user/sven/linux.git/include/linux/uprobes.h, branch v6.17.11

kernel/events/uprobes: pass VMA to set_swbp(), set_orig_insn() and uprobe_write_opcode()

2025-05-12T00:48:18Z

We already have the VMA, no need to look it up using get_user_page_vma_remote(). We can now switch to get_user_pages_remote(). Link: https://lkml.kernel.org/r/20250321113713.204682-3-david@redhat.com Signed-off-by: David Hildenbrand Acked-by: Oleg Nesterov Acked-by: Peter Zijlstra (Intel) Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Andrii Nakryiko Cc: Arnaldo Carvalho de Melo Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Mark Rutland Cc: "Masami Hiramatsu (Google)" Cc: Matthew Wilcox (Oracle) Cc: Namhyung kim Cc: Russel King Cc: tongtiangen Signed-off-by: Andrew Morton

uprobes/x86: Harden uretprobe syscall trampoline check

2025-03-06T11:22:45Z

Jann reported a possible issue when trampoline_check_ip returns address near the bottom of the address space that is allowed to call into the syscall if uretprobes are not set up: https://lore.kernel.org/bpf/202502081235.5A6F352985@keescook/T/#m9d416df341b8fbc11737dacbcd29f0054413cbbf Though the mmap minimum address restrictions will typically prevent creating mappings there, let's make sure uretprobe syscall checks for that. Fixes: ff474a78cef5 ("uprobe: Add uretprobe syscall to speed up return probe") Reported-by: Jann Horn Signed-off-by: Jiri Olsa Signed-off-by: Ingo Molnar Reviewed-by: Oleg Nesterov Reviewed-by: Kees Cook Acked-by: Andrii Nakryiko Acked-by: Masami Hiramatsu (Google) Acked-by: Alexei Starovoitov Cc: Andy Lutomirski Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250212220433.3624297-1-jolsa@kernel.org

uprobes: Remove the spinlock within handle_singlestep()

2025-02-05T09:29:12Z

This patch introduces a flag to track TIF_SIGPENDING is suppress temporarily during the uprobe single-step. Upon uprobe singlestep is handled and the flag is confirmed, it could resume the TIF_SIGPENDING directly without acquiring the siglock in most case, then reducing contention and improving overall performance. I've use the script developed by Andrii in [1] to run benchmark. The CPU used was Kunpeng916 (Hi1616), 4 NUMA nodes, 64 cores@2.4GHz running the kernel on next tree + the optimization for get_xol_insn_slot() [2]. before-opt ---------- uprobe-nop ( 1 cpus): 0.907 ± 0.003M/s ( 0.907M/s/cpu) uprobe-nop ( 2 cpus): 1.676 ± 0.008M/s ( 0.838M/s/cpu) uprobe-nop ( 4 cpus): 3.210 ± 0.003M/s ( 0.802M/s/cpu) uprobe-nop ( 8 cpus): 4.457 ± 0.003M/s ( 0.557M/s/cpu) uprobe-nop (16 cpus): 3.724 ± 0.011M/s ( 0.233M/s/cpu) uprobe-nop (32 cpus): 2.761 ± 0.003M/s ( 0.086M/s/cpu) uprobe-nop (64 cpus): 1.293 ± 0.015M/s ( 0.020M/s/cpu) uprobe-push ( 1 cpus): 0.883 ± 0.001M/s ( 0.883M/s/cpu) uprobe-push ( 2 cpus): 1.642 ± 0.005M/s ( 0.821M/s/cpu) uprobe-push ( 4 cpus): 3.086 ± 0.002M/s ( 0.771M/s/cpu) uprobe-push ( 8 cpus): 3.390 ± 0.003M/s ( 0.424M/s/cpu) uprobe-push (16 cpus): 2.652 ± 0.005M/s ( 0.166M/s/cpu) uprobe-push (32 cpus): 2.713 ± 0.005M/s ( 0.085M/s/cpu) uprobe-push (64 cpus): 1.313 ± 0.009M/s ( 0.021M/s/cpu) uprobe-ret ( 1 cpus): 1.774 ± 0.000M/s ( 1.774M/s/cpu) uprobe-ret ( 2 cpus): 3.350 ± 0.001M/s ( 1.675M/s/cpu) uprobe-ret ( 4 cpus): 6.604 ± 0.000M/s ( 1.651M/s/cpu) uprobe-ret ( 8 cpus): 6.706 ± 0.005M/s ( 0.838M/s/cpu) uprobe-ret (16 cpus): 5.231 ± 0.001M/s ( 0.327M/s/cpu) uprobe-ret (32 cpus): 5.743 ± 0.003M/s ( 0.179M/s/cpu) uprobe-ret (64 cpus): 4.726 ± 0.016M/s ( 0.074M/s/cpu) after-opt --------- uprobe-nop ( 1 cpus): 0.985 ± 0.002M/s ( 0.985M/s/cpu) uprobe-nop ( 2 cpus): 1.773 ± 0.005M/s ( 0.887M/s/cpu) uprobe-nop ( 4 cpus): 3.304 ± 0.001M/s ( 0.826M/s/cpu) uprobe-nop ( 8 cpus): 5.328 ± 0.002M/s ( 0.666M/s/cpu) uprobe-nop (16 cpus): 6.475 ± 0.002M/s ( 0.405M/s/cpu) uprobe-nop (32 cpus): 4.831 ± 0.082M/s ( 0.151M/s/cpu) uprobe-nop (64 cpus): 2.564 ± 0.053M/s ( 0.040M/s/cpu) uprobe-push ( 1 cpus): 0.964 ± 0.001M/s ( 0.964M/s/cpu) uprobe-push ( 2 cpus): 1.766 ± 0.002M/s ( 0.883M/s/cpu) uprobe-push ( 4 cpus): 3.290 ± 0.009M/s ( 0.823M/s/cpu) uprobe-push ( 8 cpus): 4.670 ± 0.002M/s ( 0.584M/s/cpu) uprobe-push (16 cpus): 5.197 ± 0.004M/s ( 0.325M/s/cpu) uprobe-push (32 cpus): 5.068 ± 0.161M/s ( 0.158M/s/cpu) uprobe-push (64 cpus): 2.605 ± 0.026M/s ( 0.041M/s/cpu) uprobe-ret ( 1 cpus): 1.833 ± 0.001M/s ( 1.833M/s/cpu) uprobe-ret ( 2 cpus): 3.384 ± 0.003M/s ( 1.692M/s/cpu) uprobe-ret ( 4 cpus): 6.677 ± 0.004M/s ( 1.669M/s/cpu) uprobe-ret ( 8 cpus): 6.854 ± 0.005M/s ( 0.857M/s/cpu) uprobe-ret (16 cpus): 6.508 ± 0.006M/s ( 0.407M/s/cpu) uprobe-ret (32 cpus): 5.793 ± 0.009M/s ( 0.181M/s/cpu) uprobe-ret (64 cpus): 4.743 ± 0.016M/s ( 0.074M/s/cpu) Above benchmark results demonstrates a obivious improvement in the scalability of trig-uprobe-nop and trig-uprobe-push, the peak throughput of which are from 4.5M/s to 6.4M/s and 3.3M/s to 5.1M/s individually. [1] https://lore.kernel.org/all/20240731214256.3588718-1-andrii@kernel.org [2] https://lore.kernel.org/all/20240727094405.1362496-1-liaochang1@huawei.com Acked-by: Masami Hiramatsu (Google) Acked-by: Oleg Nesterov Signed-off-by: Liao Chang Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20250124093826.2123675-3-liaochang1@huawei.com

uprobes: Reuse return_instances between multiple uretprobes within task

2024-12-09T14:50:30Z

Instead of constantly allocating and freeing very short-lived struct return_instance, reuse it as much as possible within current task. For that, store a linked list of reusable return_instances within current->utask. The only complication is that ri_timer() might be still processing such return_instance. And so while the main uretprobe processing logic might be already done with return_instance and would be OK to immediately reuse it for the next uretprobe instance, it's not correct to unconditionally reuse it just like that. Instead we make sure that ri_timer() can't possibly be processing it by using seqcount_t, with ri_timer() being "a writer", while free_ret_instance() being "a reader". If, after we unlink return instance from utask->return_instances list, we know that ri_timer() hasn't gotten to processing utask->return_instances yet, then we can be sure that immediate return_instance reuse is OK, and so we put it onto utask->ri_pool for future (potentially, almost immediate) reuse. This change shows improvements both in single CPU performance (by avoiding relatively expensive kmalloc/free combon) and in terms of multi-CPU scalability, where you can see that per-CPU throughput doesn't decline as steeply with increased number of CPUs (which were previously attributed to kmalloc()/free() through profiling): BASELINE (latest perf/core) =========================== uretprobe-nop ( 1 cpus): 1.898 ± 0.002M/s ( 1.898M/s/cpu) uretprobe-nop ( 2 cpus): 3.574 ± 0.011M/s ( 1.787M/s/cpu) uretprobe-nop ( 3 cpus): 5.279 ± 0.066M/s ( 1.760M/s/cpu) uretprobe-nop ( 4 cpus): 6.824 ± 0.047M/s ( 1.706M/s/cpu) uretprobe-nop ( 5 cpus): 8.339 ± 0.060M/s ( 1.668M/s/cpu) uretprobe-nop ( 6 cpus): 9.812 ± 0.047M/s ( 1.635M/s/cpu) uretprobe-nop ( 7 cpus): 11.030 ± 0.048M/s ( 1.576M/s/cpu) uretprobe-nop ( 8 cpus): 12.453 ± 0.126M/s ( 1.557M/s/cpu) uretprobe-nop (10 cpus): 14.838 ± 0.044M/s ( 1.484M/s/cpu) uretprobe-nop (12 cpus): 17.092 ± 0.115M/s ( 1.424M/s/cpu) uretprobe-nop (14 cpus): 19.576 ± 0.022M/s ( 1.398M/s/cpu) uretprobe-nop (16 cpus): 22.264 ± 0.015M/s ( 1.391M/s/cpu) uretprobe-nop (24 cpus): 33.534 ± 0.078M/s ( 1.397M/s/cpu) uretprobe-nop (32 cpus): 43.262 ± 0.127M/s ( 1.352M/s/cpu) uretprobe-nop (40 cpus): 53.252 ± 0.080M/s ( 1.331M/s/cpu) uretprobe-nop (48 cpus): 55.778 ± 0.045M/s ( 1.162M/s/cpu) uretprobe-nop (56 cpus): 56.850 ± 0.227M/s ( 1.015M/s/cpu) uretprobe-nop (64 cpus): 62.005 ± 0.077M/s ( 0.969M/s/cpu) uretprobe-nop (72 cpus): 66.445 ± 0.236M/s ( 0.923M/s/cpu) uretprobe-nop (80 cpus): 68.353 ± 0.180M/s ( 0.854M/s/cpu) THIS PATCHSET (on top of latest perf/core) ========================================== uretprobe-nop ( 1 cpus): 2.253 ± 0.004M/s ( 2.253M/s/cpu) uretprobe-nop ( 2 cpus): 4.281 ± 0.003M/s ( 2.140M/s/cpu) uretprobe-nop ( 3 cpus): 6.389 ± 0.027M/s ( 2.130M/s/cpu) uretprobe-nop ( 4 cpus): 8.328 ± 0.005M/s ( 2.082M/s/cpu) uretprobe-nop ( 5 cpus): 10.353 ± 0.001M/s ( 2.071M/s/cpu) uretprobe-nop ( 6 cpus): 12.513 ± 0.010M/s ( 2.086M/s/cpu) uretprobe-nop ( 7 cpus): 14.525 ± 0.017M/s ( 2.075M/s/cpu) uretprobe-nop ( 8 cpus): 15.633 ± 0.013M/s ( 1.954M/s/cpu) uretprobe-nop (10 cpus): 19.532 ± 0.011M/s ( 1.953M/s/cpu) uretprobe-nop (12 cpus): 21.405 ± 0.009M/s ( 1.784M/s/cpu) uretprobe-nop (14 cpus): 24.857 ± 0.020M/s ( 1.776M/s/cpu) uretprobe-nop (16 cpus): 26.466 ± 0.018M/s ( 1.654M/s/cpu) uretprobe-nop (24 cpus): 40.513 ± 0.222M/s ( 1.688M/s/cpu) uretprobe-nop (32 cpus): 54.180 ± 0.074M/s ( 1.693M/s/cpu) uretprobe-nop (40 cpus): 66.100 ± 0.082M/s ( 1.652M/s/cpu) uretprobe-nop (48 cpus): 70.544 ± 0.068M/s ( 1.470M/s/cpu) uretprobe-nop (56 cpus): 74.494 ± 0.055M/s ( 1.330M/s/cpu) uretprobe-nop (64 cpus): 79.317 ± 0.029M/s ( 1.239M/s/cpu) uretprobe-nop (72 cpus): 84.875 ± 0.020M/s ( 1.179M/s/cpu) uretprobe-nop (80 cpus): 92.318 ± 0.224M/s ( 1.154M/s/cpu) For reference, with uprobe-nop we hit the following throughput: uprobe-nop (80 cpus): 143.485 ± 0.035M/s ( 1.794M/s/cpu) So now uretprobe stays a bit closer to that performance. Signed-off-by: Andrii Nakryiko Signed-off-by: Ingo Molnar Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: Oleg Nesterov Link: https://lore.kernel.org/r/20241206002417.3295533-5-andrii@kernel.org

uprobes: Simplify session consumer tracking

2024-12-09T14:50:23Z

In practice, each return_instance will typically contain either zero or one return_consumer, depending on whether it has any uprobe session consumer attached or not. It's highly unlikely that more than one uprobe session consumers will be attached to any given uprobe, so there is no need to optimize for that case. But the way we currently do memory allocation and accounting is by pre-allocating the space for 4 session consumers in contiguous block of memory next to struct return_instance fixed part. This is unnecessarily wasteful. This patch changes this to keep struct return_instance fixed-sized with one pre-allocated return_consumer, while (in a highly unlikely scenario) allowing for more session consumers in a separate dynamically allocated and reallocated array. We also simplify accounting a bit by not maintaining a separate temporary capacity for consumers array, and, instead, relying on krealloc() to be a no-op if underlying memory can accommodate a slightly bigger allocation (but again, it's very uncommon scenario to even have to do this reallocation). All this gets rid of ri_size(), simplifies push_consumer() and removes confusing ri->consumers_cnt re-assignment, while containing this singular preallocated consumer logic contained within a few simple preexisting helpers. Having fixed-sized struct return_instance simplifies and speeds up return_instance reuse that we ultimately add later in this patch set, see follow up patches. Signed-off-by: Andrii Nakryiko Signed-off-by: Ingo Molnar Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: Oleg Nesterov Link: https://lore.kernel.org/r/20241206002417.3295533-2-andrii@kernel.org

uprobes: Re-order struct uprobe_task to save some space

2024-11-11T10:49:48Z

On x86_64, with allmodconfig, struct uprobe_task is 72 bytes long, with a hole and some padding. /* size: 72, cachelines: 2, members: 7 */ /* sum members: 64, holes: 1, sum holes: 4 */ /* padding: 4 */ /* forced alignments: 1, forced holes: 1, sum forced holes: 4 */ /* last cacheline: 8 bytes */ Reorder the structure to fill the hole and avoid the padding. This way, the whole structure fits in a single cacheline and some memory is saved when it is allocated. /* size: 64, cachelines: 1, members: 7 */ /* forced alignments: 1 */ Signed-off-by: Christophe JAILLET Signed-off-by: Peter Zijlstra (Intel) Acked-by: "Masami Hiramatsu (Google)" Link: https://lore.kernel.org/r/a9f541d0cedf421f765c77a1fb93d6a979778a88.1730495562.git.christophe.jaillet@wanadoo.fr

uprobes: SRCU-protect uretprobe lifetime (with timeout)

2024-10-30T21:42:19Z

Avoid taking refcount on uprobe in prepare_uretprobe(), instead take uretprobe-specific SRCU lock and keep it active as kernel transfers control back to user space. Given we can't rely on user space returning from traced function within reasonable time period, we need to make sure not to keep SRCU lock active for too long, though. To that effect, we employ a timer callback which is meant to terminate SRCU lock region after predefined timeout (currently set to 100ms), and instead transfer underlying struct uprobe's lifetime protection to refcounting. This fallback to less scalable refcounting after 100ms is a fine tradeoff from uretprobe's scalability and performance perspective, because uretprobing *long running* user functions inherently doesn't run into scalability issues (there is just not enough frequency to cause noticeable issues with either performance or scalability). The overall trick is in ensuring synchronization between current thread and timer's callback fired on some other thread. To cope with that with minimal logic complications, we add hprobe wrapper which is used to contain all the synchronization related issues behind a small number of basic helpers: hprobe_expire() for "downgrading" uprobe from SRCU-protected state to refcounted state, and a hprobe_consume() and hprobe_finalize() pair of single-use consuming helpers. Other than that, whatever current thread's logic is there stays the same, as timer thread cannot modify return_instance state (or add new/remove old return_instances). It only takes care of SRCU unlock and uprobe refcounting, which is hidden from the higher-level uretprobe handling logic. We use atomic xchg() in hprobe_consume(), which is called from performance critical handle_uretprobe_chain() function run in the current context. When uncontended, this xchg() doesn't seem to hurt performance as there are no other competing CPUs fighting for the same cache line. We also mark struct return_instance as ____cacheline_aligned to ensure no false sharing can happen. Another technical moment. We need to make sure that the list of return instances can be safely traversed under RCU from timer callback, so we delay return_instance freeing with kfree_rcu() and make sure that list modifications use RCU-aware operations. Also, given SRCU lock survives transition from kernel to user space and back we need to use lower-level __srcu_read_lock() and __srcu_read_unlock() to avoid lockdep complaining. Just to give an impression of a kind of performance improvements this change brings, below are benchmarking results with and without these SRCU changes, assuming other uprobe optimizations (mainly RCU Tasks Trace for entry uprobes, lockless RB-tree lookup, and lockless VMA to uprobe lookup) are left intact: WITHOUT SRCU for uretprobes =========================== uretprobe-nop ( 1 cpus): 2.197 ± 0.002M/s ( 2.197M/s/cpu) uretprobe-nop ( 2 cpus): 3.325 ± 0.001M/s ( 1.662M/s/cpu) uretprobe-nop ( 3 cpus): 4.129 ± 0.002M/s ( 1.376M/s/cpu) uretprobe-nop ( 4 cpus): 6.180 ± 0.003M/s ( 1.545M/s/cpu) uretprobe-nop ( 8 cpus): 7.323 ± 0.005M/s ( 0.915M/s/cpu) uretprobe-nop (16 cpus): 6.943 ± 0.005M/s ( 0.434M/s/cpu) uretprobe-nop (32 cpus): 5.931 ± 0.014M/s ( 0.185M/s/cpu) uretprobe-nop (64 cpus): 5.145 ± 0.003M/s ( 0.080M/s/cpu) uretprobe-nop (80 cpus): 4.925 ± 0.005M/s ( 0.062M/s/cpu) WITH SRCU for uretprobes ======================== uretprobe-nop ( 1 cpus): 1.968 ± 0.001M/s ( 1.968M/s/cpu) uretprobe-nop ( 2 cpus): 3.739 ± 0.003M/s ( 1.869M/s/cpu) uretprobe-nop ( 3 cpus): 5.616 ± 0.003M/s ( 1.872M/s/cpu) uretprobe-nop ( 4 cpus): 7.286 ± 0.002M/s ( 1.822M/s/cpu) uretprobe-nop ( 8 cpus): 13.657 ± 0.007M/s ( 1.707M/s/cpu) uretprobe-nop (32 cpus): 45.305 ± 0.066M/s ( 1.416M/s/cpu) uretprobe-nop (64 cpus): 42.390 ± 0.922M/s ( 0.662M/s/cpu) uretprobe-nop (80 cpus): 47.554 ± 2.411M/s ( 0.594M/s/cpu) Signed-off-by: Andrii Nakryiko Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20241024044159.3156646-3-andrii@kernel.org

uprobe: Add support for session consumer

2024-10-23T18:52:27Z

This change allows the uprobe consumer to behave as session which means that 'handler' and 'ret_handler' callbacks are connected in a way that allows to: - control execution of 'ret_handler' from 'handler' callback - share data between 'handler' and 'ret_handler' callbacks The session concept fits to our common use case where we do filtering on entry uprobe and based on the result we decide to run the return uprobe (or not). It's also convenient to share the data between session callbacks. To achive this we are adding new return value the uprobe consumer can return from 'handler' callback: UPROBE_HANDLER_IGNORE - Ignore 'ret_handler' callback for this consumer. And store cookie and pass it to 'ret_handler' when consumer has both 'handler' and 'ret_handler' callbacks defined. We store shared data in the return_consumer object array as part of the return_instance object. This way the handle_uretprobe_chain can find related return_consumer and its shared data. We also store entry handler return value, for cases when there are multiple consumers on single uprobe and some of them are ignored and some of them not, in which case the return probe gets installed and we need to have a way to find out which consumer needs to be ignored. The tricky part is when consumer is registered 'after' the uprobe entry handler is hit. In such case this consumer's 'ret_handler' gets executed as well, but it won't have the proper data pointer set, so we can filter it out. Suggested-by: Oleg Nesterov Signed-off-by: Jiri Olsa Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Oleg Nesterov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20241018202252.693462-3-jolsa@kernel.org

uprobe: Add data pointer to consumer handlers

2024-10-23T18:52:27Z

Adding data pointer to both entry and exit consumer handlers and all its users. The functionality itself is coming in following change. Signed-off-by: Jiri Olsa Signed-off-by: Peter Zijlstra (Intel) Acked-by: Oleg Nesterov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20241018202252.693462-2-jolsa@kernel.org

perf/uprobe: split uprobe_unregister()

2024-09-05T14:56:14Z

With uprobe_unregister() having grown a synchronize_srcu(), it becomes fairly slow to call. Esp. since both users of this API call it in a loop. Peel off the sync_srcu() and do it once, after the loop. We also need to add uprobe_unregister_sync() into uprobe_register()'s error handling path, as we need to be careful about returning to the caller before we have a guarantee that partially attached consumer won't be called anymore. This is an unlikely slow path and this should be totally fine to be slow in the case of a failed attach. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: "Peter Zijlstra (Intel)" Co-developed-by: Andrii Nakryiko Signed-off-by: Andrii Nakryiko Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Oleg Nesterov Link: https://lore.kernel.org/r/20240903174603.3554182-6-andrii@kernel.org