1. 18 May, 2011 3 commits
    • Ingo Molnar's avatar
      Merge branch 'x86/mem' into perf/core · 01ed58ab
      Ingo Molnar authored
      Merge reason: memcpy_64.S changes an assumption perf bench has, so merge this
                    here so we can fix it.
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      01ed58ab
    • Ingo Molnar's avatar
      Merge branch 'tip/perf/core-2' of... · af2d03d4
      Ingo Molnar authored
      Merge branch 'tip/perf/core-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into perf/core
      af2d03d4
    • Jiri Olsa's avatar
      x86, 64-bit: Fix copy_[to/from]_user() checks for the userspace address limit · 26afb7c6
      Jiri Olsa authored
      As reported in BZ #30352:
      
        https://bugzilla.kernel.org/show_bug.cgi?id=30352
      
      there's a kernel bug related to reading the last allowed page on x86_64.
      
      The _copy_to_user() and _copy_from_user() functions use the following
      check for address limit:
      
        if (buf + size >= limit)
      	fail();
      
      while it should be more permissive:
      
        if (buf + size > limit)
      	fail();
      
      That's because the size represents the number of bytes being
      read/write from/to buf address AND including the buf address.
      So the copy function will actually never touch the limit
      address even if "buf + size == limit".
      
      Following program fails to use the last page as buffer
      due to the wrong limit check:
      
       #include <sys/mman.h>
       #include <sys/socket.h>
       #include <assert.h>
      
       #define PAGE_SIZE       (4096)
       #define LAST_PAGE       ((void*)(0x7fffffffe000))
      
       int main()
       {
              int fds[2], err;
              void * ptr = mmap(LAST_PAGE, PAGE_SIZE, PROT_READ | PROT_WRITE,
                                MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0);
              assert(ptr == LAST_PAGE);
              err = socketpair(AF_LOCAL, SOCK_STREAM, 0, fds);
              assert(err == 0);
              err = send(fds[0], ptr, PAGE_SIZE, 0);
              perror("send");
              assert(err == PAGE_SIZE);
              err = recv(fds[1], ptr, PAGE_SIZE, MSG_WAITALL);
              perror("recv");
              assert(err == PAGE_SIZE);
              return 0;
       }
      
      The other place checking the addr limit is the access_ok() function,
      which is working properly. There's just a misleading comment
      for the __range_not_ok() macro - which this patch fixes as well.
      
      The last page of the user-space address range is a guard page and
      Brian Gerst observed that the guard page itself due to an erratum on K8 cpus
      (#121 Sequential Execution Across Non-Canonical Boundary Causes Processor
      Hang).
      
      However, the test code is using the last valid page before the guard page.
      The bug is that the last byte before the guard page can't be read
      because of the off-by-one error. The guard page is left in place.
      
      This bug would normally not show up because the last page is
      part of the process stack and never accessed via syscalls.
      Signed-off-by: default avatarJiri Olsa <jolsa@redhat.com>
      Acked-by: default avatarBrian Gerst <brgerst@gmail.com>
      Acked-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Cc: <stable@kernel.org>
      Link: http://lkml.kernel.org/r/1305210630-7136-1-git-send-email-jolsa@redhat.comSigned-off-by: default avatarIngo Molnar <mingo@elte.hu>
      26afb7c6
  2. 17 May, 2011 11 commits
  3. 16 May, 2011 14 commits
  4. 12 May, 2011 1 commit
  5. 10 May, 2011 4 commits
  6. 09 May, 2011 7 commits