linux-kernel - [RFC 10/23] ARM: mm: use physical addresses in highmem sanity checks

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Message-ID: <1343092165-9470-11-git-send-email-cyril@ti.com>
Date:	Mon, 23 Jul 2012 21:09:12 -0400
From:	Cyril Chemparathy <cyril@...com>
To:	<linux-arm-kernel@...ts.infradead.org>
CC:	<linux-kernel@...r.kernel.org>, <nico@...aro.org>,
	<will.deacon@....com>, <catalin.marinas@....com>,
	Cyril Chemparathy <cyril@...com>,
	Vitaly Andrianov <vitalya@...com>
Subject: [RFC 10/23] ARM: mm: use physical addresses in highmem sanity checks

This patch modifies the highmem sanity checking code to use physical addresses
instead.  This change eliminates the wrap-around problems associated with the
original virtual address based checks, and this simplifies the code a bit.

The one constraint imposed here is that low physical memory must be mapped in
a monotonically increasing fashion if there are multiple banks of memory,
i.e., x < y must => pa(x) < pa(y).

Signed-off-by: Cyril Chemparathy <cyril@...com>
Signed-off-by: Vitaly Andrianov <vitalya@...com>
---
 arch/arm/mm/mmu.c |   22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 226985c..adaf8c3 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -901,6 +901,7 @@ phys_addr_t arm_lowmem_limit __initdata = 0;
 void __init sanity_check_meminfo(void)
 {
 	int i, j, highmem = 0;
+	phys_addr_t vmalloc_limit = __pa(vmalloc_min - 1) + 1;
 
 	for (i = 0, j = 0; i < meminfo.nr_banks; i++) {
 		struct membank *bank = &meminfo.bank[j];
@@ -910,8 +911,7 @@ void __init sanity_check_meminfo(void)
 			highmem = 1;
 
 #ifdef CONFIG_HIGHMEM
-		if (__va(bank->start) >= vmalloc_min ||
-		    __va(bank->start) < (void *)PAGE_OFFSET)
+		if (bank->start >= vmalloc_limit)
 			highmem = 1;
 
 		bank->highmem = highmem;
@@ -920,8 +920,8 @@ void __init sanity_check_meminfo(void)
 		 * Split those memory banks which are partially overlapping
 		 * the vmalloc area greatly simplifying things later.
 		 */
-		if (!highmem && __va(bank->start) < vmalloc_min &&
-		    bank->size > vmalloc_min - __va(bank->start)) {
+		if (!highmem && bank->start < vmalloc_limit &&
+		    bank->size > vmalloc_limit - bank->start) {
 			if (meminfo.nr_banks >= NR_BANKS) {
 				printk(KERN_CRIT "NR_BANKS too low, "
 						 "ignoring high memory\n");
@@ -930,12 +930,12 @@ void __init sanity_check_meminfo(void)
 					(meminfo.nr_banks - i) * sizeof(*bank));
 				meminfo.nr_banks++;
 				i++;
-				bank[1].size -= vmalloc_min - __va(bank->start);
-				bank[1].start = __pa(vmalloc_min - 1) + 1;
+				bank[1].size -= vmalloc_limit - bank->start;
+				bank[1].start = vmalloc_limit;
 				bank[1].highmem = highmem = 1;
 				j++;
 			}
-			bank->size = vmalloc_min - __va(bank->start);
+			bank->size = vmalloc_limit - bank->start;
 		}
 #else
 		bank->highmem = highmem;
@@ -955,8 +955,7 @@ void __init sanity_check_meminfo(void)
 		 * Check whether this memory bank would entirely overlap
 		 * the vmalloc area.
 		 */
-		if (__va(bank->start) >= vmalloc_min ||
-		    __va(bank->start) < (void *)PAGE_OFFSET) {
+		if (bank->start >= vmalloc_limit) {
 			printk(KERN_NOTICE "Ignoring RAM at %.8llx-%.8llx "
 			       "(vmalloc region overlap).\n",
 			       (unsigned long long)bank->start,
@@ -968,9 +967,8 @@ void __init sanity_check_meminfo(void)
 		 * Check whether this memory bank would partially overlap
 		 * the vmalloc area.
 		 */
-		if (__va(bank->start + bank->size) > vmalloc_min ||
-		    __va(bank->start + bank->size) < __va(bank->start)) {
-			unsigned long newsize = vmalloc_min - __va(bank->start);
+		if (bank->start + bank->size > vmalloc_limit)
+			unsigned long newsize = vmalloc_limit - bank->start;
 			printk(KERN_NOTICE "Truncating RAM at %.8llx-%.8llx "
 			       "to -%.8llx (vmalloc region overlap).\n",
 			       (unsigned long long)bank->start,
-- 
1.7.9.5

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