| Message ID | tencent_F9CAE827E2BA8193D06796FBE58ECAD16B06@qq.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | selftests/bpf: Optimize kallsyms cache | expand |
On Tue, Sep 05, 2023 at 10:04:18PM +0800, Rong Tao wrote: > From: Rong Tao <rongtao@cestc.cn> > > Static ksyms often have problems because the number of symbols exceeds the > MAX_SYMS limit. Like changing the MAX_SYMS from 300000 to 400000 in > commit e76a014334a6("selftests/bpf: Bump and validate MAX_SYMS") solves > the problem somewhat, but it's not the perfect way. > > This commit uses dynamic memory allocation, which completely solves the > problem caused by the limitation of the number of kallsyms. At the same > time, add APIs: > > load_kallsyms_local() > ksym_search_local() > ksym_get_addr_local() > free_kallsyms_local() > > There are used to solve the problem of selftests/bpf updating kallsyms > after attach new symbols during testmod testing. > > Acked-by: Stanislav Fomichev <sdf@google.com> > Signed-off-by: Rong Tao <rongtao@cestc.cn> looks good, I added few more coments, with them addressed you can add my Acked-by: Jiri Olsa <jolsa@kernel.org> thanks, jirka > --- > v11: Remove useless load_kallsyms_refresh() and modify code some format > v10: https://lore.kernel.org/lkml/tencent_0A73B402B1D440480838ABF7124CE5EA5505@qq.com/ > Keep the original load_kallsyms(). > v9: https://lore.kernel.org/lkml/tencent_254B7015EED7A5D112C45E033DA1822CF107@qq.com/ > Add load_kallsyms_local,ksym_search_local,ksym_get_addr_local functions. > v8: https://lore.kernel.org/lkml/tencent_6D23FE187408D965E95DFAA858BC7E8C760A@qq.com/ > Resolves inter-thread contention for ksyms global variables. > v7: https://lore.kernel.org/lkml/tencent_BD6E19C00BF565CD5C36A9A0BD828CFA210A@qq.com/ > Fix __must_check macro. > v6: https://lore.kernel.org/lkml/tencent_4A09A36F883A06EA428A593497642AF8AF08@qq.com/ > Apply libbpf_ensure_mem() > v5: https://lore.kernel.org/lkml/tencent_0E9E1A1C0981678D5E7EA9E4BDBA8EE2200A@qq.com/ > Release the allocated memory once the load_kallsyms_refresh() upon error > given it's dynamically allocated. > v4: https://lore.kernel.org/lkml/tencent_59C74613113F0C728524B2A82FE5540A5E09@qq.com/ > Make sure most cases we don't need the realloc() path to begin with, > and check strdup() return value. > v3: https://lore.kernel.org/lkml/tencent_50B4B2622FE7546A5FF9464310650C008509@qq.com/ > Do not use structs and judge ksyms__add_symbol function return value. > v2: https://lore.kernel.org/lkml/tencent_B655EE5E5D463110D70CD2846AB3262EED09@qq.com/ > Do the usual len/capacity scheme here to amortize the cost of realloc, and > don't free symbols. > v1: https://lore.kernel.org/lkml/tencent_AB461510B10CD484E0B2F62E3754165F2909@qq.com/ SNIP > +static int ksyms__add_symbol(struct ksyms *ksyms, const char *name, > + unsigned long addr) > +{ > + void *tmp; > + > + tmp = strdup(name); > + if (!tmp) > + return -ENOMEM; > + ksyms->syms[ksyms->sym_cnt].addr = addr; > + ksyms->syms[ksyms->sym_cnt].name = tmp; > + > + ksyms->sym_cnt++; > + > + return 0; nit, extra new lines above > +} > + > +void free_kallsyms_local(struct ksyms *ksyms) > +{ > + unsigned int i; > + > + if (!ksyms) > + return; > + > + if (!ksyms->syms) { > + free(ksyms); > + return; > + } > + > + for (i = 0; i < ksyms->sym_cnt; i++) > + free(ksyms->syms[i].name); > + free(ksyms->syms); > + free(ksyms); > +} > > static int ksym_cmp(const void *p1, const void *p2) > { > return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr; > } > > -int load_kallsyms_refresh(void) > +struct ksyms *load_kallsyms_local(struct ksyms *ksyms) > { > FILE *f; > char func[256], buf[256]; > char symbol; > void *addr; > - int i = 0; > + int ret; > > - sym_cnt = 0; > + /* flush kallsyms, free the previously allocated dynamic memory */ > + free_kallsyms_local(ksyms); with the removal of the refresh function (from last version) there's no need now for ksyms argument in load_kallsyms_local all the current users of load_kallsyms_local are passing NULL arg > > f = fopen("/proc/kallsyms", "r"); > if (!f) > - return -ENOENT; > + return NULL; > + > + ksyms = calloc(1, sizeof(struct ksyms)); > + if (!ksyms) missing fclose(f); > + return NULL; > > while (fgets(buf, sizeof(buf), f)) { > if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3) > break; > if (!addr) > continue; > - if (i >= MAX_SYMS) > - return -EFBIG; > > - syms[i].addr = (long) addr; > - syms[i].name = strdup(func); > - i++; > + ret = libbpf_ensure_mem((void **) &ksyms->syms, &ksyms->sym_cap, > + sizeof(struct ksym), ksyms->sym_cnt + 1); > + if (ret) > + goto error; > + ret = ksyms__add_symbol(ksyms, func, (unsigned long)addr); > + if (ret) > + goto error; > } > fclose(f); > - sym_cnt = i; > - qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp); > - return 0; > + qsort(ksyms->syms, ksyms->sym_cnt, sizeof(struct ksym), ksym_cmp); > + return ksyms; > + > +error: > + free_kallsyms_local(ksyms); missing fclose(f); > + return NULL; > } > > int load_kallsyms(void) > { > - /* > - * This is called/used from multiplace places, > - * load symbols just once. > - */ > - if (sym_cnt) > - return 0; > - return load_kallsyms_refresh(); > + if (!ksyms) > + ksyms = load_kallsyms_local(NULL); > + return ksyms ? 0 : 1; > } > > -struct ksym *ksym_search(long key) > +struct ksym *ksym_search_local(struct ksyms *ksyms, long key) > { > - int start = 0, end = sym_cnt; > + int start = 0, end = ksyms->sym_cnt; > int result; > > + if (!ksyms) > + return NULL; I don't think we need to check !ksyms in here, you don't do that check in ksym_get_addr_local and I think it's fine > + > /* kallsyms not loaded. return NULL */ > - if (sym_cnt <= 0) > + if (ksyms->sym_cnt <= 0) > return NULL; > > while (start < end) { SNIP > diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h > index 876f3e711df6..d6eeec85a5e4 100644 > --- a/tools/testing/selftests/bpf/trace_helpers.h > +++ b/tools/testing/selftests/bpf/trace_helpers.h > @@ -11,13 +11,18 @@ struct ksym { > long addr; > char *name; > }; > +struct ksyms; > > int load_kallsyms(void); > -int load_kallsyms_refresh(void); > - > struct ksym *ksym_search(long key); > long ksym_get_addr(const char *name); > > +struct ksyms *load_kallsyms_local(struct ksyms *ksyms); > +struct ksym *ksym_search_local(struct ksyms *ksyms, long key); > +long ksym_get_addr_local(struct ksyms *ksyms, const char *name); > + nit, extra newline > +void free_kallsyms_local(struct ksyms *ksyms); > + > /* open kallsyms and find addresses on the fly, faster than load + search. */ > int kallsyms_find(const char *sym, unsigned long long *addr); > > -- > 2.41.0 >
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 4ccf4236031c..6c707ebcebb9 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -175,6 +175,7 @@ TPROGS_CFLAGS += -I$(srctree)/tools/testing/selftests/bpf/ TPROGS_CFLAGS += -I$(LIBBPF_INCLUDE) TPROGS_CFLAGS += -I$(srctree)/tools/include TPROGS_CFLAGS += -I$(srctree)/tools/perf +TPROGS_CFLAGS += -I$(srctree)/tools/lib TPROGS_CFLAGS += -DHAVE_ATTR_TEST=0 ifdef SYSROOT @@ -314,6 +315,9 @@ XDP_SAMPLE_CFLAGS += -Wall -O2 \ $(obj)/$(XDP_SAMPLE): TPROGS_CFLAGS = $(XDP_SAMPLE_CFLAGS) $(obj)/$(XDP_SAMPLE): $(src)/xdp_sample_user.h $(src)/xdp_sample_shared.h +# Override includes for trace_helpers.o because __must_check won't be defined +# in our include path. +$(obj)/$(TRACE_HELPERS): TPROGS_CFLAGS := $(TPROGS_CFLAGS) -D__must_check= -include $(BPF_SAMPLES_PATH)/Makefile.target diff --git a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c index 9d768e083714..97142a4db374 100644 --- a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c +++ b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c @@ -308,7 +308,7 @@ void test_fill_link_info(void) return; /* load kallsyms to compare the addr */ - if (!ASSERT_OK(load_kallsyms_refresh(), "load_kallsyms_refresh")) + if (!ASSERT_OK(load_kallsyms(), "load_kallsyms")) goto cleanup; kprobe_addr = ksym_get_addr(KPROBE_FUNC); diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_testmod_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_testmod_test.c index 1fbe7e4ac00a..8a8ad0613861 100644 --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_testmod_test.c +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_testmod_test.c @@ -4,6 +4,8 @@ #include "trace_helpers.h" #include "bpf/libbpf_internal.h" +static struct ksyms *ksyms; + static void kprobe_multi_testmod_check(struct kprobe_multi *skel) { ASSERT_EQ(skel->bss->kprobe_testmod_test1_result, 1, "kprobe_test1_result"); @@ -50,12 +52,12 @@ static void test_testmod_attach_api_addrs(void) LIBBPF_OPTS(bpf_kprobe_multi_opts, opts); unsigned long long addrs[3]; - addrs[0] = ksym_get_addr("bpf_testmod_fentry_test1"); - ASSERT_NEQ(addrs[0], 0, "ksym_get_addr"); - addrs[1] = ksym_get_addr("bpf_testmod_fentry_test2"); - ASSERT_NEQ(addrs[1], 0, "ksym_get_addr"); - addrs[2] = ksym_get_addr("bpf_testmod_fentry_test3"); - ASSERT_NEQ(addrs[2], 0, "ksym_get_addr"); + addrs[0] = ksym_get_addr_local(ksyms, "bpf_testmod_fentry_test1"); + ASSERT_NEQ(addrs[0], 0, "ksym_get_addr_local"); + addrs[1] = ksym_get_addr_local(ksyms, "bpf_testmod_fentry_test2"); + ASSERT_NEQ(addrs[1], 0, "ksym_get_addr_local"); + addrs[2] = ksym_get_addr_local(ksyms, "bpf_testmod_fentry_test3"); + ASSERT_NEQ(addrs[2], 0, "ksym_get_addr_local"); opts.addrs = (const unsigned long *) addrs; opts.cnt = ARRAY_SIZE(addrs); @@ -79,11 +81,15 @@ static void test_testmod_attach_api_syms(void) void serial_test_kprobe_multi_testmod_test(void) { - if (!ASSERT_OK(load_kallsyms_refresh(), "load_kallsyms_refresh")) + ksyms = load_kallsyms_local(NULL); + if (!ASSERT_OK_PTR(ksyms, "load_kallsyms_local")) return; if (test__start_subtest("testmod_attach_api_syms")) test_testmod_attach_api_syms(); + if (test__start_subtest("testmod_attach_api_addrs")) test_testmod_attach_api_addrs(); + + free_kallsyms_local(ksyms); } diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c index f83d9f65c65b..7d026c128252 100644 --- a/tools/testing/selftests/bpf/trace_helpers.c +++ b/tools/testing/selftests/bpf/trace_helpers.c @@ -14,104 +14,166 @@ #include <linux/limits.h> #include <libelf.h> #include <gelf.h> +#include "bpf/libbpf_internal.h" #define TRACEFS_PIPE "/sys/kernel/tracing/trace_pipe" #define DEBUGFS_PIPE "/sys/kernel/debug/tracing/trace_pipe" -#define MAX_SYMS 400000 -static struct ksym syms[MAX_SYMS]; -static int sym_cnt; +struct ksyms { + struct ksym *syms; + size_t sym_cap; + size_t sym_cnt; +}; + +static struct ksyms *ksyms; + +static int ksyms__add_symbol(struct ksyms *ksyms, const char *name, + unsigned long addr) +{ + void *tmp; + + tmp = strdup(name); + if (!tmp) + return -ENOMEM; + ksyms->syms[ksyms->sym_cnt].addr = addr; + ksyms->syms[ksyms->sym_cnt].name = tmp; + + ksyms->sym_cnt++; + + return 0; +} + +void free_kallsyms_local(struct ksyms *ksyms) +{ + unsigned int i; + + if (!ksyms) + return; + + if (!ksyms->syms) { + free(ksyms); + return; + } + + for (i = 0; i < ksyms->sym_cnt; i++) + free(ksyms->syms[i].name); + free(ksyms->syms); + free(ksyms); +} static int ksym_cmp(const void *p1, const void *p2) { return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr; } -int load_kallsyms_refresh(void) +struct ksyms *load_kallsyms_local(struct ksyms *ksyms) { FILE *f; char func[256], buf[256]; char symbol; void *addr; - int i = 0; + int ret; - sym_cnt = 0; + /* flush kallsyms, free the previously allocated dynamic memory */ + free_kallsyms_local(ksyms); f = fopen("/proc/kallsyms", "r"); if (!f) - return -ENOENT; + return NULL; + + ksyms = calloc(1, sizeof(struct ksyms)); + if (!ksyms) + return NULL; while (fgets(buf, sizeof(buf), f)) { if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3) break; if (!addr) continue; - if (i >= MAX_SYMS) - return -EFBIG; - syms[i].addr = (long) addr; - syms[i].name = strdup(func); - i++; + ret = libbpf_ensure_mem((void **) &ksyms->syms, &ksyms->sym_cap, + sizeof(struct ksym), ksyms->sym_cnt + 1); + if (ret) + goto error; + ret = ksyms__add_symbol(ksyms, func, (unsigned long)addr); + if (ret) + goto error; } fclose(f); - sym_cnt = i; - qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp); - return 0; + qsort(ksyms->syms, ksyms->sym_cnt, sizeof(struct ksym), ksym_cmp); + return ksyms; + +error: + free_kallsyms_local(ksyms); + return NULL; } int load_kallsyms(void) { - /* - * This is called/used from multiplace places, - * load symbols just once. - */ - if (sym_cnt) - return 0; - return load_kallsyms_refresh(); + if (!ksyms) + ksyms = load_kallsyms_local(NULL); + return ksyms ? 0 : 1; } -struct ksym *ksym_search(long key) +struct ksym *ksym_search_local(struct ksyms *ksyms, long key) { - int start = 0, end = sym_cnt; + int start = 0, end = ksyms->sym_cnt; int result; + if (!ksyms) + return NULL; + /* kallsyms not loaded. return NULL */ - if (sym_cnt <= 0) + if (ksyms->sym_cnt <= 0) return NULL; while (start < end) { size_t mid = start + (end - start) / 2; - result = key - syms[mid].addr; + result = key - ksyms->syms[mid].addr; if (result < 0) end = mid; else if (result > 0) start = mid + 1; else - return &syms[mid]; + return &ksyms->syms[mid]; } - if (start >= 1 && syms[start - 1].addr < key && - key < syms[start].addr) + if (start >= 1 && ksyms->syms[start - 1].addr < key && + key < ksyms->syms[start].addr) /* valid ksym */ - return &syms[start - 1]; + return &ksyms->syms[start - 1]; /* out of range. return _stext */ - return &syms[0]; + return &ksyms->syms[0]; } -long ksym_get_addr(const char *name) +struct ksym *ksym_search(long key) +{ + if (!ksyms) + return NULL; + return ksym_search_local(ksyms, key); +} + +long ksym_get_addr_local(struct ksyms *ksyms, const char *name) { int i; - for (i = 0; i < sym_cnt; i++) { - if (strcmp(syms[i].name, name) == 0) - return syms[i].addr; + for (i = 0; i < ksyms->sym_cnt; i++) { + if (strcmp(ksyms->syms[i].name, name) == 0) + return ksyms->syms[i].addr; } return 0; } +long ksym_get_addr(const char *name) +{ + if (!ksyms) + return 0; + return ksym_get_addr_local(ksyms, name); +} + /* open kallsyms and read symbol addresses on the fly. Without caching all symbols, * this is faster than load + find. */ diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h index 876f3e711df6..d6eeec85a5e4 100644 --- a/tools/testing/selftests/bpf/trace_helpers.h +++ b/tools/testing/selftests/bpf/trace_helpers.h @@ -11,13 +11,18 @@ struct ksym { long addr; char *name; }; +struct ksyms; int load_kallsyms(void); -int load_kallsyms_refresh(void); - struct ksym *ksym_search(long key); long ksym_get_addr(const char *name); +struct ksyms *load_kallsyms_local(struct ksyms *ksyms); +struct ksym *ksym_search_local(struct ksyms *ksyms, long key); +long ksym_get_addr_local(struct ksyms *ksyms, const char *name); + +void free_kallsyms_local(struct ksyms *ksyms); + /* open kallsyms and find addresses on the fly, faster than load + search. */ int kallsyms_find(const char *sym, unsigned long long *addr);