Skip to content
  • Masami Hiramatsu's avatar
    bpf/error-inject/kprobes: Clear current_kprobe and enable preempt in kprobe · cce188bd
    Masami Hiramatsu authored
    
    
    Clear current_kprobe and enable preemption in kprobe
    even if pre_handler returns !0.
    
    This simplifies function override using kprobes.
    
    Jprobe used to require to keep the preemption disabled and
    keep current_kprobe until it returned to original function
    entry. For this reason kprobe_int3_handler() and similar
    arch dependent kprobe handers checks pre_handler result
    and exit without enabling preemption if the result is !0.
    
    After removing the jprobe, Kprobes does not need to
    keep preempt disabled even if user handler returns !0
    anymore.
    
    But since the function override handler in error-inject
    and bpf is also returns !0 if it overrides a function,
    to balancing the preempt count, it enables preemption
    and reset current kprobe by itself.
    
    That is a bad design that is very buggy. This fixes
    such unbalanced preempt-count and current_kprobes setting
    in kprobes, bpf and error-inject.
    
    Note: for powerpc and x86, this removes all preempt_disable
    from kprobe_ftrace_handler because ftrace callbacks are
    called under preempt disabled.
    
    Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
    Acked-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Acked-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
    Cc: Alexei Starovoitov <ast@kernel.org>
    Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: David S. Miller <davem@davemloft.net>
    Cc: Fenghua Yu <fenghua.yu@intel.com>
    Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
    Cc: James Hogan <jhogan@kernel.org>
    Cc: Josef Bacik <jbacik@fb.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
    Cc: Michael Ellerman <mpe@ellerman.id.au>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: Rich Felker <dalias@libc.org>
    Cc: Russell King <linux@armlinux.org.uk>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: Tony Luck <tony.luck@intel.com>
    Cc: Vineet Gupta <vgupta@synopsys.com>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
    Cc: linux-arch@vger.kernel.org
    Cc: linux-arm-kernel@lists.infradead.org
    Cc: linux-ia64@vger.kernel.org
    Cc: linux-mips@linux-mips.org
    Cc: linux-s390@vger.kernel.org
    Cc: linux-sh@vger.kernel.org
    Cc: linux-snps-arc@lists.infradead.org
    Cc: linuxppc-dev@lists.ozlabs.org
    Cc: sparclinux@vger.kernel.org
    Link: https://lore.kernel.org/lkml/152942494574.15209.12323837825873032258.stgit@devbox
    
    
    Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
    cce188bd