ARC: build: disallow invalid PAE40 + 4K page config

The config option being built was
| CONFIG_ARC_MMU_V4=y
| CONFIG_ARC_PAGE_SIZE_4K=y
| CONFIG_HIGHMEM=y
| CONFIG_ARC_HAS_PAE40=y

This was hitting a BUILD_BUG_ON() since a 4K page can't hoist 1k, 8-byte
PTE entries (8 byte due to PAE40). BUILD_BUG_ON() is a good last ditch
resort, but such a config needs to be disallowed explicitly in Kconfig.

Side-note: the actual fix is single liner dependency, but while at it
cleaned out a few things:
 - 4K dependency on MMU v3 or v4 is always true, since 288ff7de62af09
   ("ARC: retire MMUv1 and MMUv2 support")
 - PAE40 dependency in on MMU ver not really ISA, although that follows
   eventually.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202409160223.xydgucbY-lkp@intel.com/
Signed-off-by: Vineet Gupta <vgupta@kernel.org>

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 5b24881420414729de85b3e3c42e3c1215c62ba8..69c6e71fa1e6ba21fff7b67cb2ca0442099ad5d1 100644 (file)
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -297,7 +297,6 @@ config ARC_PAGE_SIZE_16K
 config ARC_PAGE_SIZE_4K
        bool "4KB"
        select HAVE_PAGE_SIZE_4KB
-       depends on ARC_MMU_V3 || ARC_MMU_V4
 
 endchoice
 
@@ -474,7 +473,8 @@ config HIGHMEM
 
 config ARC_HAS_PAE40
        bool "Support for the 40-bit Physical Address Extension"
-       depends on ISA_ARCV2
+       depends on MMU_V4
+       depends on !ARC_PAGE_SIZE_4K
        select HIGHMEM
        select PHYS_ADDR_T_64BIT
        help