Skip to content
  1. May 20, 2009
    • Linus Torvalds's avatar
      Avoid ICE in get_random_int() with gcc-3.4.5 · 26a9a418
      Linus Torvalds authored
      
      
      Martin Knoblauch reports that trying to build 2.6.30-rc6-git3 with
      RHEL4.3 userspace (gcc (GCC) 3.4.5 20051201 (Red Hat 3.4.5-2)) causes an
      internal compiler error (ICE):
      
          drivers/char/random.c: In function `get_random_int':
          drivers/char/random.c:1672: error: unrecognizable insn:
          (insn 202 148 150 0 /scratch/build/linux-2.6.30-rc6-git3/arch/x86/include/asm/tsc.h:23 (set (reg:SI 0 ax [91])
                  (subreg:SI (plus:DI (plus:DI (reg:DI 0 ax [88])
                              (subreg:DI (reg:SI 6 bp) 0))
                          (const_int -4 [0xfffffffffffffffc])) 0)) -1 (nil)
              (nil))
          drivers/char/random.c:1672: internal compiler error: in extract_insn, at recog.c:2083
      
      and after some debugging it turns out that it's due to the code trying
      to figure out the rough value of the current stack pointer by taking an
      address of an uninitialized variable and casting that to an integer.
      
      This is clearly a compiler bug, but it's not worth fighting - while the
      current stack kernel pointer might be somewhat hard to predict in user
      space, it's also not generally going to change for a lot of the call
      chains for a particular process.
      
      So just drop it, and mumble some incoherent curses at the compiler.
      
      Tested-by: default avatarMartin Knoblauch <spamtrap@knobisoft.de>
      Cc: Matt Mackall <mpm@selenic.com>
      Cc: Ingo Molnar <mingo@elte.hu>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      26a9a418
  2. May 19, 2009
  3. May 18, 2009
  4. May 17, 2009
  5. May 16, 2009