Re: [Qemu-devel] [PATCH 01/11] S/390 CPU fake emulation

[Alexander Graf]

On 02.12.2009, at 09:17, Aurelien Jarno wrote:

> On Mon, Nov 30, 2009 at 11:30:04PM +0100, Alexander Graf wrote:
>> 
>> On 30.11.2009, at 19:18, Aurelien Jarno wrote:
>> 
>>> On Thu, Nov 26, 2009 at 02:23:10PM +0100, Alexander Graf wrote:
>>>> Because Qemu currently requires a TCG target to exist and there are quite 
>>>> some
>>>> useful helpers here to lay the groundwork for out KVM target, let's create 
>>>> a
>>>> stub TCG emulation target for S390X CPUs.
>>>> 
>>>> This is required to make tcg happy. The emulation target itself won't work
>>>> though.
>>> 
>>> Please find the comments below.
>>> 
>>>> Signed-off-by: Alexander Graf <address@hidden>
>>>> ---
>>>> cpu-exec.c               |    2 +
>>>> target-s390x/cpu.h       |  119 
>>>> ++++++++++++++++++++++++++++++++++++++++++++++
>>>> target-s390x/exec.h      |   51 ++++++++++++++++++++
>>>> target-s390x/helper.c    |   57 ++++++++++++++++++++++
>>>> target-s390x/op_helper.c |   74 ++++++++++++++++++++++++++++
>>>> target-s390x/translate.c |   57 ++++++++++++++++++++++
>>>> 6 files changed, 360 insertions(+), 0 deletions(-)
>>>> create mode 100644 target-s390x/cpu.h
>>>> create mode 100644 target-s390x/exec.h
>>>> create mode 100644 target-s390x/helper.c
>>>> create mode 100644 target-s390x/op_helper.c
>>>> create mode 100644 target-s390x/translate.c
>>>> 
>>>> diff --git a/cpu-exec.c b/cpu-exec.c
>>>> index 2c0765c..af4595b 100644
>>>> --- a/cpu-exec.c
>>>> +++ b/cpu-exec.c
>>>> @@ -249,6 +249,7 @@ int cpu_exec(CPUState *env1)
>>>> #elif defined(TARGET_MIPS)
>>>> #elif defined(TARGET_SH4)
>>>> #elif defined(TARGET_CRIS)
>>>> +#elif defined(TARGET_S390X)
>>>>    /* XXXXX */
>>>> #else
>>>> #error unsupported target CPU
>>>> @@ -673,6 +674,7 @@ int cpu_exec(CPUState *env1)
>>>> #elif defined(TARGET_SH4)
>>>> #elif defined(TARGET_ALPHA)
>>>> #elif defined(TARGET_CRIS)
>>>> +#elif defined(TARGET_S390X)
>>>>    /* XXXXX */
>>>> #else
>>>> #error unsupported target CPU
>>>> diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
>>>> new file mode 100644
>>>> index 0000000..f45b00c
>>>> --- /dev/null
>>>> +++ b/target-s390x/cpu.h
>>>> @@ -0,0 +1,119 @@
>>>> +/*
>>>> + * S/390 virtual CPU header
>>>> + *
>>>> + *  Copyright (c) 2009 Ulrich Hecht
>>>> + *
>>>> + * This library is free software; you can redistribute it and/or
>>>> + * modify it under the terms of the GNU Lesser General Public
>>>> + * License as published by the Free Software Foundation; either
>>>> + * version 2 of the License, or (at your option) any later version.
>>>> + *
>>>> + * This library is distributed in the hope that it will be useful,
>>>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>>>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>>>> + * Lesser General Public License for more details.
>>>> + *
>>>> + * You should have received a copy of the GNU Lesser General Public
>>>> + * License along with this library; if not, write to the Free Software
>>>> + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA  
>>>> 02110-1301 USA
>>>> + */
>>>> +#ifndef CPU_S390X_H
>>>> +#define CPU_S390X_H
>>>> +
>>>> +#define TARGET_LONG_BITS 64
>>>> +
>>>> +#define ELF_MACHINE       EM_S390
>>>> +
>>>> +#define CPUState struct CPUS390XState
>>>> +
>>>> +#include "cpu-defs.h"
>>>> +
>>>> +#include "softfloat.h"
>>>> +
>>>> +#define NB_MMU_MODES 2 // guess
>>>> +#define MMU_USER_IDX 0 // guess
>>>> +
>>>> +typedef union FPReg {
>>>> +    struct {
>>>> +#ifdef WORDS_BIGENDIAN
>>>> +        float32 e;
>>>> +        int32_t __pad;
>>>> +#else
>>>> +        int32_t __pad;
>>>> +        float32 e;
>>>> +#endif
>>>> +    };
>>>> +    float64 d;
>>>> +    uint64_t i;
>>>> +} FPReg;
>>>> +
>>>> +typedef struct CPUS390XState {
>>>> +    uint64_t regs[16];    /* GP registers */
>>>> +    
>>>> +    uint32_t aregs[16];   /* access registers */
>>>> +    
>>>> +    uint32_t fpc; /* floating-point control register */
>>>> +    FPReg fregs[16]; /* FP registers */
>>>> +    float_status fpu_status; /* passed to softfloat lib */
>>>> +    
>>>> +    struct {
>>>> +        uint64_t mask;
>>>> +        uint64_t addr;
>>>> +    } psw;
>>>> +    
>>>> +    int cc; /* condition code (0-3) */
>>>> +    
>>>> +    uint64_t __excp_addr;
>>>> +    
>>>> +    CPU_COMMON
>>>> +} CPUS390XState;
>>>> +
>>>> +#if defined(CONFIG_USER_ONLY)
>>>> +static inline void cpu_clone_regs(CPUState *env, target_ulong newsp)
>>>> +{
>>>> +    if (newsp)
>>>> +        env->regs[15] = newsp;
>>> 
>>> Coding style.
>>> 
>>>> +    env->regs[0] = 0;
>>>> +}
>>>> +#endif
>>>> +
>>>> +CPUS390XState *cpu_s390x_init(const char *cpu_model);
>>>> +int cpu_s390x_exec(CPUS390XState *s);
>>>> +void cpu_s390x_close(CPUS390XState *s);
>>>> +
>>>> +/* you can call this signal handler from your SIGBUS and SIGSEGV
>>>> +   signal handlers to inform the virtual CPU of exceptions. non zero
>>>> +   is returned if the signal was handled by the virtual CPU.  */
>>>> +int cpu_s390x_signal_handler(int host_signum, void *pinfo,
>>>> +                           void *puc);
>>>> +int cpu_s390x_handle_mmu_fault (CPUS390XState *env, target_ulong address, 
>>>> int rw,
>>>> +                              int mmu_idx, int is_softmuu);
>>>> +#define cpu_handle_mmu_fault cpu_s390x_handle_mmu_fault
>>>> +
>>>> +#define TARGET_PAGE_BITS 12
>>>> +
>>>> +#define cpu_init cpu_s390x_init
>>>> +#define cpu_exec cpu_s390x_exec
>>>> +#define cpu_gen_code cpu_s390x_gen_code
>>>> +
>>>> +#include "cpu-all.h"
>>>> +#include "exec-all.h"
>>>> +
>>>> +#define EXCP_OPEX 1 /* operation exception (sigill) */
>>>> +#define EXCP_SVC 2 /* supervisor call (syscall) */
>>>> +#define EXCP_ADDR 5 /* addressing exception */
>>>> +#define EXCP_EXECUTE_SVC 0xff00000 /* supervisor call via execute insn */
>>>> +
>>>> +static inline void cpu_pc_from_tb(CPUState *env, TranslationBlock* tb)
>>>> +{
>>>> +    env->psw.addr = tb->pc;
>>>> +}
>>>> +
>>>> +static inline void cpu_get_tb_cpu_state(CPUState* env, target_ulong *pc,
>>>> +                                        target_ulong *cs_base, int *flags)
>>>> +{
>>>> +    *pc = env->psw.addr;
>>>> +    *cs_base = 0;
>>>> +    *flags = env->psw.mask; // guess
>>> 
>>> I don't know what psw.mask represent, but it may be wrong. It should be
>>> a way to identify which TB can be reused, that is they have been
>>> generated in the same CPU mode.
>> 
>> psw.mask is rougly the same as RFLAGS, cr0 and cr4 on x86_64 combined. So 
>> IMHO it looked like a pretty good identifier for TB uniqueness.
>> 
> 
> Then it's most probably correct, except some bits may have to be
> ignored. Can you update the comment explaining that?

Yep.

Alex