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text data bss dec hex filename
237913 660 49284 287857 46471 strace.before
237973 660 28772 267405 4148d strace
This reduces L1 D-cache pressure a bit: instead of dirtying
20k of bss, we will reuse already dirty stack area.
* util.c (printpathn): Use on-stack buffers instead of static ones.
Saves 5*MAXPATHLEN in bss.
(printstr): Use tprints() instead of tprintf("%s") when printing
formatted string. May be a bit faster, depending on libc.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
On attempts to block or set SIGTRAP handler,
for example, using sigaction syscall, we generate
an additional SIGSTOP.
This change gets rid of this SIGSTOP sending/ignoring.
It appears to work just fine.
It also works if I force strace to not use PTRACE_O_TRACESYSGOOD,
which means strace stops will be marked with SIGTRAP,
not (SIGTRAP | 0x80) - I wondered maybe that's when
this hack is needed.
So, why we even have TCB_SIGTRAPPED? No one knows. It predates
version control: this code was present in the initial commit,
in 1999. No adequate comments, either.
Moreover, TCB_SIGTRAPPED is not set in sys_rt_sigaction
and sys_sigprocmask syscalls - the ones which are most usually
used to implement signal blocking, it is only set in obsolete
sys_signal, sys_sigaction, sys_sigsetmask, and in some dead
non-Linux code.
I think whatever bug it was fixing is gone long ago -
at least as long as sys_rt_sigaction is used by glibc.
Again, since glibc (and uclibc) uses sys_rt_sigaction
and sys_sigprocmask, modified code paths are not used
by most programs anyway.
* defs.h: Remove definition of TCB_SIGTRAPPED.
* signal.c (sys_sigvec): Don't set TCB_SIGTRAPPED and don't send SIGSTOP.
(sys_sigsetmask): Likewise.
(sys_sigaction): Likewise.
(sys_signal): Likewise.
* strace.c (trace): Remove code which executes if TCB_SIGTRAPPED is set.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
I observed a case when signal delivery message was buffered
by stdio until it was flushed along with the next syscall
entry message.
* strace.c (trace): Flush output buffers in a few more cases.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
* syscall.c: Change x86_64_regs struct type from
pt_regs to user_regs_struct, and explain the change in comment.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
There is widespread confusion about exact meaning
of ERESTARTxyz codes. Before this change, we were showing
all four of them the same: as "(To be restarted)".
This change prints better explanations for these codes,
and contains verbose comments which explain *why* we display
codes that way - or else someone confused
is bound to come later and mangle them again.
New messages are:
ERESTARTSYS (To be restarted if SA_RESTART is set)
ERESTARTNOINTR (To be restarted)
ERESTARTNOHAND (Interrupted by signal)
ERESTART_RESTARTBLOCK (Interrupted by signal)
* syscall.c (trace_syscall_exiting): Make ERESTARTxyz messages
more descriptive.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
sys_sigreturn() performs ugly manipulations in order to show
signal mask which is restored by this syscall: on syscall entry,
fetches it from the stack, saves it in tcp->u_arg[]
(where it used to overflow this array - fixed sometime ago),
then retrieves the mask and displays it on syscall exit.
Apparently, the motivation is to make it slightly more obvious
to user that signal mask is restored only when this syscall returns.
IMO, this hardly justifies the necessary hacks. It is much easier
to display the mask at the point when we fetch it - on syscall entry.
While at it, I made it so that we do display returned value/errno.
I see no point in hiding it and showing uninformative "= ?" instead.
Example of pause() being interrupted by ALRM which has installed handler
which re-arms ALRM:
Before the patch:
rt_sigsuspend([INT]) = ? ERESTARTNOHAND (To be restarted)
--- {si_signo=SIGALRM, si_code=SI_KERNEL} (Alarm clock) ---
alarm(1) = 0
sigreturn() = ? (mask now [INT])
After:
rt_sigsuspend([INT]) = ? ERESTARTNOHAND (To be restarted)
--- {si_signo=SIGALRM, si_code=SI_KERNEL} (Alarm clock) ---
alarm(1) = 0
sigreturn() (mask [INT]) = -1 EINTR (Interrupted system call)
* defs.h: Declare struct pt_regs i386_regs and struct pt_regs x86_64_regs.
* syscall.c: Remove "static" keywork from these structures' definitions.
* signal.c (sys_sigreturn): Display mask on enter, not on exit.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Before this patch, if a thread got nuked by exit in another thread
and we happened to poke it at the same time, we print "????(" thingy
and detach the thread. Since we removed "detach before death" logic,
this no longer matches the behavior of other threads.
Before patch:
[pid 1780] exit_group(1) = ?
[pid 1778] ????( <unfinished ...>
Process 1778 detached
[pid 5860] +++ exited with 1 +++
After:
[pid 17765] exit_group(1) = ?
[pid 21680] ????( <unfinished ...>
[pid 17791] +++ exited with 1 +++
[pid 21680] +++ exited with 1 +++
* strace (trace): Do not detach from tracee which experienced ptrace error.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
* strace.c (detach): Drop sig parameter - it is zero in all calls.
(cleanup): Don't pass sig = 0 to detach() call.
(detach): Ditto.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
* util.c (umoven, umovestr) [SUPPORTED_PERSONALITIES > 1]: If current
personality's wordsize is less than sizeof(long), use only significant
bits of the given address.
On syscall entry, save current personality in the tcb structure
along with scno.
On syscall exit, restore current personality from the tcb structure.
* defs.h (struct tcb) [SUPPORTED_PERSONALITIES > 1]: Add currpers
field.
* strace.c (alloc_tcb) [SUPPORTED_PERSONALITIES > 1]: Initialize
tcp->currpers.
* syscall.c (update_personality) [SUPPORTED_PERSONALITIES > 1]: New
function.
(get_scno, trace_syscall_exiting): Use it.
Reported-by: Michael A Fetterman <mafetter@nvidia.com>
The s390 kernel sys_ipc system call only takes five arguments instead of
six arguments which the common code sys_ipc implementation takes.
One of the arguments of the sys_semtimedop subcall is therefore passed in
a different register than in the common code implementation.
This leads to broken decoding of the timespec argument:
semtimedop(0, 0x3ffffb43832, 1, {...}) = -1 EAGAIN
Fixed it looks like this:
semtimedop(0, 0x3ffffc2c842, 1, {0, 10000000}) = -1 EINTR
* linux/ipc.c (sys_semtimedop): Fix timespec decoding on s390.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
* linux/dummy.h: Add aliases to printargs() for those of dummy parsers
that had no own names before.
* linux/*/syscallent.h: Use these new names instead of printargs.
* desc.c (epollflags): Define.
(sys_epoll_create1): Use epollflags to printflags. Change "O" to "EPOLL".
Reported-by: Марк Коренберг <socketpair@gmail.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
* io.c (print_loff_t): New function.
(sys_sendfile64): Use it.
(splice_flags): New xlat structure.
(sys_tee, sys_splice, sys_vmsplice): New functions.
* linux/syscall.h (sys_tee, sys_splice, sys_vmsplice): Declare them.
* linux/*/syscallent.h: Use them.
