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  1. 24 11月, 2017 2 次提交
    • G
      s390: include: Remove redundant license text · 94bf2f28
      由 Greg Kroah-Hartman 提交于 
      Now that the SPDX tag is in all arch/s390/include/ files, that
identifies the license in a specific and legally-defined manner.  So the
extra GPL text wording can be removed as it is no longer needed at all.

This is done on a quest to remove the 700+ different ways that files in
the kernel describe the GPL license text.  And there's unneeded stuff
like the address (sometimes incorrect) for the FSF which is never
needed.

No copyright headers or other non-license-description text was removed.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Cornelia Huck <cohuck@redhat.com>
Cc: Halil Pasic <pasic@linux.vnet.ibm.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
      94bf2f28
    • G
      s390: add SPDX identifiers to the remaining files · 0b73214f
      由 Greg Kroah-Hartman 提交于 
      It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.

Update the remaining arch/s390/ files with the correct SPDX license
identifier based on the license text in the file itself.  The SPDX
identifier is a legally binding shorthand, which can be used instead of
the full boiler plate text.

This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Cornelia Huck <cohuck@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
      0b73214f
  3. 12 10月, 2017 1 次提交
  5. 03 5月, 2017 1 次提交
  7. 02 3月, 2017 1 次提交
  9. 28 2月, 2017 1 次提交
    • L
      kprobes: move kprobe declarations to asm-generic/kprobes.h · 7d134b2c
      由 Luis R. Rodriguez 提交于 
      Often all is needed is these small helpers, instead of compiler.h or a
full kprobes.h.  This is important for asm helpers, in fact even some
asm/kprobes.h make use of these helpers...  instead just keep a generic
asm file with helpers useful for asm code with the least amount of
clutter as possible.

Likewise we need now to also address what to do about this file for both
when architectures have CONFIG_HAVE_KPROBES, and when they do not.  Then
for when architectures have CONFIG_HAVE_KPROBES but have disabled
CONFIG_KPROBES.

Right now most asm/kprobes.h do not have guards against CONFIG_KPROBES,
this means most architecture code cannot include asm/kprobes.h safely.
Correct this and add guards for architectures missing them.
Additionally provide architectures that not have kprobes support with
the default asm-generic solution.  This lets us force asm/kprobes.h on
the header include/linux/kprobes.h always, but most importantly we can
now safely include just asm/kprobes.h on architecture code without
bringing the full kitchen sink of header files.

Two architectures already provided a guard against CONFIG_KPROBES on its
kprobes.h: sh, arch.  The rest of the architectures needed gaurds added.
We avoid including any not-needed headers on asm/kprobes.h unless
kprobes have been enabled.

In a subsequent atomic change we can try now to remove compiler.h from
include/linux/kprobes.h.

During this sweep I've also identified a few architectures defining a
common macro needed for both kprobes and ftrace, that of the definition
of the breakput instruction up.  Some refer to this as
BREAKPOINT_INSTRUCTION.  This must be kept outside of the #ifdef
CONFIG_KPROBES guard.

[mcgrof@kernel.org: fix arm64 build]
  Link: http://lkml.kernel.org/r/CAB=NE6X1WMByuARS4mZ1g9+W=LuVBnMDnh_5zyN0CLADaVh=Jw@mail.gmail.com
[sfr@canb.auug.org.au: fixup for kprobes declarations moving]
  Link: http://lkml.kernel.org/r/20170214165933.13ebd4f4@canb.auug.org.au
Link: http://lkml.kernel.org/r/20170203233139.32682-1-mcgrof@kernel.orgSigned-off-by: NLuis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Acked-by: NMasami Hiramatsu <mhiramat@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7d134b2c
  11. 28 6月, 2016 1 次提交
  13. 27 10月, 2014 1 次提交
    • H
      s390/ftrace,kprobes: allow to patch first instruction · c933146a
      由 Heiko Carstens 提交于 
      If the function tracer is enabled, allow to set kprobes on the first
instruction of a function (which is the function trace caller):

If no kprobe is set handling of enabling and disabling function tracing
of a function simply patches the first instruction. Either it is a nop
(right now it's an unconditional branch, which skips the mcount block),
or it's a branch to the ftrace_caller() function.

If a kprobe is being placed on a function tracer calling instruction
we encode if we actually have a nop or branch in the remaining bytes
after the breakpoint instruction (illegal opcode).
This is possible, since the size of the instruction used for the nop
and branch is six bytes, while the size of the breakpoint is only
two bytes.
Therefore the first two bytes contain the illegal opcode and the last
four bytes contain either "0" for nop or "1" for branch. The kprobes
code will then execute/simulate the correct instruction.

Instruction patching for kprobes and function tracer is always done
with stop_machine(). Therefore we don't have any races where an
instruction is patched concurrently on a different cpu.
Besides that also the program check handler which executes the function
trace caller instruction won't be executed concurrently to any
stop_machine() execution.

This allows to keep full fault based kprobes handling which generates
correct pt_regs contents automatically.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
      c933146a
  15. 25 9月, 2014 1 次提交
  17. 12 9月, 2013 1 次提交
  19. 20 7月, 2012 1 次提交
    • H
      s390/comments: unify copyright messages and remove file names · a53c8fab
      由 Heiko Carstens 提交于 
      Remove the file name from the comment at top of many files. In most
cases the file name was wrong anyway, so it's rather pointless.

Also unify the IBM copyright statement. We did have a lot of sightly
different statements and wanted to change them one after another
whenever a file gets touched. However that never happened. Instead
people start to take the old/"wrong" statements to use as a template
for new files.
So unify all of them in one go.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
      a53c8fab
  21. 05 1月, 2011 5 次提交
  23. 02 8月, 2008 1 次提交
  25. 05 3月, 2008 1 次提交
  27. 17 10月, 2007 2 次提交
  29. 20 7月, 2007 1 次提交
  31. 05 5月, 2007 1 次提交
  33. 20 9月, 2006 1 次提交
  35. 01 8月, 2006 1 次提交
  37. 27 6月, 2006 1 次提交
  39. 27 3月, 2006 1 次提交
    • M
      [PATCH] x86: kprobes-booster · 311ac88f
      由 Masami Hiramatsu 提交于 
      Current kprobe copies the original instruction at the probe point and replaces
it with a breakpoint instruction (int3).  When the kernel hits the probe
point, kprobe handler is invoked.  And the copied instruction is single-step
executed on the copied buffer (not on the original address) by kprobe.  After
that, the kprobe checks registers and modify it (if need) as if the
instructions was executed on the original address.

My proposal is based on the fact there are many instructions which do NOT
require the register modification after the single-step execution.  When the
copied instruction is a kind of them, kprobe just jumps back to the next
instruction after single-step execution.  If so, why don't we execute those
instructions directly?

With kprobe-booster patch, kprobes will execute a copied instruction directly
and (if need) jump back to original code.  This direct execution is executed
when the kprobe don't have both post_handler and break_handler, and the copied
instruction can be executed directly.

I sorted instructions which can be executed directly or not;

- Call instructions are NG(can not be executed directly).
  We should correct the return address pushed into top of stack.
- Indirect instructions except for absolute indirect-jumps
  are NG. Those instructions changes EIP randomly. We should
  check EIP and correct it.
- Instructions that change EIP beyond the range of the
  instruction buffer are NG.
- Instructions that change EIP to tail 5 bytes of the
  instruction buffer (it is the size of a jump instruction).
  We must write a jump instruction which backs to original
  kernel code in the instruction buffer.
- Break point instruction is NG. We should not touch EIP and
  pass to other handlers.
- Absolute direct/indirect jumps are OK.- Conditional Jumps are NG.
- Halt and software-interruptions are NG. Because it will stay on
  the instruction buffer of kprobes.
- Prefixes are NG.
- Unknown/reserved opcode is NG.
- Other 1 byte instructions are OK. But those instructions need a
  jump back code.
- 2 bytes instructions are mapped sparsely. So, in this release,
  this patch don't boost those instructions.

>From Intel's IA-32 opcode map described in IA-32 Intel Architecture Software
Developer's Manual Vol.2 B, I determined that following opcodes are not
boostable.

- 0FH (2byte escape)
- 70H - 7FH (Jump on condition)
- 9AH (Call) and 9CH (Pushf)
- C0H-C1H (Grp 2: includes reserved opcode)
- C6H-C7H (Grp11: includes reserved opcode)
- CCH-CEH (Software-interrupt)
- D0H-D3H (Grp2: includes reserved opcode)
- D6H (Reserved)
- D8H-DFH (Coprocessor)
- E0H-E3H (loop/conditional jump)
- E8H (Call)
- F0H-F3H (Prefixes and reserved)
- F4H (Halt)
- F6H-F7H (Grp3: includes reserved opcode)
- FEH-FFH(Grp4,5: includes reserved opcode)

Kprobe-booster checks whether target instruction can be boosted (can be
executed directly) at arch_copy_kprobe() function.  If the target instruction
can be boosted, it clears "boostable" flag.  If not, it sets "boostable" flag
-1.  This is disabled status.  In resume_execution() function, If "boostable"
flag is cleared, kprobe-booster measures the size of the target instruction
and sets "boostable" flag 1.

In kprobe_handler(), kprobe checks the "boostable" flag.  If the flag is 1, it
resets current kprobe and executes instruction buffer directly instead of
single stepping.

When unregistering a boosted kprobe, it calls synchronize_sched()
after "int3" is removed. So we can ensure followings after
the synchronize_sched() called.
- interrupt handlers are finished on all CPUs.
- instruction buffer is not executed on all CPUs.
And we can release the boosted kprobe safely.

And also, on preemptible kernel, the booster is not enabled where the kernel
preemption is enabled.  So, there are no preempted threads on the instruction
buffer.

The description of kretprobe-booster:
====================================

In the normal operation, kretprobe make a target function return to trampoline
code.  And a kprobe (called trampoline_probe) have been inserted at the
trampoline code.  When the kernel hits this kprobe, it calls kretprobe's
handler and it returns to original return address.

Kretprobe-booster patch removes the trampoline_probe.  It allows the
trampoline code to call kretprobe's handler directly instead of invoking
kprobe.  And tranpoline code returns to original return address.

This new trampoline code stores and restores registers, so the kretprobe
handler is still able to access those registers.

Current kprobe has about 1.3 usec/probe(*) overhead, and kprobe-booster patch
reduces it to 0.6 usec/probe(*).  Also current kretprobe has about 2.0
usec/probe(*) overhead.  Kprobe-booster patch reduces it to 1.3 usec/probe(*),
and the combination of both kprobe-booster patch and kretprobe-booster patch
reduces it to 0.9 usec/probe(*).

I expect the combination of both patches can reduce half of a probing
overhead.

Performance numbers strongly depend on the processor model.

Andrew Morton wrote:
> These preempt tricks look rather nasty.  Can you please describe what the
> problem is, precisely?  And how this code avoids it?  Perhaps we can find
> something cleaner.

The problem is how to remove the copied instructions of the
kprobe *safely* on the preemptable kernel (CONFIG_PREEMPT=y).

Kprobes basically executes the following actions;

(1)int3
(2)preempt_disable()
(3)kprobe_prehandler()
(4)copied instructioin(single step)
(5)kprobe_posthandler()
(6)preempt_enable()
(7)return to the original code

During the execution of copied instruction, preemption is
disabled (from step (2) to (6)).
When unregistering the probes, Kprobe waits for RCU
quiescent state by using synchronize_sched() after removing
int3 instruction.
Thus we can ensure the copied instruction is not executed.

On the other hand, kprobe-booster executes the following actions;

(1)int3
(2)preempt_disable()
(3)kprobe_prehandler()
(4)preempt_enable()             <-- this one is added by my patch
(5)copied instruction(direct execution)
(6)jmp back to the original code

The problem is that we have no way to prevent preemption on
step (5) or (6). We cannot call preempt_disable() after step (6),
because there are no rooms to do that. Thus, some other
processes may be preempted at step(5) or (6) on preemptable kernel.
And I couldn't find the easy way to ensure that other processes'
stack do *not* have the address of them. (I thought some way
to do that, but those are very costly.)

So currently, I simply boost the kprobe only when the probe
point is already preemption disabled.

> Also, the patch adds a preempt_enable() but I don't see a corresponding
> preempt_disable().  Am I missing something?

It is corresponding to the preempt_disable() in the top of
kprobe_handler().
I copied the code of kprobe_handler() here:

static int __kprobes kprobe_handler(struct pt_regs *regs)
{
        struct kprobe *p;
        int ret = 0;
        kprobe_opcode_t *addr = NULL;
        unsigned long *lp;
        struct kprobe_ctlblk *kcb;

        /*
         * We don't want to be preempted for the entire
         * duration of kprobe processing
         */
        preempt_disable();             <-- HERE
        kcb = get_kprobe_ctlblk();
Signed-off-by: NMasami Hiramatsu <hiramatu@sdl.hitachi.co.jp>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      311ac88f
  41. 25 2月, 2006 1 次提交
  43. 11 1月, 2006 3 次提交
  45. 07 11月, 2005 1 次提交
  47. 24 6月, 2005 1 次提交
    • H
      [PATCH] kprobes: function-return probes · b94cce92
      由 Hien Nguyen 提交于 
      This patch adds function-return probes to kprobes for the i386
architecture.  This enables you to establish a handler to be run when a
function returns.

1. API

Two new functions are added to kprobes:

	int register_kretprobe(struct kretprobe *rp);
	void unregister_kretprobe(struct kretprobe *rp);

2. Registration and unregistration

2.1 Register

  To register a function-return probe, the user populates the following
  fields in a kretprobe object and calls register_kretprobe() with the
  kretprobe address as an argument:

  kp.addr - the function's address

  handler - this function is run after the ret instruction executes, but
  before control returns to the return address in the caller.

  maxactive - The maximum number of instances of the probed function that
  can be active concurrently.  For example, if the function is non-
  recursive and is called with a spinlock or mutex held, maxactive = 1
  should be enough.  If the function is non-recursive and can never
  relinquish the CPU (e.g., via a semaphore or preemption), NR_CPUS should
  be enough.  maxactive is used to determine how many kretprobe_instance
  objects to allocate for this particular probed function.  If maxactive <=
  0, it is set to a default value (if CONFIG_PREEMPT maxactive=max(10, 2 *
  NR_CPUS) else maxactive=NR_CPUS)

  For example:

    struct kretprobe rp;
    rp.kp.addr = /* entrypoint address */
    rp.handler = /*return probe handler */
    rp.maxactive = /* e.g., 1 or NR_CPUS or 0, see the above explanation */
    register_kretprobe(&rp);

  The following field may also be of interest:

  nmissed - Initialized to zero when the function-return probe is
  registered, and incremented every time the probed function is entered but
  there is no kretprobe_instance object available for establishing the
  function-return probe (i.e., because maxactive was set too low).

2.2 Unregister

  To unregiter a function-return probe, the user calls
  unregister_kretprobe() with the same kretprobe object as registered
  previously.  If a probed function is running when the return probe is
  unregistered, the function will return as expected, but the handler won't
  be run.

3. Limitations

3.1 This patch supports only the i386 architecture, but patches for
    x86_64 and ppc64 are anticipated soon.

3.2 Return probes operates by replacing the return address in the stack
    (or in a known register, such as the lr register for ppc).  This may
    cause __builtin_return_address(0), when invoked from the return-probed
    function, to return the address of the return-probes trampoline.

3.3 This implementation uses the "Multiprobes at an address" feature in
    2.6.12-rc3-mm3.

3.4 Due to a limitation in multi-probes, you cannot currently establish
    a return probe and a jprobe on the same function.  A patch to remove
    this limitation is being tested.

This feature is required by SystemTap (http://sourceware.org/systemtap),
and reflects ideas contributed by several SystemTap developers, including
Will Cohen and Ananth Mavinakayanahalli.
Signed-off-by: NHien Nguyen <hien@us.ibm.com>
Signed-off-by: NPrasanna S Panchamukhi <prasanna@in.ibm.com>
Signed-off-by: NFrederik Deweerdt <frederik.deweerdt@laposte.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      b94cce92
  49. 17 4月, 2005 1 次提交
    • L
      Linux-2.6.12-rc2 · 1da177e4
      由 Linus Torvalds 提交于 
      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!
      1da177e4