linux-toradex.git/arch/x86/kernel/step.c, branch v3.1.2 Linux kernel for Apalis and Colibri modules x86-64: Add user_64bit_mode paravirt op 2011-08-04T23:13:49+00:00 Andy Lutomirski luto@MIT.EDU 2011-08-03T13:31:53+00:00 318f5a2a672152328c9fb4dead504b89ec738a43 Three places in the kernel assume that the only long mode CPL 3 selector is __USER_CS. This is not true on Xen -- Xen's sysretq changes cs to the magic value 0xe033. Two of the places are corner cases, but as of "x86-64: Improve vsyscall emulation CS and RIP handling" (c9712944b2a12373cb6ff8059afcfb7e826a6c54), vsyscalls will segfault if called with Xen's extra CS selector. This causes a panic when older init builds die. It seems impossible to make Xen use __USER_CS reliably without taking a performance hit on every system call, so this fixes the tests instead with a new paravirt op. It's a little ugly because ptrace.h can't include paravirt.h. Signed-off-by: Andy Lutomirski <luto@mit.edu> Link: http://lkml.kernel.org/r/f4fcb3947340d9e96ce1054a432f183f9da9db83.1312378163.git.luto@mit.edu Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> 
Three places in the kernel assume that the only long mode CPL 3
selector is __USER_CS.  This is not true on Xen -- Xen's sysretq
changes cs to the magic value 0xe033.

Two of the places are corner cases, but as of "x86-64: Improve
vsyscall emulation CS and RIP handling"
(c9712944b2a12373cb6ff8059afcfb7e826a6c54), vsyscalls will segfault
if called with Xen's extra CS selector.  This causes a panic when
older init builds die.

It seems impossible to make Xen use __USER_CS reliably without
taking a performance hit on every system call, so this fixes the
tests instead with a new paravirt op.  It's a little ugly because
ptrace.h can't include paravirt.h.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Link: http://lkml.kernel.org/r/f4fcb3947340d9e96ce1054a432f183f9da9db83.1312378163.git.luto@mit.edu
Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
x86: Fix common misspellings 2011-03-18T09:39:30+00:00 Lucas De Marchi lucas.de.marchi@gmail.com 2011-03-17T19:24:16+00:00 0d2eb44f631d9d0a826efa3156f157477fdaecf4 They were generated by 'codespell' and then manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi> Cc: trivial@kernel.org LKML-Reference: <1300389856-1099-3-git-send-email-lucas.demarchi@profusion.mobi> Signed-off-by: Ingo Molnar <mingo@elte.hu> 
They were generated by 'codespell' and then manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: trivial@kernel.org
LKML-Reference: <1300389856-1099-3-git-send-email-lucas.demarchi@profusion.mobi>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
x86, ptrace: Fix block-step 2010-03-26T10:33:57+00:00 Peter Zijlstra a.p.zijlstra@chello.nl 2010-03-25T13:51:51+00:00 ea8e61b7bbc4a2faef77db34eb2db2a2c2372ff6 Implement ptrace-block-step using TIF_BLOCKSTEP which will set DEBUGCTLMSR_BTF when set for a task while preserving any other DEBUGCTLMSR bits. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20100325135414.017536066@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu> 
Implement ptrace-block-step using TIF_BLOCKSTEP which will set
DEBUGCTLMSR_BTF when set for a task while preserving any other
DEBUGCTLMSR bits.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100325135414.017536066@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
x86, perf, bts, mm: Delete the never used BTS-ptrace code 2010-03-26T10:33:55+00:00 Peter Zijlstra a.p.zijlstra@chello.nl 2010-03-25T13:51:50+00:00 faa4602e47690fb11221e00f9b9697c8dc0d4b19 Support for the PMU's BTS features has been upstreamed in v2.6.32, but we still have the old and disabled ptrace-BTS, as Linus noticed it not so long ago. It's buggy: TIF_DEBUGCTLMSR is trampling all over that MSR without regard for other uses (perf) and doesn't provide the flexibility needed for perf either. Its users are ptrace-block-step and ptrace-bts, since ptrace-bts was never used and ptrace-block-step can be implemented using a much simpler approach. So axe all 3000 lines of it. That includes the *locked_memory*() APIs in mm/mlock.c as well. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Roland McGrath <roland@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Markus Metzger <markus.t.metzger@intel.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Andrew Morton <akpm@linux-foundation.org> LKML-Reference: <20100325135413.938004390@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu> 
Support for the PMU's BTS features has been upstreamed in
v2.6.32, but we still have the old and disabled ptrace-BTS,
as Linus noticed it not so long ago.

It's buggy: TIF_DEBUGCTLMSR is trampling all over that MSR without
regard for other uses (perf) and doesn't provide the flexibility
needed for perf either.

Its users are ptrace-block-step and ptrace-bts, since ptrace-bts
was never used and ptrace-block-step can be implemented using a
much simpler approach.

So axe all 3000 lines of it. That includes the *locked_memory*()
APIs in mm/mlock.c as well.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Markus Metzger <markus.t.metzger@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <20100325135413.938004390@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
x86: Use get_desc_base() 2009-07-19T16:27:51+00:00 Akinobu Mita akinobu.mita@gmail.com 2009-07-18T15:08:54+00:00 254e0a6bff87ab8b22293c4bd1443507df698407 Use get_desc_base() to get the base address in desc_struct Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> LKML-Reference: <20090718150853.GA11294@localhost.localdomain> Signed-off-by: Ingo Molnar <mingo@elte.hu> 
Use get_desc_base() to get the base address in desc_struct

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
LKML-Reference: <20090718150853.GA11294@localhost.localdomain>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
x86 ptrace: user-sets-TF nits 2008-07-16T19:15:17+00:00 Roland McGrath roland@redhat.com 2008-07-09T09:39:29+00:00 380fdd7585a4c2f41b48925eba85c0654b7b858b This closes some arcane holes in single-step handling that can arise only when user programs set TF directly (via popf or sigreturn) and then use vDSO (syscall/sysenter) system call entry. In those entry paths, the clear_TF_reenable case hits and we must check TIF_SINGLESTEP to be sure our bookkeeping stays correct wrt the user's view of TF. Signed-off-by: Roland McGrath <roland@redhat.com> 
This closes some arcane holes in single-step handling that can arise
only when user programs set TF directly (via popf or sigreturn) and
then use vDSO (syscall/sysenter) system call entry.  In those entry
paths, the clear_TF_reenable case hits and we must check TIF_SINGLESTEP
to be sure our bookkeeping stays correct wrt the user's view of TF.

Signed-off-by: Roland McGrath <roland@redhat.com>
x86 ptrace: block-step fix 2008-07-16T19:15:16+00:00 Roland McGrath roland@redhat.com 2008-07-09T08:07:02+00:00 6718d0d6da2749d3bff522e6057e97e6aa85e4d1 The enable_single_step() logic bails out early if TF is already set. That skips some of the bookkeeping that keeps things straight. This makes PTRACE_SINGLEBLOCK break the behavior of a user task that was already setting TF itself in user mode. Fix the bookkeeping to notice the old TF setting as it should. Test case at: http://sources.redhat.com/cgi-bin/cvsweb.cgi/~checkout~/tests/ptrace-tests/tests/step-jump-cont-strict.c?cvsroot=systemtap Signed-off-by: Roland McGrath <roland@redhat.com> 
The enable_single_step() logic bails out early if TF is already set.
That skips some of the bookkeeping that keeps things straight.
This makes PTRACE_SINGLEBLOCK break the behavior of a user task
that was already setting TF itself in user mode.

Fix the bookkeeping to notice the old TF setting as it should.

Test case at: http://sources.redhat.com/cgi-bin/cvsweb.cgi/~checkout~/tests/ptrace-tests/tests/step-jump-cont-strict.c?cvsroot=systemtap

Signed-off-by: Roland McGrath <roland@redhat.com>
x86: prevent unconditional writes to DebugCtl MSR 2008-04-17T15:40:58+00:00 Jan Beulich jbeulich@novell.com 2008-03-10T13:11:17+00:00 5b0e508415a83989fe704b4718a1a214bc333ca7 Otherwise, enabling (or better, subsequent disabling) of single stepping would cause a kernel oops on CPUs not having this MSR. The patch could have been added a conditional to the MSR write in user_disable_single_step(), but centralizing the updates seems safer and (looking forward) better manageable. Signed-off-by: Jan Beulich <jbeulich@novell.com> Cc: Markus Metzger <markus.t.metzger@intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> 
Otherwise, enabling (or better, subsequent disabling) of single
stepping would cause a kernel oops on CPUs not having this MSR.

The patch could have been added a conditional to the MSR write in
user_disable_single_step(), but centralizing the updates seems safer
and (looking forward) better manageable.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Cc: Markus Metzger <markus.t.metzger@intel.com>

Signed-off-by: Ingo Molnar <mingo@elte.hu>
x86 ptrace: avoid unnecessary wrmsr 2008-04-03T22:42:43+00:00 Roland McGrath roland@redhat.com 2008-04-03T21:18:55+00:00 4ba51fd75cc3789be83f0d6f878dabbb0cb19bca This avoids using wrmsr on MSR_IA32_DEBUGCTLMSR when it's not needed. No wrmsr ever needs to be done if noone has ever used block stepping. Without this change, using ptrace on 2.6.25 on an x86 KVM guest will tickle KVM's missing support for the MSR and crash the guest kernel. Though host KVM is the buggy one, this makes for a regression in the guest behavior from 2.6.24->2.6.25 that we can easily avoid. I also corrected some bad whitespace. Signed-off-by: Roland McGrath <roland@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
This avoids using wrmsr on MSR_IA32_DEBUGCTLMSR when it's not needed.
No wrmsr ever needs to be done if noone has ever used block stepping.

Without this change, using ptrace on 2.6.25 on an x86 KVM guest
will tickle KVM's missing support for the MSR and crash the guest
kernel.  Though host KVM is the buggy one, this makes for a regression
in the guest behavior from 2.6.24->2.6.25 that we can easily avoid.

I also corrected some bad whitespace.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
x86: fix typo in step.c 2008-03-07T15:39:14+00:00 Jan Beulich jbeulich@novell.com 2008-03-05T08:36:48+00:00 d032b31a3a22a571cb50c0b5dffbe9ba9328d6e2 TIF_DEBUGCTLMSR has no meaning in the actual MSR... Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> 
TIF_DEBUGCTLMSR has no meaning in the actual MSR...

Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>