Re: [PATCH v2 2/2] linux-user: Add strace support for printing arguments of ioctl()

[Laurent Vivier]

Le 16/06/2020 à 12:51, Filip Bozuta a écrit :
> From: Filip Bozuta <Filip.Bozuta@syrmia.com>
> 
> This patch implements functionality for strace argument printing for ioctls.
> When running ioctls through qemu with "-strace", they get printed in format:
> 
>     "ioctl(fd_num,0x*,0x*) = ret_value"
> 
> where the request code an the ioctl's third argument get printed in a 
> hexadicemal
> format. This patch changes that by enabling strace to print both the request 
> code
> name and the contents of the third argument. For example, when running ioctl
> RTC_SET_TIME with "-strace", with changes from this patch, it gets printed in
> this way:
> 
>     "ioctl(3,RTC_SET_TIME,{12,13,15,20,10,119,0,0,0}) = 0"
> 
> In case of IOC_R type ioctls, the contents of the third argument get printed
> after the return value, and the argument inside the ioctl call gets printed
> as pointer in hexadecimal format. For example, when running RTC_RD_TIME with
> "-strace", with changes from this patch, it gets printed in this way:
> 
>     "ioctl(3,RTC_RD_TIME,0x40800374) = 0 ({22,9,13,11,5,120,0,0,0})"
> 
> In case of IOC_RW type ioctls, the contents of the third argument get printed
> both inside the ioctl call and after the return value.
> 
> Implementation notes:
> 
>     Functions "print_ioctl()" and "print_syscall_ret_ioctl()", that are 
> defined
>     in "strace.c", are listed in file "strace.list" as "call" and "result"
>     value for ioctl. Structure definition "IOCTLEntry" as well as predefined
>     values for IOC_R, IOC_W and IOC_RW were cut and pasted from file 
> "syscall.c"
>     to file "qemu.h" so that they can be used by these functions to print the
>     contents of the third ioctl argument. Also, the "static" identifier for 
> array
>     "ioctl_entries[]" was removed and this array was declared as "extern" in 
> "qemu.h"
>     so that it can also be used by these functions. To decode the structure 
> type
>     of the ioctl third argument, function "thunk_print()" was defined in file
>     "thunk.c" and its definition is somewhat simillar to that of function
>     "thunk_convert()".
> 
> Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
> Based-on: <20200616103927.20222-1-filip.bozuta@syrmia.com>

To work, I think the Based-on tag must be set in the cover-letter of the
series.

> ---
>  include/exec/user/thunk.h |   1 +
>  linux-user/qemu.h         |  20 +++++
>  linux-user/strace.c       | 107 ++++++++++++++++++++++++++
>  linux-user/strace.list    |   3 +-
>  linux-user/syscall.c      |  20 +----
>  thunk.c                   | 154 ++++++++++++++++++++++++++++++++++++++
>  6 files changed, 285 insertions(+), 20 deletions(-)
> 

Reviewed-by: Laurent Vivier <laurent@vivier.eu>