^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) /* SPDX-License-Identifier: GPL-2.0 */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3) #ifndef _KERNEL_PRINTK_RINGBUFFER_H
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) #define _KERNEL_PRINTK_RINGBUFFER_H
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) #include <linux/atomic.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7) #include <linux/dev_printk.h>
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) * Meta information about each stored message.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) * All fields are set by the printk code except for @seq, which is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) * set by the ringbuffer code.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) struct printk_info {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16) u64 seq; /* sequence number */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) u64 ts_nsec; /* timestamp in nanoseconds */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) u16 text_len; /* length of text message */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) u8 facility; /* syslog facility */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) u8 flags:5; /* internal record flags */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) u8 level:3; /* syslog level */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) u32 caller_id; /* thread id or processor id */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) struct dev_printk_info dev_info;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) * A structure providing the buffers, used by writers and readers.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) * Writers:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31) * Using prb_rec_init_wr(), a writer sets @text_buf_size before calling
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) * prb_reserve(). On success, prb_reserve() sets @info and @text_buf to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) * buffers reserved for that writer.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) * Readers:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) * Using prb_rec_init_rd(), a reader sets all fields before calling
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) * prb_read_valid(). Note that the reader provides the @info and @text_buf,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38) * buffers. On success, the struct pointed to by @info will be filled and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) * the char array pointed to by @text_buf will be filled with text data.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) struct printk_record {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42) struct printk_info *info;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) char *text_buf;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) unsigned int text_buf_size;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47) /* Specifies the logical position and span of a data block. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) struct prb_data_blk_lpos {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) unsigned long begin;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) unsigned long next;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) * A descriptor: the complete meta-data for a record.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56) * @state_var: A bitwise combination of descriptor ID and descriptor state.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) struct prb_desc {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) atomic_long_t state_var;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) struct prb_data_blk_lpos text_blk_lpos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) /* A ringbuffer of "ID + data" elements. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) struct prb_data_ring {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) unsigned int size_bits;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) char *data;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) atomic_long_t head_lpos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) atomic_long_t tail_lpos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) /* A ringbuffer of "struct prb_desc" elements. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) struct prb_desc_ring {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73) unsigned int count_bits;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) struct prb_desc *descs;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 75) struct printk_info *infos;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 76) atomic_long_t head_id;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 77) atomic_long_t tail_id;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 78) atomic_long_t last_finalized_id;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 79) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 80)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 81) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 82) * The high level structure representing the printk ringbuffer.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 83) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 84) * @fail: Count of failed prb_reserve() calls where not even a data-less
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 85) * record was created.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 86) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 87) struct printk_ringbuffer {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 88) struct prb_desc_ring desc_ring;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 89) struct prb_data_ring text_data_ring;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 90) atomic_long_t fail;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 91) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 92)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 93) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 94) * Used by writers as a reserve/commit handle.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 95) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 96) * @rb: Ringbuffer where the entry is reserved.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 97) * @irqflags: Saved irq flags to restore on entry commit.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 98) * @id: ID of the reserved descriptor.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 99) * @text_space: Total occupied buffer space in the text data ring, including
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100) * ID, alignment padding, and wrapping data blocks.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102) * This structure is an opaque handle for writers. Its contents are only
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) * to be used by the ringbuffer implementation.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) struct prb_reserved_entry {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) struct printk_ringbuffer *rb;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) unsigned long irqflags;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) unsigned long id;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) unsigned int text_space;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) /* The possible responses of a descriptor state-query. */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) enum desc_state {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) desc_miss = -1, /* ID mismatch (pseudo state) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) desc_reserved = 0x0, /* reserved, in use by writer */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) desc_committed = 0x1, /* committed by writer, could get reopened */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) desc_finalized = 0x2, /* committed, no further modification allowed */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) desc_reusable = 0x3, /* free, not yet used by any writer */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) };
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) #define _DATA_SIZE(sz_bits) (1UL << (sz_bits))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) #define _DESCS_COUNT(ct_bits) (1U << (ct_bits))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) #define DESC_SV_BITS (sizeof(unsigned long) * 8)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) #define DESC_FLAGS_SHIFT (DESC_SV_BITS - 2)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) #define DESC_FLAGS_MASK (3UL << DESC_FLAGS_SHIFT)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) #define DESC_STATE(sv) (3UL & (sv >> DESC_FLAGS_SHIFT))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) #define DESC_SV(id, state) (((unsigned long)state << DESC_FLAGS_SHIFT) | id)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128) #define DESC_ID_MASK (~DESC_FLAGS_MASK)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129) #define DESC_ID(sv) ((sv) & DESC_ID_MASK)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130) #define FAILED_LPOS 0x1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131) #define NO_LPOS 0x3
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133) #define FAILED_BLK_LPOS \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134) { \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135) .begin = FAILED_LPOS, \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136) .next = FAILED_LPOS, \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140) * Descriptor Bootstrap
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) * The descriptor array is minimally initialized to allow immediate usage
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) * by readers and writers. The requirements that the descriptor array
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) * initialization must satisfy:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) * Req1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) * The tail must point to an existing (committed or reusable) descriptor.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) * This is required by the implementation of prb_first_seq().
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) * Req2
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) * Readers must see that the ringbuffer is initially empty.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) * Req3
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) * The first record reserved by a writer is assigned sequence number 0.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) * To satisfy Req1, the tail initially points to a descriptor that is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) * minimally initialized (having no data block, i.e. data-less with the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) * data block's lpos @begin and @next values set to FAILED_LPOS).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) * To satisfy Req2, the initial tail descriptor is initialized to the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) * reusable state. Readers recognize reusable descriptors as existing
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162) * records, but skip over them.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164) * To satisfy Req3, the last descriptor in the array is used as the initial
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165) * head (and tail) descriptor. This allows the first record reserved by a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166) * writer (head + 1) to be the first descriptor in the array. (Only the first
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167) * descriptor in the array could have a valid sequence number of 0.)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169) * The first time a descriptor is reserved, it is assigned a sequence number
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170) * with the value of the array index. A "first time reserved" descriptor can
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171) * be recognized because it has a sequence number of 0 but does not have an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172) * index of 0. (Only the first descriptor in the array could have a valid
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) * sequence number of 0.) After the first reservation, all future reservations
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) * (recycling) simply involve incrementing the sequence number by the array
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) * count.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) * Hack #1
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) * Only the first descriptor in the array is allowed to have the sequence
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) * number 0. In this case it is not possible to recognize if it is being
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) * reserved the first time (set to index value) or has been reserved
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) * previously (increment by the array count). This is handled by _always_
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) * incrementing the sequence number by the array count when reserving the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) * first descriptor in the array. In order to satisfy Req3, the sequence
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) * number of the first descriptor in the array is initialized to minus
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) * the array count. Then, upon the first reservation, it is incremented
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) * to 0, thus satisfying Req3.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) * Hack #2
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) * prb_first_seq() can be called at any time by readers to retrieve the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) * sequence number of the tail descriptor. However, due to Req2 and Req3,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) * initially there are no records to report the sequence number of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) * (sequence numbers are u64 and there is nothing less than 0). To handle
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) * this, the sequence number of the initial tail descriptor is initialized
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) * to 0. Technically this is incorrect, because there is no record with
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195) * sequence number 0 (yet) and the tail descriptor is not the first
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196) * descriptor in the array. But it allows prb_read_valid() to correctly
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197) * report the existence of a record for _any_ given sequence number at all
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198) * times. Bootstrapping is complete when the tail is pushed the first
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199) * time, thus finally pointing to the first descriptor reserved by a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200) * writer, which has the assigned sequence number 0.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) * Initiating Logical Value Overflows
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) * Both logical position (lpos) and ID values can be mapped to array indexes
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) * but may experience overflows during the lifetime of the system. To ensure
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) * that printk_ringbuffer can handle the overflows for these types, initial
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) * values are chosen that map to the correct initial array indexes, but will
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) * result in overflows soon.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) * BLK0_LPOS
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) * The initial @head_lpos and @tail_lpos for data rings. It is at index
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) * 0 and the lpos value is such that it will overflow on the first wrap.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216) * DESC0_ID
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217) * The initial @head_id and @tail_id for the desc ring. It is at the last
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218) * index of the descriptor array (see Req3 above) and the ID value is such
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219) * that it will overflow on the second wrap.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221) #define BLK0_LPOS(sz_bits) (-(_DATA_SIZE(sz_bits)))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) #define DESC0_ID(ct_bits) DESC_ID(-(_DESCS_COUNT(ct_bits) + 1))
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) #define DESC0_SV(ct_bits) DESC_SV(DESC0_ID(ct_bits), desc_reusable)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) /*
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) * Define a ringbuffer with an external text data buffer. The same as
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) * DEFINE_PRINTKRB() but requires specifying an external buffer for the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 228) * text data.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 229) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 230) * Note: The specified external buffer must be of the size:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 231) * 2 ^ (descbits + avgtextbits)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 232) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 233) #define _DEFINE_PRINTKRB(name, descbits, avgtextbits, text_buf) \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 234) static struct prb_desc _##name##_descs[_DESCS_COUNT(descbits)] = { \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 235) /* the initial head and tail */ \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 236) [_DESCS_COUNT(descbits) - 1] = { \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 237) /* reusable */ \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 238) .state_var = ATOMIC_INIT(DESC0_SV(descbits)), \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 239) /* no associated data block */ \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 240) .text_blk_lpos = FAILED_BLK_LPOS, \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 241) }, \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 242) }; \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 243) static struct printk_info _##name##_infos[_DESCS_COUNT(descbits)] = { \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 244) /* this will be the first record reserved by a writer */ \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 245) [0] = { \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 246) /* will be incremented to 0 on the first reservation */ \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 247) .seq = -(u64)_DESCS_COUNT(descbits), \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 248) }, \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 249) /* the initial head and tail */ \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 250) [_DESCS_COUNT(descbits) - 1] = { \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 251) /* reports the first seq value during the bootstrap phase */ \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 252) .seq = 0, \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 253) }, \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 254) }; \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 255) static struct printk_ringbuffer name = { \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 256) .desc_ring = { \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 257) .count_bits = descbits, \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 258) .descs = &_##name##_descs[0], \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 259) .infos = &_##name##_infos[0], \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 260) .head_id = ATOMIC_INIT(DESC0_ID(descbits)), \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 261) .tail_id = ATOMIC_INIT(DESC0_ID(descbits)), \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 262) .last_finalized_id = ATOMIC_INIT(DESC0_ID(descbits)), \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 263) }, \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 264) .text_data_ring = { \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 265) .size_bits = (avgtextbits) + (descbits), \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 266) .data = text_buf, \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 267) .head_lpos = ATOMIC_LONG_INIT(BLK0_LPOS((avgtextbits) + (descbits))), \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 268) .tail_lpos = ATOMIC_LONG_INIT(BLK0_LPOS((avgtextbits) + (descbits))), \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 269) }, \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 270) .fail = ATOMIC_LONG_INIT(0), \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 271) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 272)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 273) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 274) * DEFINE_PRINTKRB() - Define a ringbuffer.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 275) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 276) * @name: The name of the ringbuffer variable.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 277) * @descbits: The number of descriptors as a power-of-2 value.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 278) * @avgtextbits: The average text data size per record as a power-of-2 value.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 279) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 280) * This is a macro for defining a ringbuffer and all internal structures
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 281) * such that it is ready for immediate use. See _DEFINE_PRINTKRB() for a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 282) * variant where the text data buffer can be specified externally.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 283) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 284) #define DEFINE_PRINTKRB(name, descbits, avgtextbits) \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 285) static char _##name##_text[1U << ((avgtextbits) + (descbits))] \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 286) __aligned(__alignof__(unsigned long)); \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 287) _DEFINE_PRINTKRB(name, descbits, avgtextbits, &_##name##_text[0])
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 288)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 289) /* Writer Interface */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 290)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 291) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 292) * prb_rec_init_wd() - Initialize a buffer for writing records.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 293) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 294) * @r: The record to initialize.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 295) * @text_buf_size: The needed text buffer size.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 296) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 297) static inline void prb_rec_init_wr(struct printk_record *r,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 298) unsigned int text_buf_size)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 299) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 300) r->info = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 301) r->text_buf = NULL;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 302) r->text_buf_size = text_buf_size;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 303) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 304)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 305) bool prb_reserve(struct prb_reserved_entry *e, struct printk_ringbuffer *rb,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 306) struct printk_record *r);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 307) bool prb_reserve_in_last(struct prb_reserved_entry *e, struct printk_ringbuffer *rb,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 308) struct printk_record *r, u32 caller_id, unsigned int max_size);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 309) void prb_commit(struct prb_reserved_entry *e);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 310) void prb_final_commit(struct prb_reserved_entry *e);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 311)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 312) void prb_init(struct printk_ringbuffer *rb,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 313) char *text_buf, unsigned int text_buf_size,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 314) struct prb_desc *descs, unsigned int descs_count_bits,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 315) struct printk_info *infos);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 316) unsigned int prb_record_text_space(struct prb_reserved_entry *e);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 317)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 318) /* Reader Interface */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 319)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 320) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 321) * prb_rec_init_rd() - Initialize a buffer for reading records.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 322) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 323) * @r: The record to initialize.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 324) * @info: A buffer to store record meta-data.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 325) * @text_buf: A buffer to store text data.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 326) * @text_buf_size: The size of @text_buf.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 327) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 328) * Initialize all the fields that a reader is interested in. All arguments
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 329) * (except @r) are optional. Only record data for arguments that are
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 330) * non-NULL or non-zero will be read.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 331) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 332) static inline void prb_rec_init_rd(struct printk_record *r,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 333) struct printk_info *info,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 334) char *text_buf, unsigned int text_buf_size)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 335) {
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 336) r->info = info;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 337) r->text_buf = text_buf;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 338) r->text_buf_size = text_buf_size;
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 339) }
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 340)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 341) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 342) * prb_for_each_record() - Iterate over the records of a ringbuffer.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 343) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 344) * @from: The sequence number to begin with.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 345) * @rb: The ringbuffer to iterate over.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 346) * @s: A u64 to store the sequence number on each iteration.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 347) * @r: A printk_record to store the record on each iteration.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 348) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 349) * This is a macro for conveniently iterating over a ringbuffer.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 350) * Note that @s may not be the sequence number of the record on each
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 351) * iteration. For the sequence number, @r->info->seq should be checked.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 352) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 353) * Context: Any context.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 354) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 355) #define prb_for_each_record(from, rb, s, r) \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 356) for ((s) = from; prb_read_valid(rb, s, r); (s) = (r)->info->seq + 1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 357)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 358) /**
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 359) * prb_for_each_info() - Iterate over the meta data of a ringbuffer.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 360) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 361) * @from: The sequence number to begin with.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 362) * @rb: The ringbuffer to iterate over.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 363) * @s: A u64 to store the sequence number on each iteration.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 364) * @i: A printk_info to store the record meta data on each iteration.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 365) * @lc: An unsigned int to store the text line count of each record.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 366) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 367) * This is a macro for conveniently iterating over a ringbuffer.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 368) * Note that @s may not be the sequence number of the record on each
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 369) * iteration. For the sequence number, @r->info->seq should be checked.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 370) *
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 371) * Context: Any context.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 372) */
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 373) #define prb_for_each_info(from, rb, s, i, lc) \
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 374) for ((s) = from; prb_read_valid_info(rb, s, i, lc); (s) = (i)->seq + 1)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 375)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 376) bool prb_read_valid(struct printk_ringbuffer *rb, u64 seq,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 377) struct printk_record *r);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 378) bool prb_read_valid_info(struct printk_ringbuffer *rb, u64 seq,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 379) struct printk_info *info, unsigned int *line_count);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 380)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 381) u64 prb_first_valid_seq(struct printk_ringbuffer *rb);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 382) u64 prb_next_seq(struct printk_ringbuffer *rb);
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 383)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 384) #endif /* _KERNEL_PRINTK_RINGBUFFER_H */
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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