| Message ID | 20200506132946.2164578-2-jolsa@kernel.org |
|---|---|
| State | RFC |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | bpf: Add d_path helper | expand |
On Wed, May 6, 2020 at 6:30 AM Jiri Olsa <jolsa@kernel.org> wrote: > > Adding d_path helper function that returns full path > for give 'struct path' object, which needs to be the > kernel BTF 'path' object. > > The helper calls directly d_path function. > > Updating also bpf.h tools uapi header and adding > 'path' to bpf_helpers_doc.py script. > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > --- > include/uapi/linux/bpf.h | 14 +++++++++++++- > kernel/trace/bpf_trace.c | 31 +++++++++++++++++++++++++++++++ > scripts/bpf_helpers_doc.py | 2 ++ > tools/include/uapi/linux/bpf.h | 14 +++++++++++++- > 4 files changed, 59 insertions(+), 2 deletions(-) > [...] > > +BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz) > +{ > + char *p = d_path(path, buf, sz - 1); > + int len; > + > + if (IS_ERR(p)) { > + len = PTR_ERR(p); > + } else { > + len = strlen(p); > + if (len && p != buf) { > + memmove(buf, p, len); > + buf[len] = 0; > + } > + } > + > + return len; > +} > + > +static u32 bpf_d_path_btf_ids[3]; Using shorter than 5 element array is "unconventional", but seems like btf_distill_func_proto will never access elements that are not ARG_PTR_TO_BTF_ID, so it's fine. But than again, if we are saving space, why not just 1-element array? :) > +static const struct bpf_func_proto bpf_d_path_proto = { > + .func = bpf_d_path, > + .gpl_only = true, > + .ret_type = RET_INTEGER, > + .arg1_type = ARG_PTR_TO_BTF_ID, > + .arg2_type = ARG_PTR_TO_MEM, > + .arg3_type = ARG_CONST_SIZE, > + .btf_id = bpf_d_path_btf_ids, > +}; > + [...] > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h > index b3643e27e264..bc13cad27872 100644 > --- a/tools/include/uapi/linux/bpf.h > +++ b/tools/include/uapi/linux/bpf.h > @@ -3068,6 +3068,17 @@ union bpf_attr { > * See: clock_gettime(CLOCK_BOOTTIME) > * Return > * Current *ktime*. > + * > + * int bpf_d_path(struct path *path, char *buf, u32 sz) > + * Description > + * Return full path for given 'struct path' object, which > + * needs to be the kernel BTF 'path' object. The path is > + * returned in buffer provided 'buf' of size 'sz'. > + * Please specify if it's always zero-terminated string (especially on truncation). > + * Return > + * length of returned string on success, or a negative > + * error in case of failure > + * > */ > #define __BPF_FUNC_MAPPER(FN) \ > FN(unspec), \ > @@ -3195,7 +3206,8 @@ union bpf_attr { > FN(get_netns_cookie), \ > FN(get_current_ancestor_cgroup_id), \ > FN(sk_assign), \ > - FN(ktime_get_boot_ns), > + FN(ktime_get_boot_ns), \ > + FN(d_path), > > /* integer value in 'imm' field of BPF_CALL instruction selects which helper > * function eBPF program intends to call > -- > 2.25.4 >
On Thu, May 14, 2020 at 03:06:01PM -0700, Andrii Nakryiko wrote: > On Wed, May 6, 2020 at 6:30 AM Jiri Olsa <jolsa@kernel.org> wrote: > > > > Adding d_path helper function that returns full path > > for give 'struct path' object, which needs to be the > > kernel BTF 'path' object. > > > > The helper calls directly d_path function. > > > > Updating also bpf.h tools uapi header and adding > > 'path' to bpf_helpers_doc.py script. > > > > Signed-off-by: Jiri Olsa <jolsa@kernel.org> > > --- > > include/uapi/linux/bpf.h | 14 +++++++++++++- > > kernel/trace/bpf_trace.c | 31 +++++++++++++++++++++++++++++++ > > scripts/bpf_helpers_doc.py | 2 ++ > > tools/include/uapi/linux/bpf.h | 14 +++++++++++++- > > 4 files changed, 59 insertions(+), 2 deletions(-) > > > > [...] > > > > > +BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz) > > +{ > > + char *p = d_path(path, buf, sz - 1); > > + int len; > > + > > + if (IS_ERR(p)) { > > + len = PTR_ERR(p); > > + } else { > > + len = strlen(p); > > + if (len && p != buf) { > > + memmove(buf, p, len); > > + buf[len] = 0; > > + } > > + } > > + > > + return len; > > +} > > + > > +static u32 bpf_d_path_btf_ids[3]; > > Using shorter than 5 element array is "unconventional", but seems like > btf_distill_func_proto will never access elements that are not > ARG_PTR_TO_BTF_ID, so it's fine. But than again, if we are saving > space, why not just 1-element array? :) right, that can be actualy just 1 element array ;-) > > > > +static const struct bpf_func_proto bpf_d_path_proto = { > > + .func = bpf_d_path, > > + .gpl_only = true, > > + .ret_type = RET_INTEGER, > > + .arg1_type = ARG_PTR_TO_BTF_ID, > > + .arg2_type = ARG_PTR_TO_MEM, > > + .arg3_type = ARG_CONST_SIZE, > > + .btf_id = bpf_d_path_btf_ids, > > +}; > > + > > [...] > > > diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h > > index b3643e27e264..bc13cad27872 100644 > > --- a/tools/include/uapi/linux/bpf.h > > +++ b/tools/include/uapi/linux/bpf.h > > @@ -3068,6 +3068,17 @@ union bpf_attr { > > * See: clock_gettime(CLOCK_BOOTTIME) > > * Return > > * Current *ktime*. > > + * > > + * int bpf_d_path(struct path *path, char *buf, u32 sz) > > + * Description > > + * Return full path for given 'struct path' object, which > > + * needs to be the kernel BTF 'path' object. The path is > > + * returned in buffer provided 'buf' of size 'sz'. > > + * > > Please specify if it's always zero-terminated string (especially on truncation). ok, will mention the zero termination in here thanks, jirka
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index b3643e27e264..bc13cad27872 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3068,6 +3068,17 @@ union bpf_attr { * See: clock_gettime(CLOCK_BOOTTIME) * Return * Current *ktime*. + * + * int bpf_d_path(struct path *path, char *buf, u32 sz) + * Description + * Return full path for given 'struct path' object, which + * needs to be the kernel BTF 'path' object. The path is + * returned in buffer provided 'buf' of size 'sz'. + * + * Return + * length of returned string on success, or a negative + * error in case of failure + * */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3195,7 +3206,8 @@ union bpf_attr { FN(get_netns_cookie), \ FN(get_current_ancestor_cgroup_id), \ FN(sk_assign), \ - FN(ktime_get_boot_ns), + FN(ktime_get_boot_ns), \ + FN(d_path), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index e875c95d3ced..3097ab04bdc4 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -779,6 +779,35 @@ static const struct bpf_func_proto bpf_send_signal_thread_proto = { .arg1_type = ARG_ANYTHING, }; +BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz) +{ + char *p = d_path(path, buf, sz - 1); + int len; + + if (IS_ERR(p)) { + len = PTR_ERR(p); + } else { + len = strlen(p); + if (len && p != buf) { + memmove(buf, p, len); + buf[len] = 0; + } + } + + return len; +} + +static u32 bpf_d_path_btf_ids[3]; +static const struct bpf_func_proto bpf_d_path_proto = { + .func = bpf_d_path, + .gpl_only = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_BTF_ID, + .arg2_type = ARG_PTR_TO_MEM, + .arg3_type = ARG_CONST_SIZE, + .btf_id = bpf_d_path_btf_ids, +}; + const struct bpf_func_proto * bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { @@ -1226,6 +1255,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_xdp_output: return &bpf_xdp_output_proto; #endif + case BPF_FUNC_d_path: + return &bpf_d_path_proto; default: return raw_tp_prog_func_proto(func_id, prog); } diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py index f43d193aff3a..8f62cbc4c3ff 100755 --- a/scripts/bpf_helpers_doc.py +++ b/scripts/bpf_helpers_doc.py @@ -418,6 +418,7 @@ class PrinterHelpers(Printer): 'struct __sk_buff', 'struct sk_msg_md', 'struct xdp_md', + 'struct path', ] known_types = { '...', @@ -450,6 +451,7 @@ class PrinterHelpers(Printer): 'struct sk_reuseport_md', 'struct sockaddr', 'struct tcphdr', + 'struct path', } mapped_types = { 'u8': '__u8', diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index b3643e27e264..bc13cad27872 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3068,6 +3068,17 @@ union bpf_attr { * See: clock_gettime(CLOCK_BOOTTIME) * Return * Current *ktime*. + * + * int bpf_d_path(struct path *path, char *buf, u32 sz) + * Description + * Return full path for given 'struct path' object, which + * needs to be the kernel BTF 'path' object. The path is + * returned in buffer provided 'buf' of size 'sz'. + * + * Return + * length of returned string on success, or a negative + * error in case of failure + * */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3195,7 +3206,8 @@ union bpf_attr { FN(get_netns_cookie), \ FN(get_current_ancestor_cgroup_id), \ FN(sk_assign), \ - FN(ktime_get_boot_ns), + FN(ktime_get_boot_ns), \ + FN(d_path), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call
Adding d_path helper function that returns full path for give 'struct path' object, which needs to be the kernel BTF 'path' object. The helper calls directly d_path function. Updating also bpf.h tools uapi header and adding 'path' to bpf_helpers_doc.py script. Signed-off-by: Jiri Olsa <jolsa@kernel.org> --- include/uapi/linux/bpf.h | 14 +++++++++++++- kernel/trace/bpf_trace.c | 31 +++++++++++++++++++++++++++++++ scripts/bpf_helpers_doc.py | 2 ++ tools/include/uapi/linux/bpf.h | 14 +++++++++++++- 4 files changed, 59 insertions(+), 2 deletions(-)