linux-user: Add strace support for printing arguments of ioctl()

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>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20200619124727.18080-3-filip.bozuta@syrmia.com>
[lv: fix close-bracket]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

1 files changed, 20 insertions, 0 deletions

diff --git a/linux-user/qemu.h b/linux-user/qemu.h
index be67391ba4..5c964389c1 100644
--- a/linux-user/qemu.h
+++ b/linux-user/qemu.h
@@ -184,6 +184,26 @@ struct linux_binprm {
         int (*core_dump)(int, const CPUArchState *); /* coredump routine */
 };
 
+typedef struct IOCTLEntry IOCTLEntry;
+
+typedef abi_long do_ioctl_fn(const IOCTLEntry *ie, uint8_t *buf_temp,
+                             int fd, int cmd, abi_long arg);
+
+struct IOCTLEntry {
+    int target_cmd;
+    unsigned int host_cmd;
+    const char *name;
+    int access;
+    do_ioctl_fn *do_ioctl;
+    const argtype arg_type[5];
+};
+
+extern IOCTLEntry ioctl_entries[];
+
+#define IOC_R 0x0001
+#define IOC_W 0x0002
+#define IOC_RW (IOC_R | IOC_W)
+
 void do_init_thread(struct target_pt_regs *regs, struct image_info *infop);
 abi_ulong loader_build_argptr(int envc, int argc, abi_ulong sp,
                               abi_ulong stringp, int push_ptr);