diff options
| author | Masami Hiramatsu <mhiramat@kernel.org> | 2018-06-19 19:16:17 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-06-21 13:33:20 +0300 |
| commit | 2bbda764d720aacabaad38374d26fcccb7843f17 (patch) | |
| tree | 25d60c92825b75c73362b455baafb5464aca07cc /arch/x86/kernel/kprobes | |
| parent | cce188bd58cfbd603b904dbce75f34de2eff959a (diff) | |
| download | linux-2bbda764d720aacabaad38374d26fcccb7843f17.tar.xz | |
kprobes/x86: Do not disable preempt on int3 path
Since int3 and debug exception(for singlestep) are run with
IRQ disabled and while running single stepping we drop IF
from regs->flags, that path must not be preemptible. So we
can remove the preempt disable/enable calls from that path.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-arch@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Link: https://lore.kernel.org/lkml/152942497779.15209.2879580696589868291.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/kprobes')
| -rw-r--r-- | arch/x86/kernel/kprobes/core.c | 18 | ||||
| -rw-r--r-- | arch/x86/kernel/kprobes/opt.c | 1 |
2 files changed, 4 insertions, 15 deletions
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 814e26b7c8a2..f7104b256de7 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -594,7 +594,6 @@ static void setup_singlestep(struct kprobe *p, struct pt_regs *regs, * stepping. */ regs->ip = (unsigned long)p->ainsn.insn; - preempt_enable_no_resched(); return; } #endif @@ -667,12 +666,10 @@ int kprobe_int3_handler(struct pt_regs *regs) addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); /* - * We don't want to be preempted for the entire - * duration of kprobe processing. We conditionally - * re-enable preemption at the end of this function, - * and also in reenter_kprobe() and setup_singlestep(). + * We don't want to be preempted for the entire duration of kprobe + * processing. Since int3 and debug trap disables irqs and we clear + * IF while singlestepping, it must be no preemptible. */ - preempt_disable(); kcb = get_kprobe_ctlblk(); p = get_kprobe(addr); @@ -694,10 +691,8 @@ int kprobe_int3_handler(struct pt_regs *regs) */ if (!p->pre_handler || !p->pre_handler(p, regs)) setup_singlestep(p, regs, kcb, 0); - else { + else reset_current_kprobe(); - preempt_enable_no_resched(); - } return 1; } } else if (*addr != BREAKPOINT_INSTRUCTION) { @@ -711,11 +706,9 @@ int kprobe_int3_handler(struct pt_regs *regs) * the original instruction. */ regs->ip = (unsigned long)addr; - preempt_enable_no_resched(); return 1; } /* else: not a kprobe fault; let the kernel handle it */ - preempt_enable_no_resched(); return 0; } NOKPROBE_SYMBOL(kprobe_int3_handler); @@ -966,8 +959,6 @@ int kprobe_debug_handler(struct pt_regs *regs) } reset_current_kprobe(); out: - preempt_enable_no_resched(); - /* * if somebody else is singlestepping across a probe point, flags * will have TF set, in which case, continue the remaining processing @@ -1014,7 +1005,6 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr) restore_previous_kprobe(kcb); else reset_current_kprobe(); - preempt_enable_no_resched(); } else if (kcb->kprobe_status == KPROBE_HIT_ACTIVE || kcb->kprobe_status == KPROBE_HIT_SSDONE) { /* diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index 203d398802a3..eaf02f2e7300 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -491,7 +491,6 @@ int setup_detour_execution(struct kprobe *p, struct pt_regs *regs, int reenter) regs->ip = (unsigned long)op->optinsn.insn + TMPL_END_IDX; if (!reenter) reset_current_kprobe(); - preempt_enable_no_resched(); return 1; } return 0; |