linux-user: Add support for adjtimex() syscall

This patch implements Qemu user mode adjtimex() syscall support.

Syscall adjtimex() reads and optionally sets parameters for a clock
adjustment algorithm used in network synchonization or similar scenarios.

Its declaration is:

int adjtimex(struct timex *buf);

The correspondent source code in the Linux kernel is at kernel/time.c,
line 206.

The Qemu implementation is based on invocation of host's adjtimex(), and
its key part is in the "TARGET_NR_adjtimex" case segment of the the main
switch statement of the function do_syscall(), in linux-user/syscalls.c. All
necessary conversions of the data structures from target to host and from
host to target are covered. Two new functions, target_to_host_timex() and
host_to_target_timex(), are provided for the purpose of such conversions.
For that purpose, the support for related structure "timex" had tp be added
to the file linux-user/syscall_defs.h, based on its definition in Linux
kernel. Also, the relevant support for "-strace" Qemu option is included
in files linux-user/strace.c and linux-user/strace.list.

This patch also fixes failures of LTP tests adjtimex01 and adjtimex02, if
executed in Qemu user mode.

Signed-off-by: Aleksandar Rikalo <aleksandar.rikalo@imgtec.com>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>

linux-user/strace.c

@@ -577,6 +577,52 @@ print_syscall_ret_newselect(const struct syscallname *name, abi_long ret)
 }
 #endif
 
+/* special meanings of adjtimex()' non-negative return values */
+#define TARGET_TIME_OK       0   /* clock synchronized, no leap second */
+#define TARGET_TIME_INS      1   /* insert leap second */
+#define TARGET_TIME_DEL      2   /* delete leap second */
+#define TARGET_TIME_OOP      3   /* leap second in progress */
+#define TARGET_TIME_WAIT     4   /* leap second has occurred */
+#define TARGET_TIME_ERROR    5   /* clock not synchronized */
+static void
+print_syscall_ret_adjtimex(const struct syscallname *name, abi_long ret)
+{
+    const char *errstr = NULL;
+
+    gemu_log(" = ");
+    if (ret < 0) {
+        gemu_log("-1 errno=%d", errno);
+        errstr = target_strerror(-ret);
+        if (errstr) {
+            gemu_log(" (%s)", errstr);
+        }
+    } else {
+        gemu_log(TARGET_ABI_FMT_ld, ret);
+        switch (ret) {
+        case TARGET_TIME_OK:
+            gemu_log(" TIME_OK (clock synchronized, no leap second)");
+            break;
+        case TARGET_TIME_INS:
+            gemu_log(" TIME_INS (insert leap second)");
+            break;
+        case TARGET_TIME_DEL:
+            gemu_log(" TIME_DEL (delete leap second)");
+            break;
+        case TARGET_TIME_OOP:
+            gemu_log(" TIME_OOP (leap second in progress)");
+            break;
+        case TARGET_TIME_WAIT:
+            gemu_log(" TIME_WAIT (leap second has occurred)");
+            break;
+        case TARGET_TIME_ERROR:
+            gemu_log(" TIME_ERROR (clock not synchronized)");
+            break;
+        }
+    }
+
+    gemu_log("\n");
+}
+
 UNUSED static struct flags access_flags[] = {
     FLAG_GENERIC(F_OK),
     FLAG_GENERIC(R_OK),

linux-user/strace.list

@@ -19,7 +19,8 @@
 { TARGET_NR_add_key, "add_key" , NULL, NULL, NULL },
 #endif
 #ifdef TARGET_NR_adjtimex
-{ TARGET_NR_adjtimex, "adjtimex" , NULL, NULL, NULL },
+{ TARGET_NR_adjtimex, "adjtimex" , "%s(%p)", NULL,
+                      print_syscall_ret_adjtimex },
 #endif
 #ifdef TARGET_NR_afs_syscall
 { TARGET_NR_afs_syscall, "afs_syscall" , NULL, NULL, NULL },

linux-user/syscall.c

@@ -35,6 +35,7 @@
 #include <sys/swap.h>
 #include <linux/capability.h>
 #include <sched.h>
+#include <sys/timex.h>
 #ifdef __ia64__
 int __clone2(int (*fn)(void *), void *child_stack_base,
              size_t stack_size, int flags, void *arg, ...);
@@ -6770,6 +6771,77 @@ static inline abi_long host_to_target_itimerspec(abi_ulong target_addr,
     return 0;
 }
 
+static inline abi_long target_to_host_timex(struct timex *host_tx,
+                                            abi_long target_addr)
+{
+    struct target_timex *target_tx;
+
+    if (!lock_user_struct(VERIFY_READ, target_tx, target_addr, 1)) {
+        return -TARGET_EFAULT;
+    }
+
+    __get_user(host_tx->modes, &target_tx->modes);
+    __get_user(host_tx->offset, &target_tx->offset);
+    __get_user(host_tx->freq, &target_tx->freq);
+    __get_user(host_tx->maxerror, &target_tx->maxerror);
+    __get_user(host_tx->esterror, &target_tx->esterror);
+    __get_user(host_tx->status, &target_tx->status);
+    __get_user(host_tx->constant, &target_tx->constant);
+    __get_user(host_tx->precision, &target_tx->precision);
+    __get_user(host_tx->tolerance, &target_tx->tolerance);
+    __get_user(host_tx->time.tv_sec, &target_tx->time.tv_sec);
+    __get_user(host_tx->time.tv_usec, &target_tx->time.tv_usec);
+    __get_user(host_tx->tick, &target_tx->tick);
+    __get_user(host_tx->ppsfreq, &target_tx->ppsfreq);
+    __get_user(host_tx->jitter, &target_tx->jitter);
+    __get_user(host_tx->shift, &target_tx->shift);
+    __get_user(host_tx->stabil, &target_tx->stabil);
+    __get_user(host_tx->jitcnt, &target_tx->jitcnt);
+    __get_user(host_tx->calcnt, &target_tx->calcnt);
+    __get_user(host_tx->errcnt, &target_tx->errcnt);
+    __get_user(host_tx->stbcnt, &target_tx->stbcnt);
+    __get_user(host_tx->tai, &target_tx->tai);
+
+    unlock_user_struct(target_tx, target_addr, 0);
+    return 0;
+}
+
+static inline abi_long host_to_target_timex(abi_long target_addr,
+                                            struct timex *host_tx)
+{
+    struct target_timex *target_tx;
+
+    if (!lock_user_struct(VERIFY_WRITE, target_tx, target_addr, 0)) {
+        return -TARGET_EFAULT;
+    }
+
+    __put_user(host_tx->modes, &target_tx->modes);
+    __put_user(host_tx->offset, &target_tx->offset);
+    __put_user(host_tx->freq, &target_tx->freq);
+    __put_user(host_tx->maxerror, &target_tx->maxerror);
+    __put_user(host_tx->esterror, &target_tx->esterror);
+    __put_user(host_tx->status, &target_tx->status);
+    __put_user(host_tx->constant, &target_tx->constant);
+    __put_user(host_tx->precision, &target_tx->precision);
+    __put_user(host_tx->tolerance, &target_tx->tolerance);
+    __put_user(host_tx->time.tv_sec, &target_tx->time.tv_sec);
+    __put_user(host_tx->time.tv_usec, &target_tx->time.tv_usec);
+    __put_user(host_tx->tick, &target_tx->tick);
+    __put_user(host_tx->ppsfreq, &target_tx->ppsfreq);
+    __put_user(host_tx->jitter, &target_tx->jitter);
+    __put_user(host_tx->shift, &target_tx->shift);
+    __put_user(host_tx->stabil, &target_tx->stabil);
+    __put_user(host_tx->jitcnt, &target_tx->jitcnt);
+    __put_user(host_tx->calcnt, &target_tx->calcnt);
+    __put_user(host_tx->errcnt, &target_tx->errcnt);
+    __put_user(host_tx->stbcnt, &target_tx->stbcnt);
+    __put_user(host_tx->tai, &target_tx->tai);
+
+    unlock_user_struct(target_tx, target_addr, 1);
+    return 0;
+}
+
+
 static inline abi_long target_to_host_sigevent(struct sigevent *host_sevp,
                                                abi_ulong target_addr)
 {
@@ -9543,7 +9615,20 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
 #endif
 #endif
     case TARGET_NR_adjtimex:
-        goto unimplemented;
+        {
+            struct timex host_buf;
+
+            if (target_to_host_timex(&host_buf, arg1) != 0) {
+                goto efault;
+            }
+            ret = get_errno(adjtimex(&host_buf));
+            if (!is_error(ret)) {
+                if (host_to_target_timex(arg1, &host_buf) != 0) {
+                    goto efault;
+                }
+            }
+        }
+        break;
 #ifdef TARGET_NR_create_module
     case TARGET_NR_create_module:
 #endif

linux-user/syscall_defs.h

@@ -207,6 +207,34 @@ struct target_itimerspec {
     struct target_timespec it_value;
 };
 
+struct target_timex {
+    abi_uint modes;              /* Mode selector */
+    abi_long offset;             /* Time offset */
+    abi_long freq;               /* Frequency offset */
+    abi_long maxerror;           /* Maximum error (microseconds) */
+    abi_long esterror;           /* Estimated error (microseconds) */
+    abi_int status;              /* Clock command/status */
+    abi_long constant;           /* PLL (phase-locked loop) time constant */
+    abi_long precision;          /* Clock precision (microseconds, ro) */
+    abi_long tolerance;          /* Clock freq. tolerance (ppm, ro) */
+    struct target_timeval time;  /* Current time */
+    abi_long tick;               /* Microseconds between clock ticks */
+    abi_long ppsfreq;            /* PPS (pulse per second) frequency */
+    abi_long jitter;             /* PPS jitter (ro); nanoseconds */
+    abi_int shift;               /* PPS interval duration (seconds) */
+    abi_long stabil;             /* PPS stability */
+    abi_long jitcnt;             /* PPS jitter limit exceeded (ro) */
+    abi_long calcnt;             /* PPS calibration intervals */
+    abi_long errcnt;             /* PPS calibration errors */
+    abi_long stbcnt;             /* PPS stability limit exceeded */
+    abi_int tai;                 /* TAI offset */
+
+    /* Further padding bytes to allow for future expansion */
+    abi_int:32; abi_int:32; abi_int:32; abi_int:32;
+    abi_int:32; abi_int:32; abi_int:32; abi_int:32;
+    abi_int:32; abi_int:32; abi_int:32;
+};
+
 typedef abi_long target_clock_t;
 
 #define TARGET_HZ 100