releases/4.5.7/mips-fix-sigreturn-via-vdso-on-micromips-kernel.patch

   1 From 13eb192d10bcc9ac518d57356179071d603bcb4e Mon Sep 17 00:00:00 2001
   2 From: James Hogan <james.hogan@imgtec.com>
   3 Date: Tue, 24 May 2016 09:35:10 +0100
   4 Subject: MIPS: Fix sigreturn via VDSO on microMIPS kernel
   5
   6 From: James Hogan <james.hogan@imgtec.com>
   7
   8 commit 13eb192d10bcc9ac518d57356179071d603bcb4e upstream.
   9
  10 In microMIPS kernels, handle_signal() sets the isa16 mode bit in the
  11 vdso address so that the sigreturn trampolines (which are offset from
  12 the VDSO) get executed as microMIPS.
  13
  14 However commit ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
  15 changed the offsets to come from the VDSO image, which already have the
  16 isa16 mode bit set correctly since they're extracted from the VDSO
  17 shared library symbol table.
  18
  19 Drop the isa16 mode bit handling from handle_signal() to fix sigreturn
  20 for cores which support both microMIPS and normal MIPS. This doesn't fix
  21 microMIPS only cores, since the VDSO is still built for normal MIPS, but
  22 thats a separate problem.
  23
  24 Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO")
  25 Signed-off-by: James Hogan <james.hogan@imgtec.com>
  26 Cc: Paul Burton <paul.burton@imgtec.com>
  27 Cc: linux-mips@linux-mips.org
  28 Patchwork: https://patchwork.linux-mips.org/patch/13348/
  29 Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
  30 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  31
  32 ---
  33  arch/mips/kernel/signal.c |    8 --------
  34  1 file changed, 8 deletions(-)
  35
  36 --- a/arch/mips/kernel/signal.c
  37 +++ b/arch/mips/kernel/signal.c
  38 @@ -770,15 +770,7 @@ static void handle_signal(struct ksignal
  39         sigset_t *oldset = sigmask_to_save();
  40         int ret;
  41         struct mips_abi *abi = current->thread.abi;
  42 -#ifdef CONFIG_CPU_MICROMIPS
  43 -       void *vdso;
  44 -       unsigned long tmp = (unsigned long)current->mm->context.vdso;
  45 -
  46 -       set_isa16_mode(tmp);
  47 -       vdso = (void *)tmp;
  48 -#else
  49         void *vdso = current->mm->context.vdso;
  50 -#endif
  51
  52         if (regs->regs[0]) {
  53                 switch(regs->regs[2]) {