[PATCH 2/2] powerpc: kdump: Override crash_free_reserved_phys_range to avoid freeing RTAS

Anton Blanchard
2010-08-25T00:28:07Z

The crashkernel region will almost always overlap RTAS. If we free the
crashkernel region via "echo 0 > /sys/kernel/kexec_crash_size" then we will
free RTAS and the machine will crash in confusing and exciting ways.

Override crash_free_reserved_phys_range and check for overlap with RTAS.

Signed-off-by: Anton Blanchard <anton@samba.org>
---

Index: powerpc.git/arch/powerpc/kernel/crash_dump.c
===================================================================
--- powerpc.git.orig/arch/powerpc/kernel/crash_dump.c 2010-08-24 09:24:32.219643256 +1000
+++ powerpc.git/arch/powerpc/kernel/crash_dump.c 2010-08-24 09:46:22.826868330 +1000
@@ -19,6 +19,7 @@
#include <asm/prom.h>
#include <asm/firmware.h>
#include <asm/uaccess.h>
+#include <asm/rtas.h>

#ifdef DEBUG
#include <asm/udbg.h>
@@ -141,3 +142,35 @@ ssize_t copy_oldmem_page(unsigned long p

return csize;
}
+
+#ifdef CONFIG_PPC_RTAS
+/*
+ * The crashkernel region will almost always overlap the RTAS region, so
+ * we have to be careful when shrinking the crashkernel region.
+ */
+void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
+{
+ unsigned long addr;
+ const u32 *basep, *sizep;
+ unsigned int rtas_start = 0, rtas_end = 0;
+
+ basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
+ sizep = of_get_property(rtas.dev, "rtas-size", NULL);
+
+ if (basep && sizep) {
+ rtas_start = *basep;
+ rtas_end = *basep + *sizep;
+ }
+
+ for (addr = begin; addr < end; addr += PAGE_SIZE) {
+ /* Does this page overlap with the RTAS region? */
+ if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
+ continue;
+
+ ClearPageReserved(pfn_to_page(addr >> PAGE_SHIFT));
+ init_page_count(pfn_to_page(addr >> PAGE_SHIFT));
+ free_page((unsigned long)__va(addr));
+ totalram_pages++;
+ }
+}
+#endif