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

From: Cyril Chemparathy
Date: Mon Jul 23 2012 - 21:11:08 EST


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@xxxxxx>
Signed-off-by: Vitaly Andrianov <vitalya@xxxxxx>
---
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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/