linux-toradex.git/fs/proc, branch v4.19-rc5

fs/proc/kcore.c: fix invalid memory access in multi-page read optimization

2018-09-20T20:01:11+00:00

The 'm' kcore_list item could point to kclist_head, and it is incorrect to
look at m->addr / m->size in this case.

There is no choice but to run through the list of entries for every
address if we did not find any entry in the previous iteration

Reset 'm' to NULL in that case at Omar Sandoval's suggestion.

[akpm@linux-foundation.org: add comment]
Link: http://lkml.kernel.org/r/1536100702-28706-1-git-send-email-asmadeus@codewreck.org
Fixes: bf991c2231117 ("proc/kcore: optimize multiple page reads")
Signed-off-by: Dominique Martinet 
Reviewed-by: Andrew Morton 
Cc: Omar Sandoval 
Cc: Alexey Dobriyan 
Cc: Eric Biederman 
Cc: James Morse 
Cc: Bhupesh Sharma 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-08-26T18:25:21+00:00

Pull perf updates from Thomas Gleixner:
 "Kernel:
   - Improve kallsyms coverage
   - Add x86 entry trampolines to kcore
   - Fix ARM SPE handling
   - Correct PPC event post processing

  Tools:
   - Make the build system more robust
   - Small fixes and enhancements all over the place
   - Update kernel ABI header copies
   - Preparatory work for converting libtraceevnt to a shared library
   - License cleanups"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (100 commits)
  tools arch: Update arch/x86/lib/memcpy_64.S copy used in 'perf bench mem memcpy'
  tools arch x86: Update tools's copy of cpufeatures.h
  perf python: Fix pyrf_evlist__read_on_cpu() interface
  perf mmap: Store real cpu number in 'struct perf_mmap'
  perf tools: Remove ext from struct kmod_path
  perf tools: Add gzip_is_compressed function
  perf tools: Add lzma_is_compressed function
  perf tools: Add is_compressed callback to compressions array
  perf tools: Move the temp file processing into decompress_kmodule
  perf tools: Use compression id in decompress_kmodule()
  perf tools: Store compression id into struct dso
  perf tools: Add compression id into 'struct kmod_path'
  perf tools: Make is_supported_compression() static
  perf tools: Make decompress_to_file() function static
  perf tools: Get rid of dso__needs_decompress() call in __open_dso()
  perf tools: Get rid of dso__needs_decompress() call in symbol__disassemble()
  perf tools: Get rid of dso__needs_decompress() call in read_object_code()
  tools lib traceevent: Change to SPDX License format
  perf llvm: Allow passing options to llc in addition to clang
  perf parser: Improve error message for PMU address filters
  ...

fs/proc/vmcore.c: hide vmcoredd_mmap_dumps() for nommu builds

2018-08-24T01:48:43+00:00

Without CONFIG_MMU, we get a build warning:

  fs/proc/vmcore.c:228:12: error: 'vmcoredd_mmap_dumps' defined but not used [-Werror=unused-function]
   static int vmcoredd_mmap_dumps(struct vm_area_struct *vma, unsigned long dst,

The function is only referenced from an #ifdef'ed caller, so
this uses the same #ifdef around it.

Link: http://lkml.kernel.org/r/20180525213526.2117790-1-arnd@arndb.de
Fixes: 7efe48df8a3d ("vmcore: append device dumps to vmcore as elf notes")
Signed-off-by: Arnd Bergmann 
Cc: Ganesh Goudar 
Cc: "David S. Miller" 
Cc: Rahul Lakkireddy 
Cc: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc/kcore: add vmcoreinfo note to /proc/kcore

2018-08-22T17:52:46+00:00

The vmcoreinfo information is useful for runtime debugging tools, not just
for crash dumps.  A lot of this information can be determined by other
means, but this is much more convenient, and it only adds a page at most
to the file.

Link: http://lkml.kernel.org/r/fddbcd08eed76344863303878b12de1c1e2a04b6.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval 
Cc: Alexey Dobriyan 
Cc: Bhupesh Sharma 
Cc: Eric Biederman 
Cc: James Morse 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc/kcore: optimize multiple page reads

2018-08-22T17:52:46+00:00

The current code does a full search of the segment list every time for
every page.  This is wasteful, since it's almost certain that the next
page will be in the same segment.  Instead, check if the previous segment
covers the current page before doing the list search.

Link: http://lkml.kernel.org/r/fd346c11090cf93d867e01b8d73a6567c5ac6361.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval 
Cc: Alexey Dobriyan 
Cc: Bhupesh Sharma 
Cc: Eric Biederman 
Cc: James Morse 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc/kcore: clean up ELF header generation

2018-08-22T17:52:46+00:00

Currently, the ELF file header, program headers, and note segment are
allocated all at once, in some icky code dating back to 2.3.  Programs
tend to read the file header, then the program headers, then the note
segment, all separately, so this is a waste of effort.  It's cleaner and
more efficient to handle the three separately.

Link: http://lkml.kernel.org/r/19c92cbad0e11f6103ff3274b2e7a7e51a1eb74b.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval 
Cc: Alexey Dobriyan 
Cc: Bhupesh Sharma 
Cc: Eric Biederman 
Cc: James Morse 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc/kcore: hold lock during read

2018-08-22T17:52:46+00:00

Now that we're using an rwsem, we can hold it during the entirety of
read_kcore() and have a common return path.  This is preparation for the
next change.

[akpm@linux-foundation.org: fix locking bug reported by Tetsuo Handa]
Link: http://lkml.kernel.org/r/d7cfbc1e8a76616f3b699eaff9df0a2730380534.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval 
Cc: Alexey Dobriyan 
Cc: Bhupesh Sharma 
Cc: Eric Biederman 
Cc: James Morse 
Cc: Tetsuo Handa 
Cc: Stephen Rothwell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc/kcore: fix memory hotplug vs multiple opens race

2018-08-22T17:52:46+00:00

There's a theoretical race condition that will cause /proc/kcore to miss
a memory hotplug event:

CPU0                              CPU1
// hotplug event 1
kcore_need_update = 1

open_kcore()                      open_kcore()
    kcore_update_ram()                kcore_update_ram()
        // Walk RAM                       // Walk RAM
        __kcore_update_ram()              __kcore_update_ram()
            kcore_need_update = 0

// hotplug event 2
kcore_need_update = 1
                                              kcore_need_update = 0

Note that CPU1 set up the RAM kcore entries with the state after hotplug
event 1 but cleared the flag for hotplug event 2.  The RAM entries will
therefore be stale until there is another hotplug event.

This is an extremely unlikely sequence of events, but the fix makes the
synchronization saner, anyways: we serialize the entire update sequence,
which means that whoever clears the flag will always succeed in replacing
the kcore list.

Link: http://lkml.kernel.org/r/6106c509998779730c12400c1b996425df7d7089.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval 
Cc: Alexey Dobriyan 
Cc: Bhupesh Sharma 
Cc: Eric Biederman 
Cc: James Morse 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc/kcore: replace kclist_lock rwlock with rwsem

2018-08-22T17:52:46+00:00

Now we only need kclist_lock from user context and at fs init time, and
the following changes need to sleep while holding the kclist_lock.

Link: http://lkml.kernel.org/r/521ba449ebe921d905177410fee9222d07882f0d.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval 
Reviewed-by: Andrew Morton 
Cc: Alexey Dobriyan 
Cc: Bhupesh Sharma 
Cc: Eric Biederman 
Cc: James Morse 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc/kcore: don't grab lock for memory hotplug notifier

2018-08-22T17:52:46+00:00

The memory hotplug notifier kcore_callback() only needs kclist_lock to
prevent races with __kcore_update_ram(), but we can easily eliminate that
race by using an atomic xchg() in __kcore_update_ram().  This is
preparation for converting kclist_lock to an rwsem.

Link: http://lkml.kernel.org/r/0a4bc89f4dbde8b5b2ea309f7b4fb6a85fe29df2.1531953780.git.osandov@fb.com
Signed-off-by: Omar Sandoval 
Reviewed-by: Andrew Morton 
Cc: Alexey Dobriyan 
Cc: Bhupesh Sharma 
Cc: Eric Biederman 
Cc: James Morse 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds