releases/4.7.7/mips-uprobes-remove-incorrect-set_orig_insn.patch

   1 From ddabfa5c2e33f1b495f3e0176de7057850915c0b Mon Sep 17 00:00:00 2001
   2 From: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
   3 Date: Thu, 22 Sep 2016 15:38:32 +0200
   4 Subject: MIPS: uprobes: remove incorrect set_orig_insn
   5
   6 From: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
   7
   8 commit ddabfa5c2e33f1b495f3e0176de7057850915c0b upstream.
   9
  10 Generic kernel code implements a weak version of set_orig_insn that
  11 moves cached 'insn' from arch_uprobe to the original code location when
  12 the trap is removed.
  13 MIPS variant used arch_uprobe->orig_inst which was never initialised
  14 properly, so this code only inserted a nop instead of the original
  15 instruction. With that change orig_inst can also be safely removed.
  16
  17 Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
  18 Fixes: 40e084a506eb ('MIPS: Add uprobes support.')
  19 Cc: linux-mips@linux-mips.org
  20 Patchwork: https://patchwork.linux-mips.org/patch/14299/
  21 Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
  22 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  23
  24 ---
  25  arch/mips/include/asm/uprobes.h |    1 -
  26  arch/mips/kernel/uprobes.c      |   18 ------------------
  27  2 files changed, 19 deletions(-)
  28
  29 --- a/arch/mips/include/asm/uprobes.h
  30 +++ b/arch/mips/include/asm/uprobes.h
  31 @@ -36,7 +36,6 @@ struct arch_uprobe {
  32         unsigned long   resume_epc;
  33         u32     insn[2];
  34         u32     ixol[2];
  35 -       union   mips_instruction orig_inst[MAX_UINSN_BYTES / 4];
  36  };
  37
  38  struct arch_uprobe_task {
  39 --- a/arch/mips/kernel/uprobes.c
  40 +++ b/arch/mips/kernel/uprobes.c
  41 @@ -280,24 +280,6 @@ int __weak set_swbp(struct arch_uprobe *
  42         return uprobe_write_opcode(mm, vaddr, UPROBE_SWBP_INSN);
  43  }
  44
  45 -/**
  46 - * set_orig_insn - Restore the original instruction.
  47 - * @mm: the probed process address space.
  48 - * @auprobe: arch specific probepoint information.
  49 - * @vaddr: the virtual address to insert the opcode.
  50 - *
  51 - * For mm @mm, restore the original opcode (opcode) at @vaddr.
  52 - * Return 0 (success) or a negative errno.
  53 - *
  54 - * This overrides the weak version in kernel/events/uprobes.c.
  55 - */
  56 -int set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
  57 -                unsigned long vaddr)
  58 -{
  59 -       return uprobe_write_opcode(mm, vaddr,
  60 -                       *(uprobe_opcode_t *)&auprobe->orig_inst[0].word);
  61 -}
  62 -
  63  void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
  64                                   void *src, unsigned long len)
  65  {