powerpc: DEBUG_PAGEALLOC for 32 bits

PATCH In review Benjamin Herrenschmidt 1 participant 1 message Mar 22, 2007 PowerPC

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Benjamin Herrenschmidt

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2007-03-22 02:59 UTC #0 lore raw

PATCH 3/4 powerpc: DEBUG_PAGEALLOC for 32 bits

Here's an implementation of DEBUG_PAGEALLOC for ppc32. It disables BAT mapping and is only tested with Hash table based processor though it shouldn't be too hard to adapt it to others.

Signed-off-by Benjamin Herrenschmidt <[email protected]>

 arch/powerpc/Kconfig.debug       |    9 ++++++
 arch/powerpc/mm/init_32.c        |    4 +++
 arch/powerpc/mm/pgtable_32.c     |   52 +++++++++++++++++++++++++++++++++++++++
 arch/powerpc/mm/ppc_mmu_32.c     |    4 ++-
 include/asm-powerpc/cacheflush.h |    6 ++++
 5 files changed, 74 insertions(+), 1 deletion(-)

arch/powerpc/Kconfig.debug +9 -0

Index: linux-cell/arch/powerpc/Kconfig.debug
===================================================================
@@ -18,6 +18,15 @@ config DEBUG_STACK_USAGE
 
 	  This option will slow down process creation somewhat.
 
+config DEBUG_PAGEALLOC
+        bool "Debug page memory allocations"
+        depends on DEBUG_KERNEL && !SOFTWARE_SUSPEND && PPC32
+        help
+          Unmap pages from the kernel linear mapping after free_pages().
+          This results in a large slowdown, but helps to find certain types
+          of memory corruptions.
+
+
 config HCALL_STATS
 	bool "Hypervisor call instrumentation"
 	depends on PPC_PSERIES && DEBUG_FS

arch/powerpc/mm/init_32.c +4 -0

Index: linux-cell/arch/powerpc/mm/init_32.c
===================================================================
@@ -115,6 +115,10 @@ void MMU_setup(void)
 	if (strstr(cmd_line, "noltlbs")) {
 		__map_without_ltlbs = 1;
 	}
+#ifdef CONFIG_DEBUG_PAGEALLOC
+	__map_without_bats = 1;
+	__map_without_ltlbs = 1;
+#endif
 }
 
 /*

arch/powerpc/mm/pgtable_32.c +52 -0

55 lines not on this page · raw message

arch/powerpc/mm/ppc_mmu_32.c +3 -1

Index: linux-cell/arch/powerpc/mm/ppc_mmu_32.c
===================================================================
@@ -85,8 +85,10 @@ unsigned long __init mmu_mapin_ram(void)
 	unsigned long max_size = (256<<20);
 	unsigned long align;
 
-	if (__map_without_bats)
+	if (__map_without_bats) {
+		printk(KERN_DEBUG "RAM mapped without BATs\n");
 		return 0;
+	}
 
 	/* Set up BAT2 and if necessary BAT3 to cover RAM. */

include/asm-powerpc/cacheflush.h +6 -0

Index: linux-cell/include/asm-powerpc/cacheflush.h
===================================================================
@@ -64,6 +64,12 @@ extern void flush_dcache_phys_range(unsi
 	memcpy(dst, src, len)
 
 
+
+#ifdef CONFIG_DEBUG_PAGEALLOC
+/* internal debugging function */
+void kernel_map_pages(struct page *page, int numpages, int enable);
+#endif
+
 #endif /* __KERNEL__ */
 
 #endif /* _ASM_POWERPC_CACHEFLUSH_H */