History log of /arch/x86/kernel/step.c
Revision Date Author Comments
318f5a2a672152328c9fb4dead504b89ec738a43 03-Aug-2011 Andy Lutomirski <luto@MIT.EDU> x86-64: Add user_64bit_mode paravirt op

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>
0d2eb44f631d9d0a826efa3156f157477fdaecf4 17-Mar-2011 Lucas De Marchi <lucas.de.marchi@gmail.com> x86: Fix common misspellings

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>
ea8e61b7bbc4a2faef77db34eb2db2a2c2372ff6 25-Mar-2010 Peter Zijlstra <a.p.zijlstra@chello.nl> x86, ptrace: Fix block-step

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>
faa4602e47690fb11221e00f9b9697c8dc0d4b19 25-Mar-2010 Peter Zijlstra <a.p.zijlstra@chello.nl> x86, perf, bts, mm: Delete the never used BTS-ptrace code

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>
254e0a6bff87ab8b22293c4bd1443507df698407 18-Jul-2009 Akinobu Mita <akinobu.mita@gmail.com> x86: Use get_desc_base()

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>
380fdd7585a4c2f41b48925eba85c0654b7b858b 09-Jul-2008 Roland McGrath <roland@redhat.com> x86 ptrace: user-sets-TF nits

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>
6718d0d6da2749d3bff522e6057e97e6aa85e4d1 09-Jul-2008 Roland McGrath <roland@redhat.com> x86 ptrace: block-step fix

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>
5b0e508415a83989fe704b4718a1a214bc333ca7 10-Mar-2008 Jan Beulich <jbeulich@novell.com> x86: prevent unconditional writes to DebugCtl MSR

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>
4ba51fd75cc3789be83f0d6f878dabbb0cb19bca 03-Apr-2008 Roland McGrath <roland@redhat.com> x86 ptrace: avoid unnecessary wrmsr

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>
d032b31a3a22a571cb50c0b5dffbe9ba9328d6e2 05-Mar-2008 Jan Beulich <jbeulich@novell.com> x86: fix typo in step.c

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>
f2857ce92023409df1544737d5b3499b4630a183 30-Jan-2008 Harvey Harrison <harvey.harrison@gmail.com> x86: remove last user of get_segment_eip

is_prefetch was the last user of get_segment_eip and only on
X86_32. This function returned the faulting instruction's
address and set the upper segment limit.

Instead, use the convert_ip_to_linear helper and rely on
probe_kernel_address to do the segment checks which was
already done everywhere the segment limit was being checked
on X86_32.

Remove get_segment_eip as well.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
37cd9cf3dafed82f7cf905785883300f6ff7c818 30-Jan-2008 Harvey Harrison <harvey.harrison@gmail.com> x86: common x86_32|64 naming

Rename convert_rip_to_linear to convert_ip_to_linear for shared
X86_32|64 use.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
f13bd3e7935f7020f7c622bf3f8cae8eee757a53 30-Jan-2008 Harvey Harrison <harvey.harrison@gmail.com> x86: use wrmsrl in kprobes.c, step.c

Where x86_32 passed zero in the high 32 bits, use wrmsrl which
will zero extend for us. This allows ifdefs for 32/64 bit to
be eliminated.

Eliminate ifdef in step.c. Similar cleanup was done when unifying
kprobes_32|64.c and wrmsr() was chosen there over wrmsrl(). This
patch changes these to wrmsrl.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
1379a5ce3ffc549a7ff3daffc49c5e1c372717a3 30-Jan-2008 Harvey Harrison <harvey.harrison@gmail.com> x86: move get_segment_eip() to step.c

get_segment_eip has similarities to convert_rip_to_linear(),
and is used in a similar context. Move get_segment_eip to
step.c to allow easier consolidation.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
eee3af4a2c83a97fff107ddc445d9df6fded9ce4 30-Jan-2008 Markus Metzger <markus.t.metzger@intel.com> x86, ptrace: support for branch trace store(BTS)

Resend using different mail client

Changes to the last version:
- split implementation into two layers: ds/bts and ptrace
- renamed TIF's
- save/restore ds save area msr in __switch_to_xtra()
- make block-stepping only look at BTF bit

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
65ea5b0349903585bfed9720fa06f5edb4f1cd25 30-Jan-2008 H. Peter Anvin <hpa@zytor.com> x86: rename the struct pt_regs members for 32/64-bit consistency

We have a lot of code which differs only by the naming of specific
members of structures that contain registers. In order to enable
additional unifications, this patch drops the e- or r- size prefix
from the register names in struct pt_regs, and drops the x- prefixes
for segment registers on the 32-bit side.

This patch also performs the equivalent renames in some additional
places that might be candidates for unification in the future.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
10faa81e102e2b7695f386812055cd2ef9e44b4c 30-Jan-2008 Roland McGrath <roland@redhat.com> x86: debugctlmsr arch_has_block_step

This implements user-mode step-until-branch on x86 using the BTF bit
in MSR_IA32_DEBUGCTLMSR. It's just like single-step, only less so.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
e1f287735c1e58c653b516931b5d3dd899edcb77 30-Jan-2008 Roland McGrath <roland@redhat.com> x86 single_step: TIF_FORCED_TF

This changes the single-step support to use a new thread_info flag
TIF_FORCED_TF instead of the PT_DTRACE flag in task_struct.ptrace.
This keeps arch implementation uses out of this non-arch field.

This changes the ptrace access to eflags to mask TF and maintain
the TIF_FORCED_TF flag directly if userland sets TF, instead of
relying on ptrace_signal_deliver. The 64-bit and 32-bit kernels
are harmonized on this same behavior. The ptrace_signal_deliver
approach works now, but this change makes the low-level register
access code reliable when called from different contexts than a
ptrace stop, which will be possible in the future.

The 64-bit do_debug exception handler is also changed not to clear TF
from user-mode registers. This matches the 32-bit kernel's behavior.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
7122ec8158b0f88befd94f4da8feae2c8d08d1b4 30-Jan-2008 Roland McGrath <roland@redhat.com> x86: single_step: share code

This removes the single-step code from ptrace_32.c and uses the step.c code
shared with the 64-bit kernel. The two versions of the code were nearly
identical already, so the shared code has only a couple of simple #ifdef's.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
5f76cb1f6c42e7575256595f85b8b97d84ec669e 30-Jan-2008 Roland McGrath <roland@redhat.com> x86: single_step 0xf0

This fixes the 64-bit single-step handling code's instruction
decoder to grok the 0xf0 (lock) prefix, which the 32-bit code
already does correctly.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
3f80c1adc900769f2070432419da3b5ddbf066fc 30-Jan-2008 Roland McGrath <roland@redhat.com> x86: single_step segment macros

This cleans up the single-step code to use the asm/segment.h macros
for segment selector magic bits, rather than its own constant.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
fa1e03eae2f38e7b38095301b043da9c274d2284 30-Jan-2008 Roland McGrath <roland@redhat.com> x86: single_step moved

This moves the single-step support code from ptrace_64.c into a new file
step.c, verbatim. This paves the way for consolidating this code between
64-bit and 32-bit versions.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>