linux-user: Add /proc/cpuinfo handler for RISC-V

Signed-off-by: Andreas Schwab <schwab@suse.de>
---
 linux-user/syscall.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

On Tue, 02 May 2023 06:44:00 PDT (-0700), schwab@suse.de wrote:
> Signed-off-by: Andreas Schwab <schwab@suse.de>
> ---
>  linux-user/syscall.c | 30 ++++++++++++++++++++++++++++--
>  1 file changed, 28 insertions(+), 2 deletions(-)
>
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 69f740ff98..c72456a34b 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -8231,7 +8231,8 @@ void target_exception_dump(CPUArchState *env, const char *fmt, int code)
>  }
>
>  #if HOST_BIG_ENDIAN != TARGET_BIG_ENDIAN || \
> -    defined(TARGET_SPARC) || defined(TARGET_M68K) || defined(TARGET_HPPA)
> +    defined(TARGET_SPARC) || defined(TARGET_M68K) || defined(TARGET_HPPA) || \
> +    defined(TARGET_RISCV)
>  static int is_proc(const char *filename, const char *entry)
>  {
>      return strcmp(filename, entry) == 0;
> @@ -8309,6 +8310,31 @@ static int open_cpuinfo(CPUArchState *cpu_env, int fd)
>  }
>  #endif
>
> +#if defined(TARGET_RISCV)
> +static int open_cpuinfo(CPUArchState *cpu_env, int fd)
> +{
> +    int i, num_cpus;
> +
> +    num_cpus = sysconf(_SC_NPROCESSORS_ONLN);
> +    for (i = 0; i < num_cpus; i++) {
> +        dprintf(fd, "processor\t: %d\n", i);
> +        dprintf(fd, "hart\t\t: %d\n", i);
> +#if defined(TARGET_RISCV32)
> +        dprintf(fd, "isa\t\t: rv32imafdc\n");
> +        dprintf(fd, "mmu\t\t: sv32\n");
> +#endif
> +#if defined(TARGET_RISCV64)
> +        dprintf(fd, "isa\t\t: rv64imafdc\n");
> +        dprintf(fd, "mmu\t\t: sv57\n");

Unless I'm misunderstanding something, we've got support for both 
non-sv57 system (via sv* CPU properties) and non-GC systems (also via 
CPU properties).  Not sure how much userspace cares about that, but at 
least dropping FD when those instructions aren't emulated by QEMEU seems 
reasonable.

> +#endif
> +        dprintf(fd, "mvendorid\t: 0x0\n");
> +        dprintf(fd, "marchid\t\t: 0x0\n");
> +        dprintf(fd, "mimpid\t\t: 0x0\n\n");
> +    }
> +    return 0;
> +}
> +#endif
> +
>  #if defined(TARGET_M68K)
>  static int open_hardware(CPUArchState *cpu_env, int fd)
>  {
> @@ -8333,7 +8359,7 @@ static int do_openat(CPUArchState *cpu_env, int dirfd, const char *pathname, int
>  #if HOST_BIG_ENDIAN != TARGET_BIG_ENDIAN
>          { "/proc/net/route", open_net_route, is_proc },
>  #endif
> -#if defined(TARGET_SPARC) || defined(TARGET_HPPA)
> +#if defined(TARGET_SPARC) || defined(TARGET_HPPA) || defined(TARGET_RISCV)
>          { "/proc/cpuinfo", open_cpuinfo, is_proc },
>  #endif
>  #if defined(TARGET_M68K)

Aside from that this looks great.  Thanks for fixing this, it's been a 
headache for folks for a while.

On Mai 02 2023, Palmer Dabbelt wrote:

> On Tue, 02 May 2023 06:44:00 PDT (-0700), schwab@suse.de wrote:
>> Signed-off-by: Andreas Schwab <schwab@suse.de>
>> ---
>>  linux-user/syscall.c | 30 ++++++++++++++++++++++++++++--
>>  1 file changed, 28 insertions(+), 2 deletions(-)
>>
>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>> index 69f740ff98..c72456a34b 100644
>> --- a/linux-user/syscall.c
>> +++ b/linux-user/syscall.c
>> @@ -8231,7 +8231,8 @@ void target_exception_dump(CPUArchState *env, const char *fmt, int code)
>>  }
>>
>>  #if HOST_BIG_ENDIAN != TARGET_BIG_ENDIAN || \
>> -    defined(TARGET_SPARC) || defined(TARGET_M68K) || defined(TARGET_HPPA)
>> +    defined(TARGET_SPARC) || defined(TARGET_M68K) || defined(TARGET_HPPA) || \
>> +    defined(TARGET_RISCV)
>>  static int is_proc(const char *filename, const char *entry)
>>  {
>>      return strcmp(filename, entry) == 0;
>> @@ -8309,6 +8310,31 @@ static int open_cpuinfo(CPUArchState *cpu_env, int fd)
>>  }
>>  #endif
>>
>> +#if defined(TARGET_RISCV)
>> +static int open_cpuinfo(CPUArchState *cpu_env, int fd)
>> +{
>> +    int i, num_cpus;
>> +
>> +    num_cpus = sysconf(_SC_NPROCESSORS_ONLN);
>> +    for (i = 0; i < num_cpus; i++) {
>> +        dprintf(fd, "processor\t: %d\n", i);
>> +        dprintf(fd, "hart\t\t: %d\n", i);
>> +#if defined(TARGET_RISCV32)
>> +        dprintf(fd, "isa\t\t: rv32imafdc\n");
>> +        dprintf(fd, "mmu\t\t: sv32\n");
>> +#endif
>> +#if defined(TARGET_RISCV64)
>> +        dprintf(fd, "isa\t\t: rv64imafdc\n");
>> +        dprintf(fd, "mmu\t\t: sv57\n");
>
> Unless I'm misunderstanding something, we've got support for both non-sv57
> system (via sv* CPU properties)

The mmu type is not available in linux-user emulation.  This just
matches the default the system emulation would use.

> and non-GC systems (also via CPU properties).

None of the currently defined cpus are non-GC cpus (except sifive_e, but
that is not suitable for user-space anyway), and there doesn't appear to
be any properties defined for changing the supported extensions.

On Mai 02 2023, Andreas Schwab wrote:

> None of the currently defined cpus are non-GC cpus (except sifive_e, but
> that is not suitable for user-space anyway), and there doesn't appear to
> be any properties defined for changing the supported extensions.

Actually, modifying the extensions is possible for the base cpus (rv32
and rv64).

On Wed, 03 May 2023 04:13:55 PDT (-0700), schwab@suse.de wrote:
> On Mai 02 2023, Andreas Schwab wrote:
>
>> None of the currently defined cpus are non-GC cpus (except sifive_e, but
>> that is not suitable for user-space anyway), and there doesn't appear to
>> be any properties defined for changing the supported extensions.
>
> Actually, modifying the extensions is possible for the base cpus (rv32
> and rv64).

Ya, though I think you're right about the VA width in userspace.