On 7/10/2026 1:09 PM, Masami Hiramatsu wrote: > On Thu, 9 Jul 2026 14:22:25 +0000 > Pu Hu <[email protected]> wrote: > >> From: Pu Hu <[email protected]> >> >> A kprobe can be hit while another kprobe is in KPROBE_HIT_SS state. This >> can happen when tracing or perf code runs from the debug exception path >> while the first kprobe is preparing or executing its out-of-line >> single-step instruction. >> >> Currently arm64 treats a kprobe hit in KPROBE_HIT_SS as unrecoverable, >> the same as a hit in KPROBE_REENTER. This is too strict. A hit in >> KPROBE_HIT_SS is still a one-level reentry and can be handled by saving >> the current kprobe state and setting up single-step for the new probe, >> just like reentry from KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE. >> >> The truly unrecoverable case is hitting another kprobe while already in >> KPROBE_REENTER, because the reentry save area has already been consumed. >> >> Move KPROBE_HIT_SS to the recoverable reentry cases and leave >> KPROBE_REENTER as the unrecoverable nested reentry case. >> >> This mirrors the x86 fix in commit 6a5022a56ac3 >> ("kprobes/x86: Allow to handle reentered kprobe on single-stepping"). >> > > Hi, as Sashiko commented, we have to save the saved_irqflag to > prev_kprobbe. > > https://sashiko.dev/#/patchset/20260709142215.226872-1-hupu%40transsion.com?part=2 > > Thank you, >
Hi Masami, We already added the saved_irqflag support in Patch 3 of this series: arm64: kprobes: Save and restore saved_irqflag in prev_kprobe However, I see the issue. Patch 2 and Patch 3 are separate commits, so Patch 2 alone is not bisectable. I'll prepare a v3 that folds them together, so the reentry logic and the saved_irqflag preservation land in a single commit. Thanks for pointing this out. Thanks, Pu Hu
