| Message ID | tencent_4A09A36F883A06EA428A593497642AF8AF08@qq.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf-next,v6] selftests/bpf: trace_helpers.c: optimize kallsyms cache | expand |
On Mon, Aug 21, 2023 at 02:45:20PM +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. > > Acked-by: Stanislav Fomichev <sdf@google.com> > Signed-off-by: Rong Tao <rongtao@cestc.cn> > --- > v6: 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/ > --- > samples/bpf/Makefile | 1 + > tools/testing/selftests/bpf/trace_helpers.c | 59 +++++++++++++++++---- > 2 files changed, 49 insertions(+), 11 deletions(-) > > diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile > index 595b98d825ce..a49d0f759f5a 100644 > --- a/samples/bpf/Makefile > +++ b/samples/bpf/Makefile > @@ -199,6 +199,7 @@ 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 > diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c > index f83d9f65c65b..316a7874a12b 100644 > --- a/tools/testing/selftests/bpf/trace_helpers.c > +++ b/tools/testing/selftests/bpf/trace_helpers.c > @@ -14,14 +14,48 @@ > #include <linux/limits.h> > #include <libelf.h> > #include <gelf.h> > +#ifndef __must_check > +#define __must_check > +#endif I think you need to fix this on samples/bpf side I tried to play with the samples/bpf/ includes, but couldn't find a way to make this work.. selftests base includes on tools/include, while samples have $(objtree)/usr/include as first include and AFAICS the __must_check is defined under __KERNEL__ ifdef I guess the reason samples use $(objtree)/usr/include is to get some struct definitions which are not in tools/include, but looks like some samples objects already use vmlinux.h include, so that could be the way forward to fix that or get rid of the trace_helpers.c or bpf/selftests dependency ;-) > +#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 struct ksym *syms; > +static size_t sym_cap; > static int sym_cnt; nit, sym_cnt should be size_t jirka > > +static int ksyms__add_symbol(const char *name, unsigned long addr) > +{ > + void *tmp; > + > + tmp = strdup(name); > + if (!tmp) > + return -ENOMEM; > + syms[sym_cnt].addr = addr; > + syms[sym_cnt].name = tmp; > + > + sym_cnt++; > + > + return 0; > +} > + > +static void ksyms__free(void) > +{ > + unsigned int i; > + > + if (!syms) > + return; > + > + for (i = 0; i < sym_cnt; i++) > + free(syms[i].name); > + free(syms); > + syms = NULL; > + sym_cnt = 0; > + sym_cap = 0; > +} > + > static int ksym_cmp(const void *p1, const void *p2) > { > return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr; > @@ -33,9 +67,7 @@ int load_kallsyms_refresh(void) > char func[256], buf[256]; > char symbol; > void *addr; > - int i = 0; > - > - sym_cnt = 0; > + int ret; > > f = fopen("/proc/kallsyms", "r"); > if (!f) > @@ -46,17 +78,22 @@ int load_kallsyms_refresh(void) > 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 **) &syms, &sym_cap, > + sizeof(struct ksym), sym_cnt + 1); > + if (ret) > + goto error; > + ret = ksyms__add_symbol(func, (unsigned long)addr); > + if (ret) > + goto error; > } > fclose(f); > - sym_cnt = i; > qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp); > return 0; > + > +error: > + ksyms__free(); > + return ret; > } > > int load_kallsyms(void) > -- > 2.39.3 > >
> I think you need to fix this on samples/bpf side > > I tried to play with the samples/bpf/ includes, but couldn't find a way to > make this work.. selftests base includes on tools/include, while samples > have $(objtree)/usr/include as first include and AFAICS the __must_check is > defined under __KERNEL__ ifdef > > I guess the reason samples use $(objtree)/usr/include is to get some struct > definitions which are not in tools/include, but looks like some samples objects > already use vmlinux.h include, so that could be the way forward to fix that I tried the method you suggested, and some unexpected problems occurred. Maybe, we can apply v5 [0] first, and then solve this problem? Best wishes, Rong Tao [0] v5: https://lore.kernel.org/lkml/tencent_0E9E1A1C0981678D5E7EA9E4BDBA8EE2200A@qq.com/
On Tue, Aug 22, 2023 at 08:38:58AM +0800, Rong Tao wrote: > > I think you need to fix this on samples/bpf side > > > > I tried to play with the samples/bpf/ includes, but couldn't find a way to > > make this work.. selftests base includes on tools/include, while samples > > have $(objtree)/usr/include as first include and AFAICS the __must_check is > > defined under __KERNEL__ ifdef > > > > I guess the reason samples use $(objtree)/usr/include is to get some struct > > definitions which are not in tools/include, but looks like some samples objects > > already use vmlinux.h include, so that could be the way forward to fix that > > I tried the method you suggested, and some unexpected problems occurred. Maybe, > we can apply v5 [0] first, and then solve this problem? how about change below, seem to work for me jirka --- diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 151ec320818b..3115f054dca7 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -316,6 +316,8 @@ XDP_SAMPLE_CFLAGS += -Wall -O2 \ $(obj)/$(XDP_SAMPLE): TPROGS_CFLAGS = $(XDP_SAMPLE_CFLAGS) $(obj)/$(XDP_SAMPLE): $(src)/xdp_sample_user.h $(src)/xdp_sample_shared.h +$(obj)/$(TRACE_HELPERS): TPROGS_CFLAGS := $(TPROGS_CFLAGS) -D__must_check= + -include $(BPF_SAMPLES_PATH)/Makefile.target VMLINUX_BTF_PATHS ?= $(abspath $(if $(O),$(O)/vmlinux)) \ diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c index 316a7874a12b..551547ba6829 100644 --- a/tools/testing/selftests/bpf/trace_helpers.c +++ b/tools/testing/selftests/bpf/trace_helpers.c @@ -14,9 +14,6 @@ #include <linux/limits.h> #include <libelf.h> #include <gelf.h> -#ifndef __must_check -#define __must_check -#endif #include "bpf/libbpf_internal.h" #define TRACEFS_PIPE "/sys/kernel/tracing/trace_pipe"
Thanks a lot, jirka. I just submit v7 [0], please review. Rong Tao. [0] https://lore.kernel.org/lkml/tencent_BD6E19C00BF565CD5C36A9A0BD828CFA210A@qq.com/
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 595b98d825ce..a49d0f759f5a 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -199,6 +199,7 @@ 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 diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c index f83d9f65c65b..316a7874a12b 100644 --- a/tools/testing/selftests/bpf/trace_helpers.c +++ b/tools/testing/selftests/bpf/trace_helpers.c @@ -14,14 +14,48 @@ #include <linux/limits.h> #include <libelf.h> #include <gelf.h> +#ifndef __must_check +#define __must_check +#endif +#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 struct ksym *syms; +static size_t sym_cap; static int sym_cnt; +static int ksyms__add_symbol(const char *name, unsigned long addr) +{ + void *tmp; + + tmp = strdup(name); + if (!tmp) + return -ENOMEM; + syms[sym_cnt].addr = addr; + syms[sym_cnt].name = tmp; + + sym_cnt++; + + return 0; +} + +static void ksyms__free(void) +{ + unsigned int i; + + if (!syms) + return; + + for (i = 0; i < sym_cnt; i++) + free(syms[i].name); + free(syms); + syms = NULL; + sym_cnt = 0; + sym_cap = 0; +} + static int ksym_cmp(const void *p1, const void *p2) { return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr; @@ -33,9 +67,7 @@ int load_kallsyms_refresh(void) char func[256], buf[256]; char symbol; void *addr; - int i = 0; - - sym_cnt = 0; + int ret; f = fopen("/proc/kallsyms", "r"); if (!f) @@ -46,17 +78,22 @@ int load_kallsyms_refresh(void) 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 **) &syms, &sym_cap, + sizeof(struct ksym), sym_cnt + 1); + if (ret) + goto error; + ret = ksyms__add_symbol(func, (unsigned long)addr); + if (ret) + goto error; } fclose(f); - sym_cnt = i; qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp); return 0; + +error: + ksyms__free(); + return ret; } int load_kallsyms(void)