Re: [PATCH 03/12] linux-user: Add support for getting/setting RTC periodic interrupt and epoch using ioctls

[Laurent Vivier]

Le 15/01/2020 à 16:53, Filip Bozuta a écrit :
> This patch implements functionalities of following ioctls:
> 
> RTC_IRQP_READ, RTC_IRQP_SET - Getting/Setting IRQ rate
> 
>     Read and set the frequency for periodic interrupts, for RTCs
>     that support periodic interrupts. The periodic interrupt must
>     be separately enabled or disabled using the RTC_PIE_ON,
>     RTC_PIE_OFF requests. The third ioctl's argument is an
>     unsigned long * or an unsigned long, respectively. The value
>     is the frequency in interrupts per second. The set of allow‐
>     able frequencies is the multiples of two in the range 2 to
>     8192. Only a privileged process (i.e., one having the
>     CAP_SYS_RESOURCE capability) can set frequencies above the
>     value specified in /proc/sys/dev/rtc/max-user-freq. (This
>     file contains the value 64 by default.)
> 
> RTC_EPOCH_READ, RTC_EPOCH_SET - Getting/Setting epoch
> 
>     Many RTCs encode the year in an 8-bit register which is either
>     interpreted as an 8-bit binary number or as a BCD number. In
>     both cases, the number is interpreted relative to this RTC's
>     Epoch. The RTC's Epoch is initialized to 1900 on most systems
>     but on Alpha and MIPS it might also be initialized to 1952,
>     1980, or 2000, depending on the value of an RTC register for
>     the year. With some RTCs, these operations can be used to
>     read or to set the RTC's Epoch, respectively. The third
>     ioctl's argument is an unsigned long * or an unsigned long,
>     respectively, and the value returned (or assigned) is the
>     Epoch. To set the RTC's Epoch the process must be privileged
>     (i.e., have the CAP_SYS_TIME capability).
> 
> Implementation notes:
> 
>     All ioctls in this patch have a pointer to 'ulong' as their
>     third argument. That is the reason why corresponding parts
>     of added code in linux-user/syscall_defs.h contain special
>     handling related to 'ulong' type: they use 'abi_ulong' type
>     to make sure that ioctl's code is calculated correctly for
>     both 32-bit and 64-bit targets. Also, 'MK_PTR(TYPE_ULONG)'
>     is used for the similar reason in linux-user/ioctls.h.
>     Because ioctls RTC_IRQP_SET and RTC_EPOCH_SET are ioctls of
>     type IOW(writing type) that have unsigned long as their
>     third argument, a case statement for "TYPE_ULONG" was added
>     in the appropriate place for function "abi_ulong do_ioctl"
>     in file "syscall.c". There were no implemented ioctls of
>     type IOW with unsigned long as third argument before this
>     patch, which is the reason why this case statement was added
>     now for the first time.
> 
> Signed-off-by: Filip Bozuta <address@hidden>
> ---
>  linux-user/ioctls.h       | 4 ++++
>  linux-user/syscall.c      | 1 +
>  linux-user/syscall_defs.h | 4 ++++
>  3 files changed, 9 insertions(+)
> 
...
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 74c3c08..c0b7314 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -5175,6 +5175,7 @@ static abi_long do_ioctl(int fd, int cmd, abi_long arg)
>          break;
>      case TYPE_PTRVOID:
>      case TYPE_INT:
> +    case TYPE_ULONG:
>          ret = get_errno(safe_ioctl(fd, ie->host_cmd, arg));
>          break;
>      case TYPE_PTR:

I think this can go in a separate patch as it's a fix.

You should also add TYPE_LONG.

Thanks,
Laurent