From 41bc46c12a8053a1b3279a379bd6b5e87b045b85 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Thu, 7 Sep 2023 22:06:51 +0200 Subject: bpf: Add override check to kprobe multi link attach Currently the multi_kprobe link attach does not check error injection list for programs with bpf_override_return helper and allows them to attach anywhere. Adding the missing check. Fixes: 0dcac2725406 ("bpf: Add multi kprobe link") Signed-off-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Reviewed-by: Alan Maguire Cc: stable@vger.kernel.org Link: https://lore.kernel.org/bpf/20230907200652.926951-1-jolsa@kernel.org --- kernel/trace/bpf_trace.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'kernel/trace') diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index a7264b2c17ad..c1c1af63ced2 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -2853,6 +2853,17 @@ static int get_modules_for_addrs(struct module ***mods, unsigned long *addrs, u3 return arr.mods_cnt; } +static int addrs_check_error_injection_list(unsigned long *addrs, u32 cnt) +{ + u32 i; + + for (i = 0; i < cnt; i++) { + if (!within_error_injection_list(addrs[i])) + return -EINVAL; + } + return 0; +} + int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) { struct bpf_kprobe_multi_link *link = NULL; @@ -2930,6 +2941,11 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr goto error; } + if (prog->kprobe_override && addrs_check_error_injection_list(addrs, cnt)) { + err = -EINVAL; + goto error; + } + link = kzalloc(sizeof(*link), GFP_KERNEL); if (!link) { err = -ENOMEM; -- cgit v1.2.3 From 57eb5e1c5c57972c95e8efab6bc81b87161b0b07 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Fri, 15 Sep 2023 12:14:20 +0200 Subject: bpf: Fix uprobe_multi get_pid_task error path Dan reported Smatch static checker warning due to missing error value set in uprobe multi link's get_pid_task error path. Reported-by: Dan Carpenter Closes: https://lore.kernel.org/bpf/c5ffa7c0-6b06-40d5-aca2-63833b5cd9af@moroto.mountain/ Signed-off-by: Jiri Olsa Reviewed-by: Song Liu Link: https://lore.kernel.org/r/20230915101420.1193800-1-jolsa@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/trace/bpf_trace.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel/trace') diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index c1c1af63ced2..868008f56fec 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -3223,8 +3223,10 @@ int bpf_uprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr rcu_read_lock(); task = get_pid_task(find_vpid(pid), PIDTYPE_PID); rcu_read_unlock(); - if (!task) + if (!task) { + err = -ESRCH; goto error_path_put; + } } err = -ENOMEM; -- cgit v1.2.3 From 45d99ea451d0c30bfd4864f0fe485d7dac014902 Mon Sep 17 00:00:00 2001 From: Zheng Yejian Date: Thu, 21 Sep 2023 20:54:25 +0800 Subject: ring-buffer: Fix bytes info in per_cpu buffer stats The 'bytes' info in file 'per_cpu/cpu/stats' means the number of bytes in cpu buffer that have not been consumed. However, currently after consuming data by reading file 'trace_pipe', the 'bytes' info was not changed as expected. # cat per_cpu/cpu0/stats entries: 0 overrun: 0 commit overrun: 0 bytes: 568 <--- 'bytes' is problematical !!! oldest event ts: 8651.371479 now ts: 8653.912224 dropped events: 0 read events: 8 The root cause is incorrect stat on cpu_buffer->read_bytes. To fix it: 1. When stat 'read_bytes', account consumed event in rb_advance_reader(); 2. When stat 'entries_bytes', exclude the discarded padding event which is smaller than minimum size because it is invisible to reader. Then use rb_page_commit() instead of BUF_PAGE_SIZE at where accounting for page-based read/remove/overrun. Also correct the comments of ring_buffer_bytes_cpu() in this patch. Link: https://lore.kernel.org/linux-trace-kernel/20230921125425.1708423-1-zhengyejian1@huawei.com Cc: stable@vger.kernel.org Fixes: c64e148a3be3 ("trace: Add ring buffer stats to measure rate of events") Signed-off-by: Zheng Yejian Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ring_buffer.c | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index a1651edc48d5..28daf0ce95c5 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -354,6 +354,11 @@ static void rb_init_page(struct buffer_data_page *bpage) local_set(&bpage->commit, 0); } +static __always_inline unsigned int rb_page_commit(struct buffer_page *bpage) +{ + return local_read(&bpage->page->commit); +} + static void free_buffer_page(struct buffer_page *bpage) { free_page((unsigned long)bpage->page); @@ -2003,7 +2008,7 @@ rb_remove_pages(struct ring_buffer_per_cpu *cpu_buffer, unsigned long nr_pages) * Increment overrun to account for the lost events. */ local_add(page_entries, &cpu_buffer->overrun); - local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes); + local_sub(rb_page_commit(to_remove_page), &cpu_buffer->entries_bytes); local_inc(&cpu_buffer->pages_lost); } @@ -2367,11 +2372,6 @@ rb_reader_event(struct ring_buffer_per_cpu *cpu_buffer) cpu_buffer->reader_page->read); } -static __always_inline unsigned rb_page_commit(struct buffer_page *bpage) -{ - return local_read(&bpage->page->commit); -} - static struct ring_buffer_event * rb_iter_head_event(struct ring_buffer_iter *iter) { @@ -2517,7 +2517,7 @@ rb_handle_head_page(struct ring_buffer_per_cpu *cpu_buffer, * the counters. */ local_add(entries, &cpu_buffer->overrun); - local_sub(BUF_PAGE_SIZE, &cpu_buffer->entries_bytes); + local_sub(rb_page_commit(next_page), &cpu_buffer->entries_bytes); local_inc(&cpu_buffer->pages_lost); /* @@ -2660,9 +2660,6 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, event = __rb_page_index(tail_page, tail); - /* account for padding bytes */ - local_add(BUF_PAGE_SIZE - tail, &cpu_buffer->entries_bytes); - /* * Save the original length to the meta data. * This will be used by the reader to add lost event @@ -2676,7 +2673,8 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, * write counter enough to allow another writer to slip * in on this page. * We put in a discarded commit instead, to make sure - * that this space is not used again. + * that this space is not used again, and this space will + * not be accounted into 'entries_bytes'. * * If we are less than the minimum size, we don't need to * worry about it. @@ -2701,6 +2699,9 @@ rb_reset_tail(struct ring_buffer_per_cpu *cpu_buffer, /* time delta must be non zero */ event->time_delta = 1; + /* account for padding bytes */ + local_add(BUF_PAGE_SIZE - tail, &cpu_buffer->entries_bytes); + /* Make sure the padding is visible before the tail_page->write update */ smp_wmb(); @@ -4215,7 +4216,7 @@ u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu) EXPORT_SYMBOL_GPL(ring_buffer_oldest_event_ts); /** - * ring_buffer_bytes_cpu - get the number of bytes consumed in a cpu buffer + * ring_buffer_bytes_cpu - get the number of bytes unconsumed in a cpu buffer * @buffer: The ring buffer * @cpu: The per CPU buffer to read from. */ @@ -4723,6 +4724,7 @@ static void rb_advance_reader(struct ring_buffer_per_cpu *cpu_buffer) length = rb_event_length(event); cpu_buffer->reader_page->read += length; + cpu_buffer->read_bytes += length; } static void rb_advance_iter(struct ring_buffer_iter *iter) @@ -5816,7 +5818,7 @@ int ring_buffer_read_page(struct trace_buffer *buffer, } else { /* update the entry counter */ cpu_buffer->read += rb_page_entries(reader); - cpu_buffer->read_bytes += BUF_PAGE_SIZE; + cpu_buffer->read_bytes += rb_page_commit(reader); /* swap the pages */ rb_init_page(bpage); -- cgit v1.2.3 From 1e0cb399c7653462d9dadf8ab9425337c355d358 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Google)" Date: Fri, 29 Sep 2023 18:01:13 -0400 Subject: ring-buffer: Update "shortest_full" in polling It was discovered that the ring buffer polling was incorrectly stating that read would not block, but that's because polling did not take into account that reads will block if the "buffer-percent" was set. Instead, the ring buffer polling would say reads would not block if there was any data in the ring buffer. This was incorrect behavior from a user space point of view. This was fixed by commit 42fb0a1e84ff by having the polling code check if the ring buffer had more data than what the user specified "buffer percent" had. The problem now is that the polling code did not register itself to the writer that it wanted to wait for a specific "full" value of the ring buffer. The result was that the writer would wake the polling waiter whenever there was a new event. The polling waiter would then wake up, see that there's not enough data in the ring buffer to notify user space and then go back to sleep. The next event would wake it up again. Before the polling fix was added, the code would wake up around 100 times for a hackbench 30 benchmark. After the "fix", due to the constant waking of the writer, it would wake up over 11,0000 times! It would never leave the kernel, so the user space behavior was still "correct", but this definitely is not the desired effect. To fix this, have the polling code add what it's waiting for to the "shortest_full" variable, to tell the writer not to wake it up if the buffer is not as full as it expects to be. Note, after this fix, it appears that the waiter is now woken up around 2x the times it was before (~200). This is a tremendous improvement from the 11,000 times, but I will need to spend some time to see why polling is more aggressive in its wakeups than the read blocking code. Link: https://lore.kernel.org/linux-trace-kernel/20230929180113.01c2cae3@rorschach.local.home Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Fixes: 42fb0a1e84ff ("tracing/ring-buffer: Have polling block on watermark") Reported-by: Julia Lawall Tested-by: Julia Lawall Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ring_buffer.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel/trace') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 28daf0ce95c5..515cafdb18d9 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1137,6 +1137,9 @@ __poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu, if (full) { poll_wait(filp, &work->full_waiters, poll_table); work->full_waiters_pending = true; + if (!cpu_buffer->shortest_full || + cpu_buffer->shortest_full > full) + cpu_buffer->shortest_full = full; } else { poll_wait(filp, &work->waiters, poll_table); work->waiters_pending = true; -- cgit v1.2.3 From 23cce5f25491968b23fb9c399bbfb25f13870cd9 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Cl=C3=A9ment=20L=C3=A9ger?= Date: Fri, 29 Sep 2023 21:16:37 +0200 Subject: tracing: relax trace_event_eval_update() execution with cond_resched() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When kernel is compiled without preemption, the eval_map_work_func() (which calls trace_event_eval_update()) will not be preempted up to its complete execution. This can actually cause a problem since if another CPU call stop_machine(), the call will have to wait for the eval_map_work_func() function to finish executing in the workqueue before being able to be scheduled. This problem was observe on a SMP system at boot time, when the CPU calling the initcalls executed clocksource_done_booting() which in the end calls stop_machine(). We observed a 1 second delay because one CPU was executing eval_map_work_func() and was not preempted by the stop_machine() task. Adding a call to cond_resched() in trace_event_eval_update() allows other tasks to be executed and thus continue working asynchronously like before without blocking any pending task at boot time. Link: https://lore.kernel.org/linux-trace-kernel/20230929191637.416931-1-cleger@rivosinc.com Cc: Masami Hiramatsu Signed-off-by: Clément Léger Tested-by: Atish Patra Reviewed-by: Atish Patra Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/trace') diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 91951d038ba4..f49d6ddb6342 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -2770,6 +2770,7 @@ void trace_event_eval_update(struct trace_eval_map **map, int len) update_event_fields(call, map[i]); } } + cond_resched(); } up_write(&trace_event_sem); } -- cgit v1.2.3 From 2de9ee94054263940122aee8720e902b30c27930 Mon Sep 17 00:00:00 2001 From: Beau Belgrave Date: Mon, 25 Sep 2023 23:08:28 +0000 Subject: tracing/user_events: Align set_bit() address for all archs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit All architectures should use a long aligned address passed to set_bit(). User processes can pass either a 32-bit or 64-bit sized value to be updated when tracing is enabled when on a 64-bit kernel. Both cases are ensured to be naturally aligned, however, that is not enough. The address must be long aligned without affecting checks on the value within the user process which require different adjustments for the bit for little and big endian CPUs. Add a compat flag to user_event_enabler that indicates when a 32-bit value is being used on a 64-bit kernel. Long align addresses and correct the bit to be used by set_bit() to account for this alignment. Ensure compat flags are copied during forks and used during deletion clears. Link: https://lore.kernel.org/linux-trace-kernel/20230925230829.341-2-beaub@linux.microsoft.com Link: https://lore.kernel.org/linux-trace-kernel/20230914131102.179100-1-cleger@rivosinc.com/ Cc: stable@vger.kernel.org Fixes: 7235759084a4 ("tracing/user_events: Use remote writes for event enablement") Reported-by: Clément Léger Suggested-by: Clément Léger Signed-off-by: Beau Belgrave Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_user.c | 58 +++++++++++++++++++++++++++++++++++----- 1 file changed, 51 insertions(+), 7 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index 6f046650e527..b87f41187c6a 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -127,8 +127,13 @@ struct user_event_enabler { /* Bit 7 is for freeing status of enablement */ #define ENABLE_VAL_FREEING_BIT 7 -/* Only duplicate the bit value */ -#define ENABLE_VAL_DUP_MASK ENABLE_VAL_BIT_MASK +/* Bit 8 is for marking 32-bit on 64-bit */ +#define ENABLE_VAL_32_ON_64_BIT 8 + +#define ENABLE_VAL_COMPAT_MASK (1 << ENABLE_VAL_32_ON_64_BIT) + +/* Only duplicate the bit and compat values */ +#define ENABLE_VAL_DUP_MASK (ENABLE_VAL_BIT_MASK | ENABLE_VAL_COMPAT_MASK) #define ENABLE_BITOPS(e) (&(e)->values) @@ -174,6 +179,30 @@ struct user_event_validator { int flags; }; +static inline void align_addr_bit(unsigned long *addr, int *bit, + unsigned long *flags) +{ + if (IS_ALIGNED(*addr, sizeof(long))) { +#ifdef __BIG_ENDIAN + /* 32 bit on BE 64 bit requires a 32 bit offset when aligned. */ + if (test_bit(ENABLE_VAL_32_ON_64_BIT, flags)) + *bit += 32; +#endif + return; + } + + *addr = ALIGN_DOWN(*addr, sizeof(long)); + + /* + * We only support 32 and 64 bit values. The only time we need + * to align is a 32 bit value on a 64 bit kernel, which on LE + * is always 32 bits, and on BE requires no change when unaligned. + */ +#ifdef __LITTLE_ENDIAN + *bit += 32; +#endif +} + typedef void (*user_event_func_t) (struct user_event *user, struct iov_iter *i, void *tpdata, bool *faulted); @@ -482,6 +511,7 @@ static int user_event_enabler_write(struct user_event_mm *mm, unsigned long *ptr; struct page *page; void *kaddr; + int bit = ENABLE_BIT(enabler); int ret; lockdep_assert_held(&event_mutex); @@ -497,6 +527,8 @@ static int user_event_enabler_write(struct user_event_mm *mm, test_bit(ENABLE_VAL_FREEING_BIT, ENABLE_BITOPS(enabler)))) return -EBUSY; + align_addr_bit(&uaddr, &bit, ENABLE_BITOPS(enabler)); + ret = pin_user_pages_remote(mm->mm, uaddr, 1, FOLL_WRITE | FOLL_NOFAULT, &page, NULL); @@ -515,9 +547,9 @@ static int user_event_enabler_write(struct user_event_mm *mm, /* Update bit atomically, user tracers must be atomic as well */ if (enabler->event && enabler->event->status) - set_bit(ENABLE_BIT(enabler), ptr); + set_bit(bit, ptr); else - clear_bit(ENABLE_BIT(enabler), ptr); + clear_bit(bit, ptr); kunmap_local(kaddr); unpin_user_pages_dirty_lock(&page, 1, true); @@ -849,6 +881,12 @@ static struct user_event_enabler enabler->event = user; enabler->addr = uaddr; enabler->values = reg->enable_bit; + +#if BITS_PER_LONG >= 64 + if (reg->enable_size == 4) + set_bit(ENABLE_VAL_32_ON_64_BIT, ENABLE_BITOPS(enabler)); +#endif + retry: /* Prevents state changes from racing with new enablers */ mutex_lock(&event_mutex); @@ -2377,7 +2415,8 @@ static long user_unreg_get(struct user_unreg __user *ureg, } static int user_event_mm_clear_bit(struct user_event_mm *user_mm, - unsigned long uaddr, unsigned char bit) + unsigned long uaddr, unsigned char bit, + unsigned long flags) { struct user_event_enabler enabler; int result; @@ -2385,7 +2424,7 @@ static int user_event_mm_clear_bit(struct user_event_mm *user_mm, memset(&enabler, 0, sizeof(enabler)); enabler.addr = uaddr; - enabler.values = bit; + enabler.values = bit | flags; retry: /* Prevents state changes from racing with new enablers */ mutex_lock(&event_mutex); @@ -2415,6 +2454,7 @@ static long user_events_ioctl_unreg(unsigned long uarg) struct user_event_mm *mm = current->user_event_mm; struct user_event_enabler *enabler, *next; struct user_unreg reg; + unsigned long flags; long ret; ret = user_unreg_get(ureg, ®); @@ -2425,6 +2465,7 @@ static long user_events_ioctl_unreg(unsigned long uarg) if (!mm) return -ENOENT; + flags = 0; ret = -ENOENT; /* @@ -2441,6 +2482,9 @@ static long user_events_ioctl_unreg(unsigned long uarg) ENABLE_BIT(enabler) == reg.disable_bit) { set_bit(ENABLE_VAL_FREEING_BIT, ENABLE_BITOPS(enabler)); + /* We must keep compat flags for the clear */ + flags |= enabler->values & ENABLE_VAL_COMPAT_MASK; + if (!test_bit(ENABLE_VAL_FAULTING_BIT, ENABLE_BITOPS(enabler))) user_event_enabler_destroy(enabler, true); @@ -2454,7 +2498,7 @@ static long user_events_ioctl_unreg(unsigned long uarg) /* Ensure bit is now cleared for user, regardless of event status */ if (!ret) ret = user_event_mm_clear_bit(mm, reg.disable_addr, - reg.disable_bit); + reg.disable_bit, flags); return ret; } -- cgit v1.2.3