[Crash-utility] [RFC PATCH 1/1] printk: add support for lockless ringbuffer

Linux is moving to a new lockless ringbuffer. The new ringbuffer is structured completely different to the previous iterations. Add support for retrieving the ringbuffer from debug information and/or using vmcoreinfo. The new ringbuffer is detected based on the availability of the "prb" symbol. Signed-off-by: John Ogness <john.ogness(a)linutronix.de&gt; --- Makefile | 2 +- dwarf_info.c | 36 +++++++++- makedumpfile.c | 101 ++++++++++++++++++++++++++-- makedumpfile.h | 25 +++++++ printk.c | 177 +++++++++++++++++++++++++++++++++++++++++++++++++ 5 files changed, 333 insertions(+), 8 deletions(-) create mode 100644 printk.c diff --git a/Makefile b/Makefile index ef20672..dc4ae3e 100644 --- a/Makefile +++ b/Makefile @@ -45,7 +45,7 @@ CFLAGS_ARCH += -m32 endif SRC_BASE = makedumpfile.c makedumpfile.h diskdump_mod.h sadump_mod.h sadump_info.h -SRC_PART = print_info.c dwarf_info.c elf_info.c erase_info.c sadump_info.c cache.c tools.c +SRC_PART = print_info.c dwarf_info.c elf_info.c erase_info.c sadump_info.c cache.c tools.c printk.c OBJ_PART=$(patsubst %.c,%.o,$(SRC_PART)) SRC_ARCH = arch/arm.c arch/arm64.c arch/x86.c arch/x86_64.c arch/ia64.c arch/ppc64.c arch/s390x.c arch/ppc.c arch/sparc64.c OBJ_ARCH=$(patsubst %.c,%.o,$(SRC_ARCH)) diff --git a/dwarf_info.c b/dwarf_info.c index e42a9f5..543588b 100644 --- a/dwarf_info.c +++ b/dwarf_info.c @@ -614,6 +614,7 @@ search_structure(Dwarf_Die *die, int *found) { int tag; const char *name; + Dwarf_Die die_type; /* * If we get to here then we don't have any more @@ -622,9 +623,31 @@ search_structure(Dwarf_Die *die, int *found) do { tag = dwarf_tag(die); name = dwarf_diename(die); - if ((tag != DW_TAG_structure_type) || (!name) - || strcmp(name, dwarf_info.struct_name)) + if ((!name) || strcmp(name, dwarf_info.struct_name)) + continue; + + if (tag == DW_TAG_typedef) { + if (!get_die_type(die, &die_type)) { + ERRMSG("Can't get CU die of DW_AT_type.\n"); + break; + } + + /* Resolve typedefs of typedefs. */ + while ((tag = dwarf_tag(&die_type)) == DW_TAG_typedef) { + if (!get_die_type(&die_type, &die_type)) { + ERRMSG("Can't get CU die of DW_AT_type.\n"); + return; + } + } + + if (tag != DW_TAG_structure_type) + continue; + die = &die_type; + + } else if (tag != DW_TAG_structure_type) { continue; + } + /* * Skip if DW_AT_byte_size is not included. */ @@ -740,6 +763,15 @@ search_typedef(Dwarf_Die *die, int *found) ERRMSG("Can't get CU die of DW_AT_type.\n"); break; } + + /* Resolve typedefs of typedefs. */ + while ((tag = dwarf_tag(&die_type)) == DW_TAG_typedef) { + if (!get_die_type(&die_type, &die_type)) { + ERRMSG("Can't get CU die of DW_AT_type.\n"); + return; + } + } + dwarf_info.struct_size = dwarf_bytesize(&die_type); if (dwarf_info.struct_size <= 0) continue; diff --git a/makedumpfile.c b/makedumpfile.c index f5860a1..6192ee7 100644 --- a/makedumpfile.c +++ b/makedumpfile.c @@ -1555,6 +1555,7 @@ get_symbol_info(void) SYMBOL_INIT(node_data, "node_data"); SYMBOL_INIT(pgdat_list, "pgdat_list"); SYMBOL_INIT(contig_page_data, "contig_page_data"); + SYMBOL_INIT(prb, "prb"); SYMBOL_INIT(log_buf, "log_buf"); SYMBOL_INIT(log_buf_len, "log_buf_len"); SYMBOL_INIT(log_end, "log_end"); @@ -1971,16 +1972,46 @@ get_structure_info(void) OFFSET_INIT(elf64_phdr.p_memsz, "elf64_phdr", "p_memsz"); SIZE_INIT(printk_log, "printk_log"); - if (SIZE(printk_log) != NOT_FOUND_STRUCTURE) { + SIZE_INIT(printk_ringbuffer, "printk_ringbuffer"); + if ((SIZE(printk_ringbuffer) != NOT_FOUND_STRUCTURE)) { + info->flag_use_printk_ringbuffer = TRUE; + info->flag_use_printk_log = FALSE; + + OFFSET_INIT(printk_log.desc_ring, "printk_ringbuffer", "desc_ring"); + OFFSET_INIT(printk_log.text_data_ring, "printk_ringbuffer", "text_data_ring"); + + OFFSET_INIT(printk_log.count_bits, "prb_desc_ring", "count_bits"); + OFFSET_INIT(printk_log.descs, "prb_desc_ring", "descs"); + OFFSET_INIT(printk_log.head_id, "prb_desc_ring", "head_id"); + OFFSET_INIT(printk_log.tail_id, "prb_desc_ring", "tail_id"); + + SIZE_INIT(prb_desc, "prb_desc"); + OFFSET_INIT(printk_log.info, "prb_desc", "info"); + OFFSET_INIT(printk_log.state_var, "prb_desc", "state_var"); + OFFSET_INIT(printk_log.text_blk_lpos, "prb_desc", "text_blk_lpos"); + + OFFSET_INIT(printk_log.begin, "prb_data_blk_lpos", "begin"); + OFFSET_INIT(printk_log.next, "prb_data_blk_lpos", "next"); + + OFFSET_INIT(printk_log.size_bits, "prb_data_ring", "size_bits"); + OFFSET_INIT(printk_log.data, "prb_data_ring", "data"); + + OFFSET_INIT(printk_log.ts_nsec, "printk_info", "ts_nsec"); + OFFSET_INIT(printk_log.text_len, "printk_info", "text_len"); + + OFFSET_INIT(printk_log.counter, "atomic_long_t", "counter"); + } else if (SIZE(printk_log) != NOT_FOUND_STRUCTURE) { /* * In kernel 3.11-rc4 the log structure name was renamed * to "printk_log". */ + info->flag_use_printk_ringbuffer = FALSE; info->flag_use_printk_log = TRUE; OFFSET_INIT(printk_log.ts_nsec, "printk_log", "ts_nsec"); OFFSET_INIT(printk_log.len, "printk_log", "len"); OFFSET_INIT(printk_log.text_len, "printk_log", "text_len"); } else { + info->flag_use_printk_ringbuffer = FALSE; info->flag_use_printk_log = FALSE; SIZE_INIT(printk_log, "log"); OFFSET_INIT(printk_log.ts_nsec, "log", "ts_nsec"); @@ -2191,6 +2222,7 @@ write_vmcoreinfo_data(void) WRITE_SYMBOL("node_data", node_data); WRITE_SYMBOL("pgdat_list", pgdat_list); WRITE_SYMBOL("contig_page_data", contig_page_data); + WRITE_SYMBOL("prb", prb); WRITE_SYMBOL("log_buf", log_buf); WRITE_SYMBOL("log_buf_len", log_buf_len); WRITE_SYMBOL("log_end", log_end); @@ -2222,7 +2254,10 @@ write_vmcoreinfo_data(void) WRITE_STRUCTURE_SIZE("node_memblk_s", node_memblk_s); WRITE_STRUCTURE_SIZE("nodemask_t", nodemask_t); WRITE_STRUCTURE_SIZE("pageflags", pageflags); - if (info->flag_use_printk_log) + if (info->flag_use_printk_ringbuffer) { + WRITE_STRUCTURE_SIZE("printk_ringbuffer", printk_ringbuffer); + WRITE_STRUCTURE_SIZE("prb_desc", prb_desc); + } else if (info->flag_use_printk_log) WRITE_STRUCTURE_SIZE("printk_log", printk_log); else WRITE_STRUCTURE_SIZE("log", printk_log); @@ -2268,7 +2303,30 @@ write_vmcoreinfo_data(void) WRITE_MEMBER_OFFSET("vm_struct.addr", vm_struct.addr); WRITE_MEMBER_OFFSET("vmap_area.va_start", vmap_area.va_start); WRITE_MEMBER_OFFSET("vmap_area.list", vmap_area.list); - if (info->flag_use_printk_log) { + if (info->flag_use_printk_ringbuffer) { + WRITE_MEMBER_OFFSET("printk_ringbuffer.desc_ring", printk_log.desc_ring); + WRITE_MEMBER_OFFSET("printk_ringbuffer.text_data_ring", printk_log.text_data_ring); + + WRITE_MEMBER_OFFSET("prb_desc_ring.count_bits", printk_log.count_bits); + WRITE_MEMBER_OFFSET("prb_desc_ring.descs", printk_log.descs); + WRITE_MEMBER_OFFSET("prb_desc_ring.head_id", printk_log.head_id); + WRITE_MEMBER_OFFSET("prb_desc_ring.tail_id", printk_log.tail_id); + + WRITE_MEMBER_OFFSET("prb_desc.info", printk_log.info); + WRITE_MEMBER_OFFSET("prb_desc.state_var", printk_log.state_var); + WRITE_MEMBER_OFFSET("prb_desc.text_blk_lpos", printk_log.text_blk_lpos); + + WRITE_MEMBER_OFFSET("prb_data_blk_lpos.begin", printk_log.begin); + WRITE_MEMBER_OFFSET("prb_data_blk_lpos.next", printk_log.next); + + WRITE_MEMBER_OFFSET("prb_data_ring.size_bits", printk_log.size_bits); + WRITE_MEMBER_OFFSET("prb_data_ring.data", printk_log.data); + + WRITE_MEMBER_OFFSET("printk_info.ts_nsec", printk_log.ts_nsec); + WRITE_MEMBER_OFFSET("printk_info.text_len", printk_log.text_len); + + WRITE_MEMBER_OFFSET("atomic_long_t.counter", printk_log.counter); + } else if (info->flag_use_printk_log) { WRITE_MEMBER_OFFSET("printk_log.ts_nsec", printk_log.ts_nsec); WRITE_MEMBER_OFFSET("printk_log.len", printk_log.len); WRITE_MEMBER_OFFSET("printk_log.text_len", printk_log.text_len); @@ -2606,6 +2664,7 @@ read_vmcoreinfo(void) READ_SYMBOL("node_data", node_data); READ_SYMBOL("pgdat_list", pgdat_list); READ_SYMBOL("contig_page_data", contig_page_data); + READ_SYMBOL("prb", prb); READ_SYMBOL("log_buf", log_buf); READ_SYMBOL("log_buf_len", log_buf_len); READ_SYMBOL("log_end", log_end); @@ -2684,12 +2743,42 @@ read_vmcoreinfo(void) READ_MEMBER_OFFSET("cpu_spec.mmu_features", cpu_spec.mmu_features); READ_STRUCTURE_SIZE("printk_log", printk_log); - if (SIZE(printk_log) != NOT_FOUND_STRUCTURE) { + READ_STRUCTURE_SIZE("printk_ringbuffer", printk_ringbuffer); + if (SIZE(printk_ringbuffer) != NOT_FOUND_STRUCTURE) { + info->flag_use_printk_ringbuffer = TRUE; + info->flag_use_printk_log = FALSE; + + READ_MEMBER_OFFSET("printk_ringbuffer.desc_ring", printk_log.desc_ring); + READ_MEMBER_OFFSET("printk_ringbuffer.text_data_ring", printk_log.text_data_ring); + + READ_MEMBER_OFFSET("prb_desc_ring.count_bits", printk_log.count_bits); + READ_MEMBER_OFFSET("prb_desc_ring.descs", printk_log.descs); + READ_MEMBER_OFFSET("prb_desc_ring.head_id", printk_log.head_id); + READ_MEMBER_OFFSET("prb_desc_ring.tail_id", printk_log.tail_id); + + READ_STRUCTURE_SIZE("prb_desc", prb_desc); + READ_MEMBER_OFFSET("prb_desc.info", printk_log.info); + READ_MEMBER_OFFSET("prb_desc.state_var", printk_log.state_var); + READ_MEMBER_OFFSET("prb_desc.text_blk_lpos", printk_log.text_blk_lpos); + + READ_MEMBER_OFFSET("prb_data_blk_lpos.begin", printk_log.begin); + READ_MEMBER_OFFSET("prb_data_blk_lpos.next", printk_log.next); + + READ_MEMBER_OFFSET("prb_data_ring.size_bits", printk_log.size_bits); + READ_MEMBER_OFFSET("prb_data_ring.data", printk_log.data); + + READ_MEMBER_OFFSET("printk_info.ts_nsec", printk_log.ts_nsec); + READ_MEMBER_OFFSET("printk_info.text_len", printk_log.text_len); + + READ_MEMBER_OFFSET("atomic_long_t.counter", printk_log.counter); + } else if (SIZE(printk_log) != NOT_FOUND_STRUCTURE) { + info->flag_use_printk_ringbuffer = FALSE; info->flag_use_printk_log = TRUE; READ_MEMBER_OFFSET("printk_log.ts_nsec", printk_log.ts_nsec); READ_MEMBER_OFFSET("printk_log.len", printk_log.len); READ_MEMBER_OFFSET("printk_log.text_len", printk_log.text_len); } else { + info->flag_use_printk_ringbuffer = FALSE; info->flag_use_printk_log = FALSE; READ_STRUCTURE_SIZE("log", printk_log); READ_MEMBER_OFFSET("log.ts_nsec", printk_log.ts_nsec); @@ -5303,6 +5392,9 @@ dump_dmesg() if (!initial()) return FALSE; + if ((SYMBOL(prb) != NOT_FOUND_SYMBOL)) + return dump_lockless_dmesg(); + if ((SYMBOL(log_buf) == NOT_FOUND_SYMBOL) || (SYMBOL(log_buf_len) == NOT_FOUND_SYMBOL)) { ERRMSG("Can't find some symbols for log_buf.\n"); @@ -5447,7 +5539,6 @@ out: return ret; } - int _exclude_free_page(struct cycle *cycle) { diff --git a/makedumpfile.h b/makedumpfile.h index 03fb4ce..70bc805 100644 --- a/makedumpfile.h +++ b/makedumpfile.h @@ -1317,6 +1317,7 @@ struct DumpInfo { int flag_partial_dmesg; /* dmesg dump only from the last cleared index*/ int flag_mem_usage; /*show the page number of memory in different use*/ int flag_use_printk_log; /* did we read printk_log symbol name? */ + int flag_use_printk_ringbuffer; /* using lockless printk ringbuffer? */ int flag_nospace; /* the flag of "No space on device" error */ int flag_vmemmap; /* kernel supports vmemmap address space */ int flag_excludevm; /* -e - excluding unused vmemmap pages */ @@ -1602,6 +1603,7 @@ struct symbol_table { unsigned long long node_data; unsigned long long pgdat_list; unsigned long long contig_page_data; + unsigned long long prb; unsigned long long log_buf; unsigned long long log_buf_len; unsigned long long log_end; @@ -1689,6 +1691,12 @@ struct size_table { long nodemask_t; long printk_log; + /* + * for lockless printk + */ + long printk_ringbuffer; + long prb_desc; + /* * for Xen extraction */ @@ -1862,6 +1870,20 @@ struct offset_table { long ts_nsec; long len; long text_len; + long desc_ring; + long text_data_ring; + long count_bits; + long descs; + long head_id; + long tail_id; + long info; + long state_var; + long text_blk_lpos; + long begin; + long next; + long size_bits; + long data; + long counter; } printk_log; /* @@ -2390,4 +2412,7 @@ int hexadecimal(char *s, int count); int decimal(char *s, int count); int file_exists(char *file); +int open_dump_file(void); +int dump_lockless_dmesg(void); + #endif /* MAKEDUMPFILE_H */ diff --git a/printk.c b/printk.c new file mode 100644 index 0000000..a7239b2 --- /dev/null +++ b/printk.c @@ -0,0 +1,177 @@ +#include "makedumpfile.h" +#include <ctype.h> + +#define DESC_SV_BITS (sizeof(unsigned long) * 8) +#define DESC_COMMITTED_MASK (1UL << (DESC_SV_BITS - 1)) +#define DESC_REUSE_MASK (1UL << (DESC_SV_BITS - 2)) +#define DESC_FLAGS_MASK (DESC_COMMITTED_MASK | DESC_REUSE_MASK) +#define DESC_ID_MASK (~DESC_FLAGS_MASK) + +/* convenience struct for passing many values to helper functions */ +struct prb_map { + char *prb; + + char *desc_ring; + unsigned long desc_ring_count; + char *descs; + + char *text_data_ring; + unsigned long text_data_ring_size; + char *text_data; +}; + +static void +dump_record(struct prb_map *m, unsigned long id) +{ + unsigned long long ts_nsec; + unsigned long state_var; + unsigned short text_len; + unsigned long begin; + unsigned long next; + char buf[BUFSIZE]; + ulonglong nanos; + int indent_len; + int buf_need; + char *bufp; + char *text; + char *desc; + char *inf; + ulong rem; + char *p; + int i; + + desc = m->descs + ((id % m->desc_ring_count) * SIZE(prb_desc)); + + /* skip non-committed record */ + state_var = ULONG(desc + OFFSET(printk_log.state_var) + + OFFSET(printk_log.counter)); + if ((state_var & DESC_FLAGS_MASK) != DESC_COMMITTED_MASK) + return; + + inf = desc + OFFSET(printk_log.info); + + begin = ULONG(desc + OFFSET(printk_log.text_blk_lpos) + + OFFSET(printk_log.begin)) % + m->text_data_ring_size; + next = ULONG(desc + OFFSET(printk_log.text_blk_lpos) + + OFFSET(printk_log.next)) % + m->text_data_ring_size; + + /* skip data-less text blocks */ + if (begin == next) + return; + + text_len = USHORT(inf + OFFSET(printk_log.text_len)); + + /* handle wrapping data block */ + if (begin > next) + begin = 0; + + /* skip over descriptor ID */ + begin += sizeof(unsigned long); + + /* handle truncated messages */ + if (next - begin < text_len) + text_len = next - begin; + + text = m->text_data + begin; + + ts_nsec = ULONGLONG(inf + OFFSET(printk_log.ts_nsec)); + nanos = (ulonglong)ts_nsec / (ulonglong)1000000000; + rem = (ulonglong)ts_nsec % (ulonglong)1000000000; + + bufp = buf; + bufp += sprintf(buf, "[%5lld.%06ld] ", nanos, rem/1000); + indent_len = strlen(buf); + + /* How much buffer space is needed in the worst case */ + buf_need = MAX(sizeof("\\xXX\n"), sizeof("\n") + indent_len); + + for (i = 0, p = text; i < text_len; i++, p++) { + if (bufp - buf >= sizeof(buf) - buf_need) { + if (write(info->fd_dumpfile, buf, bufp - buf) < 0) + return; + bufp = buf; + } + + if (*p == '\n') + bufp += sprintf(bufp, "\n%-*s", indent_len, ""); + else if (isprint(*p) || isspace(*p)) + *bufp++ = *p; + else + bufp += sprintf(bufp, "\\x%02x", *p); + } + + *bufp++ = '\n'; + + write(info->fd_dumpfile, buf, bufp - buf); +} + +int +dump_lockless_dmesg(void) +{ + unsigned long head_id; + unsigned long tail_id; + unsigned long kaddr; + unsigned long id; + struct prb_map m; + int ret = FALSE; + + /* setup printk_ringbuffer */ + readmem(VADDR, SYMBOL(prb), &kaddr, sizeof(kaddr)); + m.prb = malloc(SIZE(printk_ringbuffer)); + if (!readmem(VADDR, kaddr, m.prb, SIZE(printk_ringbuffer))) { + ERRMSG("Can't get prb.\n"); + goto out_prb; + } + + /* setup descriptor ring */ + m.desc_ring = m.prb + OFFSET(printk_log.desc_ring); + m.desc_ring_count = 1 << UINT(m.desc_ring + + OFFSET(printk_log.count_bits)); + kaddr = ULONG(m.desc_ring + OFFSET(printk_log.descs)); + m.descs = malloc(SIZE(prb_desc) * m.desc_ring_count); + if (!readmem(VADDR, kaddr, m.descs, + SIZE(prb_desc) * m.desc_ring_count)) { + ERRMSG("Can't get prb.desc_ring.\n"); + goto out_descs; + } + + /* setup text data ring */ + m.text_data_ring = m.prb + OFFSET(printk_log.text_data_ring); + m.text_data_ring_size = 1 << UINT(m.text_data_ring + + OFFSET(printk_log.size_bits)); + kaddr = ULONG(m.text_data_ring + OFFSET(printk_log.data)); + m.text_data = malloc(m.text_data_ring_size); + if (!readmem(VADDR, kaddr, m.text_data, m.text_data_ring_size)) { + ERRMSG("Can't get prb.text_data_ring.\n"); + goto out_text_data; + } + + /* ready to go */ + + tail_id = ULONG(m.desc_ring + OFFSET(printk_log.tail_id) + + OFFSET(printk_log.counter)); + head_id = ULONG(m.desc_ring + OFFSET(printk_log.head_id) + + OFFSET(printk_log.counter)); + + if (!open_dump_file()) { + ERRMSG("Can't open output file.\n"); + goto out_text_data; + } + + for (id = tail_id; id != head_id; id = (id + 1) & DESC_ID_MASK) + dump_record(&m, id); + + if (!close_files_for_creating_dumpfile()) + goto out_text_data; + + ret = TRUE; +out_text_data: + free(m.text_data); +out_descs: + free(m.descs); +out_prb: + free(m.prb); + return ret; +} -- 2.20.1