Masami Hiramatsu wrote: > 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: Masami Hiramatsu <mhiramat at kernel.org> > Cc: Vineet Gupta <vgupta at synopsys.com> > Cc: Russell King <linux at armlinux.org.uk> > Cc: Catalin Marinas <catalin.marinas at arm.com> > Cc: Will Deacon <will.deacon at arm.com> > Cc: Tony Luck <tony.luck at intel.com> > Cc: Fenghua Yu <fenghua.yu at intel.com> > Cc: Ralf Baechle <ralf at linux-mips.org> > Cc: James Hogan <jhogan at kernel.org> > Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org> > Cc: Paul Mackerras <paulus at samba.org> > Cc: Michael Ellerman <mpe at ellerman.id.au> > Cc: Martin Schwidefsky <schwidefsky at de.ibm.com> > Cc: Heiko Carstens <heiko.carstens at de.ibm.com> > Cc: Yoshinori Sato <ysato at users.sourceforge.jp> > Cc: Rich Felker <dalias at libc.org> > Cc: "David S. Miller" <davem at davemloft.net> > Cc: "Naveen N. Rao" <naveen.n.rao at linux.vnet.ibm.com> > Cc: Josef Bacik <jbacik at fb.com> > Cc: Alexei Starovoitov <ast at kernel.org> > Cc: x86 at kernel.org > Cc: linux-snps-arc at lists.infradead.org > Cc: linux-kernel at vger.kernel.org > Cc: linux-arm-kernel at lists.infradead.org > Cc: linux-ia64 at vger.kernel.org > Cc: linux-mips at linux-mips.org > Cc: linuxppc-dev at lists.ozlabs.org > Cc: linux-s390 at vger.kernel.org > Cc: linux-sh at vger.kernel.org > Cc: sparclinux at vger.kernel.org > --- > Changes in v5: > - Fix kprobe_ftrace_handler in arch/powerpc too. > --- > arch/arc/kernel/kprobes.c | 5 +++-- > arch/arm/probes/kprobes/core.c | 10 +++++----- > arch/arm64/kernel/probes/kprobes.c | 10 +++++----- > arch/ia64/kernel/kprobes.c | 13 ++++--------- > arch/mips/kernel/kprobes.c | 4 ++-- > arch/powerpc/kernel/kprobes-ftrace.c | 15 ++++++--------- > arch/powerpc/kernel/kprobes.c | 7 +++++-- For the powerpc bits: Acked-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com> Thanks, Naveen
