Commit Graph

157 Commits

Author SHA1 Message Date
Johannes Weiner
00501b531c mm: memcontrol: rewrite charge API
These patches rework memcg charge lifetime to integrate more naturally
with the lifetime of user pages.  This drastically simplifies the code and
reduces charging and uncharging overhead.  The most expensive part of
charging and uncharging is the page_cgroup bit spinlock, which is removed
entirely after this series.

Here are the top-10 profile entries of a stress test that reads a 128G
sparse file on a freshly booted box, without even a dedicated cgroup (i.e.
 executing in the root memcg).  Before:

    15.36%              cat  [kernel.kallsyms]   [k] copy_user_generic_string
    13.31%              cat  [kernel.kallsyms]   [k] memset
    11.48%              cat  [kernel.kallsyms]   [k] do_mpage_readpage
     4.23%              cat  [kernel.kallsyms]   [k] get_page_from_freelist
     2.38%              cat  [kernel.kallsyms]   [k] put_page
     2.32%              cat  [kernel.kallsyms]   [k] __mem_cgroup_commit_charge
     2.18%          kswapd0  [kernel.kallsyms]   [k] __mem_cgroup_uncharge_common
     1.92%          kswapd0  [kernel.kallsyms]   [k] shrink_page_list
     1.86%              cat  [kernel.kallsyms]   [k] __radix_tree_lookup
     1.62%              cat  [kernel.kallsyms]   [k] __pagevec_lru_add_fn

After:

    15.67%           cat  [kernel.kallsyms]   [k] copy_user_generic_string
    13.48%           cat  [kernel.kallsyms]   [k] memset
    11.42%           cat  [kernel.kallsyms]   [k] do_mpage_readpage
     3.98%           cat  [kernel.kallsyms]   [k] get_page_from_freelist
     2.46%           cat  [kernel.kallsyms]   [k] put_page
     2.13%       kswapd0  [kernel.kallsyms]   [k] shrink_page_list
     1.88%           cat  [kernel.kallsyms]   [k] __radix_tree_lookup
     1.67%           cat  [kernel.kallsyms]   [k] __pagevec_lru_add_fn
     1.39%       kswapd0  [kernel.kallsyms]   [k] free_pcppages_bulk
     1.30%           cat  [kernel.kallsyms]   [k] kfree

As you can see, the memcg footprint has shrunk quite a bit.

   text    data     bss     dec     hex filename
  37970    9892     400   48262    bc86 mm/memcontrol.o.old
  35239    9892     400   45531    b1db mm/memcontrol.o

This patch (of 4):

The memcg charge API charges pages before they are rmapped - i.e.  have an
actual "type" - and so every callsite needs its own set of charge and
uncharge functions to know what type is being operated on.  Worse,
uncharge has to happen from a context that is still type-specific, rather
than at the end of the page's lifetime with exclusive access, and so
requires a lot of synchronization.

Rewrite the charge API to provide a generic set of try_charge(),
commit_charge() and cancel_charge() transaction operations, much like
what's currently done for swap-in:

  mem_cgroup_try_charge() attempts to reserve a charge, reclaiming
  pages from the memcg if necessary.

  mem_cgroup_commit_charge() commits the page to the charge once it
  has a valid page->mapping and PageAnon() reliably tells the type.

  mem_cgroup_cancel_charge() aborts the transaction.

This reduces the charge API and enables subsequent patches to
drastically simplify uncharging.

As pages need to be committed after rmap is established but before they
are added to the LRU, page_add_new_anon_rmap() must stop doing LRU
additions again.  Revive lru_cache_add_active_or_unevictable().

[hughd@google.com: fix shmem_unuse]
[hughd@google.com: Add comments on the private use of -EAGAIN]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-08-08 15:57:17 -07:00
Oleg Nesterov
06d0713904 uprobes: Change unregister/apply to WARN() if uprobe/consumer is gone
Add WARN_ON's into uprobe_unregister() and uprobe_apply() to ensure
that nobody tries to play with the dead uprobe/consumer. This helps
to catch the bugs like the one fixed by the previous patch.

In the longer term we should fix this poorly designed interface.
uprobe_register() should return "struct uprobe *" which should be
passed to apply/unregister. Plus other semantic changes, see the
changelog in commit 41ccba029e.

Link: http://lkml.kernel.org/p/20140627170140.GA18322@redhat.com

Acked-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2014-06-30 13:22:15 -04:00
Linus Torvalds
3737a12761 Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull more perf updates from Ingo Molnar:
 "A second round of perf updates:

   - wide reaching kprobes sanitization and robustization, with the hope
     of fixing all 'probe this function crashes the kernel' bugs, by
     Masami Hiramatsu.

   - uprobes updates from Oleg Nesterov: tmpfs support, corner case
     fixes and robustization work.

   - perf tooling updates and fixes from Jiri Olsa, Namhyung Ki, Arnaldo
     et al:
        * Add support to accumulate hist periods (Namhyung Kim)
        * various fixes, refactorings and enhancements"

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (101 commits)
  perf: Differentiate exec() and non-exec() comm events
  perf: Fix perf_event_comm() vs. exec() assumption
  uprobes/x86: Rename arch_uprobe->def to ->defparam, minor comment updates
  perf/documentation: Add description for conditional branch filter
  perf/x86: Add conditional branch filtering support
  perf/tool: Add conditional branch filter 'cond' to perf record
  perf: Add new conditional branch filter 'PERF_SAMPLE_BRANCH_COND'
  uprobes: Teach copy_insn() to support tmpfs
  uprobes: Shift ->readpage check from __copy_insn() to uprobe_register()
  perf/x86: Use common PMU interrupt disabled code
  perf/ARM: Use common PMU interrupt disabled code
  perf: Disable sampled events if no PMU interrupt
  perf: Fix use after free in perf_remove_from_context()
  perf tools: Fix 'make help' message error
  perf record: Fix poll return value propagation
  perf tools: Move elide bool into perf_hpp_fmt struct
  perf tools: Remove elide setup for SORT_MODE__MEMORY mode
  perf tools: Fix "==" into "=" in ui_browser__warning assignment
  perf tools: Allow overriding sysfs and proc finding with env var
  perf tools: Consider header files outside perf directory in tags target
  ...
2014-06-12 19:18:49 -07:00
Linus Torvalds
eb3d3ec567 Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm into next
Pull ARM updates from Russell King:

 - Major clean-up of the L2 cache support code.  The existing mess was
   becoming rather unmaintainable through all the additions that others
   have done over time.  This turns it into a much nicer structure, and
   implements a few performance improvements as well.

 - Clean up some of the CP15 control register tweaks for alignment
   support, moving some code and data into alignment.c

 - DMA properties for ARM, from Santosh and reviewed by DT people.  This
   adds DT properties to specify bus translations we can't discover
   automatically, and to indicate whether devices are coherent.

 - Hibernation support for ARM

 - Make ftrace work with read-only text in modules

 - add suspend support for PJ4B CPUs

 - rework interrupt masking for undefined instruction handling, which
   allows us to enable interrupts earlier in the handling of these
   exceptions.

 - support for big endian page tables

 - fix stacktrace support to exclude stacktrace functions from the
   trace, and add save_stack_trace_regs() implementation so that kprobes
   can record stack traces.

 - Add support for the Cortex-A17 CPU.

 - Remove last vestiges of ARM710 support.

 - Removal of ARM "meminfo" structure, finally converting us solely to
   memblock to handle the early memory initialisation.

* 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm: (142 commits)
  ARM: ensure C page table setup code follows assembly code (part II)
  ARM: ensure C page table setup code follows assembly code
  ARM: consolidate last remaining open-coded alignment trap enable
  ARM: remove global cr_no_alignment
  ARM: remove CPU_CP15 conditional from alignment.c
  ARM: remove unused adjust_cr() function
  ARM: move "noalign" command line option to alignment.c
  ARM: provide common method to clear bits in CPU control register
  ARM: 8025/1: Get rid of meminfo
  ARM: 8060/1: mm: allow sub-architectures to override PCI I/O memory type
  ARM: 8066/1: correction for ARM patch 8031/2
  ARM: 8049/1: ftrace/add save_stack_trace_regs() implementation
  ARM: 8065/1: remove last use of CONFIG_CPU_ARM710
  ARM: 8062/1: Modify ldrt fixup handler to re-execute the userspace instruction
  ARM: 8047/1: rwsem: use asm-generic rwsem implementation
  ARM: l2c: trial at enabling some Cortex-A9 optimisations
  ARM: l2c: add warnings for stuff modifying aux_ctrl register values
  ARM: l2c: print a warning with L2C-310 caches if the cache size is modified
  ARM: l2c: remove old .set_debug method
  ARM: l2c: kill L2X0_AUX_CTRL_MASK before anyone else makes use of this
  ...
2014-06-05 15:57:04 -07:00
Oleg Nesterov
40814f6805 uprobes: Teach copy_insn() to support tmpfs
tmpfs is widely used but as Denys reports shmem_aops doesn't have
->readpage() and thus you can't probe a binary on this filesystem.

As Hugh suggested we can use shmem_read_mapping_page() in this case,
just we need to check shmem_mapping() if ->readpage == NULL.

Reported-by: Denys Vlasenko <dvlasenk@redhat.com>
Suggested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140519184136.GB6750@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-06-05 12:30:11 +02:00
Oleg Nesterov
41ccba029e uprobes: Shift ->readpage check from __copy_insn() to uprobe_register()
copy_insn() fails with -EIO if ->readpage == NULL, but this error
is not propagated unless uprobe_register() path finds ->mm which
already mmaps this file. In this case (say) "perf record" does not
actually install the probe, but the user can't know about this.

Move this check into uprobe_register() so that this problem can be
detected earlier and reported to user.

Note: this is still not perfect,

	- copy_insn() and arch_uprobe_analyze_insn() should be called
	  by uprobe_register() but this is not simple, we need vm_file
	  for read_mapping_page() (although perhaps we can pass NULL),
	  and we need ->mm for is_64bit_mm() (although this logic is
	  broken anyway).

	- uprobe_register() should be called by create_trace_uprobe(),
	  not by probe_event_enable(), so that an error can be detected
	  at "perf probe -x" time. This also needs more changes in the
	  core uprobe code, uprobe register/unregister interface was
	  poorly designed from the very beginning.

Reported-by: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140519184054.GA6750@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-06-05 12:30:07 +02:00
Victor Kamensky
72e6ae285a ARM: 8043/1: uprobes need icache flush after xol write
After instruction write into xol area, on ARM V7
architecture code need to flush dcache and icache to sync
them up for given set of addresses. Having just
'flush_dcache_page(page)' call is not enough - it is
possible to have stale instruction sitting in icache
for given xol area slot address.

Introduce arch_uprobe_ixol_copy weak function
that by default calls uprobes copy_to_page function and
than flush_dcache_page function and on ARM define new one
that handles xol slot copy in ARM specific way

flush_uprobe_xol_access function shares/reuses implementation
with/of flush_ptrace_access function and takes care of writing
instruction to user land address space on given variety of
different cache types on ARM CPUs. Because
flush_uprobe_xol_access does not have vma around
flush_ptrace_access was split into two parts. First that
retrieves set of condition from vma and common that receives
those conditions as flags.

Note ARM cache flush function need kernel address
through which instruction write happened, so instead
of using uprobes copy_to_page function changed
code to explicitly map page and do memcpy.

Note arch_uprobe_copy_ixol function, in similar way as
copy_to_user_page function, has preempt_disable/preempt_enable.

Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: David A. Long <dave.long@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-05-25 23:48:45 +01:00
Oleg Nesterov
b02ef20a9f uprobes/x86: Fix the wrong ->si_addr when xol triggers a trap
If the probed insn triggers a trap, ->si_addr = regs->ip is technically
correct, but this is not what the signal handler wants; we need to pass
the address of the probed insn, not the address of xol slot.

Add the new arch-agnostic helper, uprobe_get_trap_addr(), and change
fill_trap_info() and math_error() to use it. !CONFIG_UPROBES case in
uprobes.h uses a macro to avoid include hell and ensure that it can be
compiled even if an architecture doesn't define instruction_pointer().

Test-case:

	#include <signal.h>
	#include <stdio.h>
	#include <unistd.h>

	extern void probe_div(void);

	void sigh(int sig, siginfo_t *info, void *c)
	{
		int passed = (info->si_addr == probe_div);
		printf(passed ? "PASS\n" : "FAIL\n");
		_exit(!passed);
	}

	int main(void)
	{
		struct sigaction sa = {
			.sa_sigaction	= sigh,
			.sa_flags	= SA_SIGINFO,
		};

		sigaction(SIGFPE, &sa, NULL);

		asm (
			"xor %ecx,%ecx\n"
			".globl probe_div; probe_div:\n"
			"idiv %ecx\n"
		);

		return 0;
	}

it fails if probe_div() is probed.

Note: show_unhandled_signals users should probably use this helper too,
but we need to cleanup them first.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
2014-05-14 13:57:28 +02:00
Oleg Nesterov
29dedee0e6 uprobes: Add mem_cgroup_charge_anon() into uprobe_write_opcode()
Hugh says:

    The one I noticed was that it forgets all about memcg (because
    it was copied from KSM, and there the replacement page has already
    been charged to a memcg). See how mm/memory.c do_anonymous_page()
    does a mem_cgroup_charge_anon().

Hopefully not a big problem, uprobes is a system-wide thing and only
root can insert the probes. But I agree, should be fixed anyway.

Add mem_cgroup_{un,}charge_anon() into uprobe_write_opcode(). To simplify
the error handling (and avoid the new "uncharge" label) the patch also
moves anon_vma_prepare() up before we alloc/charge the new page.

While at it fix the comment about ->mmap_sem, it is held for write.

Suggested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2014-05-14 13:57:24 +02:00
Oleg Nesterov
13f59c5e45 uprobes: Refuse to insert a probe into MAP_SHARED vma
valid_vma() rejects the VM_SHARED vmas, but this still allows to insert
a probe into the MAP_SHARED but not VM_MAYWRITE vma.

Currently this is fine, such a mapping doesn't really differ from the
private read-only mmap except mprotect(PROT_WRITE) won't work. However,
get_user_pages(FOLL_WRITE | FOLL_FORCE) doesn't allow to COW in this
case, and it would be safer to follow the same conventions as mm even
if currently this happens to work.

After the recent cda540ace6 "mm: get_user_pages(write,force) refuse
to COW in shared areas" only uprobes can insert an anon page into the
shared file-backed area, lets stop this and change valid_vma() to check
VM_MAYSHARE instead.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2014-04-30 19:10:43 +02:00
Oleg Nesterov
014940bad8 uprobes/x86: Send SIGILL if arch_uprobe_post_xol() fails
Currently the error from arch_uprobe_post_xol() is silently ignored.
This doesn't look good and this can lead to the hard-to-debug problems.

1. Change handle_singlestep() to loudly complain and send SIGILL.

   Note: this only affects x86, ppc/arm can't fail.

2. Change arch_uprobe_post_xol() to call arch_uprobe_abort_xol() and
   avoid TF games if it is going to return an error.

   This can help to to analyze the problem, if nothing else we should
   not report ->ip = xol_slot in the core-file.

   Note: this means that handle_riprel_post_xol() can be called twice,
   but this is fine because it is idempotent.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
2014-04-17 21:58:20 +02:00
Oleg Nesterov
8a6b173287 uprobes: Kill UPROBE_SKIP_SSTEP and can_skip_sstep()
UPROBE_COPY_INSN, UPROBE_SKIP_SSTEP, and uprobe->flags must die. This
patch kills UPROBE_SKIP_SSTEP. I never understood why it was added;
not only it doesn't help, it harms.

It can only help to avoid arch_uprobe_skip_sstep() if it was already
called before and failed. But this is ugly, if we want to know whether
we can emulate this instruction or not we should do this analysis in
arch_uprobe_analyze_insn(), not when we hit this probe for the first
time.

And in fact this logic is simply wrong. arch_uprobe_skip_sstep() can
fail or not depending on the task/register state, if this insn can be
emulated but, say, put_user() fails we need to xol it this time, but
this doesn't mean we shouldn't try to emulate it when this or another
thread hits this bp next time.

And this is the actual reason for this change. We need to emulate the
"call" insn, but push(return-address) can obviously fail.

Per-arch notes:

	x86: __skip_sstep() can only emulate "rep;nop". With this
	     change it will be called every time and most probably
	     for no reason.

	     This will be fixed by the next changes. We need to
	     change this suboptimal code anyway.

	arm: Should not be affected. It has its own "bool simulate"
	     flag checked in arch_uprobe_skip_sstep().

	ppc: Looks like, it can emulate almost everything. Does it
	     actually need to record the fact that emulate_step()
	     failed? Hopefully not. But if yes, it can add the ppc-
	     specific flag into arch_uprobe.

TODO: rename arch_uprobe_skip_sstep() to arch_uprobe_emulate_insn(),

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: David A. Long <dave.long@linaro.org>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2014-04-17 21:58:16 +02:00
David A. Long
6fe50a28ba uprobes: allow ignoring of probe hits
Allow arches to decided to ignore a probe hit.  ARM will use this to
only call handlers if the conditions to execute a conditionally executed
instruction are satisfied.

Signed-off-by: David A. Long <dave.long@linaro.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
2014-03-18 16:39:34 -04:00
Linus Torvalds
60eaa0190f This pull request has a new feature to ftrace, namely the trace event
triggers by Tom Zanussi. A trigger is a way to enable an action when an
 event is hit. The actions are:
 
  o  trace on/off - enable or disable tracing
  o  snapshot     - save the current trace buffer in the snapshot
  o  stacktrace   - dump the current stack trace to the ringbuffer
  o  enable/disable events - enable or disable another event
 
 Namhyung Kim added updates to the tracing uprobes code. Having the
 uprobes add support for fetch methods.
 
 The rest are various bug fixes with the new code, and minor ones for
 the old code.
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Merge tag 'trace-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing updates from Steven Rostedt:
 "This pull request has a new feature to ftrace, namely the trace event
  triggers by Tom Zanussi.  A trigger is a way to enable an action when
  an event is hit.  The actions are:

   o  trace on/off - enable or disable tracing
   o  snapshot     - save the current trace buffer in the snapshot
   o  stacktrace   - dump the current stack trace to the ringbuffer
   o  enable/disable events - enable or disable another event

  Namhyung Kim added updates to the tracing uprobes code.  Having the
  uprobes add support for fetch methods.

  The rest are various bug fixes with the new code, and minor ones for
  the old code"

* tag 'trace-3.14' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (38 commits)
  tracing: Fix buggered tee(2) on tracing_pipe
  tracing: Have trace buffer point back to trace_array
  ftrace: Fix synchronization location disabling and freeing ftrace_ops
  ftrace: Have function graph only trace based on global_ops filters
  ftrace: Synchronize setting function_trace_op with ftrace_trace_function
  tracing: Show available event triggers when no trigger is set
  tracing: Consolidate event trigger code
  tracing: Fix counter for traceon/off event triggers
  tracing: Remove double-underscore naming in syscall trigger invocations
  tracing/kprobes: Add trace event trigger invocations
  tracing/probes: Fix build break on !CONFIG_KPROBE_EVENT
  tracing/uprobes: Add @+file_offset fetch method
  uprobes: Allocate ->utask before handler_chain() for tracing handlers
  tracing/uprobes: Add support for full argument access methods
  tracing/uprobes: Fetch args before reserving a ring buffer
  tracing/uprobes: Pass 'is_return' to traceprobe_parse_probe_arg()
  tracing/probes: Implement 'memory' fetch method for uprobes
  tracing/probes: Add fetch{,_size} member into deref fetch method
  tracing/probes: Move 'symbol' fetch method to kprobes
  tracing/probes: Implement 'stack' fetch method for uprobes
  ...
2014-01-22 16:35:21 -08:00
Oleg Nesterov
72fd293aa9 uprobes: Allocate ->utask before handler_chain() for tracing handlers
uprobe_trace_print() and uprobe_perf_print() need to pass the additional
info to call_fetch() methods, currently there is no simple way to do this.

current->utask looks like a natural place to hold this info, but we need
to allocate it before handler_chain().

This is a bit unfortunate, perhaps we will find a better solution later,
but this is simple and should work right now.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
2014-01-02 20:57:04 -05:00
Oleg Nesterov
ad439356ae uprobes: Document xol_area and arch_uprobe->insn/ixol
Document xol_area and arch_uprobe.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-11-20 16:31:07 +01:00
Oleg Nesterov
c912dae60a uprobes: Cleanup !CONFIG_UPROBES decls, unexport xol_area
1. Don't include asm/uprobes.h unconditionally, we only need
   it if CONFIG_UPROBES.

2. Move the definition of "struct xol_area" into uprobes.c.

   Perhaps we should simply kill struct uprobes_state, it buys
   nothing.

3. Kill the dummy definition of uprobe_get_swbp_addr(), nobody
   except handle_swbp() needs it.

4. Purely cosmetic, but move the decl of uprobe_get_swbp_addr()
   up, close to other __weak helpers.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-11-20 16:31:01 +01:00
Oleg Nesterov
803200e24a uprobes: Don't assume that arch_uprobe->insn/ixol is u8[MAX_UINSN_BYTES]
arch_uprobe should be opaque as much as possible to the generic
code, but currently it assumes that insn/ixol must be u8[] of the
known size. Remove this unnecessary dependency, we can use "&" and
and sizeof() with the same effect.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-11-20 16:31:00 +01:00
Oleg Nesterov
3247343118 uprobes: Add uprobe_task->dup_xol_work/dup_xol_addr
uprobe_task->vaddr is a bit strange. The generic code uses it only
to pass the additional argument to arch_uprobe_pre_xol(), and since
it is always equal to instruction_pointer() this looks even more
strange.

And both utask->vaddr and and utask->autask have the same scope,
they only have the meaning when the task executes the probed insn
out-of-line, so it is safe to reuse both in UTASK_RUNNING state.

This all means that logically ->vaddr belongs to arch_uprobe_task
and we should probably move it there, arch_uprobe_pre_xol() can
record instruction_pointer() itself.

OTOH, it is also used by uprobe_copy_process() and dup_xol_work()
for another purpose, this doesn't look clean and doesn't allow to
move this member into arch_uprobe_task.

This patch adds the union with 2 anonymous structs into uprobe_task.

The first struct is autask + vaddr, this way we "almost" move vaddr
into autask.

The second struct has 2 new members for uprobe_copy_process() paths:
->dup_xol_addr which can be used instead ->vaddr, and ->dup_xol_work
which can be used to avoid kmalloc() and simplify the code.

Note that this union will likely have another member(s), we need
something like "private_data_for_handlers" so that the tracing
handlers could use it to communicate with call_fetch() methods.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-11-20 16:30:57 +01:00
Oleg Nesterov
2ded0980a6 uprobes: Fix the memory out of bound overwrite in copy_insn()
1. copy_insn() doesn't look very nice, all calculations are
   confusing and it is not immediately clear why do we read
   the 2nd page first.

2. The usage of inode->i_size is wrong on 32-bit machines.

3. "Instruction at end of binary" logic is simply wrong, it
   doesn't handle the case when uprobe->offset > inode->i_size.

   In this case "bytes" overflows, and __copy_insn() writes to
   the memory outside of uprobe->arch.insn.

   Yes, uprobe_register() checks i_size_read(), but this file
   can be truncated after that. All i_size checks are racy, we
   do this only to catch the obvious mistakes.

Change copy_insn() to call __copy_insn() in a loop, simplify
and fix the bytes/nbytes calculations.

Note: we do not care if we read extra bytes after inode->i_size
if we got the valid page. This is fine because the task gets the
same page after page-fault, and arch_uprobe_analyze_insn() can't
know how many bytes were actually read anyway.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-11-09 17:05:43 +01:00
Oleg Nesterov
70d7f98722 uprobes: Fix the wrong usage of current->utask in uprobe_copy_process()
Commit aa59c53fd4 "uprobes: Change uprobe_copy_process() to dup
xol_area" has a stupid typo, we need to setup t->utask->vaddr but
the code wrongly uses current->utask.

Even with this bug dup_xol_work() works "in practice", but only
because get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE) likely
returns the same address every time.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-11-09 17:05:41 +01:00
Oleg Nesterov
f72d41fa90 uprobes: Export write_opcode() as uprobe_write_opcode()
set_swbp() and set_orig_insn() are __weak, but this is pointless
because write_opcode() is static.

Export write_opcode() as uprobe_write_opcode() for the upcoming
arm port, this way it can actually override set_swbp() and use
__opcode_to_mem_arm(bpinsn) instead if UPROBE_SWBP_INSN.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-11-06 20:00:09 +01:00
Oleg Nesterov
8a8de66c4f uprobes: Introduce arch_uprobe->ixol
Currently xol_get_insn_slot() assumes that we should simply copy
arch_uprobe->insn[] which is (ignoring arch_uprobe_analyze_insn)
just the copy of the original insn.

This is not true for arm which needs to create another insn to
execute it out-of-line.

So this patch simply adds the new member, ->ixol into the union.
This doesn't make any difference for x86 and powerpc, but arm
can divorce insn/ixol and initialize the correct xol insn in
arch_uprobe_analyze_insn().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-11-06 20:00:05 +01:00
Oleg Nesterov
736e89d9f7 uprobes: Kill module_init() and module_exit()
Turn module_init() into __initcall() and kill module_exit().

This code can't be compiled as a module so these module_*()
calls only add the confusion, especially if arch-dependant
code needs its own initialization hooks.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-11-06 19:59:50 +01:00
Oleg Nesterov
3ab6796617 uprobes: Teach uprobe_copy_process() to handle CLONE_VFORK
uprobe_copy_process() does nothing if the child shares ->mm with
the forking process, but there is a special case: CLONE_VFORK.
In this case it would be more correct to do dup_utask() but avoid
dup_xol(). This is not that important, the child should not unwind
its stack too much, this can corrupt the parent's stack, but at
least we need this to allow to ret-probe __vfork() itself.

Note: in theory, it would be better to check task_pt_regs(p)->sp
instead of CLONE_VFORK, we need to dup_utask() if and only if the
child can return from the function called by the parent. But this
needs the arch-dependant helper, and I think that nobody actually
does clone(same_stack, CLONE_VM).

Reported-by: Martin Cermak <mcermak@redhat.com>
Reported-by: David Smith <dsmith@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-10-29 18:02:55 +01:00
Oleg Nesterov
aa59c53fd4 uprobes: Change uprobe_copy_process() to dup xol_area
This finally fixes the serious bug in uretprobes: a forked child
crashes if the parent called fork() with the pending ret probe.

Trivial test-case:

	# perf probe -x /lib/libc.so.6 __fork%return
	# perf record -e probe_libc:__fork perl -le 'fork || print "OK"'

(the child doesn't print "OK", it is killed by SIGSEGV)

If the child returns from the probed function it actually returns
to trampoline_vaddr, because it got the copy of parent's stack
mangled by prepare_uretprobe() when the parent entered this func.

It crashes because a) this address is not mapped and b) until the
previous change it doesn't have the proper->return_instances info.

This means that uprobe_copy_process() has to create xol_area which
has the trampoline slot, and its vaddr should be equal to parent's
xol_area->vaddr.

Unfortunately, uprobe_copy_process() can not simply do
__create_xol_area(child, xol_area->vaddr). This could actually work
but perf_event_mmap() doesn't expect the usage of foreign ->mm. So
we offload this to task_work_run(), and pass the argument via not
yet used utask->vaddr.

We know that this vaddr is fine for install_special_mapping(), the
necessary hole was recently "created" by dup_mmap() which skips the
parent's VM_DONTCOPY area, and nobody else could use the new mm.

Unfortunately, this also means that we can not handle the errors
properly, we obviously can not abort the already completed fork().
So we simply print the warning if GFP_KERNEL allocation (the only
possible reason) fails.

Reported-by: Martin Cermak <mcermak@redhat.com>
Reported-by: David Smith <dsmith@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-10-29 18:02:54 +01:00
Oleg Nesterov
248d3a7b2f uprobes: Change uprobe_copy_process() to dup return_instances
uprobe_copy_process() assumes that the new child doesn't need
->utask, it should be allocated by demand.

But this is not true if the forking task has the pending ret-
probes, the child should report them as well and thus it needs
the copy of parent's ->return_instances chain. Otherwise the
child crashes when it returns from the probed function.

Alternatively we could cleanup the child's stack, but this needs
per-arch changes and this is not what we want. At least systemtap
expects a .return in the child too.

Note: this change alone doesn't fix the problem, see the next
change.

Reported-by: Martin Cermak <mcermak@redhat.com>
Reported-by: David Smith <dsmith@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-10-29 18:02:53 +01:00
Oleg Nesterov
af0d95af79 uprobes: Teach __create_xol_area() to accept the predefined vaddr
Currently xol_add_vma() uses get_unmapped_area() for area->vaddr,
but the next patches need to use the fixed address. So this patch
adds the new "vaddr" argument to __create_xol_area() which should
be used as area->vaddr if it is nonzero.

xol_add_vma() doesn't bother to verify that the predefined addr is
not used, insert_vm_struct() should fail if find_vma_links() detects
the overlap with the existing vma.

Also, __create_xol_area() doesn't need __GFP_ZERO to allocate area.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-10-29 18:02:51 +01:00
Oleg Nesterov
6441ec8b7c uprobes: Introduce __create_xol_area()
No functional changes, preparation.

Extract the code which actually allocates/installs the new area
into the new helper, __create_xol_area().

While at it remove the unnecessary "ret = ENOMEM" and "ret = 0"
in xol_add_vma(), they both have no effect.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-10-29 18:02:50 +01:00
Oleg Nesterov
b68e074910 uprobes: Change the callsite of uprobe_copy_process()
Preparation for the next patches.

Move the callsite of uprobe_copy_process() in copy_process() down
to the succesfull return. We do not care if copy_process() fails,
uprobe_free_utask() won't be called in this case so the wrong
->utask != NULL doesn't matter.

OTOH, with this change we know that copy_process() can't fail when
uprobe_copy_process() is called, the new task should either return
to user-mode or call do_exit(). This way uprobe_copy_process() can:

	1. setup p->utask != NULL if necessary

	2. setup uprobes_state.xol_area

	3. use task_work_add(p)

Also, move the definition of uprobe_copy_process() down so that it
can see get_utask().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-10-29 18:02:48 +01:00
Oleg Nesterov
878b5a6efd uprobes: Fix utask->depth accounting in handle_trampoline()
Currently utask->depth is simply the number of allocated/pending
return_instance's in uprobe_task->return_instances list.

handle_trampoline() should decrement this counter every time we
handle/free an instance, but due to typo it does this only if
->chained == T. This means that in the likely case this counter
is never decremented and the probed task can't report more than
MAX_URETPROBE_DEPTH events.

Reported-by: Mikhail Kulemin <Mikhail.Kulemin@ru.ibm.com>
Reported-by: Hemant Kumar Shaw <hkshaw@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
Cc: masami.hiramatsu.pt@hitachi.com
Cc: srikar@linux.vnet.ibm.com
Cc: systemtap@sourceware.org
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20130911154726.GA8093@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-12 08:00:55 +02:00
Anton Arapov
a0d60aef4b uretprobes: Remove -ENOSYS as return probes implemented
Enclose return probes implementation.

Signed-off-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-04-13 15:31:58 +02:00
Anton Arapov
ded49c5530 uretprobes: Limit the depth of return probe nestedness
Unlike the kretprobes we can't trust userspace, thus must have
protection from user space attacks. User-space have  "unlimited"
stack, and this patch limits the return probes nestedness as a
simple remedy for it.

Note that this implementation leaks return_instance on siglongjmp
until exit()/exec().

The intention is to have KISS and bare minimum solution for the
initial implementation in order to not complicate the uretprobes
code.

In the future we may come up with more sophisticated solution that
remove this depth limitation. It is not easy task and lays beyond
this patchset.

Signed-off-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-04-13 15:31:58 +02:00
Anton Arapov
fec8898d86 uretprobes: Return probe exit, invoke handlers
Uretprobe handlers are invoked when the trampoline is hit, on completion
the trampoline is replaced with the saved return address and the uretprobe
instance deleted.

TODO: handle_trampoline() assumes that ->return_instances is always valid.
We should teach it to handle longjmp() which can invalidate the pending
return_instance's. This is nontrivial, we will try to do this in a separate
series.

Signed-off-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-04-13 15:31:57 +02:00
Anton Arapov
0dfd0eb8e4 uretprobes: Return probe entry, prepare_uretprobe()
When a uprobe with return probe consumer is hit, prepare_uretprobe()
function is invoked. It creates return_instance, hijacks return address
and replaces it with the trampoline.

* Return instances are kept as stack per uprobed task.
* Return instance is chained, when the original return address is
  trampoline's page vaddr (e.g. recursive call of the probed function).

Signed-off-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-04-13 15:31:57 +02:00
Anton Arapov
e78aebfd27 uretprobes: Reserve the first slot in xol_vma for trampoline
Allocate trampoline page, as the very first one in uprobed
task xol area, and fill it with breakpoint opcode.

Also introduce get_trampoline_vaddr() helper, to wrap the
trampoline address extraction from area->vaddr. That removes
confusion and eases the debug experience in case ->vaddr
notion will be changed.

Signed-off-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-04-13 15:31:54 +02:00
Anton Arapov
ea024870cf uretprobes: Introduce uprobe_consumer->ret_handler()
Enclose return probes implementation, introduce ->ret_handler() and update
existing code to rely on ->handler() *and* ->ret_handler() for uprobe and
uretprobe respectively.

Signed-off-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-04-13 15:31:53 +02:00
Oleg Nesterov
3f47107c5c uprobes: Change write_opcode() to use copy_*page()
Change write_opcode() to use copy_highpage() + copy_to_page()
and simplify the code.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-04-04 13:57:06 +02:00
Oleg Nesterov
5669ccee21 uprobes: Introduce copy_to_page()
Extract the kmap_atomic/memcpy/kunmap_atomic code from
xol_get_insn_slot() into the new simple helper, copy_to_page().
It will have more users soon.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-04-04 13:57:05 +02:00
Oleg Nesterov
98763a1bb1 uprobes: Kill the unnecesary filp != NULL check in __copy_insn()
__copy_insn(filp) can only be called after valid_vma() returns T,
vma->vm_file passed as "filp" can not be NULL.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-04-04 13:57:05 +02:00
Oleg Nesterov
2edb7b5574 uprobes: Change __copy_insn() to use copy_from_page()
Change __copy_insn() to use copy_from_page() and simplify the code.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-04-04 13:57:05 +02:00
Oleg Nesterov
ab0d805c7b uprobes: Turn copy_opcode() into copy_from_page()
No functional changes. Rename copy_opcode() into copy_from_page() and
add the new "int len" argument to make it more more generic for the
new users.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-04-04 13:57:04 +02:00
Ananth N Mavinakayanahalli
0908ad6e56 uprobes: Add trap variant helper
Some architectures like powerpc have multiple variants of the trap
instruction. Introduce an additional helper is_trap_insn() for run-time
handling of non-uprobe traps on such architectures.

While there, change is_swbp_at_addr() to is_trap_at_addr() for reading
clarity.

With this change, the uprobe registration path will supercede any trap
instruction inserted at the requested location, while taking care of
delivering the SIGTRAP for cases where the trap notification came in
for an address without a uprobe. See [1] for a more detailed explanation.

[1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2013-March/104771.html

This change was suggested by Oleg Nesterov.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-04-04 13:57:04 +02:00
Oleg Nesterov
f281769e81 uprobes: Use file_inode()
Cleanup. Now that we have f_inode/file_inode() we can use it instead
of vm_file->f_mapping->host.

This should not make any difference for uprobes, but in theory this
change is more correct. We use this inode as a key, to compare it
with uprobe->inode set by uprobe_register(inode), and the caller uses
d_inode.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-04-04 13:57:03 +02:00
Oleg Nesterov
bdf8647c44 uprobes: Introduce uprobe_apply()
Currently it is not possible to change the filtering constraints after
uprobe_register(), so a consumer can not, say, start to trace a task/mm
which was previously filtered out, or remove the no longer needed bp's.

Introduce uprobe_apply() which simply does register_for_each_vma() again
to consult uprobe_consumer->filter() and install/remove the breakpoints.
The only complication is that register_for_each_vma() can no longer
assume that uprobe->consumers should be consulter if is_register == T,
so we change it to accept "struct uprobe_consumer *new" instead.

Unlike uprobe_register(), uprobe_apply(true) doesn't do "unregister" if
register_for_each_vma() fails, it is up to caller to handle the error.

Note: we probably need to cleanup the current interface, it is strange
that uprobe_apply/unregister need inode/offset. We should either change
uprobe_register() to return "struct uprobe *", or add a private ->uprobe
member in uprobe_consumer. And in the long term uprobe_apply() should
take a single argument, uprobe or consumer, even "bool add" should go
away.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-02-08 18:28:04 +01:00
Josh Stone
e8440c1458 uprobes: Add exports for module use
The original pull message for uprobes (commit 654443e2) noted:

  This tree includes uprobes support in 'perf probe' - but SystemTap
  (and other tools) can take advantage of user probe points as well.

In order to actually be usable in module-based tools like SystemTap, the
interface needs to be exported.  This patch first adds the obvious
exports for uprobe_register and uprobe_unregister.  Then it also adds
one for task_user_regset_view, which is necessary to get the correct
state of userspace registers.

Signed-off-by: Josh Stone <jistone@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
2013-02-08 17:47:13 +01:00
Oleg Nesterov
af4355e91f uprobes: Kill the bogus IS_ERR_VALUE(xol_vaddr) check
utask->xol_vaddr is either zero or valid, remove the bogus
IS_ERR_VALUE() check in xol_free_insn_slot().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08 17:47:13 +01:00
Oleg Nesterov
608e7427c0 uprobes: Do not allocate current->utask unnecessary
handle_swbp() does get_utask() before can_skip_sstep() for no reason,
we do not need ->utask if can_skip_sstep() succeeds.

Move get_utask() to pre_ssout() who actually starts to use it. Move
the initialization of utask->active_uprobe/state as well. This way
the whole initialization is consolidated in pre_ssout().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
2013-02-08 17:47:12 +01:00
Oleg Nesterov
aba51024e7 uprobes: Fix utask->xol_vaddr leak in pre_ssout()
pre_ssout() should do xol_free_insn_slot() if arch_uprobe_pre_xol()
fails, otherwise nobody will free the allocated slot.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08 17:47:12 +01:00
Oleg Nesterov
a6cb3f6d51 uprobes: Do not play with utask in xol_get_insn_slot()
pre_ssout()->xol_get_insn_slot() path is confusing and buggy. This patch
cleanups the code, the next one fixes the bug.

Change xol_get_insn_slot() to only allocate the slot and do nothing more,
move the initialization of utask->xol_vaddr/vaddr into pre_ssout().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
2013-02-08 17:47:12 +01:00