path: root/arch/powerpc/kernel
diff options
authorPaul Mackerras <>2013-06-14 20:07:41 +1000
committerBenjamin Herrenschmidt <>2013-06-15 12:24:11 +1000
commitbf593907f7236e95698a76b7c7a2bbf8b1165327 (patch)
treeec0f1c5adc9fdb5c81cf51724d2e36601b854d5a /arch/powerpc/kernel
parent0e37739b1c96d65e6433998454985de994383019 (diff)
powerpc: Fix emulation of illegal instructions on PowerNV platform
Normally, the kernel emulates a few instructions that are unimplemented on some processors (e.g. the old dcba instruction), or privileged (e.g. mfpvr). The emulation of unimplemented instructions is currently not working on the PowerNV platform. The reason is that on these machines, unimplemented and illegal instructions cause a hypervisor emulation assist interrupt, rather than a program interrupt as on older CPUs. Our vector for the emulation assist interrupt just calls program_check_exception() directly, without setting the bit in SRR1 that indicates an illegal instruction interrupt. This fixes it by making the emulation assist interrupt set that bit before calling program_check_interrupt(). With this, old programs that use no-longer implemented instructions such as dcba now work again. CC: <> Signed-off-by: Paul Mackerras <> Signed-off-by: Benjamin Herrenschmidt <>
Diffstat (limited to 'arch/powerpc/kernel')
2 files changed, 11 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index e783453f910d..40e4a17c8ba0 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -683,7 +683,7 @@ machine_check_common:
STD_EXCEPTION_COMMON(0xb00, trap_0b, .unknown_exception)
STD_EXCEPTION_COMMON(0xd00, single_step, .single_step_exception)
STD_EXCEPTION_COMMON(0xe00, trap_0e, .unknown_exception)
- STD_EXCEPTION_COMMON(0xe40, emulation_assist, .program_check_exception)
+ STD_EXCEPTION_COMMON(0xe40, emulation_assist, .emulation_assist_interrupt)
STD_EXCEPTION_COMMON(0xe60, hmi_exception, .unknown_exception)
STD_EXCEPTION_COMMON_ASYNC(0xe80, h_doorbell, .doorbell_exception)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index f18c79c324ef..c0e5caf8ccc7 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1165,6 +1165,16 @@ bail:
+ * This occurs when running in hypervisor mode on POWER6 or later
+ * and an illegal instruction is encountered.
+ */
+void __kprobes emulation_assist_interrupt(struct pt_regs *regs)
+ regs->msr |= REASON_ILLEGAL;
+ program_check_exception(regs);
void alignment_exception(struct pt_regs *regs)
enum ctx_state prev_state = exception_enter();