So, forever, we've had this ptrace_signal_deliver implementation
which tries to handle all of the nasties that can occur when the
debugger looks at a process about to take a signal. It's meant
to address all of these issues inside of the kernel so that the
debugger need not be mindful of such things.
Problem is, this doesn't work.
The idea was that we should do the syscall restart business first, so
that the debugger captures that state. Otherwise, if the debugger for
example saves the child's state, makes the child execute something
else, then restores the saved state, we won't handle the syscall
restart properly because we lose the "we're in a syscall" state.
The code here worked for most cases, but if the debugger actually
passes the signal through to the child unaltered, it's possible that
we would do a syscall restart when we shouldn't have.
In particular this breaks the case of debugging a process under a gdb
which is being debugged by yet another gdb. gdb uses sigsuspend
to wait for SIGCHLD of the inferior, but if gdb itself is being
debugged by a top-level gdb we get a ptrace_stop(). The top-level gdb
does a PTRACE_CONT with SIGCHLD to let the inferior gdb see the
signal. But ptrace_signal_deliver() assumed the debugger would cancel
out the signal and therefore did a syscall restart, because the return
error was ERESTARTNOHAND.
Fix this by simply making ptrace_signal_deliver() a nop, and providing
a way for the debugger to control system call restarting properly:
1) Report a "in syscall" software bit in regs->{tstate,psr}.
It is set early on in trap entry to a system call and is fully
visible to the debugger via ptrace() and regsets.
2) Test this bit right before doing a syscall restart. We have
to do a final recheck right after get_signal_to_deliver() in
case the debugger cleared the bit during ptrace_stop().
3) Clear the bit in trap return so we don't accidently try to set
that bit in the real register.
As a result we also get a ptrace_{is,clear}_syscall() for sparc32 just
like sparc64 has.
M68K has this same exact bug, and is now the only other user of the
ptrace_signal_deliver hook. It needs to be fixed in the same exact
way as sparc.
Signed-off-by: David S. Miller <davem@davemloft.net>
Forever we had a PTRACE_SUNOS_DETACH which was unconditionally
recognized, regardless of the personality of the process.
Unfortunately, this value is what ended up in the GLIBC sys/ptrace.h
header file on sparc as PTRACE_DETACH and PT_DETACH.
So continue to recognize this old value. Luckily, it doesn't conflict
with anything we actually care about.
Signed-off-by: David S. Miller <davem@davemloft.net>
1) ptrace should pass 'current' to task_user_regset_view()
2) When fetching general registers using a 64-bit view, and
the target is 32-bit, we have to convert.
3) Skip the whole register window get/set code block if
the user isn't asking to access anything in there.
Otherwise we have problems if the user doesn't have
an address space setup. Fetching ptrace register is
still valid at such a time, and ptrace does not try
to access the register window area of the regset.
Signed-off-by: David S. Miller <davem@davemloft.net>
Supporting SunOS ptrace() is pretty pointless and these
kinds of quirks keep us from being able to share more
code with other platforms.
Signed-off-by: David S. Miller <davem@davemloft.net>
ptrace_traceme() consolidation made
ret = ptrace_traceme();
dead write.
Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
GDB uses a PTRACE_PEEKUSR call with offset 0 to see
if a thread is alive, so provide a success return for
this particular special case.
Signed-off-by: David S. Miller <davem@davemloft.net>
The ptrace_get_task_struct() helper that I added as part of the ptrace
consolidation is useful in variety of places that currently opencode it.
Switch them to the common helpers.
Add a ptrace_traceme() helper that needs to be explicitly called, and simplify
the ptrace_get_task_struct() interface. We don't need the request argument
now, and we return the task_struct directly, using ERR_PTR() for error
returns. It's a bit more code in the callers, but we have two sane routines
that do one thing well now.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1) Use cpudata cache line sizes, not magic constants.
2) Align start address in cheetah case so we do not get
unaligned address traps. (pgrep was good at triggering
this, via /proc/${pid}/cmdline accesses)
Signed-off-by: David S. Miller <davem@davemloft.net>
This showed that arch/sparc64/kernel/ptrace.c was not getting
the define properly, and thus the code protected by this ifdef
was never actually compiled before. So fix that too.
Signed-off-by: David S. Miller <davem@davemloft.net>
Also fix a bug in 32-bit syscall tracing. We forgot to update
this code when we moved over to the convention that all 32-bit
syscall arguments are zero extended by default.
Signed-off-by: David S. Miller <davem@davemloft.net>
Convert most of the current code that uses _NSIG directly to instead use
valid_signal(). This avoids gcc -W warnings and off-by-one errors.
Signed-off-by: Jesper Juhl <juhl-lkml@dif.dk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
We were flushing the D-cache excessively for ptrace() processing
and this makes debugging threads so slow as to be totally unusable.
All process page accesses via ptrace() go via access_process_vm().
This routine, for each process page, uses get_user_pages(). That
in turn does a flush_dcache_page() on the child pages before we
copy in/out the ptrace request data.
Therefore, all we need to do after the data movement is:
1) Flush the D-cache pages if the kernel maps the page to a different
color than userspace does.
2) If we wrote to the page, we need to flush the I-cache on older cpus.
Previously we just flushed the entire cache at the end of a ptrace()
request, and that was beyond stupid.
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
SunOS aparently had this weird PTRACE_CONT semantic which
we copied. If the addr argument is something other than
1, it sets the process program counter to whatever that
value is.
This is different from every other Linux architecture, which
don't do anything with the addr and data args.
This difference in particular breaks the Linux native GDB support
for fork and vfork tracing on sparc and sparc64.
There is no interest in running SunOS binaries using this weird
PTRACE_CONT behavior, so just delete it so we behave like other
platforms do.
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
