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authorToshi Kani <toshi.kani@hp.com>2015-07-16 17:23:15 -0600
committerThomas Gleixner <tglx@linutronix.de>2015-07-22 17:20:34 +0200
commit9a58eebe1ace609bedf8c5a65e70a097459f5696 (patch)
tree535f154aa71ed83cd26da83842b20e6e080b251f /arch/x86
parent1c9cf9b211030a454a84cbc1cb15b82d9aa49011 (diff)
x86/mm: Remove region_is_ram() call from ioremap
__ioremap_caller() calls region_is_ram() to walk through the iomem_resource table to check if a target range is in RAM, which was added to improve the lookup performance over page_is_ram() (commit 906e36c5c717 "x86: use optimized ioresource lookup in ioremap function"). page_is_ram() was no longer used when this change was added, though. __ioremap_caller() then calls walk_system_ram_range(), which had replaced page_is_ram() to improve the lookup performance (commit c81c8a1eeede "x86, ioremap: Speed up check for RAM pages"). Since both checks walk through the same iomem_resource table for the same purpose, there is no need to call both functions. Aside of that walk_system_ram_range() is the only useful check at the moment because region_is_ram() always returns -1 due to an implementation bug. That bug in region_is_ram() cannot be fixed without breaking existing ioremap callers, which rely on the subtle difference of walk_system_ram_range() versus non page aligned ranges. Once these offending callers are fixed we can use region_is_ram() and remove walk_system_ram_range(). [ tglx: Massaged changelog ] Signed-off-by: Toshi Kani <toshi.kani@hp.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Cc: Roland Dreier <roland@purestorage.com> Cc: Mike Travis <travis@sgi.com> Cc: Luis R. Rodriguez <mcgrof@suse.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/1437088996-28511-3-git-send-email-toshi.kani@hp.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/mm/ioremap.c24
1 files changed, 6 insertions, 18 deletions
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index fd3df0ddb4d4..b9d4a33017fd 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -92,7 +92,6 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
pgprot_t prot;
int retval;
void __iomem *ret_addr;
- int ram_region;
/* Don't allow wraparound or zero size */
last_addr = phys_addr + size - 1;
@@ -115,26 +114,15 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
/*
* Don't allow anybody to remap normal RAM that we're using..
*/
- /* First check if whole region can be identified as RAM or not */
- ram_region = region_is_ram(phys_addr, size);
- if (ram_region > 0) {
- WARN_ONCE(1, "ioremap on RAM at 0x%lx - 0x%lx\n",
- (unsigned long int)phys_addr,
- (unsigned long int)last_addr);
- return NULL;
- }
-
- /* If could not be identified(-1), check page by page */
- if (ram_region < 0) {
- pfn = phys_addr >> PAGE_SHIFT;
- last_pfn = last_addr >> PAGE_SHIFT;
- if (walk_system_ram_range(pfn, last_pfn - pfn + 1, NULL,
+ pfn = phys_addr >> PAGE_SHIFT;
+ last_pfn = last_addr >> PAGE_SHIFT;
+ if (walk_system_ram_range(pfn, last_pfn - pfn + 1, NULL,
__ioremap_check_ram) == 1) {
- WARN_ONCE(1, "ioremap on RAM at 0x%llx - 0x%llx\n",
+ WARN_ONCE(1, "ioremap on RAM at 0x%llx - 0x%llx\n",
phys_addr, last_addr);
- return NULL;
- }
+ return NULL;
}
+
/*
* Mappings have to be page-aligned
*/