:
        jb 10b
        movl %edi,(init_pg_tables_end - __PAGE_OFFSET)
 
+       /* Do an early initialization of the fixmap area */
+       movl $(swapper_pg_dir - __PAGE_OFFSET), %edx
+       movl $(swapper_pg_pmd - __PAGE_OFFSET), %eax
+       addl $0x007, %eax                       /* 0x007 = PRESENT+RW+USER */
+       movl %eax, 4092(%edx)
+
        xorl %ebx,%ebx                          /* This is the boot CPU (BSP) */
        jmp 3f
 /*
@@ -208,12 +214,6 @@ default_entry:
 .section .init.text,"ax",@progbits
 #endif
 
-       /* Do an early initialization of the fixmap area */
-       movl $(swapper_pg_dir - __PAGE_OFFSET), %edx
-       movl $(swapper_pg_pmd - __PAGE_OFFSET), %eax
-       addl $0x007, %eax                       /* 0x007 = PRESENT+RW+USER */
-       movl %eax, 4092(%edx)
-
 #ifdef CONFIG_SMP
 ENTRY(startup_32_smp)
        cld