From c8c9b1d2d5b4377c72a979f5a26e842a869aefc9 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Sat, 8 Feb 2025 00:15:11 -0500 Subject: fgraph: Fix set_graph_notrace with setting TRACE_GRAPH_NOTRACE_BIT The code was restructured where the function graph notrace code, that would not trace a function and all its children is done by setting a NOTRACE flag when the function that is not to be traced is hit. There's a TRACE_GRAPH_NOTRACE_BIT which defines the bit in the flags and a TRACE_GRAPH_NOTRACE which is the mask with that bit set. But the restructuring used TRACE_GRAPH_NOTRACE_BIT when it should have used TRACE_GRAPH_NOTRACE. For example: # cd /sys/kernel/tracing # echo set_track_prepare stack_trace_save > set_graph_notrace # echo function_graph > current_tracer # cat trace [..] 0) | __slab_free() { 0) | free_to_partial_list() { 0) | arch_stack_walk() { 0) | __unwind_start() { 0) 0.501 us | get_stack_info(); Where a non filter trace looks like: # echo > set_graph_notrace # cat trace 0) | free_to_partial_list() { 0) | set_track_prepare() { 0) | stack_trace_save() { 0) | arch_stack_walk() { 0) | __unwind_start() { Where the filter should look like: # cat trace 0) | free_to_partial_list() { 0) | _raw_spin_lock_irqsave() { 0) 0.350 us | preempt_count_add(); 0) 0.351 us | do_raw_spin_lock(); 0) 2.440 us | } Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mark Rutland Cc: Mathieu Desnoyers Link: https://lore.kernel.org/20250208001511.535be150@batman.local.home Fixes: b84214890a9bc ("function_graph: Move graph notrace bit to shadow stack global var") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_functions_graph.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/trace') diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index 54d850997c0a..136c750b0b4d 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -198,7 +198,7 @@ int trace_graph_entry(struct ftrace_graph_ent *trace, * returning from the function. */ if (ftrace_graph_notrace_addr(trace->func)) { - *task_var |= TRACE_GRAPH_NOTRACE_BIT; + *task_var |= TRACE_GRAPH_NOTRACE; /* * Need to return 1 to have the return called * that will clear the NOTRACE bit. -- cgit v1.2.3 From 9ba0e1755a40f9920ad0f4168031291b3eb58d7b Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 13 Feb 2025 13:19:57 -0500 Subject: ring-buffer: Unlock resize on mmap error Memory mapping the tracing ring buffer will disable resizing the buffer. But if there's an error in the memory mapping like an invalid parameter, the function exits out without re-enabling the resizing of the ring buffer, preventing the ring buffer from being resized after that. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Vincent Donnefort Link: https://lore.kernel.org/20250213131957.530ec3c5@gandalf.local.home Fixes: 117c39200d9d7 ("ring-buffer: Introducing ring-buffer mapping functions") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ring_buffer.c | 1 + 1 file changed, 1 insertion(+) (limited to 'kernel/trace') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index b8e0ae15ca5b..07b421115692 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -7126,6 +7126,7 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu, kfree(cpu_buffer->subbuf_ids); cpu_buffer->subbuf_ids = NULL; rb_free_meta_page(cpu_buffer); + atomic_dec(&cpu_buffer->resize_disabled); } unlock: -- cgit v1.2.3 From 60b8f711143de7cd9c0f55be0fe7eb94b19eb5c7 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 13 Feb 2025 13:41:32 -0500 Subject: tracing: Have the error of __tracing_resize_ring_buffer() passed to user Currently if __tracing_resize_ring_buffer() returns an error, the tracing_resize_ringbuffer() returns -ENOMEM. But it may not be a memory issue that caused the function to fail. If the ring buffer is memory mapped, then the resizing of the ring buffer will be disabled. But if the user tries to resize the buffer, it will get an -ENOMEM returned, which is confusing because there is plenty of memory. The actual error returned was -EBUSY, which would make much more sense to the user. Cc: stable@vger.kernel.org Cc: Mathieu Desnoyers Cc: Vincent Donnefort Link: https://lore.kernel.org/20250213134132.7e4505d7@gandalf.local.home Fixes: 117c39200d9d7 ("ring-buffer: Introducing ring-buffer mapping functions") Signed-off-by: Steven Rostedt (Google) Reviewed-by: Masami Hiramatsu (Google) --- kernel/trace/trace.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 1496a5ac33ae..25ff37aab00f 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -5977,8 +5977,6 @@ static int __tracing_resize_ring_buffer(struct trace_array *tr, ssize_t tracing_resize_ring_buffer(struct trace_array *tr, unsigned long size, int cpu_id) { - int ret; - guard(mutex)(&trace_types_lock); if (cpu_id != RING_BUFFER_ALL_CPUS) { @@ -5987,11 +5985,7 @@ ssize_t tracing_resize_ring_buffer(struct trace_array *tr, return -EINVAL; } - ret = __tracing_resize_ring_buffer(tr, size, cpu_id); - if (ret < 0) - ret = -ENOMEM; - - return ret; + return __tracing_resize_ring_buffer(tr, size, cpu_id); } static void update_last_data(struct trace_array *tr) -- cgit v1.2.3 From f5b95f1fa2ef3a03f49eeec658ba97e721412b32 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 14 Feb 2025 10:28:20 -0500 Subject: ring-buffer: Validate the persistent meta data subbuf array The meta data for a mapped ring buffer contains an array of indexes of all the subbuffers. The first entry is the reader page, and the rest of the entries lay out the order of the subbuffers in how the ring buffer link list is to be created. The validator currently makes sure that all the entries are within the range of 0 and nr_subbufs. But it does not check if there are any duplicates. While working on the ring buffer, I corrupted this array, where I added duplicates. The validator did not catch it and created the ring buffer link list on top of it. Luckily, the corruption was only that the reader page was also in the writer path and only presented corrupted data but did not crash the kernel. But if there were duplicates in the writer side, then it could corrupt the ring buffer link list and cause a crash. Create a bitmask array with the size of the number of subbuffers. Then clear it. When walking through the subbuf array checking to see if the entries are within the range, test if its bit is already set in the subbuf_mask. If it is, then there is duplicates and fail the validation. If not, set the corresponding bit and continue. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Vincent Donnefort Link: https://lore.kernel.org/20250214102820.7509ddea@gandalf.local.home Fixes: c76883f18e59b ("ring-buffer: Add test if range of boot buffer is valid") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ring_buffer.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 07b421115692..0419d41a2060 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1672,7 +1672,8 @@ static void *rb_range_buffer(struct ring_buffer_per_cpu *cpu_buffer, int idx) * must be the same. */ static bool rb_meta_valid(struct ring_buffer_meta *meta, int cpu, - struct trace_buffer *buffer, int nr_pages) + struct trace_buffer *buffer, int nr_pages, + unsigned long *subbuf_mask) { int subbuf_size = PAGE_SIZE; struct buffer_data_page *subbuf; @@ -1680,6 +1681,9 @@ static bool rb_meta_valid(struct ring_buffer_meta *meta, int cpu, unsigned long buffers_end; int i; + if (!subbuf_mask) + return false; + /* Check the meta magic and meta struct size */ if (meta->magic != RING_BUFFER_META_MAGIC || meta->struct_size != sizeof(*meta)) { @@ -1712,6 +1716,8 @@ static bool rb_meta_valid(struct ring_buffer_meta *meta, int cpu, subbuf = rb_subbufs_from_meta(meta); + bitmap_clear(subbuf_mask, 0, meta->nr_subbufs); + /* Is the meta buffers and the subbufs themselves have correct data? */ for (i = 0; i < meta->nr_subbufs; i++) { if (meta->buffers[i] < 0 || @@ -1725,6 +1731,12 @@ static bool rb_meta_valid(struct ring_buffer_meta *meta, int cpu, return false; } + if (test_bit(meta->buffers[i], subbuf_mask)) { + pr_info("Ring buffer boot meta [%d] array has duplicates\n", cpu); + return false; + } + + set_bit(meta->buffers[i], subbuf_mask); subbuf = (void *)subbuf + subbuf_size; } @@ -1889,17 +1901,22 @@ static void rb_meta_init_text_addr(struct ring_buffer_meta *meta) static void rb_range_meta_init(struct trace_buffer *buffer, int nr_pages) { struct ring_buffer_meta *meta; + unsigned long *subbuf_mask; unsigned long delta; void *subbuf; int cpu; int i; + /* Create a mask to test the subbuf array */ + subbuf_mask = bitmap_alloc(nr_pages + 1, GFP_KERNEL); + /* If subbuf_mask fails to allocate, then rb_meta_valid() will return false */ + for (cpu = 0; cpu < nr_cpu_ids; cpu++) { void *next_meta; meta = rb_range_meta(buffer, nr_pages, cpu); - if (rb_meta_valid(meta, cpu, buffer, nr_pages)) { + if (rb_meta_valid(meta, cpu, buffer, nr_pages, subbuf_mask)) { /* Make the mappings match the current address */ subbuf = rb_subbufs_from_meta(meta); delta = (unsigned long)subbuf - meta->first_buffer; @@ -1943,6 +1960,7 @@ static void rb_range_meta_init(struct trace_buffer *buffer, int nr_pages) subbuf += meta->subbuf_size; } } + bitmap_free(subbuf_mask); } static void *rbm_start(struct seq_file *m, loff_t *pos) -- cgit v1.2.3 From 129fe718819cc5e24ea2f489db9ccd4371f0c6f6 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 14 Feb 2025 11:55:47 -0500 Subject: tracing: Do not allow mmap() of persistent ring buffer When trying to mmap a trace instance buffer that is attached to reserve_mem, it would crash: BUG: unable to handle page fault for address: ffffe97bd00025c8 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 2862f3067 P4D 2862f3067 PUD 0 Oops: Oops: 0000 [#1] PREEMPT_RT SMP PTI CPU: 4 UID: 0 PID: 981 Comm: mmap-rb Not tainted 6.14.0-rc2-test-00003-g7f1a5e3fbf9e-dirty #233 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:validate_page_before_insert+0x5/0xb0 Code: e2 01 89 d0 c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 <48> 8b 46 08 a8 01 75 67 66 90 48 89 f0 8b 50 34 85 d2 74 76 48 89 RSP: 0018:ffffb148c2f3f968 EFLAGS: 00010246 RAX: ffff9fa5d3322000 RBX: ffff9fa5ccff9c08 RCX: 00000000b879ed29 RDX: ffffe97bd00025c0 RSI: ffffe97bd00025c0 RDI: ffff9fa5ccff9c08 RBP: ffffb148c2f3f9f0 R08: 0000000000000004 R09: 0000000000000004 R10: 0000000000000000 R11: 0000000000000200 R12: 0000000000000000 R13: 00007f16a18d5000 R14: ffff9fa5c48db6a8 R15: 0000000000000000 FS: 00007f16a1b54740(0000) GS:ffff9fa73df00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffe97bd00025c8 CR3: 00000001048c6006 CR4: 0000000000172ef0 Call Trace: ? __die_body.cold+0x19/0x1f ? __die+0x2e/0x40 ? page_fault_oops+0x157/0x2b0 ? search_module_extables+0x53/0x80 ? validate_page_before_insert+0x5/0xb0 ? kernelmode_fixup_or_oops.isra.0+0x5f/0x70 ? __bad_area_nosemaphore+0x16e/0x1b0 ? bad_area_nosemaphore+0x16/0x20 ? do_kern_addr_fault+0x77/0x90 ? exc_page_fault+0x22b/0x230 ? asm_exc_page_fault+0x2b/0x30 ? validate_page_before_insert+0x5/0xb0 ? vm_insert_pages+0x151/0x400 __rb_map_vma+0x21f/0x3f0 ring_buffer_map+0x21b/0x2f0 tracing_buffers_mmap+0x70/0xd0 __mmap_region+0x6f0/0xbd0 mmap_region+0x7f/0x130 do_mmap+0x475/0x610 vm_mmap_pgoff+0xf2/0x1d0 ksys_mmap_pgoff+0x166/0x200 __x64_sys_mmap+0x37/0x50 x64_sys_call+0x1670/0x1d70 do_syscall_64+0xbb/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f The reason was that the code that maps the ring buffer pages to user space has: page = virt_to_page((void *)cpu_buffer->subbuf_ids[s]); And uses that in: vm_insert_pages(vma, vma->vm_start, pages, &nr_pages); But virt_to_page() does not work with vmap()'d memory which is what the persistent ring buffer has. It is rather trivial to allow this, but for now just disable mmap() of instances that have their ring buffer from the reserve_mem option. If an mmap() is performed on a persistent buffer it will return -ENODEV just like it would if the .mmap field wasn't defined in the file_operations structure. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Vincent Donnefort Link: https://lore.kernel.org/20250214115547.0d7287d3@gandalf.local.home Fixes: 9b7bdf6f6ece6 ("tracing: Have trace_printk not use binary prints if boot buffer") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'kernel/trace') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 25ff37aab00f..0e6d517e74e0 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -8279,6 +8279,10 @@ static int tracing_buffers_mmap(struct file *filp, struct vm_area_struct *vma) struct trace_iterator *iter = &info->iter; int ret = 0; + /* Currently the boot mapped buffer is not supported for mmap */ + if (iter->tr->flags & TRACE_ARRAY_FL_BOOT) + return -ENODEV; + ret = get_snapshot_map(iter->tr); if (ret) return ret; -- cgit v1.2.3 From 97937834ae876f29565415ab15f1284666dc6be3 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 14 Feb 2025 12:35:12 -0500 Subject: ring-buffer: Update pages_touched to reflect persistent buffer content The pages_touched field represents the number of subbuffers in the ring buffer that have content that can be read. This is used in accounting of "dirty_pages" and "buffer_percent" to allow the user to wait for the buffer to be filled to a certain amount before it reads the buffer in blocking mode. The persistent buffer never updated this value so it was set to zero, and this accounting would take it as it had no content. This would cause user space to wait for content even though there's enough content in the ring buffer that satisfies the buffer_percent. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Vincent Donnefort Link: https://lore.kernel.org/20250214123512.0631436e@gandalf.local.home Fixes: 5f3b6e839f3ce ("ring-buffer: Validate boot range memory events") Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ring_buffer.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'kernel/trace') diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 0419d41a2060..bb6089c2951e 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1850,6 +1850,11 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer) cpu_buffer->cpu); goto invalid; } + + /* If the buffer has content, update pages_touched */ + if (ret) + local_inc(&cpu_buffer->pages_touched); + entries += ret; entry_bytes += local_read(&head_page->page->commit); local_set(&cpu_buffer->head_page->entries, ret); -- cgit v1.2.3