Implement file-backed ring buffer

[lttng-ust.git] / libringbuffer / frontend_types.h

diff --git a/libringbuffer/frontend_types.h b/libringbuffer/frontend_types.h
index b44783f713630a584e99e28bd6c6982f5bf08444..bf4b4185e2368945494dd39e3df86efed5ff1aa8 100644 (file)
--- a/libringbuffer/frontend_types.h
+++ b/libringbuffer/frontend_types.h
@@ -94,10 +94,90 @@ struct commit_counters_cold {
 } __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
 
 /* ring buffer state */
-#define RB_RING_BUFFER_PADDING         64
+#define RB_CRASH_DUMP_ABI_LEN          256
+#define RB_RING_BUFFER_PADDING         60
+
+#define RB_CRASH_DUMP_ABI_MAGIC_LEN    16
+
+/*
+ * The 128-bit magic number is xor'd in the process data so it does not
+ * cause a false positive when searching for buffers by scanning memory.
+ * The actual magic number is:
+ *   0x17, 0x7B, 0xF1, 0x77, 0xBF, 0x17, 0x7B, 0xF1,
+ *   0x77, 0xBF, 0x17, 0x7B, 0xF1, 0x77, 0xBF, 0x17,
+ */
+#define RB_CRASH_DUMP_ABI_MAGIC_XOR                                    \
+       {                                                               \
+               0x17 ^ 0xFF, 0x7B ^ 0xFF, 0xF1 ^ 0xFF, 0x77 ^ 0xFF,     \
+               0xBF ^ 0xFF, 0x17 ^ 0xFF, 0x7B ^ 0xFF, 0xF1 ^ 0xFF,     \
+               0x77 ^ 0xFF, 0xBF ^ 0xFF, 0x17 ^ 0xFF, 0x7B ^ 0xFF,     \
+               0xF1 ^ 0xFF, 0x77 ^ 0xFF, 0xBF ^ 0xFF, 0x17 ^ 0xFF,     \
+       }
+
+#define RB_CRASH_ENDIAN                        0x1234
+
+#define RB_CRASH_DUMP_ABI_MAJOR                0
+#define RB_CRASH_DUMP_ABI_MINOR                0
+
+enum lttng_crash_type {
+       LTTNG_CRASH_TYPE_UST = 0,
+       LTTNG_CRASH_TYPE_KERNEL = 1,
+};
+
+struct lttng_crash_abi {
+       uint8_t magic[RB_CRASH_DUMP_ABI_MAGIC_LEN];
+       uint64_t mmap_length;   /* Overall lenght of crash record */
+       uint16_t endian;        /*
+                                * { 0x12, 0x34 }: big endian
+                                * { 0x34, 0x12 }: little endian
+                                */
+       uint16_t major;         /* Major number. */
+       uint16_t minor;         /* Minor number. */
+       uint8_t word_size;      /* Word size (bytes). */
+       uint8_t layout_type;    /* enum lttng_crash_type */
+
+       struct {
+               uint32_t prod_offset;
+               uint32_t consumed_offset;
+               uint32_t commit_hot_array;
+               uint32_t commit_hot_seq;
+               uint32_t buf_wsb_array;
+               uint32_t buf_wsb_id;
+               uint32_t sb_array;
+               uint32_t sb_array_shmp_offset;
+               uint32_t sb_backend_p_offset;
+               uint32_t content_size;
+               uint32_t packet_size;
+       } __attribute__((packed)) offset;
+       struct {
+               uint8_t prod_offset;
+               uint8_t consumed_offset;
+               uint8_t commit_hot_seq;
+               uint8_t buf_wsb_id;
+               uint8_t sb_array_shmp_offset;
+               uint8_t sb_backend_p_offset;
+               uint8_t content_size;
+               uint8_t packet_size;
+       } __attribute__((packed)) length;
+       struct {
+               uint32_t commit_hot_array;
+               uint32_t buf_wsb_array;
+               uint32_t sb_array;
+       } __attribute__((packed)) stride;
+
+       uint64_t buf_size;      /* Size of the buffer */
+       uint64_t subbuf_size;   /* Sub-buffer size */
+       uint64_t num_subbuf;    /* Number of sub-buffers for writer */
+       uint32_t mode;          /* Buffer mode: 0: overwrite, 1: discard */
+} __attribute__((packed));
+
 struct lttng_ust_lib_ring_buffer {
-       /* First 32 bytes cache-hot cacheline */
-       union v_atomic offset;          /* Current offset in the buffer */
+       /* First 32 bytes are for the buffer crash dump ABI */
+       struct lttng_crash_abi crash_abi;
+
+       /* 32 bytes cache-hot cacheline */
+       union v_atomic __attribute__((aligned(32))) offset;
+                                       /* Current offset in the buffer */
        DECLARE_SHMP(struct commit_counters_hot, commit_hot);
                                        /* Commit count per sub-buffer */
        long consumed;                  /*
@@ -105,12 +185,14 @@ struct lttng_ust_lib_ring_buffer {
                                         * standard atomic access (shared)
                                         */
        int record_disabled;
-       /* End of first 32 bytes cacheline */
+       /* End of cache-hot 32 bytes cacheline */
+
        union v_atomic last_tsc;        /*
                                         * Last timestamp written in the buffer.
                                         */
 
-       struct lttng_ust_lib_ring_buffer_backend backend;       /* Associated backend */
+       struct lttng_ust_lib_ring_buffer_backend backend;
+                                       /* Associated backend */
 
        DECLARE_SHMP(struct commit_counters_cold, commit_cold);
                                        /* Commit count per sub-buffer */