[PATCH v3] Make instruction dumping work in real mode.

Scott Wood scottwood at freescale.com
Fri Sep 28 04:00:01 EST 2007

On non-book-E-or-4xx, exceptions execute in real mode.  If a fault happens
that leads to a register dump, the kernel currently prints XXXXXXXX because
it doesn't realize that PC is a physical address.

This patch checks the state of the IMMU, and if necessary converts PC into a
virtual address.

Signed-off-by: Scott Wood <scottwood at freescale.com>
Resent with 40x->44x.

 arch/powerpc/kernel/process.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 57c589c..6dbde7f 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -354,6 +354,14 @@ static void show_instructions(struct pt_regs *regs)
 		if (!(i % 8))
+#if !defined(CONFIG_BOOKE) && !defined(CONFIG_44x)
+		/* If executing with the IMMU off, adjust pc rather
+		 * than print XXXXXXXX.
+		 */
+		if (!(regs->msr & MSR_IR))
+			pc = (unsigned long)phys_to_virt(pc);
 		/* We use __get_user here *only* to avoid an OOPS on a
 		 * bad address because the pc *should* only be a
 		 * kernel address.

More information about the Linuxppc-dev mailing list