Re: [Qemu-devel] [PATCH v1 1/8] s390x/tcg: factor out and fix DATA exception injection

[Richard Henderson]

On 08/22/2018 12:57 AM, David Hildenbrand wrote:
> The DXC is to be stored in the low core, and only in the FPC in case AFP
> is enabled in CR0.
> 
> Signed-off-by: David Hildenbrand <address@hidden>
> ---
>  target/s390x/cpu.h         |  1 +
>  target/s390x/excp_helper.c | 28 ++++++++++++++++++++++++++++
>  target/s390x/fpu_helper.c  | 13 +++----------
>  target/s390x/helper.h      |  1 +
>  target/s390x/tcg_s390x.h   |  2 ++
>  target/s390x/translate.c   | 19 +++++++++----------
>  6 files changed, 44 insertions(+), 20 deletions(-)
> 
> diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
> index 6f8861e554..5e50c3a303 100644
> --- a/target/s390x/cpu.h
> +++ b/target/s390x/cpu.h
> @@ -322,6 +322,7 @@ extern const struct VMStateDescription vmstate_s390_cpu;
>  #define CR0_LOWPROT             0x0000000010000000ULL
>  #define CR0_SECONDARY           0x0000000004000000ULL
>  #define CR0_EDAT                0x0000000000800000ULL
> +#define CR0_AFP                 0x0000000000040000ULL
>  #define CR0_EMERGENCY_SIGNAL_SC 0x0000000000004000ULL
>  #define CR0_EXTERNAL_CALL_SC    0x0000000000002000ULL
>  #define CR0_CKC_SC              0x0000000000000800ULL
> diff --git a/target/s390x/excp_helper.c b/target/s390x/excp_helper.c
> index f0ce60cff2..f5cab94ec5 100644
> --- a/target/s390x/excp_helper.c
> +++ b/target/s390x/excp_helper.c
> @@ -21,11 +21,13 @@
>  #include "qemu/osdep.h"
>  #include "cpu.h"
>  #include "internal.h"
> +#include "exec/helper-proto.h"
>  #include "qemu/timer.h"
>  #include "exec/exec-all.h"
>  #include "exec/cpu_ldst.h"
>  #include "hw/s390x/ioinst.h"
>  #include "exec/address-spaces.h"
> +#include "tcg_s390x.h"
>  #ifndef CONFIG_USER_ONLY
>  #include "sysemu/sysemu.h"
>  #include "hw/s390x/s390_flic.h"
> @@ -48,6 +50,32 @@
>      do { } while (0)
>  #endif
>  
> +void QEMU_NORETURN tcg_s390_data_exception(CPUS390XState *env, uint32_t dxc,
> +                                           uintptr_t ra)
> +{
> +    CPUState *cs = CPU(s390_env_get_cpu(env));
> +
> +    g_assert(!(dxc & ~0xff));
> +#if !defined(CONFIG_USER_ONLY)
> +    /* Store the DXC into the lowcore */
> +    stw_phys(cs->as, env->psa + offsetof(LowCore, data_exc_code), dxc);
> +#endif
> +
> +    /* Store the DXC into the FPC if AFP is enabled */
> +    if (env->cregs[0] & CR0_AFP) {
> +        env->fpc = (env->fpc & ~0xff00) | (dxc << 8);
> +    }
> +    s390_program_interrupt(env, PGM_DATA, ILEN_AUTO, ra);

We should probably export tcg_s390_program_interrupt, so ...

> +
> +    /* the following is not necessary, but allows us to use noreturn */
> +    cpu_loop_exit_restore(cs, ra);

... you don't have to do this.
But even if not, g_assert_not_reached() is better here.

I'll note that s390_program_interrupt is buggy for tcg, in that it logs
env->psw.addr before cpu_loop_restore, and therefore psw.addr is essentially
random data.


r~