From: Wang Nan <wangnan0@huawei.com>
To: <acme@kernel.org>, <ast@plumgrid.com>
Cc: <linux-kernel@vger.kernel.org>, <lizefan@huawei.com>,
<hekuang@huawei.com>, <xiakaixu@huawei.com>, <pi3orama@163.com>
Subject: [PATCH 07/39] bpf tools: Relocate eBPF programs
Date: Thu, 9 Jul 2015 12:35:10 +0000 [thread overview]
Message-ID: <1436445342-1402-8-git-send-email-wangnan0@huawei.com> (raw)
In-Reply-To: <1436445342-1402-1-git-send-email-wangnan0@huawei.com>
If an eBPF program accesses a map, LLVM generates a load instruction
which loads an absolute address into a register, like this:
ld_64 r1, <MCOperand Expr:(mymap)>
...
call 2
That ld_64 instruction will be recorded in relocation section.
To enable the usage of that map, relocation must be done by replacing
the immediate value by real map file descriptor so it can be found by
eBPF map functions.
This patch to the relocation work based on information collected by
patches:
'bpf tools: Collect symbol table from SHT_SYMTAB section',
'bpf tools: Collect relocation sections from SHT_REL sections'
and
'bpf tools: Record map accessing instructions for each program'.
For each instruction which needs relocation, it inject corresponding
file descriptor to imm field. As a part of protocol, src_reg is set to
BPF_PSEUDO_MAP_FD to notify kernel this is a map loading instruction.
This is the final part of map relocation patch. The principle of map
relocation is described in commit message of 'bpf tools: Collect symbol
table from SHT_SYMTAB section'.
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1435716878-189507-18-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/lib/bpf/libbpf.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 52 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index c214e1c..cd40ae0 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -633,6 +633,56 @@ bpf_object__create_maps(struct bpf_object *obj)
return 0;
}
+static int
+bpf_program__relocate(struct bpf_program *prog, int *map_fds)
+{
+ int i;
+
+ if (!prog || !prog->reloc_desc)
+ return 0;
+
+ for (i = 0; i < prog->nr_reloc; i++) {
+ int insn_idx, map_idx;
+ struct bpf_insn *insns = prog->insns;
+
+ insn_idx = prog->reloc_desc[i].insn_idx;
+ map_idx = prog->reloc_desc[i].map_idx;
+
+ if (insn_idx >= (int)prog->insns_cnt) {
+ pr_warning("relocation out of range: '%s'\n",
+ prog->section_name);
+ return -ERANGE;
+ }
+ insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD;
+ insns[insn_idx].imm = map_fds[map_idx];
+ }
+
+ zfree(&prog->reloc_desc);
+ prog->nr_reloc = 0;
+ return 0;
+}
+
+
+static int
+bpf_object__relocate(struct bpf_object *obj)
+{
+ struct bpf_program *prog;
+ size_t i;
+ int err;
+
+ for (i = 0; i < obj->nr_programs; i++) {
+ prog = &obj->programs[i];
+
+ err = bpf_program__relocate(prog, obj->map_fds);
+ if (err) {
+ pr_warning("failed to relocate '%s'\n",
+ prog->section_name);
+ return err;
+ }
+ }
+ return 0;
+}
+
static int bpf_object__collect_reloc(struct bpf_object *obj)
{
int i, err;
@@ -764,6 +814,8 @@ int bpf_object__load(struct bpf_object *obj)
obj->loaded = true;
if (bpf_object__create_maps(obj))
goto out;
+ if (bpf_object__relocate(obj))
+ goto out;
return 0;
out:
--
1.8.3.4
next prev parent reply other threads:[~2015-07-09 12:36 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-09 12:35 [GIT PULL 00/39] perf tools: filtering events using eBPF programs Wang Nan
2015-07-09 12:35 ` [PATCH 01/39] bpf tools: Collect symbol table from SHT_SYMTAB section Wang Nan
2015-07-09 12:35 ` [PATCH 02/39] bpf tools: Collect eBPF programs from their own sections Wang Nan
2015-07-09 15:58 ` Arnaldo Carvalho de Melo
2015-07-10 3:07 ` Wangnan (F)
2015-07-13 19:51 ` Arnaldo Carvalho de Melo
2015-07-14 3:58 ` Wangnan (F)
2015-07-09 12:35 ` [PATCH 03/39] bpf tools: Collect relocation sections from SHT_REL sections Wang Nan
2015-07-09 12:35 ` [PATCH 04/39] bpf tools: Record map accessing instructions for each program Wang Nan
2015-07-09 12:35 ` [PATCH 05/39] bpf tools: Add bpf.c/h for common bpf operations Wang Nan
2015-07-09 12:35 ` [PATCH 06/39] bpf tools: Create eBPF maps defined in an object file Wang Nan
2015-07-13 19:54 ` Arnaldo Carvalho de Melo
2015-07-14 3:59 ` Wangnan (F)
2015-07-09 12:35 ` Wang Nan [this message]
2015-07-09 12:35 ` [PATCH 08/39] bpf tools: Introduce bpf_load_program() to bpf.c Wang Nan
2015-07-09 12:35 ` [PATCH 09/39] bpf tools: Load eBPF programs in object files into kernel Wang Nan
2015-07-09 12:35 ` [PATCH 10/39] bpf tools: Introduce accessors for struct bpf_program Wang Nan
2015-07-09 12:35 ` [PATCH 11/39] bpf tools: Link all bpf objects onto a list Wang Nan
2015-07-09 12:35 ` [PATCH 12/39] perf tools: Introduce llvm config options Wang Nan
2015-07-21 11:13 ` [PATCH 12/39 update] " Wang Nan
2015-08-08 8:16 ` [tip:perf/core] " tip-bot for Wang Nan
2015-07-09 12:35 ` [PATCH 13/39] perf tools: Call clang to compile C source to object code Wang Nan
2015-07-09 12:35 ` [PATCH 14/39] perf tools: Auto detecting kernel build directory Wang Nan
2015-07-13 21:46 ` Arnaldo Carvalho de Melo
2015-07-14 6:56 ` Wangnan (F)
2015-07-14 7:16 ` Wangnan (F)
2015-07-09 12:35 ` [PATCH 15/39] perf tools: Auto detecting kernel include options Wang Nan
2015-08-08 8:17 ` [tip:perf/core] " tip-bot for Wang Nan
2015-07-09 12:35 ` [PATCH 16/39] perf tests: Add LLVM test for eBPF on-the-fly compiling Wang Nan
2015-07-15 10:54 ` [PATCH updated " Wang Nan
2015-07-22 4:46 ` [PATCH 16/39 RESEND] " Wang Nan
2015-07-09 12:35 ` [PATCH 17/39] perf tools: Make perf depend on libbpf Wang Nan
2015-07-09 12:35 ` [PATCH 18/39] perf record: Enable passing bpf object file to --event Wang Nan
2015-07-09 12:35 ` [PATCH 19/39] perf record: Compile scriptlets if pass '.c' " Wang Nan
2015-07-09 12:35 ` [PATCH 20/39] perf tools: Parse probe points of eBPF programs during preparation Wang Nan
2015-07-09 12:35 ` [PATCH 21/39] perf probe: Attach trace_probe_event with perf_probe_event Wang Nan
2015-07-09 12:35 ` [PATCH 22/39] perf record: Probe at kprobe points Wang Nan
2015-07-09 12:35 ` [PATCH 23/39] perf record: Load all eBPF object into kernel Wang Nan
2015-07-09 12:35 ` [PATCH 24/39] perf tools: Add bpf_fd field to evsel and config it Wang Nan
2015-07-09 12:35 ` [PATCH 25/39] perf tools: Attach eBPF program to perf event Wang Nan
2015-07-09 12:35 ` [PATCH 26/39] perf tools: Suppress probing messages when probing by BPF loading Wang Nan
2015-07-09 12:35 ` [PATCH 27/39] perf record: Add clang options for compiling BPF scripts Wang Nan
2015-07-09 12:35 ` [PATCH 28/39] bpf tools: Load a program with different instances using preprocessor Wang Nan
2015-07-13 5:44 ` Wangnan (F)
2015-07-09 12:35 ` [PATCH 29/39] perf tools: Fix probe-event.h include Wang Nan
2015-07-09 12:35 ` [PATCH 30/39] perf probe: Reset args and nargs for probe_trace_event when failure Wang Nan
2015-07-09 12:35 ` [PATCH 31/39] perf tools: Move linux/filter.h to tools/include Wang Nan
2015-07-09 12:35 ` [PATCH 32/39] perf tools: Add BPF_PROLOGUE config options for further patches Wang Nan
2015-07-09 12:35 ` [PATCH 33/39] perf tools: Introduce arch_get_reg_info() for x86 Wang Nan
2015-07-09 12:35 ` [PATCH 34/39] perf tools: Add prologue for BPF programs for fetching arguments Wang Nan
2015-07-09 12:35 ` [PATCH 35/39] perf tools: Generate prologue for BPF programs Wang Nan
2015-07-09 12:35 ` [PATCH 36/39] perf tools: Use same BPF program if arguments are identical Wang Nan
2015-07-09 12:35 ` [PATCH 37/39] perf record: Support custom vmlinux path Wang Nan
2015-07-09 12:35 ` [PATCH 38/39] perf probe: Init symbol as kprobe if any event is kprobe Wang Nan
2015-07-09 12:35 ` [PATCH 39/39] perf tools: Support attach BPF program on uprobe events Wang Nan
2015-07-14 15:36 ` perf test LLVM was: Re: [GIT PULL 00/39] perf tools: filtering events using eBPF programs Arnaldo Carvalho de Melo
2015-07-15 10:49 ` Wangnan (F)
2015-07-15 11:20 ` Arnaldo Carvalho de Melo
2015-07-17 2:34 ` Wangnan (F)
[not found] ` <CA+JHD93=ZMFP0gB1NqTXGBjTfSyYC-53Uj7r11gQJnKtQRKcDg@mail.gmail.com>
2015-07-21 11:09 ` Wangnan (F)
2015-07-21 11:41 ` Arnaldo Carvalho de Melo
2015-07-22 4:40 ` Wangnan (F)
2015-07-31 15:35 ` perf eBPF patch ordering. was: " Arnaldo Carvalho de Melo
2015-07-31 20:31 ` Arnaldo Carvalho de Melo
2015-08-03 2:37 ` Wangnan (F)
2015-08-03 15:07 ` Arnaldo Carvalho de Melo
2015-08-03 15:19 ` Arnaldo Carvalho de Melo
2015-08-03 15:53 ` pi3orama
2015-08-03 16:11 ` Arnaldo Carvalho de Melo
2015-08-03 19:49 ` Arnaldo Carvalho de Melo
2015-08-04 5:28 ` Wangnan (F)
2015-08-04 10:39 ` Wangnan (F)
2015-08-04 15:55 ` Arnaldo Carvalho de Melo
2015-08-04 16:11 ` Arnaldo Carvalho de Melo
2015-08-04 16:13 ` pi3orama
2015-08-06 1:44 ` Wangnan (F)
2015-08-06 14:46 ` Arnaldo Carvalho de Melo
2015-08-06 15:58 ` Arnaldo Carvalho de Melo
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