It is sure confusing that linux/ptrace.h has:
#define PTRACE_SINGLESTEP 9
#define PTRACE_ATTACH 0x10
#define PTRACE_DETACH 0x11
#define PTRACE_SYSCALL 24
All the low-numbered constants are in decimal, but the last two in hex.
It sure makes it likely that someone will look at this and think that
9, 10, 11 are used, and that 16 and 17 are not used.
How about we use the same notation for all the numbers [0,24] in the
same short list?
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This tightens up __dequeue_signal a little. It also avoids doing
recalc_sigpending twice in a row, instead doing it once in dequeue_signal.
Signed-off-by: Roland McGrath <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Ingo Molnar <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
The latest toolchains can produce a new ELF section in DSOs and
dynamically-linked executables. The new section ".gnu.hash" replaces
".hash", and allows for more efficient runtime symbol lookups by the
dynamic linker. The new ld option --hash-style={sysv|gnu|both} controls
whether to produce the old ".hash", the new ".gnu.hash", or both. In some
new systems such as Fedora Core 6, gcc by default passes --hash-style=gnu
to the linker, so that a standard invocation of "gcc -shared" results in
producing a DSO with only ".gnu.hash". The new ".gnu.hash" sections need
to be dealt with the same way as ".hash" sections in all respects; only the
dynamic linker cares about their contents. To work with older dynamic
linkers (i.e. preexisting releases of glibc), a binary must have the old
".hash" section. The --hash-style=both option produces binaries that a new
dynamic linker can use more efficiently, but an old dynamic linker can
still handle.
The new section runs afoul of the custom linker scripts used to build vDSO
images for the kernel. On ia64, the failure mode for this is a boot-time
panic because the vDSO's PT_IA_64_UNWIND segment winds up ill-formed.
This patch addresses the problem in two ways.
First, it mentions ".gnu.hash" in all the linker scripts alongside ".hash".
This produces correct vDSO images with --hash-style=sysv (or old tools),
with --hash-style=gnu, or with --hash-style=both.
Second, it passes the --hash-style=sysv option when building the vDSO
images, so that ".gnu.hash" is not actually produced. This is the most
conservative choice for compatibility with any old userland. There is some
concern that some ancient glibc builds (though not any known old production
system) might choke on --hash-style=both binaries. The optimizations
provided by the new style of hash section do not really matter for a DSO
with a tiny number of symbols, as the vDSO has. If someone wants to use
=gnu or =both for their vDSO builds and worry less about that
compatibility, just change the option and the linker script changes will
make any choice work fine.
Signed-off-by: Roland McGrath <[email protected]>
Cc: "Luck, Tony" <[email protected]>
Cc: Kyle McMartin <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Jeff Dike <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Sam Ravnborg <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This reverts most of commit 30e0fca6c1.
It broke the case of non-leader MT exec when ptraced.
I think the bug it was intended to fix was already addressed by commit
788e05a67c.
Signed-off-by: Roland McGrath <[email protected]>
Acked-by: Oleg Nesterov <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
The only record we have of the real-time age of a process, regardless of
execs it's done, is start_time. When a non-leader thread exec, the
original start_time of the process is lost. Things looking at the
real-time age of the process are fooled, for example the process accounting
record when the process finally dies. This change makes the oldest
start_time stick around with the process after a non-leader exec. This way
the association between PID and start_time is kept constant, which seems
correct to me.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This change corrects an omission in posix_cpu_timer_schedule, so that it
correctly propagates the overrun calculation to where it will get reported
to the user.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Back about a year ago when I last fiddled heavily with the do_wait code, I
was thinking too hard about the wrong thing and I now think I introduced a
bug whose inverse thought I was fixing.
Apparently noone was looking too hard over much shoulder, so as to cite my
bogus reasoning at the time. In the race condition when PTRACE_ATTACH is
about to steal a child and then the child hits a tracing event (what
my_ptrace_child checks for), the real parent does need to set its flag
noting it has some eligible live children. Otherwise a spurious ECHILD
error is possible, since the child in question is not yet on the
ptrace_children list.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This just makes sure that a thread's expiry times can't get reset after
it clears them in do_exit.
This is what allowed us to re-introduce the stricter BUG_ON() check in
a362f463a6.
Signed-off-by: Linus Torvalds <[email protected]>
When I originally moved exit_itimers into __exit_signal, that was the only
place where we could reliably know it was the last thread in the group
dying, without races. Since then we've gotten the signal_struct.live
counter, and do_exit can reliably do group-wide cleanup work.
This patch moves the call to do_exit, where it's made without locks. This
avoids the deadlock issues that the old __exit_signal code's comment talks
about, and the one that Oleg found recently with process CPU timers.
[ This replaces e03d13e985, which is why
it was just reverted. ]
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Oleg Nesterov reported an SMP deadlock. If there is a running timer
tracking a different process's CPU time clock when the process owning
the timer exits, we deadlock on tasklist_lock in posix_cpu_timer_del via
exit_itimers.
That code was using tasklist_lock to check for a race with __exit_signal
being called on the timer-target task and clearing its ->signal.
However, there is actually no such race. __exit_signal will have called
posix_cpu_timers_exit and posix_cpu_timers_exit_group before it does
that. Those will clear those k_itimer's association with the dying
task, so posix_cpu_timer_del will return early and never reach the code
in question.
In addition, posix_cpu_timer_del called from exit_itimers during execve
or directly from timer_delete in the process owning the timer can race
with an exiting timer-target task to cause a double put on timer-target
task struct. Make sure we always access cpu_timers lists with sighand
lock held.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Chris Wright <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Any tests using < TASK_STOPPED or the like are left over from the time
when the TASK_ZOMBIE and TASK_DEAD bits were in the same word, and it
served to check for "stopped or dead". I think this one in
do_signal_stop is the only such case. It has been buggy ever since
exit_state was separated, and isn't testing the exit_state value.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
GCC 4 emits more DWARF debugging information than before and there is now a
.debug_loc section as well. This causes "make buildcheck" to fail. Rather
than just add that one to the special case list, I used a regexp to ignore
any .debug_ANYTHING sections in case more show up in the future.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Sam Ravnborg <[email protected]>
This makes the vDSO use nops for all its padding around instructions,
rather than sometimes zeros, and nop-pads the end of the area containing
instructions to a 32-byte cache line, to keep text and data in separate
lines.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
When a noninitial thread does exec, it becomes the new group leader. If
there is a ITIMER_REAL timer running, it points at the old group leader and
when it fires it can follow a stale pointer. The timer data needs to be
reset to point at the exec'ing thread that is becoming the group leader.
This has to synchronize with any concurrent firing of the timer to make
sure that it_real_fn can never run when the data points to a thread that
might have been reaped already.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This is the x86_64 version of the signal fix I just posted for i386.
This problem was first noticed on PPC and has already been fixed there.
But the exact same issue applies to other platforms in the same way. The
signal blocking for sa_mask and the handled signal takes place after the
handler setup. When the stack is bogus, the handler setup forces a
SIGSEGV. But then this will be blocked, and returning to user mode will
fault again and iterate. This patch fixes the problem by checking whether
signal handler setup failed, and not doing the signal-blocking if so. This
copies what was done in the ppc code. I think all architectures' signal
handler setup code follows this pattern and needs the change.
Signed-off-by: Roland McGrath <[email protected]>
Cc: Andi Kleen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This problem was first noticed on PPC and has already been fixed there.
But the exact same issue applies to other platforms in the same way. The
signal blocking for sa_mask and the handled signal takes place after the
handler setup. When the stack is bogus, the handler setup forces a
SIGSEGV. But then this will be blocked, and returning to user mode will
fault again and iterate. This patch fixes the problem by checking whether
signal handler setup failed, and not doing the signal-blocking if so. This
copies what was done in the ppc code. I think all architectures' signal
handler setup code follows this pattern and needs the change.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
We fixed this bug before, but it didn't take. It may have been the case
that the problem was first noticed to occur in a CONFIG_REGPARM compile.
But it's not regparm functions that need not to make tail calls, it's
asmlinkage functions called with a user pt_regs frame on the stack
supplying their arguments. prevent_tail_call probably doesn't do anything
at all in regparm functions (your argument registers are going to be
clobbered, period). It was a braino to conditionalize that definition in
the first place.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
The addition of the PT_NOTE didn't take in the x86_64 version of the i386
vDSO, because I forgot the linker script bit in that copy.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
If arch_setup_additional_pages fails, the error path will do some double-frees.
This fixes it.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This patch adds an ELF note to the vDSO giving the LINUX_VERSION_CODE
value. Having this in the vDSO lets the dynamic linker avoid the `uname'
syscall it now always does at startup to ascertain the kernel ABI
available.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This moves the macro loaddebug from asm-i386/suspend.h to
asm-i386/processor.h, which is the place that makes sense for it to be
defined, removes the extra copy of the same macro in
arch/i386/kernel/process.c, and makes arch/i386/kernel/signal.c use the
macro in place of its expansion.
This is a purely cosmetic cleanup for the normal i386 kernel. However, it
is handy for Xen to be able to just redefine the loaddebug macro once
instead of also changing the signal.c code.
Signed-off-by: Roland McGrath <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Roland McGrath