linux-kernel - [PATCH 2/2] powerpc: kdump: Override crash_free_reserved_phys

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 25 Aug 2010 10:23:44 +1000
From:	Anton Blanchard <anton@...ba.org>
To:	benh@...nel.crashing.org, ebiederm@...ssion.com,
	akpm@...ux-foundation.org
Cc:	kexec@...ts.infradead.org, linuxppc-dev@...abs.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] powerpc: kdump: Override
 crash_free_reserved_phys_range to avoid freeing RTAS


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@...ba.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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/