The refactoring of commit 296e5a0a6c3935 has a nasty bug: it accidentally dropped the generation of code to raise the UNDEF exception when disas_thumb2_insn() returns nonzero. This means that 32-bit Thumb2 instruction patterns that ought to UNDEF just act like nops instead. This is likely to break any number of things, including the kernel's "disable the FPU and use the UNDEF exception to identify when to turn it back on again" trick.
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org> --- This is the smallest possible fix that will correct the bug, for possible inclusion in 2.11; for 2.12 we should fix the asymmetry where disas_thumb() generates its own exception-raising code but disas_thumb2() wants the caller to do it. (This asymmetry is why we didn't notice the problem in code review.) I'm not sure whether this should go into 2.11 or not -- this time last week it would have been an easy "yes". --- target/arm/translate.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/target/arm/translate.c b/target/arm/translate.c index 4afb0c8..f120932 100644 --- a/target/arm/translate.c +++ b/target/arm/translate.c @@ -12245,7 +12245,10 @@ static void thumb_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu) if (is_16bit) { disas_thumb_insn(dc, insn); } else { - disas_thumb2_insn(dc, insn); + if (disas_thumb2_insn(dc, insn)) { + gen_exception_insn(dc, 4, EXCP_UDEF, syn_uncategorized(), + default_exception_el(dc)); + } } /* Advance the Thumb condexec condition. */ -- 2.7.4