The following commit has been merged into the perf/core branch of tip:
Commit-ID: 8e791f7eba4c7711f56616ae163ee3cbc00b1bf4
Gitweb: https://git.kernel.org/tip/8e791f7eba4c7711f56616ae163ee3cbc00b1bf4
Author: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
AuthorDate: Wed, 30 Nov 2022 22:33:09 +09:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Sat, 07 Jan 2023 12:29:08 +01:00
x86/kprobes: Drop removed INT3 handling code
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, it is already safe. The commit 5c02ece81848d
("x86/kprobes: Fix ordering while text-patching") introduced
text_poke_sync() to the arch_disarm_kprobe() right after removing INT3.
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@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/166981518895.1131462.4693062055762912734.stgit@devnote3
---
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 6629968..33390ed 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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