From: Tom Musta <tommu...@gmail.com>
This patch modifies the endian chicken switch in the single step
emulation code (emulate_step()). The old (big endian) code bailed
early if a load or store instruction was to be emulated in little
endian mode.
The new code modifies the check and only bails in a cross-endian
situation (LE mode in a kernel compiled for BE and vice verse).
V2: fixed bug in MSR[LE] check identified by Andreas Schwab and
Geert Uytterhoeven.
Signed-off-by: Tom Musta <tommu...@gmail.com>
---
arch/powerpc/lib/sstep.c | 12 +++++++++---
1 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index b1faa15..7bfaa9d 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -1222,12 +1222,18 @@ int __kprobes emulate_step(struct pt_regs *regs,
unsigned int instr)
}
/*
- * Following cases are for loads and stores, so bail out
- * if we're in little-endian mode.
+ * Following cases are for loads and stores and this
+ * implementation does not support cross-endian. So
+ * bail out if this is the case.
*/
+#ifdef __BIG_ENDIAN__
if (regs->msr & MSR_LE)
return 0;
-
+#endif
+#ifdef __LITTLE_ENDIAN__
+ if (!(regs->msr & MSR_LE))
+ return 0;
+#endif
/*
* Save register RA in case it's an update form load or store
* and the access faults.
--
1.7.1
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