Re: [Qemu-devel] [PATCH 03/11] S/390 fake TCG implementation

[Alexander Graf]

On 30.11.2009, at 19:18, Aurelien Jarno wrote:

> On Thu, Nov 26, 2009 at 02:23:12PM +0100, Alexander Graf wrote:
>> Qemu won't let us run a KVM target without having host TCG support. Well, for
>> now we don't have any so let's implement a fake target that only stubs out
>> everything.
>> 
>> I tried to keep the patch as close to Uli's source as possible, so whenever
>> he feels like it he can easily diff his version against this one.
> 
> Please find the comments below.
> 
>> Signed-off-by: Alexander Graf <address@hidden>
>> ---
>> dyngen-exec.h         |    2 +-
>> target-s390x/helper.c |    5 ++
>> tcg/s390/tcg-target.c |  103 
>> +++++++++++++++++++++++++++++++++++++++++++++++++
>> tcg/s390/tcg-target.h |   48 +++++++++++++++++++++++
>> 4 files changed, 157 insertions(+), 1 deletions(-)
>> create mode 100644 tcg/s390/tcg-target.c
>> create mode 100644 tcg/s390/tcg-target.h
>> 
>> diff --git a/dyngen-exec.h b/dyngen-exec.h
>> index 86e61c3..0353f36 100644
>> --- a/dyngen-exec.h
>> +++ b/dyngen-exec.h
>> @@ -117,7 +117,7 @@ extern int printf(const char *, ...);
>> 
>> /* The return address may point to the start of the next instruction.
>>    Subtracting one gets us the call instruction itself.  */
>> -#if defined(__s390__)
>> +#if defined(__s390__) && !defined(__s390x__)
>> # define GETPC() ((void*)(((unsigned long)__builtin_return_address(0) & 
>> 0x7fffffffUL) - 1))
>> #elif defined(__arm__)
>> /* Thumb return addresses have the low bit set, so we need to subtract two.
>> diff --git a/target-s390x/helper.c b/target-s390x/helper.c
>> index 4e23b4a..0e222e3 100644
>> --- a/target-s390x/helper.c
>> +++ b/target-s390x/helper.c
>> @@ -44,6 +44,11 @@ CPUS390XState *cpu_s390x_init(const char *cpu_model)
>>     return env;
>> }
>> 
>> +target_phys_addr_t cpu_get_phys_page_debug(CPUState *env, target_ulong addr)
>> +{
>> +    return addr;
>> +}
>> +
> 
> Why does it appear in this patch? It has nothing to do with TCG support.

I don't remember. What is this used for anyways?

>> void cpu_reset(CPUS390XState *env)
>> {
>>     if (qemu_loglevel_mask(CPU_LOG_RESET)) {
>> diff --git a/tcg/s390/tcg-target.c b/tcg/s390/tcg-target.c
>> new file mode 100644
>> index 0000000..53bbf69
>> --- /dev/null
>> +++ b/tcg/s390/tcg-target.c
>> @@ -0,0 +1,103 @@
>> +/*
>> + * Tiny Code Generator for QEMU
>> + *
>> + * Copyright (c) 2009 Ulrich Hecht <address@hidden>
>> + *
>> + * Permission is hereby granted, free of charge, to any person obtaining a 
>> copy
>> + * of this software and associated documentation files (the "Software"), to 
>> deal
>> + * in the Software without restriction, including without limitation the 
>> rights
>> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
>> + * copies of the Software, and to permit persons to whom the Software is
>> + * furnished to do so, subject to the following conditions:
>> + *
>> + * The above copyright notice and this permission notice shall be included 
>> in
>> + * all copies or substantial portions of the Software.
>> + *
>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 
>> OR
>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
>> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
>> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR 
>> OTHER
>> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
>> FROM,
>> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
>> + * THE SOFTWARE.
>> + */
>> +
>> +static const int tcg_target_reg_alloc_order[] = {
>> +};
>> +
>> +static const int tcg_target_call_iarg_regs[] = {
>> +};
>> +
>> +static const int tcg_target_call_oarg_regs[] = {
>> +};
>> +
>> +static void patch_reloc(uint8_t *code_ptr, int type,
>> +                tcg_target_long value, tcg_target_long addend)
>> +{
>> +    tcg_abort();
>> +}
>> +
>> +static inline int tcg_target_get_call_iarg_regs_count(int flags)
>> +{
>> +    tcg_abort();
>> +    return 0;
>> +}
>> +
>> +/* parse target specific constraints */
>> +static int target_parse_constraint(TCGArgConstraint *ct, const char 
>> **pct_str)
>> +{
>> +    tcg_abort();
>> +    return 0;
>> +}
>> +
>> +/* Test if a constant matches the constraint. */
>> +static inline int tcg_target_const_match(tcg_target_long val,
>> +                const TCGArgConstraint *arg_ct)
>> +{
>> +    tcg_abort();
>> +    return 0;
>> +}
>> +
>> +/* load a register with an immediate value */
>> +static inline void tcg_out_movi(TCGContext *s, TCGType type,
>> +                int ret, tcg_target_long arg)
>> +{
>> +    tcg_abort();
>> +}
>> +
>> +/* load data without address translation or endianness conversion */
>> +static inline void tcg_out_ld(TCGContext *s, TCGType type, int arg,
>> +                int arg1, tcg_target_long arg2)
>> +{
>> +    tcg_abort();
>> +}
>> +
>> +static inline void tcg_out_st(TCGContext *s, TCGType type, int arg,
>> +                              int arg1, tcg_target_long arg2)
>> +{
>> +    tcg_abort();
>> +}
>> +
>> +static inline void tcg_out_op(TCGContext *s, int opc,
>> +                const TCGArg *args, const int *const_args)
>> +{
>> +    tcg_abort();
>> +}
>> +
>> +void tcg_target_init(TCGContext *s)
>> +{
>> +}
> 
> This is probably here that tcg_abort() is actually the most important.
> 
>> +
>> +void tcg_target_qemu_prologue(TCGContext *s)
>> +{
>> +}
>> +
> 
> Also adding it here doesn't cost a lot.

Both places get called with KVM as well. If I call tcg_abort() here KVM doesn't 
start.

> 
>> +static inline void tcg_out_mov(TCGContext *s, int ret, int arg)
>> +{
>> +    tcg_abort();
>> +}
>> +
>> +static inline void tcg_out_addi(TCGContext *s, int reg, tcg_target_long val)
>> +{
>> +    tcg_abort();
>> +}
>> diff --git a/tcg/s390/tcg-target.h b/tcg/s390/tcg-target.h
>> new file mode 100644
>> index 0000000..2e66553
>> --- /dev/null
>> +++ b/tcg/s390/tcg-target.h
>> @@ -0,0 +1,48 @@
>> +/*
>> + * Tiny Code Generator for QEMU
>> + *
>> + * Copyright (c) 2009 Ulrich Hecht <address@hidden>
>> + *
>> + * Permission is hereby granted, free of charge, to any person obtaining a 
>> copy
>> + * of this software and associated documentation files (the "Software"), to 
>> deal
>> + * in the Software without restriction, including without limitation the 
>> rights
>> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
>> + * copies of the Software, and to permit persons to whom the Software is
>> + * furnished to do so, subject to the following conditions:
>> + *
>> + * The above copyright notice and this permission notice shall be included 
>> in
>> + * all copies or substantial portions of the Software.
>> + *
>> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 
>> OR
>> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
>> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
>> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR 
>> OTHER
>> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
>> FROM,
>> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
>> + * THE SOFTWARE.
>> + */
>> +#define TCG_TARGET_S390 1
>> +
>> +#define TCG_TARGET_REG_BITS 64
>> +#define TCG_TARGET_WORDS_BIGENDIAN
>> +
>> +#define TCG_TARGET_NB_REGS 0
>> +
>> +enum {
>> +    TCG_AREG0 = 0,
>> +};
> 
> As this is defined in Uli's patch, I think it might be a good idea to
> define that correctly. Same for the list of registers.

I wasn't sure how much of the real architecture I should actually keep. So you 
think registers belong in?

>> +/* used for function call generation */
>> +#define TCG_REG_CALL_STACK          0
>> +#define TCG_TARGET_STACK_ALIGN              8
>> +#define TCG_TARGET_CALL_STACK_OFFSET        0
>> +
>> +static inline void flush_icache_range(unsigned long start, unsigned long 
>> stop)
>> +{
>> +#if QEMU_GNUC_PREREQ(4, 1)
>> +    void __clear_cache(char *beg, char *end);
>> +    __clear_cache((char *) start, (char *) stop);
> 
> You should use __builtin___clear_cache instead to avoid having to
> declare the function.

Oh, ok :)

Alex