linux-kernel - [PATCH 39/42] x86, 64bit: add pfn_range_is

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Date:	Tue,  7 Jul 2015 13:20:25 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Kees Cook <keescook@...omium.org>,
	"H. Peter Anvin" <hpa@...or.com>, Baoquan He <bhe@...hat.com>
Cc:	linux-kernel@...r.kernel.org, Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH 39/42] x86, 64bit: add pfn_range_is_highmapped()

Need to use it to support holes in highmap when remove not
used range in highmap.

Signed-off-by: Yinghai Lu <yinghai@...nel.org>
---
 arch/x86/include/asm/pgtable_64.h |  2 ++
 arch/x86/mm/init_64.c             | 22 ++++++++++++++++++++++
 arch/x86/mm/pageattr.c            | 16 +---------------
 3 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 2ee7811..6b2aae2 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -158,6 +158,8 @@ static inline int pgd_large(pgd_t pgd) { return 0; }
 extern int kern_addr_valid(unsigned long addr);
 extern void cleanup_highmap(void);
 
+int pfn_range_is_highmapped(unsigned long start_pfn, unsigned long end_pfn);
+
 #define HAVE_ARCH_UNMAPPED_AREA
 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
 
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 3b7453a..2507b98 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -290,6 +290,23 @@ void __init init_extra_mapping_uc(unsigned long phys, unsigned long size)
 	__init_extra_mapping(phys, size, _PAGE_CACHE_MODE_UC);
 }
 
+/* three holes at most*/
+#define NR_RANGE 4
+static struct range pfn_highmapped[NR_RANGE];
+static int nr_pfn_highmapped;
+
+int pfn_range_is_highmapped(unsigned long start_pfn, unsigned long end_pfn)
+{
+	int i;
+
+	for (i = 0; i < nr_pfn_highmapped; i++)
+		if ((start_pfn >= pfn_highmapped[i].start) &&
+		    (end_pfn <= pfn_highmapped[i].end))
+			return 1;
+
+	return 0;
+}
+
 /*
  * The head.S code sets up the kernel high mapping:
  *
@@ -324,6 +341,11 @@ void __init cleanup_highmap(void)
 		if (vaddr < (unsigned long) _text || vaddr > end)
 			set_pmd(pmd, __pmd(0));
 	}
+
+	nr_pfn_highmapped = add_range(pfn_highmapped, NR_RANGE,
+			nr_pfn_highmapped,
+			__pa_symbol(_text) >> PAGE_SHIFT,
+			__pa_symbol(roundup(_brk_end, PMD_SIZE)) >> PAGE_SHIFT);
 }
 
 static unsigned long __meminit
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 727158c..06a0116 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -90,20 +90,6 @@ void arch_report_meminfo(struct seq_file *m)
 static inline void split_page_count(int level) { }
 #endif
 
-#ifdef CONFIG_X86_64
-
-static inline unsigned long highmap_start_pfn(void)
-{
-	return __pa_symbol(_text) >> PAGE_SHIFT;
-}
-
-static inline unsigned long highmap_end_pfn(void)
-{
-	return __pa_symbol(roundup(_brk_end, PMD_SIZE)) >> PAGE_SHIFT;
-}
-
-#endif
-
 #ifdef CONFIG_DEBUG_PAGEALLOC
 # define debug_pagealloc 1
 #else
@@ -1271,7 +1257,7 @@ static int cpa_process_alias(struct cpa_data *cpa)
 	 * to touch the high mapped kernel as well:
 	 */
 	if (!within(vaddr, (unsigned long)_text, _brk_end) &&
-	    within(cpa->pfn, highmap_start_pfn(), highmap_end_pfn())) {
+	    pfn_range_is_highmapped(cpa->pfn, 1)) {
 		unsigned long temp_cpa_vaddr = (cpa->pfn << PAGE_SHIFT) +
 					       __START_KERNEL_map - phys_base;
 		alias_cpa = *cpa;
-- 
1.8.4.5

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