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

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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>
This commit is contained in:
Filip Bozuta 2020-06-19 14:47:27 +02:00 • committed by Laurent Vivier
parent a20a7c2640
commit 79482e5987
6 changed files with 285 additions and 20 deletions
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107
linux-user/strace.c
View file

@ -860,6 +860,44 @@ print_syscall_ret_listxattr(const struct syscallname *name, abi_long ret,
#define print_syscall_ret_flistxattr print_syscall_ret_listxattr
#endif
#ifdef TARGET_NR_ioctl
static void
print_syscall_ret_ioctl(const struct syscallname *name, abi_long ret,
abi_long arg0, abi_long arg1, abi_long arg2,
abi_long arg3, abi_long arg4, abi_long arg5)
{
print_syscall_err(ret);
if (ret >= 0) {
qemu_log(TARGET_ABI_FMT_ld, ret);
const IOCTLEntry *ie;
const argtype *arg_type;
void *argptr;
int target_size;
for (ie = ioctl_entries; ie->target_cmd != 0; ie++) {
if (ie->target_cmd == arg1) {
break;
}
}
if (ie->target_cmd == arg1 &&
(ie->access == IOC_R || ie->access == IOC_RW)) {
arg_type = ie->arg_type;
qemu_log(" (");
arg_type++;
target_size = thunk_type_size(arg_type, 0);
argptr = lock_user(VERIFY_READ, arg2, target_size, 1);
thunk_print(argptr, arg_type);
unlock_user(argptr, arg2, target_size);
qemu_log(")");
}
}
qemu_log("\n");
}
#endif
UNUSED static struct flags access_flags[] = {
FLAG_GENERIC(F_OK),
FLAG_GENERIC(R_OK),
@ -3026,6 +3064,75 @@ print_statx(const struct syscallname *name,
}
#endif
#ifdef TARGET_NR_ioctl
static void
print_ioctl(const struct syscallname *name,
abi_long arg0, abi_long arg1, abi_long arg2,
abi_long arg3, abi_long arg4, abi_long arg5)
{
print_syscall_prologue(name);
print_raw_param("%d", arg0, 0);
const IOCTLEntry *ie;
const argtype *arg_type;
void *argptr;
int target_size;
for (ie = ioctl_entries; ie->target_cmd != 0; ie++) {
if (ie->target_cmd == arg1) {
break;
}
}
if (ie->target_cmd == 0) {
print_raw_param("%#x", arg1, 0);
print_raw_param("%#x", arg2, 1);
} else {
qemu_log("%s", ie->name);
arg_type = ie->arg_type;
if (arg_type[0] != TYPE_NULL) {
qemu_log(",");
switch (arg_type[0]) {
case TYPE_PTRVOID:
print_pointer(arg2, 1);
break;
case TYPE_CHAR:
case TYPE_SHORT:
case TYPE_INT:
print_raw_param("%d", arg2, 1);
break;
case TYPE_LONG:
print_raw_param(TARGET_ABI_FMT_ld, arg2, 1);
break;
case TYPE_ULONG:
print_raw_param(TARGET_ABI_FMT_lu, arg2, 1);
break;
case TYPE_PTR:
switch (ie->access) {
case IOC_R:
print_pointer(arg2, 1);
break;
case IOC_W:
case IOC_RW:
arg_type++;
target_size = thunk_type_size(arg_type, 0);
argptr = lock_user(VERIFY_READ, arg2, target_size, 1);
thunk_print(argptr, arg_type);
unlock_user(argptr, arg2, target_size);
break;
}
break;
default:
g_assert_not_reached();
}
}
}
print_syscall_epilogue(name);
}
#endif
/*
* An array of all of the syscalls we know about
*/