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The user space program can change its addressing mode between the
24-bit, 31-bit and the 64-bit mode if the kernel is 64 bit. Currently
the kernel always forces the standard amode on signal delivery and
signal return and on ptrace: 64-bit for a 64-bit process, 31-bit for
a compat process and 31-bit kernels. Change the signal and ptrace code
to allow the full range of addressing modes. Signal handlers are
run in the standard addressing mode for the process.
One caveat is that even an 31-bit compat process can switch to the
64-bit mode. The next signal will switch back into the 31-bit mode
and there is no room in the 31-bit compat signal frame to store the
information that the program came from the 64-bit mode.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Split out addressing mode bits from PSW_BASE_BITS, rename PSW_BASE_BITS
to PSW_MASK_BASE, get rid of psw_user32_bits, remove unused function
enabled_wait(), introduce PSW_MASK_USER, and drop PSW_MASK_MERGE macros.
Change psw_kernel_bits / psw_user_bits to contain only the bits that
are always set in the respective mode.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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An instruction with an address right below the adress limit for the
current addressing mode will wrap. The instruction restart logic in
the protection fault handler and the signal code need to follow the
wrapping rules to find the correct instruction address.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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For a ERESTARTNOHAND/ERESTARTSYS/ERESTARTNOINTR restarting system call
do_signal will prepare the restart of the system call with a rewind of
the PSW before calling get_signal_to_deliver (where the debugger might
take control). For A ERESTART_RESTARTBLOCK restarting system call
do_signal will set -EINTR as return code.
There are two issues with this approach:
1) strace never sees ERESTARTNOHAND, ERESTARTSYS, ERESTARTNOINTR or
ERESTART_RESTARTBLOCK as the rewinding already took place or the
return code has been changed to -EINTR
2) if get_signal_to_deliver does not return with a signal to deliver
the restart via the repeat of the svc instruction is left in place.
This opens a race if another signal is made pending before the
system call instruction can be reexecuted. The original system call
will be restarted even if the second signal would have ended the
system call with -EINTR.
These two issues can be solved by dropping the early rewind of the
system call before get_signal_to_deliver has been called and by using
the TIF_RESTART_SVC magic to do the restart if no signal has to be
delivered. The only situation where the system call restart via the
repeat of the svc instruction is appropriate is when a SA_RESTART
signal is delivered to user space.
Unfortunately this breaks inferior calls by the debugger again. The
system call number and the length of the system call instruction is
lost over the inferior call and user space will see ERESTARTNOHAND/
ERESTARTSYS/ERESTARTNOINTR/ERESTART_RESTARTBLOCK. To correct this a
new ptrace interface is added to save/restore the system call number
and system call instruction length.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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[ poleg@redhat.com: no need to declare show_regs() in ptrace.h, sched.h does this ]
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Overhaul program event recording and the code dealing with the ptrace
user space interface.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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The ieee_instruction_pointer can not be read from user space anymore
since git commit 613e1def6b52c399a8b72a5e11bc2e57d2546fb8, the ptrace
interface always returns zero. Remove it from the thread_struct. It
is still present in the user_regs_struct for compatability reasons.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Copy the last breaking event address from the lowcore to a new
field in the thread_struct on each system entry. Add a new
ptrace request PTRACE_GET_LAST_BREAK and a new utrace regset
REGSET_LAST_BREAK to query the last breaking event.
This is useful for debugging wild branches in user space code.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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While in theory user_enable_single_step/user_disable_single_step/
user_enable_blockstep could also be provided as an inline or macro there's
no good reason to do so, and having the prototype in one places keeps code
size and confusion down.
Roland said:
The original thought there was that user_enable_single_step() et al
might well be only an instruction or three on a sane machine (as if we
have any of those!), and since there is only one call site inlining
would be beneficial. But I agree that there is no strong reason to care
about inlining it.
As to the arch changes, there is only one thought I'd add to the
record. It was always my thinking that for an arch where
PTRACE_SINGLESTEP does text-modifying breakpoint insertion,
user_enable_single_step() should not be provided. That is,
arch_has_single_step()=>true means that there is an arch facility with
"pure" semantics that does not have any unexpected side effects.
Inserting a breakpoint might do very unexpected strange things in
multi-threaded situations. Aside from that, it is a peculiar side
effect that user_{enable,disable}_single_step() should cause COW
de-sharing of text pages and so forth. For PTRACE_SINGLESTEP, all these
peculiarities are the status quo ante for that arch, so having
arch_ptrace() itself do those is one thing. But for building other
things in the future, it is nicer to have a uniform "pure" semantics
that arch-independent code can expect.
OTOH, all such arch issues are really up to the arch maintainer. As
of today, there is nothing but ptrace using user_enable_single_step() et
al so it's a distinction without a practical difference. If/when there
are other facilities that use user_enable_single_step() and might care,
the affected arch's can revisit the question when someone cares about
the quality of the arch support for said new facility.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This API is needed for the kprobe-based event tracer.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
LKML-Reference: <20100212123840.GB27548@osiris.boeblingen.de.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
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From: Heiko Carstens <heiko.carstens@de.ibm.com>
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Currently the storage of the machine flags is a globally exported unsigned
long long variable. By moving the storage location into the lowcore struct we
allow assembler code to check machine_flags directly even without needing a
register. Addtionally the lowcore and therefore the machine flags too will be
in cache most of the time.
Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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We need to use this value in the checkpoint/restart code and would like to
have a constant instead of a magic '3'.
Cc: linux-s390@vger.kernel.org
Signed-off-by: Dan Smith <danms@us.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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/include/asm/ptrace.h:275: extern's make no sense in userspace
/include/asm/ptrace.h:279: extern's make no sense in userspace
/include/asm/ptrace.h:280: extern's make no sense in userspace
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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* 'for-linus' of git://git390.osdl.marist.edu/pub/scm/linux-2.6:
[S390] Update default configuration.
[S390] Fix alignment of initial kernel stack.
[S390] pgtable.h: Fix oops in unmap_vmas for KVM processes
[S390] fix/cleanup sched_clock
[S390] fix system call parameter functions.
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All architectures now use the generic compat_sys_ptrace, as should every
new architecture that needs 32bit compat (if we'll ever get another).
Remove the now superflous __ARCH_WANT_COMPAT_SYS_PTRACE define, and also
kill a comment about __ARCH_SYS_PTRACE that was added after
__ARCH_SYS_PTRACE was already gone.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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syscall_get_nr() currently returns a valid result only if the call
chain of the traced process includes do_syscall_trace_enter(). But
collect_syscall() can be called for any sleeping task, the result of
syscall_get_nr() in general is completely bogus.
To make syscall_get_nr() work for any sleeping task the traps field
in pt_regs is replace with svcnr - the system call number the process
is executing. If svcnr == 0 the process is not on a system call path.
The syscall_get_arguments and syscall_set_arguments use regs->gprs[2]
for the first system call parameter. This is incorrect since gprs[2]
may have been overwritten with the system call number if the call
chain includes do_syscall_trace_enter. Use regs->orig_gprs2 instead.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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* System call parameter and result access functions
* Add tracehook calls
* Split syscall_trace into two functions do_syscall_trace_enter and
do_syscall_trace_exit
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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