user/sven/linux.git/kernel/events, branch v6.10.14

uprobes: fix kernel info leak via "[uprobes]" vma

2024-10-10T10:01:09Z

commit 34820304cc2cd1804ee1f8f3504ec77813d29c8e upstream. xol_add_vma() maps the uninitialized page allocated by __create_xol_area() into userspace. On some architectures (x86) this memory is readable even without VM_READ, VM_EXEC results in the same pgprot_t as VM_EXEC|VM_READ, although this doesn't really matter, debugger can read this memory anyway. Link: https://lore.kernel.org/all/20240929162047.GA12611@redhat.com/ Reported-by: Will Deacon Fixes: d4b3b6384f98 ("uprobes/core: Allocate XOL slots for uprobes use") Cc: stable@vger.kernel.org Acked-by: Masami Hiramatsu (Google) Signed-off-by: Oleg Nesterov Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Sasha Levin

perf/core: Fix small negative period being ignored

2024-10-10T10:00:48Z

commit 62c0b1061593d7012292f781f11145b2d46f43ab upstream. In perf_adjust_period, we will first calculate period, and then use this period to calculate delta. However, when delta is less than 0, there will be a deviation compared to when delta is greater than or equal to 0. For example, when delta is in the range of [-14,-1], the range of delta = delta + 7 is between [-7,6], so the final value of delta/8 is 0. Therefore, the impact of -1 and -2 will be ignored. This is unacceptable when the target period is very short, because we will lose a lot of samples. Here are some tests and analyzes: before: # perf record -e cs -F 1000 ./a.out [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.022 MB perf.data (518 samples) ] # perf script ... a.out 396 257.956048: 23 cs: ffffffff81f4eeec schedul> a.out 396 257.957891: 23 cs: ffffffff81f4eeec schedul> a.out 396 257.959730: 23 cs: ffffffff81f4eeec schedul> a.out 396 257.961545: 23 cs: ffffffff81f4eeec schedul> a.out 396 257.963355: 23 cs: ffffffff81f4eeec schedul> a.out 396 257.965163: 23 cs: ffffffff81f4eeec schedul> a.out 396 257.966973: 23 cs: ffffffff81f4eeec schedul> a.out 396 257.968785: 23 cs: ffffffff81f4eeec schedul> a.out 396 257.970593: 23 cs: ffffffff81f4eeec schedul> ... after: # perf record -e cs -F 1000 ./a.out [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.058 MB perf.data (1466 samples) ] # perf script ... a.out 395 59.338813: 11 cs: ffffffff81f4eeec schedul> a.out 395 59.339707: 12 cs: ffffffff81f4eeec schedul> a.out 395 59.340682: 13 cs: ffffffff81f4eeec schedul> a.out 395 59.341751: 13 cs: ffffffff81f4eeec schedul> a.out 395 59.342799: 12 cs: ffffffff81f4eeec schedul> a.out 395 59.343765: 11 cs: ffffffff81f4eeec schedul> a.out 395 59.344651: 11 cs: ffffffff81f4eeec schedul> a.out 395 59.345539: 12 cs: ffffffff81f4eeec schedul> a.out 395 59.346502: 13 cs: ffffffff81f4eeec schedul> ... test.c int main() { for (int i = 0; i < 20000; i++) usleep(10); return 0; } # time ./a.out real 0m1.583s user 0m0.040s sys 0m0.298s The above results were tested on x86-64 qemu with KVM enabled using test.c as test program. Ideally, we should have around 1500 samples, but the previous algorithm had only about 500, whereas the modified algorithm now has about 1400. Further more, the new version shows 1 sample per 0.001s, while the previous one is 1 sample per 0.002s.This indicates that the new algorithm is more sensitive to small negative values compared to old algorithm. Fixes: bd2b5b12849a ("perf_counter: More aggressive frequency adjustment") Signed-off-by: Luo Gengkun Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Adrian Hunter Reviewed-by: Kan Liang Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20240831074316.2106159-2-luogengkun@huaweicloud.com Signed-off-by: Greg Kroah-Hartman

perf: Really fix event_function_call() locking

2024-10-10T10:00:42Z

[ Upstream commit fe826cc2654e8561b64246325e6a51b62bf2488c ] Commit 558abc7e3f89 ("perf: Fix event_function_call() locking") lost IRQ disabling by mistake. Fixes: 558abc7e3f89 ("perf: Fix event_function_call() locking") Reported-by: Pengfei Xu Reported-by: Naresh Kamboju Tested-by: Pengfei Xu Signed-off-by: Namhyung Kim Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Sasha Levin

perf: Fix event_function_call() locking

2024-10-10T10:00:36Z

[ Upstream commit 558abc7e3f895049faa46b08656be4c60dc6e9fd ] All the event_function/@func call context already uses perf_ctx_lock() except for the !ctx->is_active case. Make it all consistent. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Kan Liang Reviewed-by: Namhyung Kim Link: https://lore.kernel.org/r/20240807115550.138301094@infradead.org Signed-off-by: Sasha Levin

perf,x86: avoid missing caller address in stack traces captured in uprobe

2024-10-10T10:00:35Z

[ Upstream commit cfa7f3d2c526c224a6271cc78a4a27a0de06f4f0 ] When tracing user functions with uprobe functionality, it's common to install the probe (e.g., a BPF program) at the first instruction of the function. This is often going to be `push %rbp` instruction in function preamble, which means that within that function frame pointer hasn't been established yet. This leads to consistently missing an actual caller of the traced function, because perf_callchain_user() only records current IP (capturing traced function) and then following frame pointer chain (which would be caller's frame, containing the address of caller's caller). So when we have target_1 -> target_2 -> target_3 call chain and we are tracing an entry to target_3, captured stack trace will report target_1 -> target_3 call chain, which is wrong and confusing. This patch proposes a x86-64-specific heuristic to detect `push %rbp` (`push %ebp` on 32-bit architecture) instruction being traced. Given entire kernel implementation of user space stack trace capturing works under assumption that user space code was compiled with frame pointer register (%rbp/%ebp) preservation, it seems pretty reasonable to use this instruction as a strong indicator that this is the entry to the function. In that case, return address is still pointed to by %rsp/%esp, so we fetch it and add to stack trace before proceeding to unwind the rest using frame pointer-based logic. We also check for `endbr64` (for 64-bit modes) as another common pattern for function entry, as suggested by Josh Poimboeuf. Even if we get this wrong sometimes for uprobes attached not at the function entry, it's OK because stack trace will still be overall meaningful, just with one extra bogus entry. If we don't detect this, we end up with guaranteed to be missing caller function entry in the stack trace, which is worse overall. Signed-off-by: Andrii Nakryiko Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20240729175223.23914-1-andrii@kernel.org Signed-off-by: Sasha Levin

drivers/perf: arm_spe: Use perf_allow_kernel() for permissions

2024-10-10T10:00:20Z

[ Upstream commit 5e9629d0ae977d6f6916d7e519724804e95f0b07 ] Use perf_allow_kernel() for 'pa_enable' (physical addresses), 'pct_enable' (physical timestamps) and context IDs. This means that perf_event_paranoid is now taken into account and LSM hooks can be used, which is more consistent with other perf_event_open calls. For example PERF_SAMPLE_PHYS_ADDR uses perf_allow_kernel() rather than just perfmon_capable(). This also indirectly fixes the following error message which is misleading because perf_event_paranoid is not taken into account by perfmon_capable(): $ perf record -e arm_spe/pa_enable/ Error: Access to performance monitoring and observability operations is limited. Consider adjusting /proc/sys/kernel/perf_event_paranoid setting ... Suggested-by: Al Grant Signed-off-by: James Clark Link: https://lore.kernel.org/r/20240827145113.1224604-1-james.clark@linaro.org Link: https://lore.kernel.org/all/20240807120039.GD37996@noisy.programming.kicks-ass.net/ Signed-off-by: Will Deacon Signed-off-by: Sasha Levin

perf/aux: Fix AUX buffer serialization

2024-09-12T09:13:08Z

commit 2ab9d830262c132ab5db2f571003d80850d56b2a upstream. Ole reported that event->mmap_mutex is strictly insufficient to serialize the AUX buffer, add a per RB mutex to fully serialize it. Note that in the lock order comment the perf_event::mmap_mutex order was already wrong, that is, it nesting under mmap_lock is not new with this patch. Fixes: 45bfb2e50471 ("perf: Add AUX area to ring buffer for raw data streams") Reported-by: Ole Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman

uprobes: Use kzalloc to allocate xol area

2024-09-12T09:13:08Z

commit e240b0fde52f33670d1336697c22d90a4fe33c84 upstream. To prevent unitialized members, use kzalloc to allocate the xol area. Fixes: b059a453b1cf1 ("x86/vdso: Add mremap hook to vm_special_mapping") Signed-off-by: Sven Schnelle Signed-off-by: Peter Zijlstra (Intel) Acked-by: Oleg Nesterov Link: https://lore.kernel.org/r/20240903102313.3402529-1-svens@linux.ibm.com Signed-off-by: Greg Kroah-Hartman

perf/bpf: Don't call bpf_overflow_handler() for tracing events

2024-08-29T15:35:39Z

commit 100bff23818eb61751ed05d64a7df36ce9728a4d upstream. The regressing commit is new in 6.10. It assumed that anytime event->prog is set bpf_overflow_handler() should be invoked to execute the attached bpf program. This assumption is false for tracing events, and as a result the regressing commit broke bpftrace by invoking the bpf handler with garbage inputs on overflow. Prior to the regression the overflow handlers formed a chain (of length 0, 1, or 2) and perf_event_set_bpf_handler() (the !tracing case) added bpf_overflow_handler() to that chain, while perf_event_attach_bpf_prog() (the tracing case) did not. Both set event->prog. The chain of overflow handlers was replaced by a single overflow handler slot and a fixed call to bpf_overflow_handler() when appropriate. This modifies the condition there to check event->prog->type == BPF_PROG_TYPE_PERF_EVENT, restoring the previous behavior and fixing bpftrace. Signed-off-by: Kyle Huey Suggested-by: Andrii Nakryiko Reported-by: Joe Damato Closes: https://lore.kernel.org/lkml/ZpFfocvyF3KHaSzF@LQ3V64L9R2/ Fixes: f11f10bfa1ca ("perf/bpf: Call BPF handler directly, not through overflow machinery") Cc: stable@vger.kernel.org Tested-by: Joe Damato # bpftrace Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240813151727.28797-1-jdamato@fastly.com Signed-off-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman

bpf, events: Use prog to emit ksymbol event for main program

2024-08-03T07:01:01Z

[ Upstream commit 0be9ae5486cd9e767138c13638820d240713f5f1 ] Since commit 0108a4e9f358 ("bpf: ensure main program has an extable"), prog->aux->func[0]->kallsyms is left as uninitialized. For BPF programs with subprogs, the symbol for the main program is missing just as shown in the output of perf script below: ffffffff81284b69 qp_trie_lookup_elem+0xb9 ([kernel.kallsyms]) ffffffffc0011125 bpf_prog_a4a0eb0651e6af8b_lookup_qp_trie+0x5d (bpf...) ffffffff8127bc2b bpf_for_each_array_elem+0x7b ([kernel.kallsyms]) ffffffffc00110a1 +0x25 () ffffffff8121a89a trace_call_bpf+0xca ([kernel.kallsyms]) Fix it by always using prog instead prog->aux->func[0] to emit ksymbol event for the main program. After the fix, the output of perf script will be correct: ffffffff81284b96 qp_trie_lookup_elem+0xe6 ([kernel.kallsyms]) ffffffffc001382d bpf_prog_a4a0eb0651e6af8b_lookup_qp_trie+0x5d (bpf...) ffffffff8127bc2b bpf_for_each_array_elem+0x7b ([kernel.kallsyms]) ffffffffc0013779 bpf_prog_245c55ab25cfcf40_qp_trie_lookup+0x25 (bpf...) ffffffff8121a89a trace_call_bpf+0xca ([kernel.kallsyms]) Fixes: 0108a4e9f358 ("bpf: ensure main program has an extable") Signed-off-by: Hou Tao Signed-off-by: Daniel Borkmann Tested-by: Yonghong Song Reviewed-by: Krister Johansen Reviewed-by: Jiri Olsa Link: https://lore.kernel.org/bpf/20240714065533.1112616-1-houtao@huaweicloud.com Signed-off-by: Sasha Levin