On Mon, Jan 03, 2022 at 10:19:56AM -0800, Walt Drummond wrote:
> Support TTY VSTATUS character, NOKERNINFO local control bit and the
> signal SIGINFO, all as in 4.3BSD.
>
> Signed-off-by: Walt Drummond <walt@xxxxxxxxxxx>
> ---
> arch/x86/include/asm/signal.h | 2 +-
> arch/x86/include/uapi/asm/signal.h | 4 +-
> drivers/tty/Makefile | 2 +-
> drivers/tty/n_tty.c | 21 +++++
> drivers/tty/tty_io.c | 10 ++-
> drivers/tty/tty_ioctl.c | 4 +
> drivers/tty/tty_status.c | 135 ++++++++++++++++++++++++++++
> fs/proc/array.c | 29 +-----
> include/asm-generic/termios.h | 4 +-
> include/linux/sched.h | 52 ++++++++++-
> include/linux/signal.h | 4 +
> include/linux/tty.h | 8 ++
> include/uapi/asm-generic/ioctls.h | 2 +
> include/uapi/asm-generic/signal.h | 6 +-
> include/uapi/asm-generic/termbits.h | 34 +++----
> 15 files changed, 264 insertions(+), 53 deletions(-)
> create mode 100644 drivers/tty/tty_status.c
>
> diff --git a/arch/x86/include/asm/signal.h b/arch/x86/include/asm/signal.h
> index d8e2efe6cd46..0a01877c11ab 100644
> --- a/arch/x86/include/asm/signal.h
> +++ b/arch/x86/include/asm/signal.h
> @@ -8,7 +8,7 @@
> /* Most things should be clean enough to redefine this at will, if care
> is taken to make libc match. */
>
> -#define _NSIG 64
> +#define _NSIG 65
>
> #ifdef __i386__
> # define _NSIG_BPW 32
> diff --git a/arch/x86/include/uapi/asm/signal.h b/arch/x86/include/uapi/asm/signal.h
> index 164a22a72984..60dca62d3dcf 100644
> --- a/arch/x86/include/uapi/asm/signal.h
> +++ b/arch/x86/include/uapi/asm/signal.h
> @@ -60,7 +60,9 @@ typedef unsigned long sigset_t;
>
> /* These should not be considered constants from userland. */
> #define SIGRTMIN 32
> -#define SIGRTMAX _NSIG
> +#define SIGRTMAX 64
> +
> +#define SIGINFO 65
>
> #define SA_RESTORER 0x04000000
>
> diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile
> index a2bd75fbaaa4..d50ba690bb87 100644
> --- a/drivers/tty/Makefile
> +++ b/drivers/tty/Makefile
> @@ -2,7 +2,7 @@
> obj-$(CONFIG_TTY) += tty_io.o n_tty.o tty_ioctl.o tty_ldisc.o \
> tty_buffer.o tty_port.o tty_mutex.o \
> tty_ldsem.o tty_baudrate.o tty_jobctrl.o \
> - n_null.o
> + n_null.o tty_status.o
> obj-$(CONFIG_LEGACY_PTYS) += pty.o
> obj-$(CONFIG_UNIX98_PTYS) += pty.o
> obj-$(CONFIG_AUDIT) += tty_audit.o
> diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
> index 0ec93f1a61f5..b510e01289fd 100644
> --- a/drivers/tty/n_tty.c
> +++ b/drivers/tty/n_tty.c
> @@ -1334,6 +1334,24 @@ static void n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
> commit_echoes(tty);
> return;
> }
> +#ifdef VSTATUS
> + if (c == STATUS_CHAR(tty)) {
> + /* Do the status message first and then send
> + * the signal, otherwise signal delivery can
> + * change the process state making the status
> + * message misleading. Also, use __isig() and
> + * not sig(), as if we flush the tty we can
> + * lose parts of the message.
...As well as the character input in the canonical mode's built-in line
editor.
> + */
> +
> + if (!L_NOKERNINFO(tty))
> + tty_status(tty);
> +# if defined(SIGINFO) && SIGINFO != SIGPWR
> + __isig(SIGINFO, tty);
> +# endif
> + return;
> + }
> +#endif /* VSTATUS */
> if (c == '\n') {
> if (L_ECHO(tty) || L_ECHONL(tty)) {
> echo_char_raw('\n', ldata);
> @@ -1763,6 +1781,9 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old)
> set_bit(EOF_CHAR(tty), ldata->char_map);
> set_bit('\n', ldata->char_map);
> set_bit(EOL_CHAR(tty), ldata->char_map);
> +#ifdef VSTATUS
> + set_bit(STATUS_CHAR(tty), ldata->char_map);
> +#endif
> if (L_IEXTEN(tty)) {
> set_bit(WERASE_CHAR(tty), ldata->char_map);
> set_bit(LNEXT_CHAR(tty), ldata->char_map);
> diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
> index 6616d4a0d41d..8e488ecba330 100644
> --- a/drivers/tty/tty_io.c
> +++ b/drivers/tty/tty_io.c
> @@ -120,18 +120,26 @@
> #define TTY_PARANOIA_CHECK 1
> #define CHECK_TTY_COUNT 1
>
> +/* Less ugly than an ifdef in the middle of the initalizer below, maybe? */
> +#ifdef NOKERNINFO
> +# define __NOKERNINFO NOKERNINFO
> +#else
> +# define __NOKERNINFO 0
> +#endif
> +
> struct ktermios tty_std_termios = { /* for the benefit of tty drivers */
> .c_iflag = ICRNL | IXON,
> .c_oflag = OPOST | ONLCR,
> .c_cflag = B38400 | CS8 | CREAD | HUPCL,
> .c_lflag = ISIG | ICANON | ECHO | ECHOE | ECHOK |
> - ECHOCTL | ECHOKE | IEXTEN,
> + ECHOCTL | ECHOKE | IEXTEN | __NOKERNINFO,
> .c_cc = INIT_C_CC,
> .c_ispeed = 38400,
> .c_ospeed = 38400,
> /* .c_line = N_TTY, */
> };
> EXPORT_SYMBOL(tty_std_termios);
> +#undef __NOKERNINFO
>
> /* This list gets poked at by procfs and various bits of boot up code. This
> * could do with some rationalisation such as pulling the tty proc function
> diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
> index 507a25d692bb..b250eabca1ba 100644
> --- a/drivers/tty/tty_ioctl.c
> +++ b/drivers/tty/tty_ioctl.c
> @@ -809,6 +809,10 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
> if (get_user(arg, (unsigned int __user *) arg))
> return -EFAULT;
> return tty_change_softcar(real_tty, arg);
> +#ifdef TIOCSTAT
> + case TIOCSTAT:
> + return tty_status(real_tty);
> +#endif
> default:
> return -ENOIOCTLCMD;
> }
> diff --git a/drivers/tty/tty_status.c b/drivers/tty/tty_status.c
> new file mode 100644
Nitpick: the new functionality is part of n_tty and not the generic tty
subsystem, so "tty_status.c" is a misleading name for the new file,
unlike e. g. "n_tty_status.c". It has no use in the various modem
drivers, for example.
Likewise for the tty_status() function.
> index 000000000000..a9600f5bd48c
> --- /dev/null
> +++ b/drivers/tty/tty_status.c
> @@ -0,0 +1,135 @@
> +// SPDX-License-Identifier: GPL-1.0+
> +/*
> + * tty_status.c --- implements VSTATUS and TIOCSTAT from BSD4.3/4.4
> + *
> + */
> +
> +#include <linux/sched.h>
> +#include <linux/mm.h>
> +#include <linux/tty.h>
> +#include <linux/sched/cputime.h>
> +#include <linux/sched/loadavg.h>
> +#include <linux/pid.h>
> +#include <linux/slab.h>
> +#include <linux/math64.h>
> +
> +#define MSGLEN (160 + TASK_COMM_LEN)
> +
> +inline unsigned long getRSSk(struct mm_struct *mm)
> +{
> + if (mm == NULL)
> + return 0;
> + return get_mm_rss(mm) * PAGE_SIZE / 1024;
> +}
> +
> +inline long nstoms(long l)
> +{
> + l /= NSEC_PER_MSEC * 10;
> + if (l < 10)
> + l *= 10;
> + return l;
> +}
> +
> +inline struct task_struct *compare(struct task_struct *new,
> + struct task_struct *old)
> +{
> + unsigned int ostate, nstate;
> +
> + if (old == NULL)
> + return new;
> +
> + ostate = task_state_index(old);
> + nstate = task_state_index(new);
> +
> + if (ostate == nstate) {
> + if (old->start_time > new->start_time)
> + return old;
> + return new;
> + }
> +
> + if (ostate < nstate)
> + return old;
> +
> + return new;
> +}
> +
> +struct task_struct *pick_process(struct pid *pgrp)
> +{
> + struct task_struct *p, *winner = NULL;
> +
> + read_lock(&tasklist_lock);
> + do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
> + winner = compare(p, winner);
> + } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
> + read_unlock(&tasklist_lock);
> +
> + return winner;
> +}
> +
> +int tty_status(struct tty_struct *tty)
> +{
> + char tname[TASK_COMM_LEN];
> + unsigned long loadavg[3];
> + uint64_t pcpu, cputime, wallclock;
> + struct task_struct *p;
> + struct rusage rusage;
> + struct timespec64 utime, stime, rtime;
> + char msg[MSGLEN] = {0};
> + int len = 0;
> +
> + if (tty == NULL)
> + return -ENOTTY;
> +
> + get_avenrun(loadavg, FIXED_1/200, 0);
> + len += scnprintf((char *)&msg[len], MSGLEN - len, "load: %lu.%02lu ",
> + LOAD_INT(loadavg[0]), LOAD_FRAC(loadavg[0]));
> +
> + if (tty->ctrl.session == NULL) {
> + len += scnprintf((char *)&msg[len], MSGLEN - len,
> + "not a controlling terminal");
> + goto print;
> + }
> +
> + if (tty->ctrl.pgrp == NULL) {
> + len += scnprintf((char *)&msg[len], MSGLEN - len,
> + "no foreground process group");
> + goto print;
> + }
> +
> + p = pick_process(tty->ctrl.pgrp);
> + if (p == NULL) {
> + len += scnprintf((char *)&msg[len], MSGLEN - len,
> + "empty foreground process group");
> + goto print;
> + }
> +
> + get_task_comm(tname, p);
> + getrusage(p, RUSAGE_BOTH, &rusage);
> + wallclock = ktime_get_ns() - p->start_time;
> +
> + utime.tv_sec = rusage.ru_utime.tv_sec;
> + utime.tv_nsec = rusage.ru_utime.tv_usec * NSEC_PER_USEC;
> + stime.tv_sec = rusage.ru_stime.tv_sec;
> + stime.tv_nsec = rusage.ru_stime.tv_usec * NSEC_PER_USEC;
> + rtime = ns_to_timespec64(wallclock);
> +
> + cputime = timespec64_to_ns(&utime) + timespec64_to_ns(&stime);
> + pcpu = div64_u64(cputime * 100, wallclock);
> +
> + len += scnprintf((char *)&msg[len], MSGLEN - len,
> + /* task, PID, task state */
> + "cmd: %s %d [%s] "
> + /* rtime, utime, stime, %cpu, rss */
> + "%llu.%02lur %llu.%02luu %llu.%02lus %llu%% %luk",
> + tname, task_pid_vnr(p), (char *)get_task_state_name(p),
> + rtime.tv_sec, nstoms(rtime.tv_nsec),
> + utime.tv_sec, nstoms(utime.tv_nsec),
> + stime.tv_sec, nstoms(stime.tv_nsec),
> + pcpu, getRSSk(p->mm));
> +
> +print:
> + len += scnprintf((char *)&msg[len], MSGLEN - len, "\r\n");
> + tty_write_message(tty, msg);
tty_write_message() is quite risky to use; while writing my
implementation a couple of years ago I've found it easy to accidentally
set up deadlocks with this interface — in particular if the function is
called from the tty character receive path.
I hope you're testing the functionality with CONFIG_PROVE_LOCKING enabled.
> +
> + return 0;
> +}
> diff --git a/fs/proc/array.c b/fs/proc/array.c
> index f37c03077b58..eb14306cdde2 100644
> --- a/fs/proc/array.c
> +++ b/fs/proc/array.c
> @@ -62,6 +62,7 @@
> #include <linux/tty.h>
> #include <linux/string.h>
> #include <linux/mman.h>
> +#include <linux/sched.h>
> #include <linux/sched/mm.h>
> #include <linux/sched/numa_balancing.h>
> #include <linux/sched/task_stack.h>
> @@ -111,34 +112,6 @@ void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape)
> seq_printf(m, "%.64s", tcomm);
> }
>
> -/*
> - * The task state array is a strange "bitmap" of
> - * reasons to sleep. Thus "running" is zero, and
> - * you can test for combinations of others with
> - * simple bit tests.
> - */
> -static const char * const task_state_array[] = {
> -
> - /* states in TASK_REPORT: */
> - "R (running)", /* 0x00 */
> - "S (sleeping)", /* 0x01 */
> - "D (disk sleep)", /* 0x02 */
> - "T (stopped)", /* 0x04 */
> - "t (tracing stop)", /* 0x08 */
> - "X (dead)", /* 0x10 */
> - "Z (zombie)", /* 0x20 */
> - "P (parked)", /* 0x40 */
> -
> - /* states beyond TASK_REPORT: */
> - "I (idle)", /* 0x80 */
> -};
> -
> -static inline const char *get_task_state(struct task_struct *tsk)
> -{
> - BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_array));
> - return task_state_array[task_state_index(tsk)];
> -}
> -
> static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
> struct pid *pid, struct task_struct *p)
> {
> diff --git a/include/asm-generic/termios.h b/include/asm-generic/termios.h
> index b1398d0d4a1d..9b080e1a82d4 100644
> --- a/include/asm-generic/termios.h
> +++ b/include/asm-generic/termios.h
> @@ -10,9 +10,9 @@
> eof=^D vtime=\0 vmin=\1 sxtc=\0
> start=^Q stop=^S susp=^Z eol=\0
> reprint=^R discard=^U werase=^W lnext=^V
> - eol2=\0
> + eol2=\0 status=^T
> */
> -#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0"
> +#define INIT_C_CC "\003\034\177\025\004\0\1\0\021\023\032\0\022\017\027\026\0\024"
>
> /*
> * Translate a "termio" structure into a "termios". Ugh.
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index c1a927ddec64..2171074ec8f5 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -70,7 +70,7 @@ struct task_group;
>
> /*
> * Task state bitmask. NOTE! These bits are also
> - * encoded in fs/proc/array.c: get_task_state().
> + * encoded in get_task_state().
> *
> * We have two separate sets of flags: task->state
> * is about runnability, while task->exit_state are
> @@ -1643,6 +1643,56 @@ static inline char task_state_to_char(struct task_struct *tsk)
> return task_index_to_char(task_state_index(tsk));
> }
>
> +static inline const char *get_task_state_name(struct task_struct *tsk)
> +{
> + static const char * const task_state_array[] = {
> +
> + /* states in TASK_REPORT: */
> + "running", /* 0x00 */
> + "sleeping", /* 0x01 */
> + "disk sleep", /* 0x02 */
> + "stopped", /* 0x04 */
> + "tracing stop", /* 0x08 */
> + "dead", /* 0x10 */
> + "zombie", /* 0x20 */
> + "parked", /* 0x40 */
> +
> + /* states beyond TASK_REPORT: */
> + "idle", /* 0x80 */
> + };
> +
> + BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_array));
> + return task_state_array[task_state_index(tsk)];
> +}
> +
> +static inline const char *get_task_state(struct task_struct *tsk)
> +{
> + /*
> + * The task state array is a strange "bitmap" of
> + * reasons to sleep. Thus "running" is zero, and
> + * you can test for combinations of others with
> + * simple bit tests.
> + */
> + static const char * const task_state_array[] = {
> +
> + /* states in TASK_REPORT: */
> + "R (running)", /* 0x00 */
> + "S (sleeping)", /* 0x01 */
> + "D (disk sleep)", /* 0x02 */
> + "T (stopped)", /* 0x04 */
> + "t (tracing stop)", /* 0x08 */
> + "X (dead)", /* 0x10 */
> + "Z (zombie)", /* 0x20 */
> + "P (parked)", /* 0x40 */
> +
> + /* states beyond TASK_REPORT: */
> + "I (idle)", /* 0x80 */
> + };
> +
> + BUILD_BUG_ON(1 + ilog2(TASK_REPORT_MAX) != ARRAY_SIZE(task_state_array));
> + return task_state_array[task_state_index(tsk)];
> +}
> +
> /**
> * is_global_init - check if a task structure is init. Since init
> * is free to have sub-threads we need to check tgid.
> diff --git a/include/linux/signal.h b/include/linux/signal.h
> index b77f9472a37c..76bda1a20578 100644
> --- a/include/linux/signal.h
> +++ b/include/linux/signal.h
> @@ -541,6 +541,7 @@ extern bool unhandled_signal(struct task_struct *tsk, int sig);
> * | non-POSIX signal | default action |
> * +--------------------+------------------+
> * | SIGEMT | coredump |
> + * | SIGINFO | ignore |
> * +--------------------+------------------+
> *
> * (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
> @@ -567,6 +568,9 @@ static inline int sig_kernel_ignore(unsigned long sig)
> return sig == SIGCONT ||
> sig == SIGCHLD ||
> sig == SIGWINCH ||
> +#if defined(SIGINFO) && SIGINFO != SIGPWR
> + sig == SIGINFO ||
> +#endif
> sig == SIGURG;
> }
>
> diff --git a/include/linux/tty.h b/include/linux/tty.h
> index 168e57e40bbb..943d85aa471c 100644
> --- a/include/linux/tty.h
> +++ b/include/linux/tty.h
> @@ -49,6 +49,9 @@
> #define WERASE_CHAR(tty) ((tty)->termios.c_cc[VWERASE])
> #define LNEXT_CHAR(tty) ((tty)->termios.c_cc[VLNEXT])
> #define EOL2_CHAR(tty) ((tty)->termios.c_cc[VEOL2])
> +#ifdef VSTATUS
> +#define STATUS_CHAR(tty) ((tty)->termios.c_cc[VSTATUS])
> +#endif
>
> #define _I_FLAG(tty, f) ((tty)->termios.c_iflag & (f))
> #define _O_FLAG(tty, f) ((tty)->termios.c_oflag & (f))
> @@ -114,6 +117,9 @@
> #define L_PENDIN(tty) _L_FLAG((tty), PENDIN)
> #define L_IEXTEN(tty) _L_FLAG((tty), IEXTEN)
> #define L_EXTPROC(tty) _L_FLAG((tty), EXTPROC)
> +#ifdef NOKERNINFO
> +#define L_NOKERNINFO(tty) _L_FLAG((tty), NOKERNINFO)
> +#endif
>
> struct device;
> struct signal_struct;
> @@ -428,4 +434,6 @@ extern void tty_lock_slave(struct tty_struct *tty);
> extern void tty_unlock_slave(struct tty_struct *tty);
> extern void tty_set_lock_subclass(struct tty_struct *tty);
>
> +extern int tty_status(struct tty_struct *tty);
> +
> #endif
> diff --git a/include/uapi/asm-generic/ioctls.h b/include/uapi/asm-generic/ioctls.h
> index cdc9f4ca8c27..baa2b8d42679 100644
> --- a/include/uapi/asm-generic/ioctls.h
> +++ b/include/uapi/asm-generic/ioctls.h
> @@ -97,6 +97,8 @@
>
> #define TIOCMIWAIT 0x545C /* wait for a change on serial input line(s) */
> #define TIOCGICOUNT 0x545D /* read serial port inline interrupt counts */
> +/* Some architectures use 0x545E for FIOQSIZE */
> +#define TIOCSTAT 0x545F /* display process group stats on tty */
>
> /*
> * Some arches already define FIOQSIZE due to a historical
> diff --git a/include/uapi/asm-generic/signal.h b/include/uapi/asm-generic/signal.h
> index 3c4cc9b8378e..0b771eb1db94 100644
> --- a/include/uapi/asm-generic/signal.h
> +++ b/include/uapi/asm-generic/signal.h
> @@ -4,7 +4,7 @@
>
> #include <linux/types.h>
>
> -#define _NSIG 64
> +#define _NSIG 65
> #define _NSIG_BPW __BITS_PER_LONG
> #define _NSIG_WORDS ((_NSIG + _NSIG_BPW - 1) / _NSIG_BPW)
>
> @@ -49,9 +49,11 @@
> /* These should not be considered constants from userland. */
> #define SIGRTMIN 32
> #ifndef SIGRTMAX
> -#define SIGRTMAX _NSIG
> +#define SIGRTMAX 64
> #endif
>
> +#define SIGINFO 65
> +
> #if !defined MINSIGSTKSZ || !defined SIGSTKSZ
> #define MINSIGSTKSZ 2048
> #define SIGSTKSZ 8192
> diff --git a/include/uapi/asm-generic/termbits.h b/include/uapi/asm-generic/termbits.h
> index 2fbaf9ae89dd..cb4e9c6d629f 100644
> --- a/include/uapi/asm-generic/termbits.h
> +++ b/include/uapi/asm-generic/termbits.h
> @@ -58,6 +58,7 @@ struct ktermios {
> #define VWERASE 14
> #define VLNEXT 15
> #define VEOL2 16
> +#define VSTATUS 17
>
> /* c_iflag bits */
> #define IGNBRK 0000001
> @@ -164,22 +165,23 @@ struct ktermios {
> #define IBSHIFT 16 /* Shift from CBAUD to CIBAUD */
>
> /* c_lflag bits */
> -#define ISIG 0000001
> -#define ICANON 0000002
> -#define XCASE 0000004
> -#define ECHO 0000010
> -#define ECHOE 0000020
> -#define ECHOK 0000040
> -#define ECHONL 0000100
> -#define NOFLSH 0000200
> -#define TOSTOP 0000400
> -#define ECHOCTL 0001000
> -#define ECHOPRT 0002000
> -#define ECHOKE 0004000
> -#define FLUSHO 0010000
> -#define PENDIN 0040000
> -#define IEXTEN 0100000
> -#define EXTPROC 0200000
> +#define ISIG 0000001
> +#define ICANON 0000002
> +#define XCASE 0000004
> +#define ECHO 0000010
> +#define ECHOE 0000020
> +#define ECHOK 0000040
> +#define ECHONL 0000100
> +#define NOFLSH 0000200
> +#define TOSTOP 0000400
> +#define ECHOCTL 0001000
> +#define ECHOPRT 0002000
> +#define ECHOKE 0004000
> +#define FLUSHO 0010000
> +#define PENDIN 0040000
> +#define IEXTEN 0100000
> +#define EXTPROC 0200000
> +#define NOKERNINFO 0400000
>
> /* tcflow() and TCXONC use these */
> #define TCOOFF 0
> --
> 2.30.2
>
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