On x86, ioremap() and remap_pfn_range() fail on conflicting cache
type of an alias mapping request only if the case is not allowed
by the rule set in is_new_memtype_allowed(). While this exemption
is necessary for remap_pfn_range() called for /dev/mem mappings,
it is not necessary for ioremap(). Drivers should never call
ioremap() with a conflicting cache type. This exemption handling
may hide possible bugs in drivers.
Add a warning message to ioremap() when a conflicting cache type
is allowed by is_new_memtype_allowed(). This helps us identify
such usages in drivers.
There is no change in the behavior.
Link: https://lkml.org/lkml/2016/4/16/54
Signed-off-by: Toshi Kani <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Luis R. Rodriguez <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Dan Williams <[email protected]>
---
arch/x86/mm/ioremap.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
index 0d8d53d..16c5887 100644
--- a/arch/x86/mm/ioremap.c
+++ b/arch/x86/mm/ioremap.c
@@ -138,14 +138,16 @@ static void __iomem *__ioremap_caller(resource_size_t phys_addr,
}
if (pcm != new_pcm) {
- if (!is_new_memtype_allowed(phys_addr, size, pcm, new_pcm)) {
- printk(KERN_ERR
- "ioremap error for 0x%llx-0x%llx, requested 0x%x, got 0x%x\n",
+ retval = is_new_memtype_allowed(phys_addr, size, pcm, new_pcm);
+ pr_err(
+ "ioremap %s for 0x%llx-0x%llx, requested 0x%x, got 0x%x\n",
+ retval ? "warning" : "error",
(unsigned long long)phys_addr,
(unsigned long long)(phys_addr + size),
pcm, new_pcm);
+ if (!retval)
goto err_free_memtype;
- }
+
pcm = new_pcm;
}