| Message ID | 20200114224426.3028966-1-kafai@fb.com |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | bpftool: Support dumping a map with btf_vmlinux_value_type_id | expand |
On Tue, Jan 14, 2020 at 2:46 PM Martin KaFai Lau <kafai@fb.com> wrote: > > This patch makes bpftool support dumping a map's value properly > when the map's value type is a type of the running kernel's btf. > (i.e. map_info.btf_vmlinux_value_type_id is set instead of > map_info.btf_value_type_id). The first usecase is for the > BPF_MAP_TYPE_STRUCT_OPS. > > Signed-off-by: Martin KaFai Lau <kafai@fb.com> > --- > tools/bpf/bpftool/map.c | 43 +++++++++++++++++++++++++++++++---------- > 1 file changed, 33 insertions(+), 10 deletions(-) > > diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c > index 4c5b15d736b6..d25f3b2355ad 100644 > --- a/tools/bpf/bpftool/map.c > +++ b/tools/bpf/bpftool/map.c > @@ -20,6 +20,7 @@ > #include "btf.h" > #include "json_writer.h" > #include "main.h" > +#include "libbpf_internal.h" > > const char * const map_type_name[] = { > [BPF_MAP_TYPE_UNSPEC] = "unspec", > @@ -252,6 +253,7 @@ static int do_dump_btf(const struct btf_dumper *d, > struct bpf_map_info *map_info, void *key, > void *value) > { > + __u32 value_id; > int ret; > > /* start of key-value pair */ > @@ -265,9 +267,12 @@ static int do_dump_btf(const struct btf_dumper *d, > goto err_end_obj; > } > > + value_id = map_info->btf_vmlinux_value_type_id ? > + : map_info->btf_value_type_id; > + > if (!map_is_per_cpu(map_info->type)) { > jsonw_name(d->jw, "value"); > - ret = btf_dumper_type(d, map_info->btf_value_type_id, value); > + ret = btf_dumper_type(d, value_id, value); > } else { > unsigned int i, n, step; > > @@ -279,8 +284,7 @@ static int do_dump_btf(const struct btf_dumper *d, > jsonw_start_object(d->jw); > jsonw_int_field(d->jw, "cpu", i); > jsonw_name(d->jw, "value"); > - ret = btf_dumper_type(d, map_info->btf_value_type_id, > - value + i * step); > + ret = btf_dumper_type(d, value_id, value + i * step); > jsonw_end_object(d->jw); > if (ret) > break; > @@ -932,6 +936,27 @@ static int maps_have_btf(int *fds, int nb_fds) > return 1; > } > > +static struct btf *get_map_kv_btf(const struct bpf_map_info *info) > +{ > + struct btf *btf = NULL; > + > + if (info->btf_vmlinux_value_type_id) { > + btf = bpf_find_kernel_btf(); If there are multiple maps we are dumping, it might become quite costly to re-read and re-parse kernel BTF all the time. Can we lazily load it, when required, and cache instead? > + if (IS_ERR(btf)) > + p_err("failed to get kernel btf"); > + } else if (info->btf_value_type_id) { > + int err; > + > + err = btf__get_from_id(info->btf_id, &btf); > + if (err || !btf) { > + p_err("failed to get btf"); > + btf = err ? ERR_PTR(err) : ERR_PTR(-ESRCH); > + } > + } > + > + return btf; > +} > + > static int > map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr, > bool show_header) > @@ -952,13 +977,11 @@ map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr, > prev_key = NULL; > > if (wtr) { > - if (info->btf_id) { > - err = btf__get_from_id(info->btf_id, &btf); > - if (err || !btf) { > - err = err ? : -ESRCH; > - p_err("failed to get btf"); > - goto exit_free; > - } > + btf = get_map_kv_btf(info); > + if (IS_ERR(btf)) { > + err = PTR_ERR(btf); > + btf = NULL; > + goto exit_free; > } > > if (show_header) { > -- > 2.17.1 >
On Tue, Jan 14, 2020 at 05:49:00PM -0800, Andrii Nakryiko wrote: > On Tue, Jan 14, 2020 at 2:46 PM Martin KaFai Lau <kafai@fb.com> wrote: > > > > This patch makes bpftool support dumping a map's value properly > > when the map's value type is a type of the running kernel's btf. > > (i.e. map_info.btf_vmlinux_value_type_id is set instead of > > map_info.btf_value_type_id). The first usecase is for the > > BPF_MAP_TYPE_STRUCT_OPS. > > > > Signed-off-by: Martin KaFai Lau <kafai@fb.com> > > --- > > tools/bpf/bpftool/map.c | 43 +++++++++++++++++++++++++++++++---------- > > 1 file changed, 33 insertions(+), 10 deletions(-) > > > > diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c > > index 4c5b15d736b6..d25f3b2355ad 100644 > > --- a/tools/bpf/bpftool/map.c > > +++ b/tools/bpf/bpftool/map.c > > @@ -20,6 +20,7 @@ > > #include "btf.h" > > #include "json_writer.h" > > #include "main.h" > > +#include "libbpf_internal.h" > > > > const char * const map_type_name[] = { > > [BPF_MAP_TYPE_UNSPEC] = "unspec", > > @@ -252,6 +253,7 @@ static int do_dump_btf(const struct btf_dumper *d, > > struct bpf_map_info *map_info, void *key, > > void *value) > > { > > + __u32 value_id; > > int ret; > > > > /* start of key-value pair */ > > @@ -265,9 +267,12 @@ static int do_dump_btf(const struct btf_dumper *d, > > goto err_end_obj; > > } > > > > + value_id = map_info->btf_vmlinux_value_type_id ? > > + : map_info->btf_value_type_id; > > + > > if (!map_is_per_cpu(map_info->type)) { > > jsonw_name(d->jw, "value"); > > - ret = btf_dumper_type(d, map_info->btf_value_type_id, value); > > + ret = btf_dumper_type(d, value_id, value); > > } else { > > unsigned int i, n, step; > > > > @@ -279,8 +284,7 @@ static int do_dump_btf(const struct btf_dumper *d, > > jsonw_start_object(d->jw); > > jsonw_int_field(d->jw, "cpu", i); > > jsonw_name(d->jw, "value"); > > - ret = btf_dumper_type(d, map_info->btf_value_type_id, > > - value + i * step); > > + ret = btf_dumper_type(d, value_id, value + i * step); > > jsonw_end_object(d->jw); > > if (ret) > > break; > > @@ -932,6 +936,27 @@ static int maps_have_btf(int *fds, int nb_fds) > > return 1; > > } > > > > +static struct btf *get_map_kv_btf(const struct bpf_map_info *info) > > +{ > > + struct btf *btf = NULL; > > + > > + if (info->btf_vmlinux_value_type_id) { > > + btf = bpf_find_kernel_btf(); > > If there are multiple maps we are dumping, it might become quite > costly to re-read and re-parse kernel BTF all the time. Can we lazily > load it, when required, It is loaded lazily. > and cache instead? Cache it in bpftool/map.c? Sure. > > > + if (IS_ERR(btf)) > > + p_err("failed to get kernel btf"); > > + } else if (info->btf_value_type_id) { > > + int err; > > + > > + err = btf__get_from_id(info->btf_id, &btf); > > + if (err || !btf) { > > + p_err("failed to get btf"); > > + btf = err ? ERR_PTR(err) : ERR_PTR(-ESRCH); > > + } > > + } > > + > > + return btf; > > +} > > + > > static int > > map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr, > > bool show_header) > > @@ -952,13 +977,11 @@ map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr, > > prev_key = NULL; > > > > if (wtr) { > > - if (info->btf_id) { > > - err = btf__get_from_id(info->btf_id, &btf); > > - if (err || !btf) { > > - err = err ? : -ESRCH; > > - p_err("failed to get btf"); > > - goto exit_free; > > - } > > + btf = get_map_kv_btf(info); > > + if (IS_ERR(btf)) { > > + err = PTR_ERR(btf); > > + btf = NULL; > > + goto exit_free; > > } > > > > if (show_header) { > > -- > > 2.17.1 > >
On Tue, Jan 14, 2020 at 10:04 PM Martin Lau <kafai@fb.com> wrote: > > On Tue, Jan 14, 2020 at 05:49:00PM -0800, Andrii Nakryiko wrote: > > On Tue, Jan 14, 2020 at 2:46 PM Martin KaFai Lau <kafai@fb.com> wrote: > > > > > > This patch makes bpftool support dumping a map's value properly > > > when the map's value type is a type of the running kernel's btf. > > > (i.e. map_info.btf_vmlinux_value_type_id is set instead of > > > map_info.btf_value_type_id). The first usecase is for the > > > BPF_MAP_TYPE_STRUCT_OPS. > > > > > > Signed-off-by: Martin KaFai Lau <kafai@fb.com> > > > --- > > > tools/bpf/bpftool/map.c | 43 +++++++++++++++++++++++++++++++---------- > > > 1 file changed, 33 insertions(+), 10 deletions(-) > > > > > > diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c > > > index 4c5b15d736b6..d25f3b2355ad 100644 > > > --- a/tools/bpf/bpftool/map.c > > > +++ b/tools/bpf/bpftool/map.c > > > @@ -20,6 +20,7 @@ > > > #include "btf.h" > > > #include "json_writer.h" > > > #include "main.h" > > > +#include "libbpf_internal.h" > > > > > > const char * const map_type_name[] = { > > > [BPF_MAP_TYPE_UNSPEC] = "unspec", > > > @@ -252,6 +253,7 @@ static int do_dump_btf(const struct btf_dumper *d, > > > struct bpf_map_info *map_info, void *key, > > > void *value) > > > { > > > + __u32 value_id; > > > int ret; > > > > > > /* start of key-value pair */ > > > @@ -265,9 +267,12 @@ static int do_dump_btf(const struct btf_dumper *d, > > > goto err_end_obj; > > > } > > > > > > + value_id = map_info->btf_vmlinux_value_type_id ? > > > + : map_info->btf_value_type_id; > > > + > > > if (!map_is_per_cpu(map_info->type)) { > > > jsonw_name(d->jw, "value"); > > > - ret = btf_dumper_type(d, map_info->btf_value_type_id, value); > > > + ret = btf_dumper_type(d, value_id, value); > > > } else { > > > unsigned int i, n, step; > > > > > > @@ -279,8 +284,7 @@ static int do_dump_btf(const struct btf_dumper *d, > > > jsonw_start_object(d->jw); > > > jsonw_int_field(d->jw, "cpu", i); > > > jsonw_name(d->jw, "value"); > > > - ret = btf_dumper_type(d, map_info->btf_value_type_id, > > > - value + i * step); > > > + ret = btf_dumper_type(d, value_id, value + i * step); > > > jsonw_end_object(d->jw); > > > if (ret) > > > break; > > > @@ -932,6 +936,27 @@ static int maps_have_btf(int *fds, int nb_fds) > > > return 1; > > > } > > > > > > +static struct btf *get_map_kv_btf(const struct bpf_map_info *info) > > > +{ > > > + struct btf *btf = NULL; > > > + > > > + if (info->btf_vmlinux_value_type_id) { > > > + btf = bpf_find_kernel_btf(); > > > > If there are multiple maps we are dumping, it might become quite > > costly to re-read and re-parse kernel BTF all the time. Can we lazily > > load it, when required, > It is loaded lazily. > yeah, it was meant as "lazy load and cache" vs "pre-load always" (which makes caching simpler). > > and cache instead? > Cache it in bpftool/map.c? Sure. yeah, for the duration of dumping > > > > > > + if (IS_ERR(btf)) > > > + p_err("failed to get kernel btf"); > > > + } else if (info->btf_value_type_id) { > > > + int err; > > > + > > > + err = btf__get_from_id(info->btf_id, &btf); > > > + if (err || !btf) { > > > + p_err("failed to get btf"); > > > + btf = err ? ERR_PTR(err) : ERR_PTR(-ESRCH); > > > + } > > > + } > > > + > > > + return btf; > > > +} > > > + > > > static int > > > map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr, > > > bool show_header) > > > @@ -952,13 +977,11 @@ map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr, > > > prev_key = NULL; > > > > > > if (wtr) { > > > - if (info->btf_id) { > > > - err = btf__get_from_id(info->btf_id, &btf); > > > - if (err || !btf) { > > > - err = err ? : -ESRCH; > > > - p_err("failed to get btf"); > > > - goto exit_free; > > > - } > > > + btf = get_map_kv_btf(info); > > > + if (IS_ERR(btf)) { > > > + err = PTR_ERR(btf); > > > + btf = NULL; > > > + goto exit_free; > > > } > > > > > > if (show_header) { > > > -- > > > 2.17.1 > > >
diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c index 4c5b15d736b6..d25f3b2355ad 100644 --- a/tools/bpf/bpftool/map.c +++ b/tools/bpf/bpftool/map.c @@ -20,6 +20,7 @@ #include "btf.h" #include "json_writer.h" #include "main.h" +#include "libbpf_internal.h" const char * const map_type_name[] = { [BPF_MAP_TYPE_UNSPEC] = "unspec", @@ -252,6 +253,7 @@ static int do_dump_btf(const struct btf_dumper *d, struct bpf_map_info *map_info, void *key, void *value) { + __u32 value_id; int ret; /* start of key-value pair */ @@ -265,9 +267,12 @@ static int do_dump_btf(const struct btf_dumper *d, goto err_end_obj; } + value_id = map_info->btf_vmlinux_value_type_id ? + : map_info->btf_value_type_id; + if (!map_is_per_cpu(map_info->type)) { jsonw_name(d->jw, "value"); - ret = btf_dumper_type(d, map_info->btf_value_type_id, value); + ret = btf_dumper_type(d, value_id, value); } else { unsigned int i, n, step; @@ -279,8 +284,7 @@ static int do_dump_btf(const struct btf_dumper *d, jsonw_start_object(d->jw); jsonw_int_field(d->jw, "cpu", i); jsonw_name(d->jw, "value"); - ret = btf_dumper_type(d, map_info->btf_value_type_id, - value + i * step); + ret = btf_dumper_type(d, value_id, value + i * step); jsonw_end_object(d->jw); if (ret) break; @@ -932,6 +936,27 @@ static int maps_have_btf(int *fds, int nb_fds) return 1; } +static struct btf *get_map_kv_btf(const struct bpf_map_info *info) +{ + struct btf *btf = NULL; + + if (info->btf_vmlinux_value_type_id) { + btf = bpf_find_kernel_btf(); + if (IS_ERR(btf)) + p_err("failed to get kernel btf"); + } else if (info->btf_value_type_id) { + int err; + + err = btf__get_from_id(info->btf_id, &btf); + if (err || !btf) { + p_err("failed to get btf"); + btf = err ? ERR_PTR(err) : ERR_PTR(-ESRCH); + } + } + + return btf; +} + static int map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr, bool show_header) @@ -952,13 +977,11 @@ map_dump(int fd, struct bpf_map_info *info, json_writer_t *wtr, prev_key = NULL; if (wtr) { - if (info->btf_id) { - err = btf__get_from_id(info->btf_id, &btf); - if (err || !btf) { - err = err ? : -ESRCH; - p_err("failed to get btf"); - goto exit_free; - } + btf = get_map_kv_btf(info); + if (IS_ERR(btf)) { + err = PTR_ERR(btf); + btf = NULL; + goto exit_free; } if (show_header) {
This patch makes bpftool support dumping a map's value properly when the map's value type is a type of the running kernel's btf. (i.e. map_info.btf_vmlinux_value_type_id is set instead of map_info.btf_value_type_id). The first usecase is for the BPF_MAP_TYPE_STRUCT_OPS. Signed-off-by: Martin KaFai Lau <kafai@fb.com> --- tools/bpf/bpftool/map.c | 43 +++++++++++++++++++++++++++++++---------- 1 file changed, 33 insertions(+), 10 deletions(-)