Messages in this thread Patch in this message | | | From | "Masami Hiramatsu (Google)" <> | Subject | [PATCH -tip] x86/kprobes: Drop removed INT3 handling code | Date | Fri, 25 Nov 2022 23:44:47 +0900 |
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From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Drop removed INT3 handling code from kprobe_int3_handler() because this case (get_kprobe() doesn't return corresponding kprobe AND the INT3 is removed) must not happen with the kprobe managed INT3, but can happen with the non-kprobe INT3, which should be handled by other callbacks.
For the kprobe managed INT3, the arch_disarm_kprobe() removes the INT3 and then calls text_poke_sync(). Since this text_poke_sync() uses IPI to call sync_core() on all online cpus, that ensures that all running INT3 exception handlers have done. And, the unregister_kprobe() will remove the kprobe from the hash table after arch_disarm_kprobe().
Thus, when the kprobe managed INT3 hits, kprobe_int3_handler() should be able to find corresponding kprobe always by get_kprobe(). If it can not find any kprobe, this means that is NOT a kprobe managed INT3.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> --- arch/x86/kernel/kprobes/core.c | 14 -------------- 1 file changed, 14 deletions(-)
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 66299682b6b7..33390ed4dcf3 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -986,20 +986,6 @@ int kprobe_int3_handler(struct pt_regs *regs) kprobe_post_process(p, regs, kcb); return 1; } - } - - if (*addr != INT3_INSN_OPCODE) { - /* - * The breakpoint instruction was removed right - * after we hit it. Another cpu has removed - * either a probepoint or a debugger breakpoint - * at this address. In either case, no further - * handling of this interrupt is appropriate. - * Back up over the (now missing) int3 and run - * the original instruction. - */ - regs->ip = (unsigned long)addr; - return 1; } /* else: not a kprobe fault; let the kernel handle it */ return 0;
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