Update Linux to v5.10.109
Sourced from [1]
[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz
Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/kernel/printk/printk_ringbuffer.h b/kernel/printk/printk_ringbuffer.h
new file mode 100644
index 0000000..5dc9d02
--- /dev/null
+++ b/kernel/printk/printk_ringbuffer.h
@@ -0,0 +1,382 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _KERNEL_PRINTK_RINGBUFFER_H
+#define _KERNEL_PRINTK_RINGBUFFER_H
+
+#include <linux/atomic.h>
+#include <linux/dev_printk.h>
+
+/*
+ * Meta information about each stored message.
+ *
+ * All fields are set by the printk code except for @seq, which is
+ * set by the ringbuffer code.
+ */
+struct printk_info {
+ u64 seq; /* sequence number */
+ u64 ts_nsec; /* timestamp in nanoseconds */
+ u16 text_len; /* length of text message */
+ u8 facility; /* syslog facility */
+ u8 flags:5; /* internal record flags */
+ u8 level:3; /* syslog level */
+ u32 caller_id; /* thread id or processor id */
+
+ struct dev_printk_info dev_info;
+};
+
+/*
+ * A structure providing the buffers, used by writers and readers.
+ *
+ * Writers:
+ * Using prb_rec_init_wr(), a writer sets @text_buf_size before calling
+ * prb_reserve(). On success, prb_reserve() sets @info and @text_buf to
+ * buffers reserved for that writer.
+ *
+ * Readers:
+ * Using prb_rec_init_rd(), a reader sets all fields before calling
+ * prb_read_valid(). Note that the reader provides the @info and @text_buf,
+ * buffers. On success, the struct pointed to by @info will be filled and
+ * the char array pointed to by @text_buf will be filled with text data.
+ */
+struct printk_record {
+ struct printk_info *info;
+ char *text_buf;
+ unsigned int text_buf_size;
+};
+
+/* Specifies the logical position and span of a data block. */
+struct prb_data_blk_lpos {
+ unsigned long begin;
+ unsigned long next;
+};
+
+/*
+ * A descriptor: the complete meta-data for a record.
+ *
+ * @state_var: A bitwise combination of descriptor ID and descriptor state.
+ */
+struct prb_desc {
+ atomic_long_t state_var;
+ struct prb_data_blk_lpos text_blk_lpos;
+};
+
+/* A ringbuffer of "ID + data" elements. */
+struct prb_data_ring {
+ unsigned int size_bits;
+ char *data;
+ atomic_long_t head_lpos;
+ atomic_long_t tail_lpos;
+};
+
+/* A ringbuffer of "struct prb_desc" elements. */
+struct prb_desc_ring {
+ unsigned int count_bits;
+ struct prb_desc *descs;
+ struct printk_info *infos;
+ atomic_long_t head_id;
+ atomic_long_t tail_id;
+};
+
+/*
+ * The high level structure representing the printk ringbuffer.
+ *
+ * @fail: Count of failed prb_reserve() calls where not even a data-less
+ * record was created.
+ */
+struct printk_ringbuffer {
+ struct prb_desc_ring desc_ring;
+ struct prb_data_ring text_data_ring;
+ atomic_long_t fail;
+};
+
+/*
+ * Used by writers as a reserve/commit handle.
+ *
+ * @rb: Ringbuffer where the entry is reserved.
+ * @irqflags: Saved irq flags to restore on entry commit.
+ * @id: ID of the reserved descriptor.
+ * @text_space: Total occupied buffer space in the text data ring, including
+ * ID, alignment padding, and wrapping data blocks.
+ *
+ * This structure is an opaque handle for writers. Its contents are only
+ * to be used by the ringbuffer implementation.
+ */
+struct prb_reserved_entry {
+ struct printk_ringbuffer *rb;
+ unsigned long irqflags;
+ unsigned long id;
+ unsigned int text_space;
+};
+
+/* The possible responses of a descriptor state-query. */
+enum desc_state {
+ desc_miss = -1, /* ID mismatch (pseudo state) */
+ desc_reserved = 0x0, /* reserved, in use by writer */
+ desc_committed = 0x1, /* committed by writer, could get reopened */
+ desc_finalized = 0x2, /* committed, no further modification allowed */
+ desc_reusable = 0x3, /* free, not yet used by any writer */
+};
+
+#define _DATA_SIZE(sz_bits) (1UL << (sz_bits))
+#define _DESCS_COUNT(ct_bits) (1U << (ct_bits))
+#define DESC_SV_BITS (sizeof(unsigned long) * 8)
+#define DESC_FLAGS_SHIFT (DESC_SV_BITS - 2)
+#define DESC_FLAGS_MASK (3UL << DESC_FLAGS_SHIFT)
+#define DESC_STATE(sv) (3UL & (sv >> DESC_FLAGS_SHIFT))
+#define DESC_SV(id, state) (((unsigned long)state << DESC_FLAGS_SHIFT) | id)
+#define DESC_ID_MASK (~DESC_FLAGS_MASK)
+#define DESC_ID(sv) ((sv) & DESC_ID_MASK)
+#define FAILED_LPOS 0x1
+#define NO_LPOS 0x3
+
+#define FAILED_BLK_LPOS \
+{ \
+ .begin = FAILED_LPOS, \
+ .next = FAILED_LPOS, \
+}
+
+/*
+ * Descriptor Bootstrap
+ *
+ * The descriptor array is minimally initialized to allow immediate usage
+ * by readers and writers. The requirements that the descriptor array
+ * initialization must satisfy:
+ *
+ * Req1
+ * The tail must point to an existing (committed or reusable) descriptor.
+ * This is required by the implementation of prb_first_seq().
+ *
+ * Req2
+ * Readers must see that the ringbuffer is initially empty.
+ *
+ * Req3
+ * The first record reserved by a writer is assigned sequence number 0.
+ *
+ * To satisfy Req1, the tail initially points to a descriptor that is
+ * minimally initialized (having no data block, i.e. data-less with the
+ * data block's lpos @begin and @next values set to FAILED_LPOS).
+ *
+ * To satisfy Req2, the initial tail descriptor is initialized to the
+ * reusable state. Readers recognize reusable descriptors as existing
+ * records, but skip over them.
+ *
+ * To satisfy Req3, the last descriptor in the array is used as the initial
+ * head (and tail) descriptor. This allows the first record reserved by a
+ * writer (head + 1) to be the first descriptor in the array. (Only the first
+ * descriptor in the array could have a valid sequence number of 0.)
+ *
+ * The first time a descriptor is reserved, it is assigned a sequence number
+ * with the value of the array index. A "first time reserved" descriptor can
+ * be recognized because it has a sequence number of 0 but does not have an
+ * index of 0. (Only the first descriptor in the array could have a valid
+ * sequence number of 0.) After the first reservation, all future reservations
+ * (recycling) simply involve incrementing the sequence number by the array
+ * count.
+ *
+ * Hack #1
+ * Only the first descriptor in the array is allowed to have the sequence
+ * number 0. In this case it is not possible to recognize if it is being
+ * reserved the first time (set to index value) or has been reserved
+ * previously (increment by the array count). This is handled by _always_
+ * incrementing the sequence number by the array count when reserving the
+ * first descriptor in the array. In order to satisfy Req3, the sequence
+ * number of the first descriptor in the array is initialized to minus
+ * the array count. Then, upon the first reservation, it is incremented
+ * to 0, thus satisfying Req3.
+ *
+ * Hack #2
+ * prb_first_seq() can be called at any time by readers to retrieve the
+ * sequence number of the tail descriptor. However, due to Req2 and Req3,
+ * initially there are no records to report the sequence number of
+ * (sequence numbers are u64 and there is nothing less than 0). To handle
+ * this, the sequence number of the initial tail descriptor is initialized
+ * to 0. Technically this is incorrect, because there is no record with
+ * sequence number 0 (yet) and the tail descriptor is not the first
+ * descriptor in the array. But it allows prb_read_valid() to correctly
+ * report the existence of a record for _any_ given sequence number at all
+ * times. Bootstrapping is complete when the tail is pushed the first
+ * time, thus finally pointing to the first descriptor reserved by a
+ * writer, which has the assigned sequence number 0.
+ */
+
+/*
+ * Initiating Logical Value Overflows
+ *
+ * Both logical position (lpos) and ID values can be mapped to array indexes
+ * but may experience overflows during the lifetime of the system. To ensure
+ * that printk_ringbuffer can handle the overflows for these types, initial
+ * values are chosen that map to the correct initial array indexes, but will
+ * result in overflows soon.
+ *
+ * BLK0_LPOS
+ * The initial @head_lpos and @tail_lpos for data rings. It is at index
+ * 0 and the lpos value is such that it will overflow on the first wrap.
+ *
+ * DESC0_ID
+ * The initial @head_id and @tail_id for the desc ring. It is at the last
+ * index of the descriptor array (see Req3 above) and the ID value is such
+ * that it will overflow on the second wrap.
+ */
+#define BLK0_LPOS(sz_bits) (-(_DATA_SIZE(sz_bits)))
+#define DESC0_ID(ct_bits) DESC_ID(-(_DESCS_COUNT(ct_bits) + 1))
+#define DESC0_SV(ct_bits) DESC_SV(DESC0_ID(ct_bits), desc_reusable)
+
+/*
+ * Define a ringbuffer with an external text data buffer. The same as
+ * DEFINE_PRINTKRB() but requires specifying an external buffer for the
+ * text data.
+ *
+ * Note: The specified external buffer must be of the size:
+ * 2 ^ (descbits + avgtextbits)
+ */
+#define _DEFINE_PRINTKRB(name, descbits, avgtextbits, text_buf) \
+static struct prb_desc _##name##_descs[_DESCS_COUNT(descbits)] = { \
+ /* the initial head and tail */ \
+ [_DESCS_COUNT(descbits) - 1] = { \
+ /* reusable */ \
+ .state_var = ATOMIC_INIT(DESC0_SV(descbits)), \
+ /* no associated data block */ \
+ .text_blk_lpos = FAILED_BLK_LPOS, \
+ }, \
+}; \
+static struct printk_info _##name##_infos[_DESCS_COUNT(descbits)] = { \
+ /* this will be the first record reserved by a writer */ \
+ [0] = { \
+ /* will be incremented to 0 on the first reservation */ \
+ .seq = -(u64)_DESCS_COUNT(descbits), \
+ }, \
+ /* the initial head and tail */ \
+ [_DESCS_COUNT(descbits) - 1] = { \
+ /* reports the first seq value during the bootstrap phase */ \
+ .seq = 0, \
+ }, \
+}; \
+static struct printk_ringbuffer name = { \
+ .desc_ring = { \
+ .count_bits = descbits, \
+ .descs = &_##name##_descs[0], \
+ .infos = &_##name##_infos[0], \
+ .head_id = ATOMIC_INIT(DESC0_ID(descbits)), \
+ .tail_id = ATOMIC_INIT(DESC0_ID(descbits)), \
+ }, \
+ .text_data_ring = { \
+ .size_bits = (avgtextbits) + (descbits), \
+ .data = text_buf, \
+ .head_lpos = ATOMIC_LONG_INIT(BLK0_LPOS((avgtextbits) + (descbits))), \
+ .tail_lpos = ATOMIC_LONG_INIT(BLK0_LPOS((avgtextbits) + (descbits))), \
+ }, \
+ .fail = ATOMIC_LONG_INIT(0), \
+}
+
+/**
+ * DEFINE_PRINTKRB() - Define a ringbuffer.
+ *
+ * @name: The name of the ringbuffer variable.
+ * @descbits: The number of descriptors as a power-of-2 value.
+ * @avgtextbits: The average text data size per record as a power-of-2 value.
+ *
+ * This is a macro for defining a ringbuffer and all internal structures
+ * such that it is ready for immediate use. See _DEFINE_PRINTKRB() for a
+ * variant where the text data buffer can be specified externally.
+ */
+#define DEFINE_PRINTKRB(name, descbits, avgtextbits) \
+static char _##name##_text[1U << ((avgtextbits) + (descbits))] \
+ __aligned(__alignof__(unsigned long)); \
+_DEFINE_PRINTKRB(name, descbits, avgtextbits, &_##name##_text[0])
+
+/* Writer Interface */
+
+/**
+ * prb_rec_init_wd() - Initialize a buffer for writing records.
+ *
+ * @r: The record to initialize.
+ * @text_buf_size: The needed text buffer size.
+ */
+static inline void prb_rec_init_wr(struct printk_record *r,
+ unsigned int text_buf_size)
+{
+ r->info = NULL;
+ r->text_buf = NULL;
+ r->text_buf_size = text_buf_size;
+}
+
+bool prb_reserve(struct prb_reserved_entry *e, struct printk_ringbuffer *rb,
+ struct printk_record *r);
+bool prb_reserve_in_last(struct prb_reserved_entry *e, struct printk_ringbuffer *rb,
+ struct printk_record *r, u32 caller_id, unsigned int max_size);
+void prb_commit(struct prb_reserved_entry *e);
+void prb_final_commit(struct prb_reserved_entry *e);
+
+void prb_init(struct printk_ringbuffer *rb,
+ char *text_buf, unsigned int text_buf_size,
+ struct prb_desc *descs, unsigned int descs_count_bits,
+ struct printk_info *infos);
+unsigned int prb_record_text_space(struct prb_reserved_entry *e);
+
+/* Reader Interface */
+
+/**
+ * prb_rec_init_rd() - Initialize a buffer for reading records.
+ *
+ * @r: The record to initialize.
+ * @info: A buffer to store record meta-data.
+ * @text_buf: A buffer to store text data.
+ * @text_buf_size: The size of @text_buf.
+ *
+ * Initialize all the fields that a reader is interested in. All arguments
+ * (except @r) are optional. Only record data for arguments that are
+ * non-NULL or non-zero will be read.
+ */
+static inline void prb_rec_init_rd(struct printk_record *r,
+ struct printk_info *info,
+ char *text_buf, unsigned int text_buf_size)
+{
+ r->info = info;
+ r->text_buf = text_buf;
+ r->text_buf_size = text_buf_size;
+}
+
+/**
+ * prb_for_each_record() - Iterate over the records of a ringbuffer.
+ *
+ * @from: The sequence number to begin with.
+ * @rb: The ringbuffer to iterate over.
+ * @s: A u64 to store the sequence number on each iteration.
+ * @r: A printk_record to store the record on each iteration.
+ *
+ * This is a macro for conveniently iterating over a ringbuffer.
+ * Note that @s may not be the sequence number of the record on each
+ * iteration. For the sequence number, @r->info->seq should be checked.
+ *
+ * Context: Any context.
+ */
+#define prb_for_each_record(from, rb, s, r) \
+for ((s) = from; prb_read_valid(rb, s, r); (s) = (r)->info->seq + 1)
+
+/**
+ * prb_for_each_info() - Iterate over the meta data of a ringbuffer.
+ *
+ * @from: The sequence number to begin with.
+ * @rb: The ringbuffer to iterate over.
+ * @s: A u64 to store the sequence number on each iteration.
+ * @i: A printk_info to store the record meta data on each iteration.
+ * @lc: An unsigned int to store the text line count of each record.
+ *
+ * This is a macro for conveniently iterating over a ringbuffer.
+ * Note that @s may not be the sequence number of the record on each
+ * iteration. For the sequence number, @r->info->seq should be checked.
+ *
+ * Context: Any context.
+ */
+#define prb_for_each_info(from, rb, s, i, lc) \
+for ((s) = from; prb_read_valid_info(rb, s, i, lc); (s) = (i)->seq + 1)
+
+bool prb_read_valid(struct printk_ringbuffer *rb, u64 seq,
+ struct printk_record *r);
+bool prb_read_valid_info(struct printk_ringbuffer *rb, u64 seq,
+ struct printk_info *info, unsigned int *line_count);
+
+u64 prb_first_valid_seq(struct printk_ringbuffer *rb);
+u64 prb_next_seq(struct printk_ringbuffer *rb);
+
+#endif /* _KERNEL_PRINTK_RINGBUFFER_H */