From 7d776a36277ff2685ffc3dc7eff32002d0333ac9 Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Mon, 9 Mar 2026 16:24:47 +0000 Subject: ring-buffer: Add page statistics to the meta-page Add two fields pages_touched and pages_lost to the ring-buffer meta-page. Those fields are useful to get the number of used pages in the ring-buffer. Link: https://patch.msgid.link/20260309162516.2623589-2-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google) --- include/uapi/linux/trace_mmap.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include') diff --git a/include/uapi/linux/trace_mmap.h b/include/uapi/linux/trace_mmap.h index c102ef35d11e..e8185889a1c8 100644 --- a/include/uapi/linux/trace_mmap.h +++ b/include/uapi/linux/trace_mmap.h @@ -17,8 +17,8 @@ * @entries: Number of entries in the ring-buffer. * @overrun: Number of entries lost in the ring-buffer. * @read: Number of entries that have been read. - * @Reserved1: Internal use only. - * @Reserved2: Internal use only. + * @pages_lost: Number of pages overwritten by the writer. + * @pages_touched: Number of pages written by the writer. */ struct trace_buffer_meta { __u32 meta_page_size; @@ -39,8 +39,8 @@ struct trace_buffer_meta { __u64 overrun; __u64 read; - __u64 Reserved1; - __u64 Reserved2; + __u64 pages_lost; + __u64 pages_touched; }; #define TRACE_MMAP_IOCTL_GET_READER _IO('R', 0x20) -- cgit v1.2.3 From 2e67fabd8b77c4f482df9b211bca1b495c6c2c24 Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Mon, 9 Mar 2026 16:24:49 +0000 Subject: ring-buffer: Introduce ring-buffer remotes Add ring-buffer remotes to support entities outside of the kernel (such as firmware or a hypervisor) that writes events into a ring-buffer using the tracefs format Require a description of the ring-buffer pages (struct trace_buffer_desc) and callbacks (swap_reader_page and reset) to set up the ring-buffer on the kernel side. Expect the remote entity to maintain and update the meta-page. Link: https://patch.msgid.link/20260309162516.2623589-4-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google) --- include/linux/ring_buffer.h | 58 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) (limited to 'include') diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h index d862fa610270..994f52b34344 100644 --- a/include/linux/ring_buffer.h +++ b/include/linux/ring_buffer.h @@ -251,4 +251,62 @@ int ring_buffer_map(struct trace_buffer *buffer, int cpu, void ring_buffer_map_dup(struct trace_buffer *buffer, int cpu); int ring_buffer_unmap(struct trace_buffer *buffer, int cpu); int ring_buffer_map_get_reader(struct trace_buffer *buffer, int cpu); + +struct ring_buffer_desc { + int cpu; + unsigned int nr_page_va; /* excludes the meta page */ + unsigned long meta_va; + unsigned long page_va[] __counted_by(nr_page_va); +}; + +struct trace_buffer_desc { + int nr_cpus; + size_t struct_len; + char __data[]; /* list of ring_buffer_desc */ +}; + +static inline struct ring_buffer_desc *__next_ring_buffer_desc(struct ring_buffer_desc *desc) +{ + size_t len = struct_size(desc, page_va, desc->nr_page_va); + + return (struct ring_buffer_desc *)((void *)desc + len); +} + +static inline struct ring_buffer_desc *__first_ring_buffer_desc(struct trace_buffer_desc *desc) +{ + return (struct ring_buffer_desc *)(&desc->__data[0]); +} + +static inline size_t trace_buffer_desc_size(size_t buffer_size, unsigned int nr_cpus) +{ + unsigned int nr_pages = max(DIV_ROUND_UP(buffer_size, PAGE_SIZE), 2UL) + 1; + struct ring_buffer_desc *rbdesc; + + return size_add(offsetof(struct trace_buffer_desc, __data), + size_mul(nr_cpus, struct_size(rbdesc, page_va, nr_pages))); +} + +#define for_each_ring_buffer_desc(__pdesc, __cpu, __trace_pdesc) \ + for (__pdesc = __first_ring_buffer_desc(__trace_pdesc), __cpu = 0; \ + (__cpu) < (__trace_pdesc)->nr_cpus; \ + (__cpu)++, __pdesc = __next_ring_buffer_desc(__pdesc)) + +struct ring_buffer_remote { + struct trace_buffer_desc *desc; + int (*swap_reader_page)(unsigned int cpu, void *priv); + int (*reset)(unsigned int cpu, void *priv); + void *priv; +}; + +int ring_buffer_poll_remote(struct trace_buffer *buffer, int cpu); + +struct trace_buffer * +__ring_buffer_alloc_remote(struct ring_buffer_remote *remote, + struct lock_class_key *key); + +#define ring_buffer_alloc_remote(remote) \ +({ \ + static struct lock_class_key __key; \ + __ring_buffer_alloc_remote(remote, &__key); \ +}) #endif /* _LINUX_RING_BUFFER_H */ -- cgit v1.2.3 From 96e43537af5461b26f50904c6055046ba65d742f Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Mon, 9 Mar 2026 16:24:51 +0000 Subject: tracing: Introduce trace remotes A trace remote relies on ring-buffer remotes to read and control compatible tracing buffers, written by entity such as firmware or hypervisor. Add a Tracefs directory remotes/ that contains all instances of trace remotes. Each instance follows the same hierarchy as any other to ease the support by existing user-space tools. This currently does not provide any event support, which will come later. Link: https://patch.msgid.link/20260309162516.2623589-6-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google) --- include/linux/trace_remote.h | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) create mode 100644 include/linux/trace_remote.h (limited to 'include') diff --git a/include/linux/trace_remote.h b/include/linux/trace_remote.h new file mode 100644 index 000000000000..65b7e7b8267c --- /dev/null +++ b/include/linux/trace_remote.h @@ -0,0 +1,36 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _LINUX_TRACE_REMOTE_H +#define _LINUX_TRACE_REMOTE_H + +#include + +/** + * struct trace_remote_callbacks - Callbacks used by Tracefs to control the remote + * @load_trace_buffer: Called before Tracefs accesses the trace buffer for the first + * time. Must return a &trace_buffer_desc + * (most likely filled with trace_remote_alloc_buffer()) + * @unload_trace_buffer: + * Called once Tracefs has no use for the trace buffer + * (most likely call trace_remote_free_buffer()) + * @enable_tracing: Called on Tracefs tracing_on. It is expected from the + * remote to allow writing. + * @swap_reader_page: Called when Tracefs consumes a new page from a + * ring-buffer. It is expected from the remote to isolate a + * new reader-page from the @cpu ring-buffer. + */ +struct trace_remote_callbacks { + struct trace_buffer_desc *(*load_trace_buffer)(unsigned long size, void *priv); + void (*unload_trace_buffer)(struct trace_buffer_desc *desc, void *priv); + int (*enable_tracing)(bool enable, void *priv); + int (*swap_reader_page)(unsigned int cpu, void *priv); +}; + +int trace_remote_register(const char *name, struct trace_remote_callbacks *cbs, void *priv); + +int trace_remote_alloc_buffer(struct trace_buffer_desc *desc, size_t desc_size, size_t buffer_size, + const struct cpumask *cpumask); + +void trace_remote_free_buffer(struct trace_buffer_desc *desc); + +#endif -- cgit v1.2.3 From 9af4ab0e11e336e2671d303ffcc6578e3546d9fc Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Mon, 9 Mar 2026 16:24:52 +0000 Subject: tracing: Add reset to trace remotes Allow to reset the trace remote buffer by writing to the Tracefs "trace" file. This is similar to the regular Tracefs interface. Link: https://patch.msgid.link/20260309162516.2623589-7-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google) --- include/linux/trace_remote.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include') diff --git a/include/linux/trace_remote.h b/include/linux/trace_remote.h index 65b7e7b8267c..10ca03dc192b 100644 --- a/include/linux/trace_remote.h +++ b/include/linux/trace_remote.h @@ -17,6 +17,8 @@ * remote to allow writing. * @swap_reader_page: Called when Tracefs consumes a new page from a * ring-buffer. It is expected from the remote to isolate a + * @reset: Called on `echo 0 > trace`. It is expected from the + * remote to reset all ring-buffer pages. * new reader-page from the @cpu ring-buffer. */ struct trace_remote_callbacks { @@ -24,6 +26,7 @@ struct trace_remote_callbacks { void (*unload_trace_buffer)(struct trace_buffer_desc *desc, void *priv); int (*enable_tracing)(bool enable, void *priv); int (*swap_reader_page)(unsigned int cpu, void *priv); + int (*reset)(unsigned int cpu, void *priv); }; int trace_remote_register(const char *name, struct trace_remote_callbacks *cbs, void *priv); -- cgit v1.2.3 From bf2ba0f8ca1af14aaaa765cbb93caf564d383aad Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Mon, 9 Mar 2026 16:24:54 +0000 Subject: tracing: Add init callback to trace remotes Add a .init call back so the trace remote callers can add entries to the tracefs directory. Link: https://patch.msgid.link/20260309162516.2623589-9-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google) --- include/linux/trace_remote.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include') diff --git a/include/linux/trace_remote.h b/include/linux/trace_remote.h index 10ca03dc192b..090c58b7d92b 100644 --- a/include/linux/trace_remote.h +++ b/include/linux/trace_remote.h @@ -3,10 +3,13 @@ #ifndef _LINUX_TRACE_REMOTE_H #define _LINUX_TRACE_REMOTE_H +#include #include /** * struct trace_remote_callbacks - Callbacks used by Tracefs to control the remote + * @init: Called once the remote has been registered. Allows the + * caller to extend the Tracefs remote directory * @load_trace_buffer: Called before Tracefs accesses the trace buffer for the first * time. Must return a &trace_buffer_desc * (most likely filled with trace_remote_alloc_buffer()) @@ -22,6 +25,7 @@ * new reader-page from the @cpu ring-buffer. */ struct trace_remote_callbacks { + int (*init)(struct dentry *d, void *priv); struct trace_buffer_desc *(*load_trace_buffer)(unsigned long size, void *priv); void (*unload_trace_buffer)(struct trace_buffer_desc *desc, void *priv); int (*enable_tracing)(bool enable, void *priv); -- cgit v1.2.3 From 072529158e604cc964feb78dcf094c6975828146 Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Mon, 9 Mar 2026 16:24:55 +0000 Subject: tracing: Add events to trace remotes An event is predefined point in the writer code that allows to log data. Following the same scheme as kernel events, add remote events, described to user-space within the events/ tracefs directory found in the corresponding trace remote. Remote events are expected to be described during the trace remote registration. Add also a .enable_event callback for trace_remote to toggle the event logging, if supported. Link: https://patch.msgid.link/20260309162516.2623589-10-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google) --- include/linux/trace_remote.h | 7 ++++++- include/linux/trace_remote_event.h | 23 +++++++++++++++++++++++ 2 files changed, 29 insertions(+), 1 deletion(-) create mode 100644 include/linux/trace_remote_event.h (limited to 'include') diff --git a/include/linux/trace_remote.h b/include/linux/trace_remote.h index 090c58b7d92b..fcd1d46ea466 100644 --- a/include/linux/trace_remote.h +++ b/include/linux/trace_remote.h @@ -5,6 +5,7 @@ #include #include +#include /** * struct trace_remote_callbacks - Callbacks used by Tracefs to control the remote @@ -23,6 +24,8 @@ * @reset: Called on `echo 0 > trace`. It is expected from the * remote to reset all ring-buffer pages. * new reader-page from the @cpu ring-buffer. + * @enable_event: Called on events/event_name/enable. It is expected from + * the remote to allow the writing event @id. */ struct trace_remote_callbacks { int (*init)(struct dentry *d, void *priv); @@ -31,9 +34,11 @@ struct trace_remote_callbacks { int (*enable_tracing)(bool enable, void *priv); int (*swap_reader_page)(unsigned int cpu, void *priv); int (*reset)(unsigned int cpu, void *priv); + int (*enable_event)(unsigned short id, bool enable, void *priv); }; -int trace_remote_register(const char *name, struct trace_remote_callbacks *cbs, void *priv); +int trace_remote_register(const char *name, struct trace_remote_callbacks *cbs, void *priv, + struct remote_event *events, size_t nr_events); int trace_remote_alloc_buffer(struct trace_buffer_desc *desc, size_t desc_size, size_t buffer_size, const struct cpumask *cpumask); diff --git a/include/linux/trace_remote_event.h b/include/linux/trace_remote_event.h new file mode 100644 index 000000000000..a4449008a075 --- /dev/null +++ b/include/linux/trace_remote_event.h @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _LINUX_TRACE_REMOTE_EVENTS_H +#define _LINUX_TRACE_REMOTE_EVENTS_H + +struct trace_remote; +struct trace_event_fields; + +struct remote_event_hdr { + unsigned short id; +}; + +#define REMOTE_EVENT_NAME_MAX 30 +struct remote_event { + char name[REMOTE_EVENT_NAME_MAX]; + unsigned short id; + bool enabled; + struct trace_remote *remote; + struct trace_event_fields *fields; + char *print_fmt; + void (*print)(void *evt, struct trace_seq *seq); +}; +#endif -- cgit v1.2.3 From 5f3efd1dcebc35d44cce39630ae00980a45d9247 Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Mon, 9 Mar 2026 16:24:57 +0000 Subject: tracing: Add helpers to create trace remote events Declaring remote events can be cumbersome let's add a set of macros to simplify developers life. The declaration of a remote event is very similar to kernel's events: REMOTE_EVENT(name, id, RE_STRUCT( re_field(u64 foo) ), RE_PRINTK("foo=%llu", __entry->foo) ) Link: https://patch.msgid.link/20260309162516.2623589-12-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google) --- include/linux/trace_remote_event.h | 10 +++++ include/trace/define_remote_events.h | 73 ++++++++++++++++++++++++++++++++++++ 2 files changed, 83 insertions(+) create mode 100644 include/trace/define_remote_events.h (limited to 'include') diff --git a/include/linux/trace_remote_event.h b/include/linux/trace_remote_event.h index a4449008a075..c8ae1e1f5e72 100644 --- a/include/linux/trace_remote_event.h +++ b/include/linux/trace_remote_event.h @@ -5,6 +5,7 @@ struct trace_remote; struct trace_event_fields; +struct trace_seq; struct remote_event_hdr { unsigned short id; @@ -20,4 +21,13 @@ struct remote_event { char *print_fmt; void (*print)(void *evt, struct trace_seq *seq); }; + +#define RE_STRUCT(__args...) __args +#define re_field(__type, __field) __type __field; + +#define REMOTE_EVENT_FORMAT(__name, __struct) \ + struct remote_event_format_##__name { \ + struct remote_event_hdr hdr; \ + __struct \ + } #endif diff --git a/include/trace/define_remote_events.h b/include/trace/define_remote_events.h new file mode 100644 index 000000000000..676e803dc144 --- /dev/null +++ b/include/trace/define_remote_events.h @@ -0,0 +1,73 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#include +#include +#include +#include + +#define REMOTE_EVENT_INCLUDE(__file) __stringify(../../__file) + +#ifdef REMOTE_EVENT_SECTION +# define __REMOTE_EVENT_SECTION(__name) __used __section(REMOTE_EVENT_SECTION"."#__name) +#else +# define __REMOTE_EVENT_SECTION(__name) +#endif + +#define REMOTE_PRINTK_COUNT_ARGS(__args...) \ + __COUNT_ARGS(, ##__args, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 0) + +#define __remote_printk0() \ + trace_seq_putc(seq, '\n') + +#define __remote_printk1(__fmt) \ + trace_seq_puts(seq, " " __fmt "\n") \ + +#define __remote_printk2(__fmt, __args...) \ +do { \ + trace_seq_putc(seq, ' '); \ + trace_seq_printf(seq, __fmt, __args); \ + trace_seq_putc(seq, '\n'); \ +} while (0) + +/* Apply the appropriate trace_seq sequence according to the number of arguments */ +#define remote_printk(__args...) \ + CONCATENATE(__remote_printk, REMOTE_PRINTK_COUNT_ARGS(__args))(__args) + +#define RE_PRINTK(__args...) __args + +#define REMOTE_EVENT(__name, __id, __struct, __printk) \ + REMOTE_EVENT_FORMAT(__name, __struct); \ + static void remote_event_print_##__name(void *evt, struct trace_seq *seq) \ + { \ + struct remote_event_format_##__name __maybe_unused *__entry = evt; \ + trace_seq_puts(seq, #__name); \ + remote_printk(__printk); \ + } +#include REMOTE_EVENT_INCLUDE(REMOTE_EVENT_INCLUDE_FILE) + +#undef REMOTE_EVENT +#undef RE_PRINTK +#undef re_field +#define re_field(__type, __field) \ + { \ + .type = #__type, .name = #__field, \ + .size = sizeof(__type), .align = __alignof__(__type), \ + .is_signed = is_signed_type(__type), \ + }, +#define __entry REC +#define RE_PRINTK(__fmt, __args...) "\"" __fmt "\", " __stringify(__args) +#define REMOTE_EVENT(__name, __id, __struct, __printk) \ + static struct trace_event_fields remote_event_fields_##__name[] = { \ + __struct \ + {} \ + }; \ + static char remote_event_print_fmt_##__name[] = __printk; \ + static struct remote_event __REMOTE_EVENT_SECTION(__name) \ + remote_event_##__name = { \ + .name = #__name, \ + .id = __id, \ + .fields = remote_event_fields_##__name, \ + .print_fmt = remote_event_print_fmt_##__name, \ + .print = remote_event_print_##__name, \ + } +#include REMOTE_EVENT_INCLUDE(REMOTE_EVENT_INCLUDE_FILE) -- cgit v1.2.3 From 93ae1b76fff9e745f870a2f2cd32f472328c4a8f Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Mon, 9 Mar 2026 16:24:58 +0000 Subject: ring-buffer: Export buffer_data_page and macros In preparation for allowing the writing of ring-buffer compliant pages outside of ring_buffer.c, move buffer_data_page and timestamps encoding macros into the publicly available ring_buffer_types.h. Link: https://patch.msgid.link/20260309162516.2623589-13-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google) --- include/linux/ring_buffer_types.h | 41 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100644 include/linux/ring_buffer_types.h (limited to 'include') diff --git a/include/linux/ring_buffer_types.h b/include/linux/ring_buffer_types.h new file mode 100644 index 000000000000..54577021a49d --- /dev/null +++ b/include/linux/ring_buffer_types.h @@ -0,0 +1,41 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_RING_BUFFER_TYPES_H +#define _LINUX_RING_BUFFER_TYPES_H + +#include + +#define TS_SHIFT 27 +#define TS_MASK ((1ULL << TS_SHIFT) - 1) +#define TS_DELTA_TEST (~TS_MASK) + +/* + * We need to fit the time_stamp delta into 27 bits. + */ +static inline bool test_time_stamp(u64 delta) +{ + return !!(delta & TS_DELTA_TEST); +} + +#define BUF_PAGE_HDR_SIZE offsetof(struct buffer_data_page, data) + +#define RB_EVNT_HDR_SIZE (offsetof(struct ring_buffer_event, array)) +#define RB_ALIGNMENT 4U +#define RB_MAX_SMALL_DATA (RB_ALIGNMENT * RINGBUF_TYPE_DATA_TYPE_LEN_MAX) +#define RB_EVNT_MIN_SIZE 8U /* two 32bit words */ + +#ifndef CONFIG_HAVE_64BIT_ALIGNED_ACCESS +# define RB_FORCE_8BYTE_ALIGNMENT 0 +# define RB_ARCH_ALIGNMENT RB_ALIGNMENT +#else +# define RB_FORCE_8BYTE_ALIGNMENT 1 +# define RB_ARCH_ALIGNMENT 8U +#endif + +#define RB_ALIGN_DATA __aligned(RB_ARCH_ALIGNMENT) + +struct buffer_data_page { + u64 time_stamp; /* page time stamp */ + local_t commit; /* write committed index */ + unsigned char data[] RB_ALIGN_DATA; /* data of buffer page */ +}; +#endif -- cgit v1.2.3 From 34e5b958bdad0f9cf16306368bbc2dc5b2a50143 Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Mon, 9 Mar 2026 16:24:59 +0000 Subject: tracing: Introduce simple_ring_buffer Add a simple implementation of the kernel ring-buffer. This intends to be used later by ring-buffer remotes such as the pKVM hypervisor, hence the need for a cut down version (write only) without any dependency. Link: https://patch.msgid.link/20260309162516.2623589-14-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google) --- include/linux/simple_ring_buffer.h | 57 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) create mode 100644 include/linux/simple_ring_buffer.h (limited to 'include') diff --git a/include/linux/simple_ring_buffer.h b/include/linux/simple_ring_buffer.h new file mode 100644 index 000000000000..2c4c0ae336bc --- /dev/null +++ b/include/linux/simple_ring_buffer.h @@ -0,0 +1,57 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_SIMPLE_RING_BUFFER_H +#define _LINUX_SIMPLE_RING_BUFFER_H + +#include +#include +#include +#include + +/* + * Ideally those struct would stay private but the caller needs to know + * the allocation size for simple_ring_buffer_init(). + */ +struct simple_buffer_page { + struct list_head link; + struct buffer_data_page *page; + u64 entries; + u32 write; + u32 id; +}; + +struct simple_rb_per_cpu { + struct simple_buffer_page *tail_page; + struct simple_buffer_page *reader_page; + struct simple_buffer_page *head_page; + struct simple_buffer_page *bpages; + struct trace_buffer_meta *meta; + u32 nr_pages; + +#define SIMPLE_RB_UNAVAILABLE 0 +#define SIMPLE_RB_READY 1 +#define SIMPLE_RB_WRITING 2 + u32 status; + + u64 last_overrun; + u64 write_stamp; + + struct simple_rb_cbs *cbs; +}; + +int simple_ring_buffer_init(struct simple_rb_per_cpu *cpu_buffer, struct simple_buffer_page *bpages, + const struct ring_buffer_desc *desc); + +void simple_ring_buffer_unload(struct simple_rb_per_cpu *cpu_buffer); + +void *simple_ring_buffer_reserve(struct simple_rb_per_cpu *cpu_buffer, unsigned long length, + u64 timestamp); + +void simple_ring_buffer_commit(struct simple_rb_per_cpu *cpu_buffer); + +int simple_ring_buffer_enable_tracing(struct simple_rb_per_cpu *cpu_buffer, bool enable); + +int simple_ring_buffer_reset(struct simple_rb_per_cpu *cpu_buffer); + +int simple_ring_buffer_swap_reader_page(struct simple_rb_per_cpu *cpu_buffer); + +#endif -- cgit v1.2.3 From 635923081c792c830fb87e680d6dd5f348926b3f Mon Sep 17 00:00:00 2001 From: Vincent Donnefort Date: Mon, 9 Mar 2026 16:25:03 +0000 Subject: tracing: load/unload page callbacks for simple_ring_buffer Add load/unload callback used for each admitted page in the ring-buffer. This will be later useful for the pKVM hypervisor which uses a different VA space and need to dynamically map/unmap the ring-buffer pages. Link: https://patch.msgid.link/20260309162516.2623589-18-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google) --- include/linux/simple_ring_buffer.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include') diff --git a/include/linux/simple_ring_buffer.h b/include/linux/simple_ring_buffer.h index 2c4c0ae336bc..21aec556293e 100644 --- a/include/linux/simple_ring_buffer.h +++ b/include/linux/simple_ring_buffer.h @@ -54,4 +54,12 @@ int simple_ring_buffer_reset(struct simple_rb_per_cpu *cpu_buffer); int simple_ring_buffer_swap_reader_page(struct simple_rb_per_cpu *cpu_buffer); +int simple_ring_buffer_init_mm(struct simple_rb_per_cpu *cpu_buffer, + struct simple_buffer_page *bpages, + const struct ring_buffer_desc *desc, + void *(*load_page)(unsigned long va), + void (*unload_page)(void *va)); + +void simple_ring_buffer_unload_mm(struct simple_rb_per_cpu *cpu_buffer, + void (*unload_page)(void *)); #endif -- cgit v1.2.3