config HIGHPTE
bool "Allocate 2nd-level pagetables from highmem"
depends on HIGHMEM
+ help
+ The VM uses one page of physical memory for each page table.
+ For systems with a lot of processes, this can use a lot of
+ precious low memory, eventually leading to low memory being
+ consumed by page tables. Setting this option will allow
+ user-space 2nd level page tables to reside in high memory.
+ config CPU_SW_DOMAIN_PAN
+ bool "Enable use of CPU domains to implement privileged no-access"
+ depends on MMU && !ARM_LPAE
+ default y
+ help
+ Increase kernel security by ensuring that normal kernel accesses
+ are unable to access userspace addresses. This can help prevent
+ use-after-free bugs becoming an exploitable privilege escalation
+ by ensuring that magic values (such as LIST_POISON) will always
+ fault when dereferenced.
+
+ CPUs with low-vector mappings use a best-efforts implementation.
+ Their lower 1MB needs to remain accessible for the vectors, but
+ the remainder of userspace will become appropriately inaccessible.
+
config HW_PERF_EVENTS
bool "Enable hardware performance counter support for perf events"
depends on PERF_EVENTS