Skip to content

L
linux
Switch branch/tag
  1. 22 Feb, 2009 2 commits
  3. 20 Feb, 2009 11 commits
    • Steven Rostedt's avatar
      ftrace: break out modify loop immediately on detection of error · 4377245a
      Steven Rostedt authored 
      Impact: added precaution on failure detection

Break out of the modifying loop as soon as a failure is detected.
This is just an added precaution found by code review and was not
found by any bug chasing.
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
      4377245a
    • Steven Rostedt's avatar
      ftrace: immediately stop code modification if failure is detected · 90c7ac49
      Steven Rostedt authored 
      Impact: fix to prevent NMI lockup

If the page fault handler produces a WARN_ON in the modifying of
text, and the system is setup to have a high frequency of NMIs,
we can lock up the system on a failure to modify code.

The modifying of code with NMIs allows all NMIs to modify the code
if it is about to run. This prevents a modifier on one CPU from
modifying code running in NMI context on another CPU. The modifying
is done through stop_machine, so only NMIs must be considered.

But if the write causes the page fault handler to produce a warning,
the print can slow it down enough that as soon as it is done
it will take another NMI before going back to the process context.
The new NMI will perform the write again causing another print and
this will hang the box.

This patch turns off the writing as soon as a failure is detected
and does not wait for it to be turned off by the process context.
This will keep NMIs from getting stuck in this back and forth
of print outs.
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
      90c7ac49
    • Steven Rostedt's avatar
      ftrace, x86: make kernel text writable only for conversions · 16239630
      Steven Rostedt authored 
      Impact: keep kernel text read only

Because dynamic ftrace converts the calls to mcount into and out of
nops at run time, we needed to always keep the kernel text writable.

But this defeats the point of CONFIG_DEBUG_RODATA. This patch converts
the kernel code to writable before ftrace modifies the text, and converts
it back to read only afterward.

The kernel text is converted to read/write, stop_machine is called to
modify the code, then the kernel text is converted back to read only.

The original version used SYSTEM_STATE to determine when it was OK
or not to change the code to rw or ro. Andrew Morton pointed out that
using SYSTEM_STATE is a bad idea since there is no guarantee to what
its state will actually be.

Instead, I moved the check into the set_kernel_text_* functions
themselves, and use a local variable to determine when it is
OK to change the kernel text RW permissions.

[ Update: Ingo Molnar suggested moving the prototypes to cacheflush.h ]
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
      16239630
    • Frederic Weisbecker's avatar
      tracing/markers: make markers select tracepoints · 91f73f90
      Frederic Weisbecker authored 
      Sometimes it happens that KConfig dependencies are not handled
like in the following scenario:

- config A
   bool

- config B
   bool
   depends on A

- config C
   bool
   select B

If one selects C, then it will select B without checking its
dependency to A, if A hasn't been selected elsewhere, it will
result in a build failure.

This is what happens on the following build error:

 kernel/built-in.o: In function `marker_update_probe_range':
 (.text+0x52f64): undefined reference to `tracepoint_probe_register_noupdate'
 kernel/built-in.o: In function `marker_update_probe_range':
 (.text+0x52f74): undefined reference to `tracepoint_probe_unregister_noupdate'
 kernel/built-in.o: In function `marker_update_probe_range':
 (.text+0x52fb9): undefined reference to `tracepoint_probe_unregister_noupdate'
 kernel/built-in.o: In function `marker_update_probes':
 marker.c:(.text+0x530ba): undefined reference to `tracepoint_probe_update_all'

CONFIG_KVM_TRACE will select CONFIG_MARKER, but the latter
depends on CONFIG_TRACEPOINTS which will not be selected.
Reported-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      91f73f90
    • Steven Rostedt's avatar
      ftrace: allow archs to preform pre and post process for code modification · 000ab691
      Steven Rostedt authored 
      This patch creates the weak functions: ftrace_arch_code_modify_prepare
and ftrace_arch_code_modify_post_process that are called before and
after the stop machine is called to modify the kernel text.

If the arch needs to do pre or post processing, it only needs to define
these functions.

[ Update: Ingo Molnar suggested using the name ftrace_arch_code_modify_*
          over using ftrace_arch_modify_* ]
Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
      000ab691
    • Ingo Molnar's avatar
      Merge branch 'for-ingo' of... · 057685cf
      Ingo Molnar authored 
      Merge branch 'for-ingo' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6 into tracing/kmemtrace

Conflicts:
	mm/slub.c
      057685cf
    • Frederic Weisbecker's avatar
      tracing/function-graph-tracer: make set_graph_function file support ftrace regex · f9349a8f
      Frederic Weisbecker authored 
      Impact: trace only functions matching a pattern

The set_graph_function file let one to trace only one or several
chosen functions and follow all their code flow.

Currently, only a constant function name is allowed so this patch
allows the ftrace_regex functions:

- matches all functions that end with "name":
  echo *name > set_graph_function

- matches all functions that begin with "name":
  echo name* > set_graph_function

- matches all functions that contains "name":
  echo *name* > set_graph_function

Example:

echo mutex* > set_graph_function

 0)               |  mutex_lock_nested() {
 0)   0.563 us    |    __might_sleep();
 0)   2.072 us    |  }
 0)               |  mutex_unlock() {
 0)   1.036 us    |    __mutex_unlock_slowpath();
 0)   2.433 us    |  }
 0)               |  mutex_unlock() {
 0)   0.691 us    |    __mutex_unlock_slowpath();
 0)   1.787 us    |  }
 0)               |  mutex_lock_interruptible_nested() {
 0)   0.548 us    |    __might_sleep();
 0)   1.945 us    |  }
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      f9349a8f
    • Ingo Molnar's avatar
      Merge branches 'tracing/function-graph-tracer' and 'linus' into tracing/core · 64b36ca7
      Ingo Molnar authored
      64b36ca7
    • Christoph Lameter's avatar
      SLUB: Introduce and use SLUB_MAX_SIZE and SLUB_PAGE_SHIFT constants · fe1200b6
      Christoph Lameter authored 
      As a preparational patch to bump up page allocator pass-through threshold,
introduce two new constants SLUB_MAX_SIZE and SLUB_PAGE_SHIFT and convert
mm/slub.c to use them.
Reported-by: default avatar"Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Tested-by: default avatar"Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
Signed-off-by: default avatarChristoph Lameter <cl@linux-foundation.org>
Signed-off-by: default avatarPekka Enberg <penberg@cs.helsinki.fi>
      fe1200b6
    • Ingo Molnar's avatar
      x86: use the right protections for split-up pagetables · 07a66d7c
      Ingo Molnar authored 
      Steven Rostedt found a bug in where in his modified kernel
ftrace was unable to modify the kernel text, due to the PMD
itself having been marked read-only as well in
split_large_page().

The fix, suggested by Linus, is to not try to 'clone' the
reference protection of a huge-page, but to use the standard
(and permissive) page protection bits of KERNPG_TABLE.

The 'cloning' makes sense for the ptes but it's a confused and
incorrect concept at the page table level - because the
pagetable entry is a set of all ptes and hence cannot
'clone' any single protection attribute - the ptes can be any
mixture of protections.

With the permissive KERNPG_TABLE, even if the pte protections
get changed after this point (due to ftrace doing code-patching
or other similar activities like kprobes), the resulting combined
protections will still be correct and the pte's restrictive
(or permissive) protections will control it.

Also update the comment.

This bug was there for a long time but has not caused visible
problems before as it needs a rather large read-only area to
trigger. Steve possibly hacked his kernel with some really
large arrays or so. Anyway, the bug is definitely worth fixing.

[ Huang Ying also experienced problems in this area when writing
  the EFI code, but the real bug in split_large_page() was not
  realized back then. ]
Reported-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Reported-by: default avatarHuang Ying <ying.huang@intel.com>
Acked-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      07a66d7c
    • Alok N Kataria's avatar
      x86, vmi: TSC going backwards check in vmi clocksource · 48ffc70b
      Alok N Kataria authored 
      Impact: fix time warps under vmware

Similar to the check for TSC going backwards in the TSC clocksource,
we also need this check for VMI clocksource.
Signed-off-by: default avatarAlok N Kataria <akataria@vmware.com>
Cc: Zachary Amsden <zach@vmware.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Cc: stable@kernel.org
      48ffc70b
  5. 19 Feb, 2009 27 commits
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7