On 2/13/19 1:04 AM, Benjamin Herrenschmidt wrote: > On Tue, 2019-02-12 at 17:02 +1100, David Gibson wrote: >> On Mon, Jan 28, 2019 at 10:46:14AM +0100, Cédric Le Goater wrote: >>> From: Benjamin Herrenschmidt <b...@kernel.crashing.org> >>> >>> Those instructions currently raise an exception from within >>> the helper. This tends to result in a bogus nip value in >>> the env context (typically the beginning of the TB). Such >>> a helper needs a gen_update_nip() first. >>> >>> This fixes it with a different approach which is to throw >>> the exception from translate.c instead of the helper using >>> gen_exception_nip() which does the right thing. >>> >>> Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org> >>> Signed-off-by: Cédric Le Goater <c...@kaod.org> >>> --- >>> target/ppc/excp_helper.c | 1 - >>> target/ppc/translate.c | 12 ++++++++---- >>> 2 files changed, 8 insertions(+), 5 deletions(-) >>> >>> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c >>> index 751d759fcc1d..8407e0ade938 100644 >>> --- a/target/ppc/excp_helper.c >>> +++ b/target/ppc/excp_helper.c >>> @@ -958,7 +958,6 @@ void helper_pminsn(CPUPPCState *env, powerpc_pm_insn_t >>> insn) >>> * but this doesn't seem to be a problem. >>> */ >>> env->msr |= (1ull << MSR_EE); >>> - raise_exception(env, EXCP_HLT); >>> } >>> #endif /* defined(TARGET_PPC64) */ >>> >>> diff --git a/target/ppc/translate.c b/target/ppc/translate.c >>> index 7d40a1fbe6bd..55281a8975e0 100644 >>> --- a/target/ppc/translate.c >>> +++ b/target/ppc/translate.c >>> @@ -3571,7 +3571,8 @@ static void gen_doze(DisasContext *ctx) >>> t = tcg_const_i32(PPC_PM_DOZE); >>> gen_helper_pminsn(cpu_env, t); >>> tcg_temp_free_i32(t); >>> - gen_stop_exception(ctx); >>> + /* Stop translation, as the CPU is supposed to sleep from now */ >>> + gen_exception_nip(ctx, EXCP_HLT, ctx->base.pc_next); >> >> IIUC this also changes from EXCP_STOP to EXCP_HLT, is that intentional? > > Off the top of my head, it might be to break out of the outer exec > loop, but I don't remember off hand.
yes and POWERPC_EXCP_STOP is only used under linux-user, which is the wrong value to exit from the cpu exec loop. I think this is correct. C. >>> #endif /* defined(CONFIG_USER_ONLY) */ >>> } >>> >>> @@ -3586,7 +3587,8 @@ static void gen_nap(DisasContext *ctx) >>> t = tcg_const_i32(PPC_PM_NAP); >>> gen_helper_pminsn(cpu_env, t); >>> tcg_temp_free_i32(t); >>> - gen_stop_exception(ctx); >>> + /* Stop translation, as the CPU is supposed to sleep from now */ >>> + gen_exception_nip(ctx, EXCP_HLT, ctx->base.pc_next); >>> #endif /* defined(CONFIG_USER_ONLY) */ >>> } >>> >>> @@ -3606,7 +3608,8 @@ static void gen_sleep(DisasContext *ctx) >>> t = tcg_const_i32(PPC_PM_SLEEP); >>> gen_helper_pminsn(cpu_env, t); >>> tcg_temp_free_i32(t); >>> - gen_stop_exception(ctx); >>> + /* Stop translation, as the CPU is supposed to sleep from now */ >>> + gen_exception_nip(ctx, EXCP_HLT, ctx->base.pc_next); >>> #endif /* defined(CONFIG_USER_ONLY) */ >>> } >>> >>> @@ -3621,7 +3624,8 @@ static void gen_rvwinkle(DisasContext *ctx) >>> t = tcg_const_i32(PPC_PM_RVWINKLE); >>> gen_helper_pminsn(cpu_env, t); >>> tcg_temp_free_i32(t); >>> - gen_stop_exception(ctx); >>> + /* Stop translation, as the CPU is supposed to sleep from now */ >>> + gen_exception_nip(ctx, EXCP_HLT, ctx->base.pc_next); >>> #endif /* defined(CONFIG_USER_ONLY) */ >>> } >>> #endif /* #if defined(TARGET_PPC64) */ >
