Home Home > GIT Browse
diff options
authorPaul Mackerras <paulus@samba.org>2013-06-14 20:07:41 +1000
committerBen Hutchings <ben@decadent.org.uk>2013-06-19 02:17:02 +0100
commite4f37de094d8c0a55af0fe63d7f715457b2de3e6 (patch)
parent08647d0f99db39f73f37e00ebafc24ff3d3f4948 (diff)
powerpc: Fix emulation of illegal instructions on PowerNV platform
commit bf593907f7236e95698a76b7c7a2bbf8b1165327 upstream. 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. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2 files changed, 11 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index cf9c69b9189c..8c3baa08b84e 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -463,7 +463,7 @@ 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_IDLE(0xf00, performance_monitor, .performance_monitor_exception)
STD_EXCEPTION_COMMON(0x1300, instruction_breakpoint, .instruction_breakpoint_exception)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 82dcd4d8b4eb..9844662a8014 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1036,6 +1036,16 @@ void __kprobes program_check_exception(struct pt_regs *regs)
_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
+ * 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)
int sig, code, fixed = 0;