- 13 Jul, 2023 4 commits
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Alexei Starovoitov authored
Menglong Dong says: ==================== bpf, x86: allow function arguments up to 12 for TRACING From: Menglong Dong <imagedong@tencent.com> For now, the BPF program of type BPF_PROG_TYPE_TRACING can only be used on the kernel functions whose arguments count less than or equal to 6, if not considering '> 8 bytes' struct argument. This is not friendly at all, as too many functions have arguments count more than 6. According to the current kernel version, below is a statistics of the function arguments count: argument count | function count 7 | 704 8 | 270 9 | 84 10 | 47 11 | 47 12 | 27 13 | 22 14 | 5 15 | 0 16 | 1 Therefore, let's enhance it by increasing the function arguments count allowed in arch_prepare_bpf_trampoline(), for now, only x86_64. In the 1st patch, we save/restore regs with BPF_DW size to make the code in save_regs()/restore_regs() simpler. In the 2nd patch, we make arch_prepare_bpf_trampoline() support to copy function arguments in stack for x86 arch. Therefore, the maximum arguments can be up to MAX_BPF_FUNC_ARGS for FENTRY, FEXIT and MODIFY_RETURN. Meanwhile, we clean the potential garbage value when we copy the arguments on-stack. And the 3rd patch is for the testcases of the this series. Changes since v9: - fix the failed test cases of trampoline_count and get_func_args_test in the 3rd patch Changes since v8: - change the way to test fmod_ret in the 3rd patch Changes since v7: - split the testcases, and add fentry_many_args/fexit_many_args to DENYLIST.aarch64 in 3rd patch Changes since v6: - somit nits from commit message and comment in the 1st patch - remove the inline in get_nr_regs() in the 1st patch - rename some function and various in the 1st patch Changes since v5: - adjust the commit log of the 1st patch, avoiding confusing people that bugs exist in current code - introduce get_nr_regs() to get the space that used to pass args on stack correct in the 2nd patch - add testcases to tracing_struct.c instead of fentry_test.c and fexit_test.c Changes since v4: - consider the case of the struct in arguments can't be hold by regs - add comment for some code - add testcases for MODIFY_RETURN - rebase to the latest Changes since v3: - try make the stack pointer 16-byte aligned. Not sure if I'm right :) - introduce clean_garbage() to clean the grabage when argument count is 7 - use different data type in bpf_testmod_fentry_test{7,12} - add testcase for grabage values in ctx Changes since v2: - keep MAX_BPF_FUNC_ARGS still - clean garbage value in upper bytes in the 2nd patch - move bpf_fentry_test{7,12} to bpf_testmod.c and rename them to bpf_testmod_fentry_test{7,12} meanwhile in the 3rd patch Changes since v1: - change the maximun function arguments to 14 from 12 - add testcases (Jiri Olsa) - instead EMIT4 with EMIT3_off32 for "lea" to prevent overflow ==================== Link: https://lore.kernel.org/r/20230713040738.1789742-1-imagedong@tencent.comSigned-off-by:Alexei Starovoitov <ast@kernel.org>
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Menglong Dong authored
Add fentry_many_args.c and fexit_many_args.c to test the fentry/fexit with 7/11 arguments. As this feature is not supported by arm64 yet, we disable these testcases for arm64 in DENYLIST.aarch64. We can combine them with fentry_test.c/fexit_test.c when arm64 is supported too. Correspondingly, add bpf_testmod_fentry_test7() and bpf_testmod_fentry_test11() to bpf_testmod.c Meanwhile, add bpf_modify_return_test2() to test_run.c to test the MODIFY_RETURN with 7 arguments. Add bpf_testmod_test_struct_arg_7/bpf_testmod_test_struct_arg_7 in bpf_testmod.c to test the struct in the arguments. And the testcases passed on x86_64: ./test_progs -t fexit Summary: 5/14 PASSED, 0 SKIPPED, 0 FAILED ./test_progs -t fentry Summary: 3/2 PASSED, 0 SKIPPED, 0 FAILED ./test_progs -t modify_return Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED ./test_progs -t tracing_struct Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED Signed-off-by:
Menglong Dong <imagedong@tencent.com> Acked-by:
Yonghong Song <yhs@fb.com> Link: https://lore.kernel.org/r/20230713040738.1789742-4-imagedong@tencent.comSigned-off-by:
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Menglong Dong authored
For now, the BPF program of type BPF_PROG_TYPE_TRACING can only be used on the kernel functions whose arguments count less than or equal to 6, if not considering '> 8 bytes' struct argument. This is not friendly at all, as too many functions have arguments count more than 6. According to the current kernel version, below is a statistics of the function arguments count: argument count | function count 7 | 704 8 | 270 9 | 84 10 | 47 11 | 47 12 | 27 13 | 22 14 | 5 15 | 0 16 | 1 Therefore, let's enhance it by increasing the function arguments count allowed in arch_prepare_bpf_trampoline(), for now, only x86_64. For the case that we don't need to call origin function, which means without BPF_TRAMP_F_CALL_ORIG, we need only copy the function arguments that stored in the frame of the caller to current frame. The 7th and later arguments are stored in "$rbp + 0x18", and they will be copied to the stack area following where register values are saved. For the case with BPF_TRAMP_F_CALL_ORIG, we need prepare the arguments in stack before call origin function, which means we need alloc extra "8 * (arg_count - 6)" memory in the top of the stack. Note, there should not be any data be pushed to the stack before calling the origin function. So 'rbx' value will be stored on a stack position higher than where stack arguments are stored for BPF_TRAMP_F_CALL_ORIG. According to the research of Yonghong, struct members should be all in register or all on the stack. Meanwhile, the compiler will pass the argument on regs if the remaining regs can hold the argument. Therefore, we need save the arguments in order. Otherwise, disorder of the args can happen. For example: struct foo_struct { long a; int b; }; int foo(char, char, char, char, char, struct foo_struct, char); the arg1-5,arg7 will be passed by regs, and arg6 will by stack. Therefore, we should save/restore the arguments in the same order with the declaration of foo(). And the args used as ctx in stack will be like this: reg_arg6 -- copy from regs stack_arg2 -- copy from stack stack_arg1 reg_arg5 -- copy from regs reg_arg4 reg_arg3 reg_arg2 reg_arg1 We use EMIT3_off32() or EMIT4() for "lea" and "sub". The range of the imm in "lea" and "sub" is [-128, 127] if EMIT4() is used. Therefore, we use EMIT3_off32() instead if the imm out of the range. It works well for the FENTRY/FEXIT/MODIFY_RETURN. Signed-off-by: -
Menglong Dong authored
As we already reserve 8 byte in the stack for each reg, it is ok to store/restore the regs in BPF_DW size. This will make the code in save_regs()/restore_regs() simpler. Signed-off-by:
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- 12 Jul, 2023 29 commits
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Quentin Monnet authored
After using "__fallthrough;" in a switch/case block in bpftool's btf_dumper.c [0], and then turning it into a comment [1] to prevent a merge conflict in linux-next when the keyword was changed into just "fallthrough;" [2], we can now drop the comment and use the new keyword, no underscores. Also update the other occurrence of "/* fallthrough */" in bpftool. [0] commit 9fd49684 ("bpftool: Support inline annotations when dumping the CFG of a program") [1] commit 4b7ef71a ("bpftool: Replace "__fallthrough" by a comment to address merge conflict") [2] commit f7a858bf ("tools: Rename __fallthrough to fallthrough") Signed-off-by:
Quentin Monnet <quentin@isovalent.com> Signed-off-by:
Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20230712152322.81758-1-quentin@isovalent.com
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Daniel Borkmann authored
Alexei Starovoitov says: ==================== v3->v4: - extra patch 14 from Hou to check for object leaks. - fixed the race/leak in free_by_rcu_ttrace. Extra hunk in patch 8. - added Acks and fixed typos. v2->v3: - dropped _tail optimization for free_by_rcu_ttrace - new patch 5 to refactor inc/dec of c->active - change 'draining' logic in patch 7 - add rcu_barrier in patch 12 - __llist_add-> llist_add(waiting_for_gp_ttrace) in patch 9 to fix race - David's Ack in patch 13 and explanation that migrate_disable cannot be removed just yet. v1->v2: - Fixed race condition spotted by Hou. Patch 7. v1: Introduce bpf_mem_cache_free_rcu() that is similar to kfree_rcu except the objects will go through an additional RCU tasks trace grace period before being freed into slab. Patches 1-9 - a bunch of prep work Patch 10 - a patch from Paul that exports rcu_request_urgent_qs_task(). Patch 12 - the main bpf_mem_cache_free_rcu patch. Patch 13 - use it in bpf_cpumask. bpf_local_storage, bpf_obj_drop, qp-trie will be other users eventually. With additional hack patch to htab that replaces bpf_mem_cache_free with bpf_mem_cache_free_rcu the following are benchmark results: - map_perf_test 4 8 16348 1000000 drops from 800k to 600k. Waiting for RCU GP makes objects cache cold. - bench htab-mem -a -p 8 20% drop in performance and big increase in memory. From 3 Mbyte to 50 Mbyte. As expected. - bench htab-mem -a -p 16 --use-case add_del_on_diff_cpu Same performance and better memory consumption. Before these patches this bench would OOM (with or without 'reuse after GP') Patch 8 addresses the issue. At the end the performance drop and additional memory consumption due to _rcu() were expected and came out to be within reasonable margin. Without Paul's patch 10 the memory consumption in 'bench htab-mem' is in Gbytes which wouldn't be acceptable. Patch 8 is a heuristic to address 'alloc on one cpu, free on another' issue. It works well in practice. One can probably construct an artificial benchmark to make heuristic ineffective, but we have to trade off performance, code complexity, and memory consumption. The life cycle of objects: alloc: dequeue free_llist free: enqeueu free_llist free_llist above high watermark -> free_by_rcu_ttrace free_rcu: enqueue free_by_rcu -> waiting_for_gp after RCU GP waiting_for_gp -> free_by_rcu_ttrace free_by_rcu_ttrace -> waiting_for_gp_ttrace -> slab ==================== Signed-off-by: -
Hou Tao authored
The object leak check is cheap. Do it unconditionally to spot difficult races in bpf_mem_alloc. Signed-off-by:
Hou Tao <houtao1@huawei.com> Signed-off-by:
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Alexei Starovoitov authored
Convert bpf_cpumask to bpf_mem_cache_free_rcu. Note that migrate_disable() in bpf_cpumask_release() is still necessary, since bpf_cpumask_release() is a dtor. bpf_obj_free_fields() can be converted to do migrate_disable() there in a follow up. Signed-off-by:
David Vernet <void@manifault.com> Link: https://lore.kernel.org/bpf/20230706033447.54696-14-alexei.starovoitov@gmail.com
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Alexei Starovoitov authored
Introduce bpf_mem_[cache_]free_rcu() similar to kfree_rcu(). Unlike bpf_mem_[cache_]free() that links objects for immediate reuse into per-cpu free list the _rcu() flavor waits for RCU grace period and then moves objects into free_by_rcu_ttrace list where they are waiting for RCU task trace grace period to be freed into slab. The life cycle of objects: alloc: dequeue free_llist free: enqeueu free_llist free_rcu: enqueue free_by_rcu -> waiting_for_gp free_llist above high watermark -> free_by_rcu_ttrace after RCU GP waiting_for_gp -> free_by_rcu_ttrace free_by_rcu_ttrace -> waiting_for_gp_ttrace -> slab Signed-off-by:
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Alexei Starovoitov authored
bpf_obj_new() calls bpf_mem_alloc(), but doing alloc/free of 8 elements is not triggering watermark conditions in bpf_mem_alloc. Increase to 200 elements to make sure alloc_bulk/free_bulk is exercised. Signed-off-by:
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Paul E. McKenney authored
If a CPU is executing a long series of non-sleeping system calls, RCU grace periods can be delayed for on the order of a couple hundred milliseconds. This is normally not a problem, but if each system call does a call_rcu(), those callbacks can stack up. RCU will eventually notice this callback storm, but use of rcu_request_urgent_qs_task() allows the code invoking call_rcu() to give RCU a heads up. This function is not for general use, not yet, anyway. Reported-by:
Paul E. McKenney <paulmck@kernel.org> Signed-off-by:
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Alexei Starovoitov authored
alloc_bulk() can reuse elements from free_by_rcu_ttrace. Let it reuse from waiting_for_gp_ttrace as well to avoid unnecessary kmalloc(). Signed-off-by:
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Alexei Starovoitov authored
To address OOM issue when one cpu is allocating and another cpu is freeing add a target bpf_mem_cache hint to allocated objects and when local cpu free_llist overflows free to that bpf_mem_cache. The hint addresses the OOM while maintaining the same performance for common case when alloc/free are done on the same cpu. Note that do_call_rcu_ttrace() now has to check 'draining' flag in one more case, since do_call_rcu_ttrace() is called not only for current cpu. Signed-off-by:
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Alexei Starovoitov authored
The next patch will introduce cross-cpu llist access and existing irq_work_sync() + drain_mem_cache() + rcu_barrier_tasks_trace() mechanism will not be enough, since irq_work_sync() + drain_mem_cache() on cpu A won't guarantee that llist on cpu A are empty. The free_bulk() on cpu B might add objects back to llist of cpu A. Add 'bool draining' flag. The modified sequence looks like: for_each_cpu: WRITE_ONCE(c->draining, true); // do_call_rcu_ttrace() won't be doing call_rcu() any more irq_work_sync(); // wait for irq_work callback (free_bulk) to finish drain_mem_cache(); // free all objects rcu_barrier_tasks_trace(); // wait for RCU callbacks to execute Signed-off-by:
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Alexei Starovoitov authored
In certain scenarios alloc_bulk() might be taking free objects mainly from free_by_rcu_ttrace list. In such case get_memcg() and set_active_memcg() are redundant, but they show up in perf profile. Split the loop and only set memcg when allocating from slab. No performance difference in this patch alone, but it helps in combination with further patches. Signed-off-by:
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Alexei Starovoitov authored
Factor out local_inc/dec_return(&c->active) into helpers. No functional changes. Signed-off-by:
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Alexei Starovoitov authored
Factor out inner body of alloc_bulk into separate helper. No functional changes. Signed-off-by:
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Alexei Starovoitov authored
Let free_all() helper return the number of freed elements. It's not used in this patch, but helps in debug/development of bpf_mem_alloc. For example this diff for __free_rcu(): - free_all(llist_del_all(&c->waiting_for_gp_ttrace), !!c->percpu_size); + printk("cpu %d freed %d objs after tasks trace\n", raw_smp_processor_id(), + free_all(llist_del_all(&c->waiting_for_gp_ttrace), !!c->percpu_size)); would show how busy RCU tasks trace is. In artificial benchmark where one cpu is allocating and different cpu is freeing the RCU tasks trace won't be able to keep up and the list of objects would keep growing from thousands to millions and eventually OOMing. Signed-off-by: -
Alexei Starovoitov authored
Use kmemdup() to simplify the code. Signed-off-by:
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Alexei Starovoitov authored
Rename: - struct rcu_head rcu; - struct llist_head free_by_rcu; - struct llist_head waiting_for_gp; - atomic_t call_rcu_in_progress; + struct llist_head free_by_rcu_ttrace; + struct llist_head waiting_for_gp_ttrace; + struct rcu_head rcu_ttrace; + atomic_t call_rcu_ttrace_in_progress; ... - static void do_call_rcu(struct bpf_mem_cache *c) + static void do_call_rcu_ttrace(struct bpf_mem_cache *c) to better indicate intended use. The 'tasks trace' is shortened to 'ttrace' to reduce verbosity. No functional changes. Later patches will add free_by_rcu/waiting_for_gp fields to be used with normal RCU. Signed-off-by:
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Andrii Nakryiko authored
Add a per-cpu array resizing use case and demonstrate how bpf_get_smp_processor_id() can be used to directly access proper data with no extra checks. Signed-off-by:
Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20230711232400.1658562-2-andrii@kernel.orgSigned-off-by:
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Andrii Nakryiko authored
bpf_get_smp_processor_id() helper returns current CPU on which BPF program runs. It can't return value that is bigger than maximum allowed number of CPUs (minus one, due to zero indexing). Teach BPF verifier to recognize that. This makes it possible to use bpf_get_smp_processor_id() result to index into arrays without extra checks, as demonstrated in subsequent selftests/bpf patch. Signed-off-by:
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Alexei Starovoitov authored
Yafang Shao says: ==================== This patchset enhances the usability of kprobe_multi program by introducing support for ->fill_link_info. This allows users to easily determine the probed functions associated with a kprobe_multi program. While `bpftool perf show` already provides information about functions probed by perf_event programs, supporting ->fill_link_info ensures consistent access to this information across all bpf links. In addition, this patch extends support to generic perf events, which are currently not covered by `bpftool perf show`. While userspace is exposed to only the perf type and config, other attributes such as sample_period and sample_freq are disregarded. To ensure accurate identification of probed functions, it is preferable to expose the address directly rather than relying solely on the symbol name. However, this implementation respects the kptr_restrict setting and avoids exposing the address if it is not permitted. v6->v7: - From Daniel - No need to explicitly cast in many places - Use ptr_to_u64() instead of the cast - return -ENOMEM when calloc fails - Simplify the code in bpf_get_kprobe_info() further - Squash #9 with #8 - And other coding style improvement - From Andrii - Comment improvement - Use ENOSPC instead of E2BIG - Use strlen only when buf in not NULL - Clear probe_addr in bpf_get_uprobe_info() v5->v6: - From Andrii - if ucount is too less, copy ucount items and return -E2BIG - zero out kmulti_link->cnt elements if it is not permitted by kptr - avoid leaking information when ucount is greater than kmulti_link->cnt - drop the flags, and add BPF_PERF_EVENT_[UK]RETPROBE - From Quentin - use jsonw_null instead when we have no module name - add explanation on perf_type_name in the commit log - avoid the unnecessary out lable v4->v5: - Print "func [module]" in the kprobe_multi header (Andrii) - Remove MAX_BPF_PERF_EVENT_TYPE (Alexei) - Add padding field for future reuse (Yonghong) v3->v4: - From Quentin - Rename MODULE_NAME_LEN to MODULE_MAX_NAME - Convert retprobe to boolean for json output - Trim the square brackets around module names for json output - Move perf names into link.c - Use a generic helper to get perf names - Show address before func name, for consistency - Use switch-case instead of if-else - Increase the buff len to PATH_MAX - Move macros to the top of the file - From Andrii - kprobe_multi flags should always be returned - Keep it single line if it fits in under 100 characters - Change the output format when showing kprobe_multi - Imporve the format of perf_event names - Rename struct perf_link to struct perf_event, and change the names of the enum consequently - From Yonghong - Avoid disallowing extensions for all structs in the big union - From Jiri - Add flags to bpf_kprobe_multi_link - Report kprobe_multi selftests errors - Rename bpf_perf_link_fill_name and make it a separate patch - Avoid breaking compilation when CONFIG_KPROBE_EVENTS or CONFIG_UPROBE_EVENTS options are not defined v2->v3: - Expose flags instead of retporbe (Andrii) - Simplify the check on kmulti_link->cnt (Andrii) - Use kallsyms_show_value() instead (Andrii) - Show also the module name for kprobe_multi (Andrii) - Add new enum bpf_perf_link_type (Andrii) - Move perf event names into bpftool (Andrii, Quentin, Jiri) - Keep perf event names in sync with perf tools (Jiri) v1->v2: - Fix sparse warning (Stanislav, lkp@intel.com) - Fix BPF CI build error - Reuse kernel_syms_load() (Alexei) - Print 'name' instead of 'func' (Alexei) - Show whether the probe is retprobe or not (Andrii) - Add comment for the meaning of perf_event name (Andrii) - Add support for generic perf event - Adhere to the kptr_restrict setting RFC->v1: - Use a single copy_to_user() instead (Jiri) - Show also the symbol name in bpftool (Quentin, Alexei) - Use calloc() instead of malloc() in bpftool (Quentin) - Avoid having conditional entries in the JSON output (Quentin) - Drop ->show_fdinfo (Alexei) - Use __u64 instead of __aligned_u64 for the field addr (Alexei) - Avoid the contradiction in perf_event name length (Alexei) - Address a build warning reported by kernel test robot <lkp@intel.com> ==================== Signed-off-by: -
Yafang Shao authored
Enhance bpftool to display comprehensive information about exposed perf_event links, covering uprobe, kprobe, tracepoint, and generic perf event. The resulting output will include the following details: $ tools/bpf/bpftool/bpftool link show 3: perf_event prog 14 event software:cpu-clock bpf_cookie 0 pids perf_event(19483) 4: perf_event prog 14 event hw-cache:LLC-load-misses bpf_cookie 0 pids perf_event(19483) 5: perf_event prog 14 event hardware:cpu-cycles bpf_cookie 0 pids perf_event(19483) 6: perf_event prog 19 tracepoint sched_switch bpf_cookie 0 pids tracepoint(20947) 7: perf_event prog 26 uprobe /home/dev/waken/bpf/uprobe/a.out+0x1338 bpf_cookie 0 pids uprobe(21973) 8: perf_event prog 27 uretprobe /home/dev/waken/bpf/uprobe/a.out+0x1338 bpf_cookie 0 pids uprobe(21973) 10: perf_event prog 43 kprobe ffffffffb70a9660 kernel_clone bpf_cookie 0 pids kprobe(35275) 11: perf_event prog 41 kretprobe ffffffffb70a9660 kernel_clone bpf_cookie 0 pids kprobe(35275) $ tools/bpf/bpftool/bpftool link show -j [{"id":3,"type":"perf_event","prog_id":14,"event_type":"software","event_config":"cpu-clock","bpf_cookie":0,"pids":[{"pid":19483,"comm":"perf_event"}]},{"id":4,"type":"perf_event","prog_id":14,"event_type":"hw-cache","event_config":"LLC-load-misses","bpf_cookie":0,"pids":[{"pid":19483,"comm":"perf_event"}]},{"id":5,"type":"perf_event","prog_id":14,"event_type":"hardware","event_config":"cpu-cycles","bpf_cookie":0,"pids":[{"pid":19483,"comm":"perf_event"}]},{"id":6,"type":"perf_event","prog_id":19,"tracepoint":"sched_switch","bpf_cookie":0,"pids":[{"pid":20947,"comm":"tracepoint"}]},{"id":7,"type":"perf_event","prog_id":26,"retprobe":false,"file":"/home/dev/waken/bpf/uprobe/a.out","offset":4920,"bpf_cookie":0,"pids":[{"pid":21973,"comm":"uprobe"}]},{"id":8,"type":"perf_event","prog_id":27,"retprobe":true,"file":"/home/dev/waken/bpf/uprobe/a.out","offset":4920,"bpf_cookie":0,"pids":[{"pid":21973,"comm":"uprobe"}]},{"id":10,"type":"perf_event","prog_id":43,"retprobe":false,"addr":18446744072485508704,"func":"kernel_clone","offset":0,"bpf_cookie":0,"pids":[{"pid":35275,"comm":"kprobe"}]},{"id":11,"type":"perf_event","prog_id":41,"retprobe":true,"addr":18446744072485508704,"func":"kernel_clone","offset":0,"bpf_cookie":0,"pids":[{"pid":35275,"comm":"kprobe"}]}] For generic perf events, the displayed information in bpftool is limited to the type and configuration, while other attributes such as sample_period, sample_freq, etc., are not included. The kernel function address won't be exposed if it is not permitted by kptr_restrict. The result as follows when kptr_restrict is 2. $ tools/bpf/bpftool/bpftool link show 3: perf_event prog 14 event software:cpu-clock 4: perf_event prog 14 event hw-cache:LLC-load-misses 5: perf_event prog 14 event hardware:cpu-cycles 6: perf_event prog 19 tracepoint sched_switch 7: perf_event prog 26 uprobe /home/dev/waken/bpf/uprobe/a.out+0x1338 8: perf_event prog 27 uretprobe /home/dev/waken/bpf/uprobe/a.out+0x1338 10: perf_event prog 43 kprobe kernel_clone 11: perf_event prog 41 kretprobe kernel_clone Signed-off-by:Yafang Shao <laoar.shao@gmail.com> Reviewed-by:
Jiri Olsa <jolsa@kernel.org> Link: https://lore.kernel.org/r/20230709025630.3735-11-laoar.shao@gmail.comSigned-off-by:
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Yafang Shao authored
Add new functions and macros to get perf event names. These names except the perf_type_name are all copied from tool/perf/util/{parse-events,evsel}.c, so that in the future we will have a good chance to use the same code. Suggested-by:Jiri Olsa <olsajiri@gmail.com> Signed-off-by:
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Yafang Shao authored
By introducing support for ->fill_link_info to the perf_event link, users gain the ability to inspect it using `bpftool link show`. While the current approach involves accessing this information via `bpftool perf show`, consolidating link information for all link types in one place offers greater convenience. Additionally, this patch extends support to the generic perf event, which is not currently accommodated by `bpftool perf show`. While only the perf type and config are exposed to userspace, other attributes such as sample_period and sample_freq are ignored. It's important to note that if kptr_restrict is not permitted, the probed address will not be exposed, maintaining security measures. A new enum bpf_perf_event_type is introduced to help the user understand which struct is relevant. Signed-off-by:
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Yafang Shao authored
Add a common helper bpf_copy_to_user(), which will be used at multiple places. No functional change. Signed-off-by:
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Yafang Shao authored
Since different symbols can share the same name, it is insufficient to only expose the symbol name. It is essential to also expose the symbol address so that users can accurately identify which one is being probed. Signed-off-by:
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Yafang Shao authored
To avoid returning uninitialized or random values when querying the file descriptor (fd) and accessing probe_addr, it is necessary to clear the variable prior to its use. Fixes: 41bdc4b4 ("bpf: introduce bpf subcommand BPF_TASK_FD_QUERY") Signed-off-by:
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Yafang Shao authored
The probed address can be accessed by userspace through querying the task file descriptor (fd). However, it is crucial to adhere to the kptr_restrict setting and refrain from exposing the address if it is not permitted. Signed-off-by:
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Yafang Shao authored
Show the already expose kprobe_multi link info in bpftool. The result as follows, $ tools/bpf/bpftool/bpftool link show 91: kprobe_multi prog 244 kprobe.multi func_cnt 7 addr func [module] ffffffff98c44f20 schedule_timeout_interruptible ffffffff98c44f60 schedule_timeout_killable ffffffff98c44fa0 schedule_timeout_uninterruptible ffffffff98c44fe0 schedule_timeout_idle ffffffffc075b8d0 xfs_trans_get_efd [xfs] ffffffffc0768a10 xfs_trans_get_buf_map [xfs] ffffffffc076c320 xfs_trans_get_dqtrx [xfs] pids kprobe_multi(188367) 92: kprobe_multi prog 244 kretprobe.multi func_cnt 7 addr func [module] ffffffff98c44f20 schedule_timeout_interruptible ffffffff98c44f60 schedule_timeout_killable ffffffff98c44fa0 schedule_timeout_uninterruptible ffffffff98c44fe0 schedule_timeout_idle ffffffffc075b8d0 xfs_trans_get_efd [xfs] ffffffffc0768a10 xfs_trans_get_buf_map [xfs] ffffffffc076c320 xfs_trans_get_dqtrx [xfs] pids kprobe_multi(188367) $ tools/bpf/bpftool/bpftool link show -j [{"id":91,"type":"kprobe_multi","prog_id":244,"retprobe":false,"func_cnt":7,"funcs":[{"addr":18446744071977586464,"func":"schedule_timeout_interruptible","module":null},{"addr":18446744071977586528,"func":"schedule_timeout_killable","module":null},{"addr":18446744071977586592,"func":"schedule_timeout_uninterruptible","module":null},{"addr":18446744071977586656,"func":"schedule_timeout_idle","module":null},{"addr":18446744072643524816,"func":"xfs_trans_get_efd","module":"xfs"},{"addr":18446744072643578384,"func":"xfs_trans_get_buf_map","module":"xfs"},{"addr":18446744072643592992,"func":"xfs_trans_get_dqtrx","module":"xfs"}],"pids":[{"pid":188367,"comm":"kprobe_multi"}]},{"id":92,"type":"kprobe_multi","prog_id":244,"retprobe":true,"func_cnt":7,"funcs":[{"addr":18446744071977586464,"func":"schedule_timeout_interruptible","module":null},{"addr":18446744071977586528,"func":"schedule_timeout_killable","module":null},{"addr":18446744071977586592,"func":"schedule_timeout_uninterruptible","module":null},{"addr":18446744071977586656,"func":"schedule_timeout_idle","module":null},{"addr":18446744072643524816,"func":"xfs_trans_get_efd","module":"xfs"},{"addr":18446744072643578384,"func":"xfs_trans_get_buf_map","module":"xfs"},{"addr":18446744072643592992,"func":"xfs_trans_get_dqtrx","module":"xfs"}],"pids":[{"pid":188367,"comm":"kprobe_multi"}]}] When kptr_restrict is 2, the result is, $ tools/bpf/bpftool/bpftool link show 91: kprobe_multi prog 244 kprobe.multi func_cnt 7 92: kprobe_multi prog 244 kretprobe.multi func_cnt 7 Signed-off-by: -
Yafang Shao authored
If the kernel symbol is in a module, we will dump the module name as well. The square brackets around the module name are trimmed. Signed-off-by:
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Yafang Shao authored
With the addition of support for fill_link_info to the kprobe_multi link, users will gain the ability to inspect it conveniently using the `bpftool link show`. This enhancement provides valuable information to the user, including the count of probed functions and their respective addresses. It's important to note that if the kptr_restrict setting is not permitted, the probed address will not be exposed, ensuring security. Signed-off-by:
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- 11 Jul, 2023 5 commits
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Rong Tao authored
__NR_open never exist on AArch64. Signed-off-by:
Rong Tao <rongtao@cestc.cn> Signed-off-by:
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John Sanpe authored
Remove the wrong HASHMAP_INIT. It's not used anywhere in libbpf. Signed-off-by:
John Sanpe <sanpeqf@gmail.com> Signed-off-by:
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Andrii Nakryiko authored
realloc() and reallocarray() can either return NULL or a special non-NULL pointer, if their size argument is zero. This requires a bit more care to handle NULL-as-valid-result situation differently from NULL-as-error case. This has caused real issues before ([0]), and just recently bit again in production when performing bpf_program__attach_usdt(). This patch fixes 4 places that do or potentially could suffer from this mishandling of NULL, including the reported USDT-related one. There are many other places where realloc()/reallocarray() is used and NULL is always treated as an error value, but all those have guarantees that their size is always non-zero, so those spot don't need any extra handling. [0] d08ab82f ("libbpf: Fix double-free when linker processes empty sections") Fixes: 999783c8 ("libbpf: Wire up spec management and other arch-independent USDT logic") Fixes: b63b3c49 ("libbpf: Add bpf_program__set_insns function") Fixes: 697f104d ("libbpf: Support custom SEC() handlers") Fixes: b1268826 ("libbpf: Change the order of data and text relocations.") Signed-off-by:
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David Vernet authored
The BPF standardization effort is actively underway with the IETF. As described in the BPF Working Group (WG) charter in [0], there are a number of proposed documents, some informational and some proposed standards, that will be drafted as part of the standardization effort. [0]: https://datatracker.ietf.org/wg/bpf/about/ Though the specific documents that will formally be standardized will exist as Internet Drafts (I-D) and WG documents in the BPF WG datatracker page, the source of truth from where those documents will be generated will reside in the kernel documentation tree (originating in the bpf-next tree). Because these documents will be used to generate the I-D and WG documents which will be standardized with the IETF, they are a bit special as far as kernel-tree documentation goes: - They will be dual licensed with LGPL-2.1 OR BSD-2-Clause - IETF I-D and WG documents (the documents which will actually be standardized) will be auto-generated from these documents. In order to keep things clearly organized in the BPF documentation tree, and to make it abundantly clear where standards-related documentation needs to go, we should move standards-relevant documents into a separate standardization/ subdirectory. Signed-off-by:
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Andrii Nakryiko authored
Quentin Monnet says: ==================== At runtime, bpftool may run its own BPF programs to get the pids of processes referencing BPF programs, or to profile programs. The skeletons for these programs rely on a vmlinux.h header and may fail to compile when building bpftool on hosts running older kernels, where some structs or enums are not defined. In this set, we address this issue by using local definitions for struct perf_event, struct bpf_perf_link, BPF_LINK_TYPE_PERF_EVENT (pids.bpf.c) and struct bpf_perf_event_value (profiler.bpf.c). This set contains patches 1 to 3 from Alexander Lobakin's series, "bpf: random unpopular userspace fixes (32 bit et al)" (v2) [0], from April 2022. An additional patch defines a local version of BPF_LINK_TYPE_PERF_EVENT in bpftool's pids.bpf.c. [0] https://lore.kernel.org/bpf/20220421003152.339542-1-alobakin@pm.me/ v2: Fixed description (CO-RE for container_of()) in patch 2. Cc: Alexander Lobakin <aleksander.lobakin@intel.com> Cc: Michal Suchánek <msuchanek@suse.de> Alexander Lobakin (3): bpftool: use a local copy of perf_event to fix accessing ::bpf_cookie bpftool: define a local bpf_perf_link to fix accessing its fields bpftool: use a local bpf_perf_event_value to fix accessing its fields ==================== Signed-off-by:
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- 10 Jul, 2023 2 commits
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Alexander Lobakin authored
Fix the following error when building bpftool: CLANG profiler.bpf.o CLANG pid_iter.bpf.o skeleton/profiler.bpf.c:18:21: error: invalid application of 'sizeof' to an incomplete type 'struct bpf_perf_event_value' __uint(value_size, sizeof(struct bpf_perf_event_value)); ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ tools/bpf/bpftool/bootstrap/libbpf/include/bpf/bpf_helpers.h:13:39: note: expanded from macro '__uint' tools/bpf/bpftool/bootstrap/libbpf/include/bpf/bpf_helper_defs.h:7:8: note: forward declaration of 'struct bpf_perf_event_value' struct bpf_perf_event_value; ^ struct bpf_perf_event_value is being used in the kernel only when CONFIG_BPF_EVENTS is enabled, so it misses a BTF entry then. Define struct bpf_perf_event_value___local with the `preserve_access_index` attribute inside the pid_iter BPF prog to allow compiling on any configs. It is a full mirror of a UAPI structure, so is compatible both with and w/o CO-RE. bpf_perf_event_read_value() requires a pointer of the original type, so a cast is needed. Fixes: 47c09d6a ("bpftool: Introduce "prog profile" command") Suggested-by:Alexander Lobakin <alobakin@pm.me> Signed-off-by:
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Quentin Monnet authored
In order to allow the BPF program in bpftool's pid_iter.bpf.c to compile correctly on hosts where vmlinux.h does not define BPF_LINK_TYPE_PERF_EVENT (running kernel versions lower than 5.15, for example), define and use a local copy of the enum value. This requires LLVM 12 or newer to build the BPF program. Fixes: cbdaf71f ("bpftool: Add bpf_cookie to link output") Signed-off-by:
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