In some cases during a threaded core dump not all the threads will have
a full register set. This happens when the signal causing the core dump
races with a thread exiting. The race happens when the exiting thread
has entered the kernel for the last time before the signal arrives, but
doesn't get far enough through the exit code to avoid being included
in the core dump.
So we get a thread included in the core dump which is never going to go
out to userspace again and only has a partial register set recorded
Normally we would catch each thread as it is about to go into userspace
and capture the full register set then.
However, this exiting thread is never going to go out to userspace
again, so we have no way to capture its full register set. It doesn't
really matter, though, as this is a thread which is effectively
already dead.
So instead of hitting a BUG() in this case (a really bad choice of
action in the first place), we use a poison value for the register
values.
[BenH]: Some cosmetic/stylistic changes and fix build on ppc32
Signed-off-by: Mike Wolf <mjw@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Build of ptrace.h failed for assembly because it
pulls in stdint.h.
Use exportable types (__u32, __u64) to avoid the dependency
on stdint.h.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Andrey Volkov <avolkov@varma-el.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This patch ports the kprobe-based event tracer to powerpc. This patch
is based on x86 port. This brings powerpc on par with x86.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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>
powerpc: Extended ptrace interface
From: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Based on patches originally written by Torez Smith.
Add a new extended ptrace interface so that user-space has a single
interface for powerpc, without having to know the specific layout
of the debug registers.
Implement:
PPC_PTRACE_GETHWDEBUGINFO
PPC_PTRACE_SETHWDEBUG
PPC_PTRACE_DELHWDEBUG
Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Acked-by: David Gibson <dwg@au1.ibm.com>
Cc: Torez Smith <lnxtorez@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Sergio Durigan Junior <sergiodj@br.ibm.com>
Cc: Thiago Jung Bauermann <bauerman@br.ibm.com>
Cc: linuxppc-dev list <Linuxppc-dev@ozlabs.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reworked by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This adds block-step support on powerpc, including a PTRACE_SINGLEBLOCK
request for ptrace.
The BookE implementation is tweaked to fire a single step after a
block step in order to mimmic the server behaviour.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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>
__FUNCTION__ is gcc-specific, use __func__
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
from include/asm-powerpc. This is the result of a
mkdir arch/powerpc/include/asm
git mv include/asm-powerpc/* arch/powerpc/include/asm
Followed by a few documentation/comment fixups and a couple of places
where <asm-powepc/...> was being used explicitly. Of the latter only
one was outside the arch code and it is a driver only built for powerpc.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Mike Wolf