This option enables additional error checking for the kmap_local
infrastructure. Disable for production use.
+config ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
+ bool
+
+config DEBUG_KMAP_LOCAL_FORCE_MAP
+ bool "Enforce kmap_local temporary mappings"
+ depends on DEBUG_KERNEL && ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
+ select KMAP_LOCAL
+ select DEBUG_KMAP_LOCAL
+ help
+ This option enforces temporary mappings through the kmap_local
+ mechanism for non-highmem pages and on non-highmem systems.
+ Disable this for production systems!
+
config DEBUG_HIGHMEM
bool "Highmem debugging"
depends on DEBUG_KERNEL && HIGHMEM
+ select DEBUG_KMAP_LOCAL_FORCE_MAP if ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP
select DEBUG_KMAP_LOCAL
help
This option enables additional error checking for high memory
{
void *kmap;
- if (!PageHighMem(page))
+ /*
+ * To broaden the usage of the actual kmap_local() machinery always map
+ * pages when debugging is enabled and the architecture has no problems
+ * with alias mappings.
+ */
+ if (!IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP) && !PageHighMem(page))
return page_address(page);
/* Try kmap_high_get() if architecture has it enabled */
if (addr < __fix_to_virt(FIX_KMAP_END) ||
addr > __fix_to_virt(FIX_KMAP_BEGIN)) {
+ if (IS_ENABLED(CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP)) {
+ /* This _should_ never happen! See above. */
+ WARN_ON_ONCE(1);
+ return;
+ }
/*
* Handle mappings which were obtained by kmap_high_get()
* first as the virtual address of such mappings is below