[tip:core/memblock] x86-64: Only set max_pfn_mapped to 512 MiB if we enter via head_64.S

tip-bot for Jeremy Fitzhardinge
2010-10-14T07:42:53Z

Commit-ID: 67e87f0a1c5cbc750f81ebf6a128e8ff6f4376cc
Gitweb: http://git.kernel.org/tip/67e87f0a1c5cbc750f81ebf6a128e8ff6f4376cc
Author: Jeremy Fitzhardinge <jeremy@goop.org>
AuthorDate: Wed, 13 Oct 2010 16:34:15 -0700
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 14 Oct 2010 09:06:49 +0200

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>
---
arch/x86/kernel/head64.c | 2 ++
arch/x86/kernel/setup.c | 1 -
2 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 97adf98..2d2673c 100644
--- 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
--- 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

/*