| Message ID | 20201008234000.740660-6-andrii@kernel.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | None | expand |
Em Thu, Oct 08, 2020 at 04:39:57PM -0700, Andrii Nakryiko escreveu: > From: Andrii Nakryiko <andriin@fb.com> > > Right now to encode per-CPU variables in BTF, pahole iterates complete vmlinux > symbol table for each CU. There are 2500 CUs for a typical kernel image. > Overall, to encode 287 per-CPU variables pahole spends more than 10% of its CPU > budget, this is incredibly wasteful. You forgot to add Hao to the Cc list, Hao, can you take a look? I'm tentatively applying it to my local branch, but would like to hear from you since you wrote this code. - Arnaldo > > This patch revamps how this is done. Now it pre-processes symbol table once > before any of per-CU processing starts. It remembers each per-CPU variable > symbol, including its address, size, and name. Then during processing each CU, > binary search is used to correlate DWARF variable with per-CPU symbols and > figure out if variable belongs to per-CPU data section. If the match is found, > BTF_KIND_VAR is emitted and var_secinfo is recorded, just like before. At the > very end, after all CUs are processed, BTF_KIND_DATASEC is emitted with sorted > variables. > > This change makes per-CPU variables generation overhead pretty negligible and > returns back about 10% of CPU usage. > > Performance counter stats for './pahole -J /home/andriin/linux-build/default/vmlinux': > > BEFORE: > 19.160149000 seconds user > 1.304873000 seconds sys > > 24,114.05 msec task-clock # 0.999 CPUs utilized > 83 context-switches # 0.003 K/sec > 0 cpu-migrations # 0.000 K/sec > 622,417 page-faults # 0.026 M/sec > 72,897,315,125 cycles # 3.023 GHz (25.02%) > 127,807,316,959 instructions # 1.75 insn per cycle (25.01%) > 29,087,179,117 branches # 1206.234 M/sec (25.01%) > 464,105,921 branch-misses # 1.60% of all branches (25.01%) > 30,252,119,368 L1-dcache-loads # 1254.543 M/sec (25.01%) > 1,156,336,207 L1-dcache-load-misses # 3.82% of all L1-dcache hits (25.05%) > 343,373,503 LLC-loads # 14.240 M/sec (25.02%) > 12,044,977 LLC-load-misses # 3.51% of all LL-cache hits (25.01%) > > 24.136198321 seconds time elapsed > > 22.729693000 seconds user > 1.384859000 seconds sys > > AFTER: > 16.781455000 seconds user > 1.343956000 seconds sys > > 23,398.77 msec task-clock # 1.000 CPUs utilized > 86 context-switches # 0.004 K/sec > 0 cpu-migrations # 0.000 K/sec > 622,420 page-faults # 0.027 M/sec > 68,395,641,468 cycles # 2.923 GHz (25.05%) > 114,241,327,034 instructions # 1.67 insn per cycle (25.01%) > 26,330,711,718 branches # 1125.303 M/sec (25.01%) > 465,926,869 branch-misses # 1.77% of all branches (25.00%) > 24,662,984,772 L1-dcache-loads # 1054.029 M/sec (25.00%) > 1,054,052,064 L1-dcache-load-misses # 4.27% of all L1-dcache hits (25.00%) > 340,970,622 LLC-loads # 14.572 M/sec (25.00%) > 16,032,297 LLC-load-misses # 4.70% of all LL-cache hits (25.03%) > > 23.402259654 seconds time elapsed > > 21.916437000 seconds user > 1.482826000 seconds sys > > Signed-off-by: Andrii Nakryiko <andriin@fb.com> > --- > btf_encoder.c | 248 +++++++++++++++++++++++++++++--------------------- > libbtf.c | 6 +- > libbtf.h | 1 + > 3 files changed, 148 insertions(+), 107 deletions(-) > > diff --git a/btf_encoder.c b/btf_encoder.c > index 2e5df03e040f..2a6455be4c52 100644 > --- a/btf_encoder.c > +++ b/btf_encoder.c > @@ -17,6 +17,7 @@ > #include "btf_encoder.h" > > #include <ctype.h> /* for isalpha() and isalnum() */ > +#include <stdlib.h> /* for qsort() and bsearch() */ > #include <inttypes.h> > > /* > @@ -53,18 +54,18 @@ static bool btf_name_valid(const char *p) > return !*p; > } > > -static void dump_invalid_symbol(const char *msg, const char *sym, const char *cu, > +static void dump_invalid_symbol(const char *msg, const char *sym, > int verbose, bool force) > { > if (force) { > if (verbose) > - fprintf(stderr, "PAHOLE: Warning: %s, ignored (sym: '%s', cu: '%s').\n", > - msg, sym, cu); > + fprintf(stderr, "PAHOLE: Warning: %s, ignored (sym: '%s').\n", > + msg, sym); > return; > } > > - fprintf(stderr, "PAHOLE: Error: %s (sym: '%s', cu: '%s').\n", msg, sym, cu); > - fprintf(stderr, "PAHOLE: Error: Use '-j' or '--force' to ignore such symbols and force emit the btf.\n"); > + fprintf(stderr, "PAHOLE: Error: %s (sym: '%s').\n", msg, sym); > + fprintf(stderr, "PAHOLE: Error: Use '--btf_encode_force' to ignore such symbols and force emit the btf.\n"); > } > > extern struct debug_fmt_ops *dwarves__active_loader; > @@ -202,6 +203,9 @@ int btf_encoder__encode() > { > int err; > > + if (gobuffer__size(&btfe->percpu_secinfo) != 0) > + btf_elf__add_datasec_type(btfe, PERCPU_SECTION, &btfe->percpu_secinfo); > + > err = btf_elf__encode(btfe, 0); > btf_elf__delete(btfe); > btfe = NULL; > @@ -209,24 +213,117 @@ int btf_encoder__encode() > return err; > } > > -#define HASHADDR__BITS 8 > -#define HASHADDR__SIZE (1UL << HASHADDR__BITS) > -#define hashaddr__fn(key) hash_64(key, HASHADDR__BITS) > +#define MAX_PERCPU_VAR_CNT 4096 > + > +struct var_info { > + uint64_t addr; > + uint32_t sz; > + const char *name; > +}; > + > +static struct var_info percpu_vars[MAX_PERCPU_VAR_CNT]; > +static int percpu_var_cnt; > + > +static int percpu_var_cmp(const void *_a, const void *_b) > +{ > + const struct var_info *a = _a; > + const struct var_info *b = _b; > + > + if (a->addr == b->addr) > + return 0; > + return a->addr < b->addr ? -1 : 1; > +} > + > +static bool percpu_var_exists(uint64_t addr, uint32_t *sz, const char **name) > +{ > + const struct var_info *p; > + struct var_info key = { .addr = addr }; > + > + p = bsearch(&key, percpu_vars, percpu_var_cnt, > + sizeof(percpu_vars[0]), percpu_var_cmp); > + > + if (!p) > + return false; > + > + *sz = p->sz; > + *name = p->name; > + return true; > +} > > -static struct variable *hashaddr__find_variable(const struct hlist_head hashtable[], > - const uint64_t addr) > +static int find_all_percpu_vars(struct btf_elf *btfe) > { > - struct variable *variable; > - struct hlist_node *pos; > - uint16_t bucket = hashaddr__fn(addr); > - const struct hlist_head *head = &hashtable[bucket]; > - > - hlist_for_each_entry(variable, pos, head, tool_hnode) { > - if (variable->ip.addr == addr) > - return variable; > + uint32_t core_id; > + GElf_Sym sym; > + > + /* cache variables' addresses, preparing for searching in symtab. */ > + percpu_var_cnt = 0; > + > + /* search within symtab for percpu variables */ > + elf_symtab__for_each_symbol(btfe->symtab, core_id, sym) { > + const char *sym_name; > + uint64_t addr; > + uint32_t size; > + > + /* compare a symbol's shndx to determine if it's a percpu variable */ > + if (elf_sym__section(&sym) != btfe->percpu_shndx) > + continue; > + if (elf_sym__type(&sym) != STT_OBJECT) > + continue; > + > + addr = elf_sym__value(&sym); > + /* > + * Store only those symbols that have allocated space in the percpu section. > + * This excludes the following three types of symbols: > + * > + * 1. __ADDRESSABLE(sym), which are forcely emitted as symbols. > + * 2. __UNIQUE_ID(prefix), which are introduced to generate unique ids. > + * 3. __exitcall(fn), functions which are labeled as exit calls. > + * > + * In addition, the variables defined using DEFINE_PERCPU_FIRST are > + * also not included, which currently includes: > + * > + * 1. fixed_percpu_data > + */ > + if (!addr) > + continue; > + > + sym_name = elf_sym__name(&sym, btfe->symtab); > + if (!btf_name_valid(sym_name)) { > + dump_invalid_symbol("Found symbol of invalid name when encoding btf", > + sym_name, btf_elf__verbose, btf_elf__force); > + if (btf_elf__force) > + continue; > + return -1; > + } > + size = elf_sym__size(&sym); > + if (!size) { > + dump_invalid_symbol("Found symbol of zero size when encoding btf", > + sym_name, btf_elf__verbose, btf_elf__force); > + if (btf_elf__force) > + continue; > + return -1; > + } > + > + if (btf_elf__verbose) > + printf("Found per-CPU symbol '%s' at address 0x%lx\n", sym_name, addr); > + > + if (percpu_var_cnt == MAX_PERCPU_VAR_CNT) { > + fprintf(stderr, "Reached the limit of per-CPU variables: %d\n", > + MAX_PERCPU_VAR_CNT); > + return -1; > + } > + percpu_vars[percpu_var_cnt].addr = addr; > + percpu_vars[percpu_var_cnt].sz = size; > + percpu_vars[percpu_var_cnt].name = sym_name; > + percpu_var_cnt++; > } > > - return NULL; > + if (percpu_var_cnt) > + qsort(percpu_vars, percpu_var_cnt, sizeof(percpu_vars[0]), percpu_var_cmp); > + > + if (btf_elf__verbose) > + printf("Found %d per-CPU variables!\n", percpu_var_cnt); > + return 0; > } > > int cu__encode_btf(struct cu *cu, int verbose, bool force, > @@ -234,13 +331,10 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, > { > uint32_t type_id_off; > uint32_t core_id; > + struct variable *var; > struct function *fn; > struct tag *pos; > int err = 0; > - struct hlist_head hash_addr[HASHADDR__SIZE]; > - struct variable *var; > - bool has_global_var = false; > - GElf_Sym sym; > > if (btfe && strcmp(btfe->filename, cu->filename)) { > err = btf_encoder__encode(); > @@ -257,6 +351,9 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, > if (!btfe) > return -1; > > + if (!skip_encoding_vars && find_all_percpu_vars(btfe)) > + goto out; > + > has_index_type = false; > need_index_type = false; > array_index_id = 0; > @@ -278,6 +375,7 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, > } > > btf_elf__verbose = verbose; > + btf_elf__force = force; > type_id_off = btf__get_nr_types(btfe->btf); > > cu__for_each_type(cu, core_id, pos) { > @@ -325,12 +423,11 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, > if (verbose) > printf("search cu '%s' for percpu global variables.\n", cu->name); > > - /* cache variables' addresses, preparing for searching in symtab. */ > - for (core_id = 0; core_id < HASHADDR__SIZE; ++core_id) > - INIT_HLIST_HEAD(&hash_addr[core_id]); > - > cu__for_each_variable(cu, core_id, pos) { > - struct hlist_head *head; > + uint32_t size, type, linkage, offset; > + const char *name; > + uint64_t addr; > + int id; > > var = tag__variable(pos); > if (var->declaration && !var->spec) > @@ -338,89 +435,37 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, > /* percpu variables are allocated in global space */ > if (variable__scope(var) != VSCOPE_GLOBAL && !var->spec) > continue; > - has_global_var = true; > - head = &hash_addr[hashaddr__fn(var->ip.addr)]; > - hlist_add_head(&var->tool_hnode, head); > - } > - if (!has_global_var) { > - if (verbose) > - printf("cu has no global variable defined, skip.\n"); > - goto out; > - } > - > - /* search within symtab for percpu variables */ > - elf_symtab__for_each_symbol(btfe->symtab, core_id, sym) { > - uint32_t linkage, type, size, offset; > - int32_t btf_var_id, btf_var_secinfo_id; > - uint64_t addr; > - const char *sym_name; > - > - /* compare a symbol's shndx to determine if it's a percpu variable */ > - if (elf_sym__section(&sym) != btfe->percpu_shndx) > - continue; > - if (elf_sym__type(&sym) != STT_OBJECT) > - continue; > > - addr = elf_sym__value(&sym); > - /* > - * Store only those symbols that have allocated space in the percpu section. > - * This excludes the following three types of symbols: > - * > - * 1. __ADDRESSABLE(sym), which are forcely emitted as symbols. > - * 2. __UNIQUE_ID(prefix), which are introduced to generate unique ids. > - * 3. __exitcall(fn), functions which are labeled as exit calls. > - * > - * In addition, the variables defined using DEFINE_PERCPU_FIRST are > - * also not included, which currently includes: > - * > - * 1. fixed_percpu_data > - */ > - if (!addr) > - continue; > - var = hashaddr__find_variable(hash_addr, addr); > - if (var == NULL) > - continue; > + /* addr has to be recorded before we follow spec */ > + addr = var->ip.addr; > if (var->spec) > var = var->spec; > > - sym_name = elf_sym__name(&sym, btfe->symtab); > - if (!btf_name_valid(sym_name)) { > - dump_invalid_symbol("Found symbol of invalid name when encoding btf", > - sym_name, cu->name, verbose, force); > - if (force) > - continue; > - err = -1; > - break; > - } > if (var->ip.tag.type == 0) { > - dump_invalid_symbol("Found symbol of void type when encoding btf", > - sym_name, cu->name, verbose, force); > - if (force) > - continue; > - err = -1; > - break; > - } > - type = type_id_off + var->ip.tag.type; > - size = elf_sym__size(&sym); > - if (!size) { > - dump_invalid_symbol("Found symbol of zero size when encoding btf", > - sym_name, cu->name, verbose, force); > + fprintf(stderr, "error: found variable in CU '%s' that has void type\n", > + cu->name); > if (force) > continue; > err = -1; > break; > } > > - if (verbose) > - printf("symbol '%s' of address 0x%lx encoded\n", > - sym_name, addr); > + type = var->ip.tag.type + type_id_off; > + linkage = var->external ? BTF_VAR_GLOBAL_ALLOCATED : BTF_VAR_STATIC; > + if (!percpu_var_exists(addr, &size, &name)) > + continue; /* not a per-CPU variable */ > + > + if (btf_elf__verbose) { > + printf("Variable '%s' from CU '%s' at address 0x%lx encoded\n", > + name, cu->name, addr); > + } > > /* add a BTF_KIND_VAR in btfe->types */ > - linkage = var->external ? BTF_VAR_GLOBAL_ALLOCATED : BTF_VAR_STATIC; > - btf_var_id = btf_elf__add_var_type(btfe, type, sym_name, linkage); > - if (btf_var_id < 0) { > + id = btf_elf__add_var_type(btfe, type, name, linkage); > + if (id < 0) { > err = -1; > - printf("error: failed to encode variable '%s'\n", sym_name); > + fprintf(stderr, "error: failed to encode variable '%s' at addr 0x%lx\n", > + name, addr); > break; > } > > @@ -428,13 +473,12 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, > * add a BTF_VAR_SECINFO in btfe->percpu_secinfo, which will be added into > * btfe->types later when we add BTF_VAR_DATASEC. > */ > - type = btf_var_id; > offset = addr - btfe->percpu_base_addr; > - btf_var_secinfo_id = btf_elf__add_var_secinfo(&btfe->percpu_secinfo, > - type, offset, size); > - if (btf_var_secinfo_id < 0) { > + id = btf_elf__add_var_secinfo(&btfe->percpu_secinfo, id, offset, size); > + if (id < 0) { > err = -1; > - printf("error: failed to encode var secinfo '%s'\n", sym_name); > + fprintf(stderr, "error: failed to encode section info for variable '%s' at addr 0x%lx\n", > + name, addr); > break; > } > } > diff --git a/libbtf.c b/libbtf.c > index 0467f1f2a596..27aa3e5a986e 100644 > --- a/libbtf.c > +++ b/libbtf.c > @@ -28,6 +28,7 @@ > #include "elf_symtab.h" > > uint8_t btf_elf__verbose; > +uint8_t btf_elf__force; > > static int btf_var_secinfo_cmp(const void *a, const void *b) > { > @@ -62,7 +63,6 @@ int btf_elf__load(struct btf_elf *btfe) > return 0; > } > > - > struct btf_elf *btf_elf__new(const char *filename, Elf *elf) > { > struct btf_elf *btfe = zalloc(sizeof(*btfe)); > @@ -771,10 +771,6 @@ int btf_elf__encode(struct btf_elf *btfe, uint8_t flags) > { > struct btf *btf = btfe->btf; > > - if (gobuffer__size(&btfe->percpu_secinfo) != 0) > - btf_elf__add_datasec_type(btfe, PERCPU_SECTION, > - &btfe->percpu_secinfo); > - > /* Empty file, nothing to do, so... done! */ > if (btf__get_nr_types(btf) == 0) > return 0; > diff --git a/libbtf.h b/libbtf.h > index 9b3d396da31f..887b5bc55c8e 100644 > --- a/libbtf.h > +++ b/libbtf.h > @@ -30,6 +30,7 @@ struct btf_elf { > }; > > extern uint8_t btf_elf__verbose; > +extern uint8_t btf_elf__force; > #define btf_elf__verbose_log(fmt, ...) { if (btf_elf__verbose) printf(fmt, __VA_ARGS__); } > > #define PERCPU_SECTION ".data..percpu" > -- > 2.24.1 >
diff --git a/btf_encoder.c b/btf_encoder.c index 2e5df03e040f..2a6455be4c52 100644 --- a/btf_encoder.c +++ b/btf_encoder.c @@ -17,6 +17,7 @@ #include "btf_encoder.h" #include <ctype.h> /* for isalpha() and isalnum() */ +#include <stdlib.h> /* for qsort() and bsearch() */ #include <inttypes.h> /* @@ -53,18 +54,18 @@ static bool btf_name_valid(const char *p) return !*p; } -static void dump_invalid_symbol(const char *msg, const char *sym, const char *cu, +static void dump_invalid_symbol(const char *msg, const char *sym, int verbose, bool force) { if (force) { if (verbose) - fprintf(stderr, "PAHOLE: Warning: %s, ignored (sym: '%s', cu: '%s').\n", - msg, sym, cu); + fprintf(stderr, "PAHOLE: Warning: %s, ignored (sym: '%s').\n", + msg, sym); return; } - fprintf(stderr, "PAHOLE: Error: %s (sym: '%s', cu: '%s').\n", msg, sym, cu); - fprintf(stderr, "PAHOLE: Error: Use '-j' or '--force' to ignore such symbols and force emit the btf.\n"); + fprintf(stderr, "PAHOLE: Error: %s (sym: '%s').\n", msg, sym); + fprintf(stderr, "PAHOLE: Error: Use '--btf_encode_force' to ignore such symbols and force emit the btf.\n"); } extern struct debug_fmt_ops *dwarves__active_loader; @@ -202,6 +203,9 @@ int btf_encoder__encode() { int err; + if (gobuffer__size(&btfe->percpu_secinfo) != 0) + btf_elf__add_datasec_type(btfe, PERCPU_SECTION, &btfe->percpu_secinfo); + err = btf_elf__encode(btfe, 0); btf_elf__delete(btfe); btfe = NULL; @@ -209,24 +213,117 @@ int btf_encoder__encode() return err; } -#define HASHADDR__BITS 8 -#define HASHADDR__SIZE (1UL << HASHADDR__BITS) -#define hashaddr__fn(key) hash_64(key, HASHADDR__BITS) +#define MAX_PERCPU_VAR_CNT 4096 + +struct var_info { + uint64_t addr; + uint32_t sz; + const char *name; +}; + +static struct var_info percpu_vars[MAX_PERCPU_VAR_CNT]; +static int percpu_var_cnt; + +static int percpu_var_cmp(const void *_a, const void *_b) +{ + const struct var_info *a = _a; + const struct var_info *b = _b; + + if (a->addr == b->addr) + return 0; + return a->addr < b->addr ? -1 : 1; +} + +static bool percpu_var_exists(uint64_t addr, uint32_t *sz, const char **name) +{ + const struct var_info *p; + struct var_info key = { .addr = addr }; + + p = bsearch(&key, percpu_vars, percpu_var_cnt, + sizeof(percpu_vars[0]), percpu_var_cmp); + + if (!p) + return false; + + *sz = p->sz; + *name = p->name; + return true; +} -static struct variable *hashaddr__find_variable(const struct hlist_head hashtable[], - const uint64_t addr) +static int find_all_percpu_vars(struct btf_elf *btfe) { - struct variable *variable; - struct hlist_node *pos; - uint16_t bucket = hashaddr__fn(addr); - const struct hlist_head *head = &hashtable[bucket]; - - hlist_for_each_entry(variable, pos, head, tool_hnode) { - if (variable->ip.addr == addr) - return variable; + uint32_t core_id; + GElf_Sym sym; + + /* cache variables' addresses, preparing for searching in symtab. */ + percpu_var_cnt = 0; + + /* search within symtab for percpu variables */ + elf_symtab__for_each_symbol(btfe->symtab, core_id, sym) { + const char *sym_name; + uint64_t addr; + uint32_t size; + + /* compare a symbol's shndx to determine if it's a percpu variable */ + if (elf_sym__section(&sym) != btfe->percpu_shndx) + continue; + if (elf_sym__type(&sym) != STT_OBJECT) + continue; + + addr = elf_sym__value(&sym); + /* + * Store only those symbols that have allocated space in the percpu section. + * This excludes the following three types of symbols: + * + * 1. __ADDRESSABLE(sym), which are forcely emitted as symbols. + * 2. __UNIQUE_ID(prefix), which are introduced to generate unique ids. + * 3. __exitcall(fn), functions which are labeled as exit calls. + * + * In addition, the variables defined using DEFINE_PERCPU_FIRST are + * also not included, which currently includes: + * + * 1. fixed_percpu_data + */ + if (!addr) + continue; + + sym_name = elf_sym__name(&sym, btfe->symtab); + if (!btf_name_valid(sym_name)) { + dump_invalid_symbol("Found symbol of invalid name when encoding btf", + sym_name, btf_elf__verbose, btf_elf__force); + if (btf_elf__force) + continue; + return -1; + } + size = elf_sym__size(&sym); + if (!size) { + dump_invalid_symbol("Found symbol of zero size when encoding btf", + sym_name, btf_elf__verbose, btf_elf__force); + if (btf_elf__force) + continue; + return -1; + } + + if (btf_elf__verbose) + printf("Found per-CPU symbol '%s' at address 0x%lx\n", sym_name, addr); + + if (percpu_var_cnt == MAX_PERCPU_VAR_CNT) { + fprintf(stderr, "Reached the limit of per-CPU variables: %d\n", + MAX_PERCPU_VAR_CNT); + return -1; + } + percpu_vars[percpu_var_cnt].addr = addr; + percpu_vars[percpu_var_cnt].sz = size; + percpu_vars[percpu_var_cnt].name = sym_name; + percpu_var_cnt++; } - return NULL; + if (percpu_var_cnt) + qsort(percpu_vars, percpu_var_cnt, sizeof(percpu_vars[0]), percpu_var_cmp); + + if (btf_elf__verbose) + printf("Found %d per-CPU variables!\n", percpu_var_cnt); + return 0; } int cu__encode_btf(struct cu *cu, int verbose, bool force, @@ -234,13 +331,10 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, { uint32_t type_id_off; uint32_t core_id; + struct variable *var; struct function *fn; struct tag *pos; int err = 0; - struct hlist_head hash_addr[HASHADDR__SIZE]; - struct variable *var; - bool has_global_var = false; - GElf_Sym sym; if (btfe && strcmp(btfe->filename, cu->filename)) { err = btf_encoder__encode(); @@ -257,6 +351,9 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, if (!btfe) return -1; + if (!skip_encoding_vars && find_all_percpu_vars(btfe)) + goto out; + has_index_type = false; need_index_type = false; array_index_id = 0; @@ -278,6 +375,7 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, } btf_elf__verbose = verbose; + btf_elf__force = force; type_id_off = btf__get_nr_types(btfe->btf); cu__for_each_type(cu, core_id, pos) { @@ -325,12 +423,11 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, if (verbose) printf("search cu '%s' for percpu global variables.\n", cu->name); - /* cache variables' addresses, preparing for searching in symtab. */ - for (core_id = 0; core_id < HASHADDR__SIZE; ++core_id) - INIT_HLIST_HEAD(&hash_addr[core_id]); - cu__for_each_variable(cu, core_id, pos) { - struct hlist_head *head; + uint32_t size, type, linkage, offset; + const char *name; + uint64_t addr; + int id; var = tag__variable(pos); if (var->declaration && !var->spec) @@ -338,89 +435,37 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, /* percpu variables are allocated in global space */ if (variable__scope(var) != VSCOPE_GLOBAL && !var->spec) continue; - has_global_var = true; - head = &hash_addr[hashaddr__fn(var->ip.addr)]; - hlist_add_head(&var->tool_hnode, head); - } - if (!has_global_var) { - if (verbose) - printf("cu has no global variable defined, skip.\n"); - goto out; - } - - /* search within symtab for percpu variables */ - elf_symtab__for_each_symbol(btfe->symtab, core_id, sym) { - uint32_t linkage, type, size, offset; - int32_t btf_var_id, btf_var_secinfo_id; - uint64_t addr; - const char *sym_name; - - /* compare a symbol's shndx to determine if it's a percpu variable */ - if (elf_sym__section(&sym) != btfe->percpu_shndx) - continue; - if (elf_sym__type(&sym) != STT_OBJECT) - continue; - addr = elf_sym__value(&sym); - /* - * Store only those symbols that have allocated space in the percpu section. - * This excludes the following three types of symbols: - * - * 1. __ADDRESSABLE(sym), which are forcely emitted as symbols. - * 2. __UNIQUE_ID(prefix), which are introduced to generate unique ids. - * 3. __exitcall(fn), functions which are labeled as exit calls. - * - * In addition, the variables defined using DEFINE_PERCPU_FIRST are - * also not included, which currently includes: - * - * 1. fixed_percpu_data - */ - if (!addr) - continue; - var = hashaddr__find_variable(hash_addr, addr); - if (var == NULL) - continue; + /* addr has to be recorded before we follow spec */ + addr = var->ip.addr; if (var->spec) var = var->spec; - sym_name = elf_sym__name(&sym, btfe->symtab); - if (!btf_name_valid(sym_name)) { - dump_invalid_symbol("Found symbol of invalid name when encoding btf", - sym_name, cu->name, verbose, force); - if (force) - continue; - err = -1; - break; - } if (var->ip.tag.type == 0) { - dump_invalid_symbol("Found symbol of void type when encoding btf", - sym_name, cu->name, verbose, force); - if (force) - continue; - err = -1; - break; - } - type = type_id_off + var->ip.tag.type; - size = elf_sym__size(&sym); - if (!size) { - dump_invalid_symbol("Found symbol of zero size when encoding btf", - sym_name, cu->name, verbose, force); + fprintf(stderr, "error: found variable in CU '%s' that has void type\n", + cu->name); if (force) continue; err = -1; break; } - if (verbose) - printf("symbol '%s' of address 0x%lx encoded\n", - sym_name, addr); + type = var->ip.tag.type + type_id_off; + linkage = var->external ? BTF_VAR_GLOBAL_ALLOCATED : BTF_VAR_STATIC; + if (!percpu_var_exists(addr, &size, &name)) + continue; /* not a per-CPU variable */ + + if (btf_elf__verbose) { + printf("Variable '%s' from CU '%s' at address 0x%lx encoded\n", + name, cu->name, addr); + } /* add a BTF_KIND_VAR in btfe->types */ - linkage = var->external ? BTF_VAR_GLOBAL_ALLOCATED : BTF_VAR_STATIC; - btf_var_id = btf_elf__add_var_type(btfe, type, sym_name, linkage); - if (btf_var_id < 0) { + id = btf_elf__add_var_type(btfe, type, name, linkage); + if (id < 0) { err = -1; - printf("error: failed to encode variable '%s'\n", sym_name); + fprintf(stderr, "error: failed to encode variable '%s' at addr 0x%lx\n", + name, addr); break; } @@ -428,13 +473,12 @@ int cu__encode_btf(struct cu *cu, int verbose, bool force, * add a BTF_VAR_SECINFO in btfe->percpu_secinfo, which will be added into * btfe->types later when we add BTF_VAR_DATASEC. */ - type = btf_var_id; offset = addr - btfe->percpu_base_addr; - btf_var_secinfo_id = btf_elf__add_var_secinfo(&btfe->percpu_secinfo, - type, offset, size); - if (btf_var_secinfo_id < 0) { + id = btf_elf__add_var_secinfo(&btfe->percpu_secinfo, id, offset, size); + if (id < 0) { err = -1; - printf("error: failed to encode var secinfo '%s'\n", sym_name); + fprintf(stderr, "error: failed to encode section info for variable '%s' at addr 0x%lx\n", + name, addr); break; } } diff --git a/libbtf.c b/libbtf.c index 0467f1f2a596..27aa3e5a986e 100644 --- a/libbtf.c +++ b/libbtf.c @@ -28,6 +28,7 @@ #include "elf_symtab.h" uint8_t btf_elf__verbose; +uint8_t btf_elf__force; static int btf_var_secinfo_cmp(const void *a, const void *b) { @@ -62,7 +63,6 @@ int btf_elf__load(struct btf_elf *btfe) return 0; } - struct btf_elf *btf_elf__new(const char *filename, Elf *elf) { struct btf_elf *btfe = zalloc(sizeof(*btfe)); @@ -771,10 +771,6 @@ int btf_elf__encode(struct btf_elf *btfe, uint8_t flags) { struct btf *btf = btfe->btf; - if (gobuffer__size(&btfe->percpu_secinfo) != 0) - btf_elf__add_datasec_type(btfe, PERCPU_SECTION, - &btfe->percpu_secinfo); - /* Empty file, nothing to do, so... done! */ if (btf__get_nr_types(btf) == 0) return 0; diff --git a/libbtf.h b/libbtf.h index 9b3d396da31f..887b5bc55c8e 100644 --- a/libbtf.h +++ b/libbtf.h @@ -30,6 +30,7 @@ struct btf_elf { }; extern uint8_t btf_elf__verbose; +extern uint8_t btf_elf__force; #define btf_elf__verbose_log(fmt, ...) { if (btf_elf__verbose) printf(fmt, __VA_ARGS__); } #define PERCPU_SECTION ".data..percpu"