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

[Aurelien Jarno]

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?

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
address@hidden                 http://www.aurel32.net