On Fri, 17 Jul 2026 16:23:31 +0800 daichengrong <[email protected]> wrote:
> uretprobe replaces the original return address of a probed function with > a trampoline address to capture function return events. > > After the trampoline is entered and the uretprobe handler completes, the > original return address needs to be restored in the user register context > to keep the register state consistent with the state before probing. > > Add an architecture-specific hook for restoring the original return > address during uretprobe handling. > > The initial implementation adds support for RISC-V. Other architectures > keep the default empty implementation until their corresponding restore > logic is implemented. > > Signed-off-by: daichengrong <[email protected]> > --- > arch/riscv/kernel/probes/uprobes.c | 7 +++++++ > include/linux/uprobes.h | 1 + > kernel/events/uprobes.c | 5 +++++ > 3 files changed, 13 insertions(+) > > diff --git a/arch/riscv/kernel/probes/uprobes.c > b/arch/riscv/kernel/probes/uprobes.c > index eb177d0ce8ab..0b1b94d9683e 100644 > --- a/arch/riscv/kernel/probes/uprobes.c > +++ b/arch/riscv/kernel/probes/uprobes.c > @@ -139,6 +139,13 @@ arch_uretprobe_hijack_return_addr(unsigned long > trampoline_vaddr, > return ra; > } > > +void > +arch_uretprobe_hijack_set_addr(unsigned long orig_ret_vaddr, > + struct pt_regs *regs) OK, but hijack may not be a good naming, what about "arch_uretprobe_restore_return_address()"? And I need RISC-V maintainer's review. Thank you, > +{ > + regs->ra = orig_ret_vaddr; > +} > + > int arch_uprobe_exception_notify(struct notifier_block *self, > unsigned long val, void *data) > { > diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h > index f548fea2adec..2d0dc919845d 100644 > --- a/include/linux/uprobes.h > +++ b/include/linux/uprobes.h > @@ -230,6 +230,7 @@ extern bool arch_uprobe_xol_was_trapped(struct > task_struct *tsk); > extern int arch_uprobe_exception_notify(struct notifier_block *self, > unsigned long val, void *data); > extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs > *regs); > extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long > trampoline_vaddr, struct pt_regs *regs); > +extern void arch_uretprobe_hijack_set_addr(unsigned long orig_ret_vaddr, > struct pt_regs *regs); > extern bool arch_uretprobe_is_alive(struct return_instance *ret, enum > rp_check ctx, struct pt_regs *regs); > extern bool arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs > *regs); > extern void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, > diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c > index 4084e926e284..deecaae01ab7 100644 > --- a/kernel/events/uprobes.c > +++ b/kernel/events/uprobes.c > @@ -1748,6 +1748,10 @@ void * __weak arch_uretprobe_trampoline(unsigned long > *psize) > return &insn; > } > > +void __weak arch_uretprobe_hijack_set_addr(unsigned long orig_ret_vaddr, > struct pt_regs *regs) > +{ > +} > + > static struct xol_area *__create_xol_area(unsigned long vaddr) > { > struct mm_struct *mm = current->mm; > @@ -2659,6 +2663,7 @@ void uprobe_handle_trampoline(struct pt_regs *regs) > valid = !next_chain || arch_uretprobe_is_alive(next_chain, > RP_CHECK_RET, regs); > > instruction_pointer_set(regs, ri->orig_ret_vaddr); > + arch_uretprobe_hijack_set_addr(ri->orig_ret_vaddr, regs); > do { > /* pop current instance from the stack of pending > return instances, > * as it's not pending anymore: we just fixed up > original > -- > 2.25.1 > > -- Masami Hiramatsu (Google) <[email protected]>
