linux-kernel - [PATCH 03/10] x86, mm: get early page table from BRK

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Date:	Mon,  8 Oct 2012 21:39:11 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...or.com>, Jacob Shin <jacob.shin@....com>,
	Tejun Heo <tj@...nel.org>
Cc:	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	linux-kernel@...r.kernel.org, Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH 03/10] x86, mm: get early page table from BRK

Get pgt_buf early from BRK, and use it to map page table at first.

also use the left at first, then use new one.

-v2: extra xen call back for that new range.
-v3: fix compiling about #llx in print out that is reported by Fengguang
-v4: remove the early_pgt_buf_* stuff, because xen interface is ready yet.
     still need to run x86_init.mapping.pagetable_reserve separately.
     so we will waste some pages in BRK, will address that later.

Signed-off-by: Yinghai Lu <yinghai@...nel.org>
---
 arch/x86/include/asm/pgtable.h |    1 +
 arch/x86/kernel/setup.c        |    2 ++
 arch/x86/mm/init.c             |   26 +++++++++++++++++++++++++-
 3 files changed, 28 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 52d40a1..25fa5bb 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -599,6 +599,7 @@ static inline int pgd_none(pgd_t pgd)
 
 extern int direct_gbpages;
 void init_mem_mapping(void);
+void early_alloc_pgt_buf(void);
 
 /* local pte updates need not use xchg for locking */
 static inline pte_t native_local_ptep_get_and_clear(pte_t *ptep)
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 4989f80..7eb6855 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -896,6 +896,8 @@ void __init setup_arch(char **cmdline_p)
 
 	reserve_ibft_region();
 
+	early_alloc_pgt_buf();
+
 	/*
 	 * Need to conclude brk, before memblock_x86_fill()
 	 *  it could use memblock_find_in_range, could overlap with
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 0c58f2d..a89f485 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -317,12 +317,22 @@ static void __init find_early_table_space(unsigned long start,
 					  unsigned long good_end,
 					  unsigned long tables)
 {
-	phys_addr_t base;
+	unsigned long base;
 
 	base = memblock_find_in_range(start, good_end, tables, PAGE_SIZE);
 	if (!base)
 		panic("Cannot find space for the kernel page tables");
 
+	init_memory_mapping(base, base + tables);
+	if (pgt_buf_end > pgt_buf_start) {
+		printk(KERN_DEBUG "kernel direct mapping tables from %#lx to %#lx @ [mem %#010lx-%#010lx]\n",
+			base, base + tables - 1, pgt_buf_start << PAGE_SHIFT,
+			(pgt_buf_end << PAGE_SHIFT) - 1);
+
+		x86_init.mapping.pagetable_reserve(PFN_PHYS(pgt_buf_start),
+						PFN_PHYS(pgt_buf_end));
+	}
+
 	pgt_buf_start = base >> PAGE_SHIFT;
 	pgt_buf_end = pgt_buf_start;
 	pgt_buf_top = pgt_buf_start + (tables >> PAGE_SHIFT);
@@ -469,6 +479,20 @@ void __init init_mem_mapping(void)
 	early_memtest(0, max_pfn_mapped << PAGE_SHIFT);
 }
 
+RESERVE_BRK(early_pgt_alloc, 16384);
+
+void  __init early_alloc_pgt_buf(void)
+{
+	unsigned long tables = 16384;
+	phys_addr_t base;
+
+	base = __pa(extend_brk(tables, PAGE_SIZE));
+
+	pgt_buf_start = base >> PAGE_SHIFT;
+	pgt_buf_end = pgt_buf_start;
+	pgt_buf_top = pgt_buf_start + (tables >> PAGE_SHIFT);
+}
+
 /*
  * devmem_is_allowed() checks to see if /dev/mem access to a certain address
  * is valid. The argument is a physical page number.
-- 
1.7.7

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