[OpenBIOS] [PATCH 2/2] Don't map the page 0 to make NULL-dereferencing more obvious

[Artyom Tarasenko]

Signed-off-by: Artyom Tarasenko 
---
 arch/sparc32/lib.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/arch/sparc32/lib.c b/arch/sparc32/lib.c
index 483069c..215ddcc 100644
--- a/arch/sparc32/lib.c
+++ b/arch/sparc32/lib.c
@@ -19,6 +19,8 @@

#define NCTX_SWIFT  0x100
 #define LOWMEMSZ 32 * 1024 * 1024
+/* Avoid mapping the first page to make NULL-dereferencing more obvious */
+#define LOWMEM_START PAGE_SIZE

#ifdef CONFIG_DEBUG_MEM
 #define DPRINTF(fmt, args...)                   \
@@ -403,7 +405,8 @@ init_mmu_swift(void)
     ofmem_arch_map_pages(pa, va, size, ofmem_arch_default_translation_mode(pa));

// 1:1 mapping for RAM
-    ofmem_arch_map_pages(0, 0, LOWMEMSZ, ofmem_arch_default_translation_mode(0));
+    ofmem_arch_map_pages(LOWMEM_START, LOWMEM_START, LOWMEMSZ,
+                         ofmem_arch_default_translation_mode(LOWMEM_START));

/*
      * Flush cache