arm64: Add support for ARCH_SUPPORTS_DEBUG_PAGEALLOC

ARCH_SUPPORTS_DEBUG_PAGEALLOC provides a hook to map and unmap
pages for debugging purposes. This requires memory be mapped
with PAGE_SIZE mappings since breaking down larger mappings
at runtime will lead to TLB conflicts. Check if debug_pagealloc
is enabled at runtime and if so, map everyting with PAGE_SIZE
pages. Implement the functions to actually map/unmap the
pages at runtime.

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
[catalin.marinas@arm.com: static annotation block_mappings_allowed() and #ifdef]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 53e48a617fef..5a1f2e47d153 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -537,6 +537,9 @@ config HOTPLUG_CPU
 source kernel/Kconfig.preempt
 source kernel/Kconfig.hz
 
+config ARCH_SUPPORTS_DEBUG_PAGEALLOC
+        def_bool y
+
 config ARCH_HAS_HOLES_MEMORYMODEL
         def_bool y if SPARSEMEM