x86-64: Only set max_pfn_mapped to 512 MiB if we enter via head_64.S

head_64.S maps up to 512 MiB, but that is not necessarity true for
other entry paths, such as Xen.

Thus, co-locate the setting of max_pfn_mapped with the code to
actually set up the page tables in head_64.S.  The 32-bit code is
already so co-located.  (The Xen code already sets max_pfn_mapped
correctly for its own use case.)

-v2:

 Yinghai fixed the following bug in this patch:

 |
 | max_pfn_mapped is in .bss section, so we need to set that
 | after bss get cleared. Without that we crash on bootup.
 |
 | That is safe because Xen does not call x86_64_start_kernel().
 |

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Fixed-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
LKML-Reference: <4CB6AB24.9020504@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 97adf98..2d2673c 100644 (file)
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -80,6 +80,8 @@ void __init x86_64_start_kernel(char * real_mode_data)
        /* Cleanup the over mapped high alias */
        cleanup_highmap();
 
+       max_pfn_mapped = KERNEL_IMAGE_SIZE >> PAGE_SHIFT;
+
        for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) {
 #ifdef CONFIG_EARLY_PRINTK
                set_intr_gate(i, &early_idt_handlers[i]);

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index b11a238..c3cebfe 100644 (file)
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -932,7 +932,6 @@ void __init setup_arch(char **cmdline_p)
                max_low_pfn = max_pfn;
 
        high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
-       max_pfn_mapped = KERNEL_IMAGE_SIZE >> PAGE_SHIFT;
 #endif
 
        /*