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linux-user: add strace support for uinfo structure of rt_sigqueueinfo() and rt_tgsigqueueinfo()

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This commit adds support for printing the content of the target_siginfo_t
structure in a similar way to how it is printed by the host strace. The
pointer to this structure is sent as the last argument of the
rt_sigqueueinfo() and rt_tgsigqueueinfo() system calls.
For this purpose, print_siginfo() is used and the get_target_siginfo()
function is implemented in order to get the information obtained from
the pointer into the form that print_siginfo() expects.

The get_target_siginfo() function is based on
host_to_target_siginfo_noswap() in linux-user mode, but here both
arguments are pointers to target_siginfo_t, so instead of converting
the information to siginfo_t it just extracts and copies it to a
target_siginfo_t structure.

Prior to this commit, typical strace output used to look like this:
8307 rt_sigqueueinfo(8307,50,0x00000040007ff6b0) = 0

After this commit, it looks like this:
8307 rt_sigqueueinfo(8307,50,{si_signo=50, si_code=SI_QUEUE, si_pid=8307,
si_uid=1000, si_sigval=17716762128}) = 0

Signed-off-by: Miloš Stojanović <Milos.Stojanovic@rt-rk.com>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
This commit is contained in:
Miloš Stojanović 2017-05-15 16:59:49 +02:00 committed by Riku Voipio
parent f196c3700d
commit ba9fcea1cb
1 changed files with 111 additions and 2 deletions
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113
linux-user/strace.c
View File

@ -188,6 +188,93 @@ static void print_si_code(int arg)
gemu_log("%s", codename);
}
static void get_target_siginfo(target_siginfo_t *tinfo,
const target_siginfo_t *info)
{
abi_ulong sival_ptr;
int sig;
int si_errno;
int si_code;
int si_type;
__get_user(sig, &info->si_signo);
__get_user(si_errno, &tinfo->si_errno);
__get_user(si_code, &info->si_code);
tinfo->si_signo = sig;
tinfo->si_errno = si_errno;
tinfo->si_code = si_code;
/* Ensure we don't leak random junk to the guest later */
memset(tinfo->_sifields._pad, 0, sizeof(tinfo->_sifields._pad));
/* This is awkward, because we have to use a combination of
* the si_code and si_signo to figure out which of the union's
* members are valid. (Within the host kernel it is always possible
* to tell, but the kernel carefully avoids giving userspace the
* high 16 bits of si_code, so we don't have the information to
* do this the easy way...) We therefore make our best guess,
* bearing in mind that a guest can spoof most of the si_codes
* via rt_sigqueueinfo() if it likes.
*
* Once we have made our guess, we record it in the top 16 bits of
* the si_code, so that print_siginfo() later can use it.
* print_siginfo() will strip these top bits out before printing
* the si_code.
*/
switch (si_code) {
case SI_USER:
case SI_TKILL:
case SI_KERNEL:
/* Sent via kill(), tkill() or tgkill(), or direct from the kernel.
* These are the only unspoofable si_code values.
*/
__get_user(tinfo->_sifields._kill._pid, &info->_sifields._kill._pid);
__get_user(tinfo->_sifields._kill._uid, &info->_sifields._kill._uid);
si_type = QEMU_SI_KILL;
break;
default:
/* Everything else is spoofable. Make best guess based on signal */
switch (sig) {
case TARGET_SIGCHLD:
__get_user(tinfo->_sifields._sigchld._pid,
&info->_sifields._sigchld._pid);
__get_user(tinfo->_sifields._sigchld._uid,
&info->_sifields._sigchld._uid);
__get_user(tinfo->_sifields._sigchld._status,
&info->_sifields._sigchld._status);
__get_user(tinfo->_sifields._sigchld._utime,
&info->_sifields._sigchld._utime);
__get_user(tinfo->_sifields._sigchld._stime,
&info->_sifields._sigchld._stime);
si_type = QEMU_SI_CHLD;
break;
case TARGET_SIGIO:
__get_user(tinfo->_sifields._sigpoll._band,
&info->_sifields._sigpoll._band);
__get_user(tinfo->_sifields._sigpoll._fd,
&info->_sifields._sigpoll._fd);
si_type = QEMU_SI_POLL;
break;
default:
/* Assume a sigqueue()/mq_notify()/rt_sigqueueinfo() source. */
__get_user(tinfo->_sifields._rt._pid, &info->_sifields._rt._pid);
__get_user(tinfo->_sifields._rt._uid, &info->_sifields._rt._uid);
/* XXX: potential problem if 64 bit */
__get_user(sival_ptr, &info->_sifields._rt._sigval.sival_ptr);
tinfo->_sifields._rt._sigval.sival_ptr = sival_ptr;
si_type = QEMU_SI_RT;
break;
}
break;
}
tinfo->si_code = deposit32(si_code, 16, 16, si_type);
}
static void print_siginfo(const target_siginfo_t *tinfo)
{
/* Print a target_siginfo_t in the format desired for printing
@ -1907,10 +1994,21 @@ print_rt_sigqueueinfo(const struct syscallname *name,
abi_long arg0, abi_long arg1, abi_long arg2,
abi_long arg3, abi_long arg4, abi_long arg5)
{
void *p;
target_siginfo_t uinfo;
print_syscall_prologue(name);
print_raw_param("%d", arg0, 0);
print_signal(arg1, 0);
print_pointer(arg2, 1);
p = lock_user(VERIFY_READ, arg2, sizeof(target_siginfo_t), 1);
if (p) {
get_target_siginfo(&uinfo, p);
print_siginfo(&uinfo);
unlock_user(p, arg2, 0);
} else {
print_pointer(arg2, 1);
}
print_syscall_epilogue(name);
}
#endif
@ -1921,11 +2019,22 @@ print_rt_tgsigqueueinfo(const struct syscallname *name,
abi_long arg0, abi_long arg1, abi_long arg2,
abi_long arg3, abi_long arg4, abi_long arg5)
{
void *p;
target_siginfo_t uinfo;
print_syscall_prologue(name);
print_raw_param("%d", arg0, 0);
print_raw_param("%d", arg1, 0);
print_signal(arg2, 0);
print_pointer(arg3, 1);
p = lock_user(VERIFY_READ, arg3, sizeof(target_siginfo_t), 1);
if (p) {
get_target_siginfo(&uinfo, p);
print_siginfo(&uinfo);
unlock_user(p, arg3, 0);
} else {
print_pointer(arg3, 1);
}
print_syscall_epilogue(name);
}
#endif