From 91440ff4cafad4c86322a612e523f7f021a493e7 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Sun, 20 Jul 2025 13:21:18 +0200 Subject: uprobes/x86: Add mapping for optimized uprobe trampolines Adding support to add special mapping for user space trampoline with following functions: uprobe_trampoline_get - find or add uprobe_trampoline uprobe_trampoline_put - remove or destroy uprobe_trampoline The user space trampoline is exported as arch specific user space special mapping through tramp_mapping, which is initialized in following changes with new uprobe syscall. The uprobe trampoline needs to be callable/reachable from the probed address, so while searching for available address we use is_reachable_by_call function to decide if the uprobe trampoline is callable from the probe address. All uprobe_trampoline objects are stored in uprobes_state object and are cleaned up when the process mm_struct goes down. Adding new arch hooks for that, because this change is x86_64 specific. Locking is provided by callers in following changes. Signed-off-by: Jiri Olsa Signed-off-by: Peter Zijlstra (Intel) Acked-by: Andrii Nakryiko Acked-by: Oleg Nesterov Acked-by: Masami Hiramatsu (Google) Link: https://lore.kernel.org/r/20250720112133.244369-9-jolsa@kernel.org --- kernel/events/uprobes.c | 10 ++++++++++ kernel/fork.c | 1 + 2 files changed, 11 insertions(+) (limited to 'kernel') diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index da2b3d0deab6..2cd7a4c6f303 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1801,6 +1801,14 @@ static struct xol_area *get_xol_area(void) return area; } +void __weak arch_uprobe_clear_state(struct mm_struct *mm) +{ +} + +void __weak arch_uprobe_init_state(struct mm_struct *mm) +{ +} + /* * uprobe_clear_state - Free the area allocated for slots. */ @@ -1812,6 +1820,8 @@ void uprobe_clear_state(struct mm_struct *mm) delayed_uprobe_remove(NULL, mm); mutex_unlock(&delayed_uprobe_lock); + arch_uprobe_clear_state(mm); + if (!area) return; diff --git a/kernel/fork.c b/kernel/fork.c index af673856499d..d827cc6c5362 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1015,6 +1015,7 @@ static void mm_init_uprobes_state(struct mm_struct *mm) { #ifdef CONFIG_UPROBES mm->uprobes_state.xol_area = NULL; + arch_uprobe_init_state(mm); #endif } -- cgit v1.2.3