1. 08 Nov, 2017 1 commit
    • Yonghong Song's avatar
      x86/idt: Remove X86_TRAP_BP initialization in idt_setup_traps() · d0cd64b0
      Yonghong Song authored
      Commit b70543a0("x86/idt: Move regular trap init to tables") moves
      regular trap init for each trap vector into a table based
      initialization. It introduced the initialization for vector X86_TRAP_BP
      which was not in the code which it replaced. This breaks uprobe
      functionality for x86_32; the probed program segfaults instead of handling
      the probe proper.
      
      The reason for this is that TRAP_BP is set up as system interrupt gate
      (DPL3) in the early IDT and then replaced by a regular interrupt gate
      (DPL0) in idt_setup_traps(). The DPL0 restriction causes the int3 trap
      to fail with a #GP resulting in a SIGSEGV of the probed program.
      
      On 64bit this does not cause a problem because the IDT entry is replaced
      with a system interrupt gate (DPL3) with interrupt stack afterwards.
      
      Remove X86_TRAP_BP from the def_idts table which is used in
      idt_setup_traps(). Remove a redundant entry for X86_TRAP_NMI in def_idts
      while at it. Tested on both x86_64 and x86_32.
      
      [ tglx: Amended changelog with a description of the root cause ]
      
      Fixes: b70543a0
      
      ("x86/idt: Move regular trap init to tables")
      Reported-and-tested-by: default avatarYonghong Song <yhs@fb.com>
      Signed-off-by: default avatarYonghong Song <yhs@fb.com>
      Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
      Cc: a.p.zijlstra@chello.nl
      Cc: ast@fb.com
      Cc: oleg@redhat.com
      Cc: luto@kernel.org
      Cc: kernel-team@fb.com
      Link: https://lkml.kernel.org/r/20171108192845.552709-1-yhs@fb.com
      d0cd64b0
  2. 01 Sep, 2017 1 commit
  3. 29 Aug, 2017 15 commits