diff mbox series

[3/3] MIPS: Detect bad _PFN_SHIFT values

Message ID 20190918220258.29428-3-paul.burton@mips.com (mailing list archive)
State Accepted
Headers show
Series [1/3] MIPS: Disable pte_special() for MIPS32 with 4KiB pages & RiXi | expand

Commit Message

Paul Burton Sept. 18, 2019, 10:03 p.m. UTC 
2 recent commits have fixed issues where _PFN_SHIFT grew too large due
to the introduction of too many pgprot bits in our PTEs for some MIPS32
kernel configurations. Tracking down such issues can be tricky, so add a
BUILD_BUG_ON() to help.

Signed-off-by: Paul Burton <paul.burton@mips.com>
---

 arch/mips/mm/init.c | 6 ++++++
 1 file changed, 6 insertions(+)
diff mbox series

Patch

diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 6fea3b54c961..090fa653dfa9 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -446,6 +446,12 @@  static inline void __init mem_init_free_highmem(void)
 
 void __init mem_init(void)
 {
+	/*
+	 * When _PFN_SHIFT is greater than PAGE_SHIFT we won't have enough PTE
+	 * bits to hold a full 32b physical address on MIPS32 systems.
+	 */
+	BUILD_BUG_ON(IS_ENABLED(CONFIG_32BIT) && (_PFN_SHIFT > PAGE_SHIFT));
+
 #ifdef CONFIG_HIGHMEM
 #ifdef CONFIG_DISCONTIGMEM
 #error "CONFIG_HIGHMEM and CONFIG_DISCONTIGMEM dont work together yet"