From: Jason Uhlenkott <jasonuhl@sgi.com>
To: linux-ia64@vger.kernel.org
Subject: [PATCH] 2.4.25: BUG(): Use guard page instead of page 0
Date: Wed, 18 Feb 2004 22:13:03 +0000 [thread overview]
Message-ID: <20040218221302.GA87364@dragonfly.csd.sgi.com> (raw)
The ia64 BUG macro deliberately writes to address 0 in order to
trigger a page fault and an Oops. This won't work if the process has
mapped something into page zero: We'll just print the "kernel BUG"
message and continue (after having stomped on whatever user memory was
at address 0).
A solution is to write to the guard page in region 5, which is
guaranteed to trigger a page fault.
--- linux-2.4.25.orig/include/asm-ia64/page.h Wed Feb 18 05:36:32 2004
+++ linux-2.4.25/include/asm-ia64/page.h Wed Feb 18 13:59:10 2004
@@ -120,7 +120,7 @@
#define is_invalid_hugepage_range(addr, len) 0
#endif
-#define BUG() do { printk("kernel BUG at %s:%d!\n", __FILE__, __LINE__); *(int *)0=0; } while (0)
+#define BUG() do { printk("kernel BUG at %s:%d!\n", __FILE__, __LINE__); *(int *)0xa000000000000000=0; } while (0)
#define PAGE_BUG(page) do { BUG(); } while (0)
static __inline__ int
next reply other threads:[~2004-02-18 22:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-02-18 22:13 Jason Uhlenkott [this message]
2004-02-19 1:14 ` [PATCH] 2.4.25: BUG(): Use guard page instead of page 0 David Mosberger
2004-03-04 23:25 ` Bjorn Helgaas
2004-03-04 23:41 ` Keith Owens
2004-03-04 23:57 ` Bjorn Helgaas
2004-03-05 0:05 ` David Mosberger
2004-03-05 0:06 ` David Mosberger
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