7 files changed, 124 insertions, 55 deletions

diff --git a/tools/bpf/bpftool/Documentation/bpftool-map.rst b/tools/bpf/bpftool/Documentation/bpftool-map.rst
index 5318dcb2085e..3221be1b9ccc 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-map.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-map.rst
@@ -170,6 +170,61 @@ The following three commands are equivalent:
 | **# bpftool map pin id 10 /sys/fs/bpf/map**
 | **# bpftool map del pinned /sys/fs/bpf/map key 13 00 07 00**
 
+Note that map update can also be used in order to change the program references
+hold by a program array map. This can be used, for example, to change the
+programs used for tail-call jumps at runtime, without having to reload the
+entry-point program. Below is an example for this use case: we load a program
+defining a prog array map, and with a main function that contains a tail call
+to other programs that can be used either to "process" packets or to "debug"
+processing. Note that the prog array map MUST be pinned into the BPF virtual
+file system for the map update to work successfully, as kernel flushes prog
+array maps when they have no more references from user space (and the update
+would be lost as soon as bpftool exits).
+
+|
+| **# bpftool prog loadall tail_calls.o /sys/fs/bpf/foo type xdp**
+| **# bpftool prog --bpffs**
+
+::
+
+  545: xdp  name main_func  tag 674b4b5597193dc3  gpl
+          loaded_at 2018-12-12T15:02:58+0000  uid 0
+          xlated 240B  jited 257B  memlock 4096B  map_ids 294
+          pinned /sys/fs/bpf/foo/xdp
+  546: xdp  name bpf_func_process  tag e369a529024751fc  gpl
+          loaded_at 2018-12-12T15:02:58+0000  uid 0
+          xlated 200B  jited 164B  memlock 4096B
+          pinned /sys/fs/bpf/foo/process
+  547: xdp  name bpf_func_debug  tag 0b597868bc7f0976  gpl
+          loaded_at 2018-12-12T15:02:58+0000  uid 0
+          xlated 200B  jited 164B  memlock 4096B
+          pinned /sys/fs/bpf/foo/debug
+
+**# bpftool map**
+
+::
+
+  294: prog_array  name jmp_table  flags 0x0
+          key 4B  value 4B  max_entries 1  memlock 4096B
+          owner_prog_type xdp  owner jited
+
+|
+| **# bpftool map pin id 294 /sys/fs/bpf/bar**
+| **# bpftool map dump pinned /sys/fs/bpf/bar**
+
+::
+
+  Found 0 elements
+
+|
+| **# bpftool map update pinned /sys/fs/bpf/bar key 0 0 0 0 value pinned /sys/fs/bpf/foo/debug**
+| **# bpftool map dump pinned /sys/fs/bpf/bar**
+
+::
+
+  key: 00 00 00 00  value: 22 02 00 00
+  Found 1 element
+
 SEE ALSO
 ========
         **bpf**\ (2),
diff --git a/tools/bpf/bpftool/Documentation/bpftool-prog.rst b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
index bb1aeb98b6da..53920ffc48dd 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-prog.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-prog.rst
@@ -158,83 +158,94 @@ OPTIONS
                   When showing BPF programs, show file names of pinned
                   programs.
 
+        -m, --mapcompat
+                  Allow loading maps with unknown map definitions.
+
 EXAMPLES
 ========
 **# bpftool prog show**
+
 ::
 
-  10: xdp  name some_prog  tag 005a3d2123620c8b  gpl
-        loaded_at Sep 29/20:11  uid 0
-        xlated 528B  jited 370B  memlock 4096B  map_ids 10
+    10: xdp  name some_prog  tag 005a3d2123620c8b  gpl
+            loaded_at 2017-09-29T20:11:00+0000  uid 0
+            xlated 528B  jited 370B  memlock 4096B  map_ids 10
 
 **# bpftool --json --pretty prog show**
 
 ::
 
-    {
-        "programs": [{
-                "id": 10,
-                "type": "xdp",
-                "tag": "005a3d2123620c8b",
-                "gpl_compatible": true,
-                "loaded_at": "Sep 29/20:11",
-                "uid": 0,
-                "bytes_xlated": 528,
-                "jited": true,
-                "bytes_jited": 370,
-                "bytes_memlock": 4096,
-                "map_ids": [10
-                ]
-            }
-        ]
-    }
+    [{
+            "id": 10,
+            "type": "xdp",
+            "tag": "005a3d2123620c8b",
+            "gpl_compatible": true,
+            "loaded_at": 1506715860,
+            "uid": 0,
+            "bytes_xlated": 528,
+            "jited": true,
+            "bytes_jited": 370,
+            "bytes_memlock": 4096,
+            "map_ids": [10
+            ]
+        }
+    ]
 
 |
 | **# bpftool prog dump xlated id 10 file /tmp/t**
 | **# ls -l /tmp/t**
-|   -rw------- 1 root root 560 Jul 22 01:42 /tmp/t
 
-**# bpftool prog dum jited tag 005a3d2123620c8b**
+::
+
+    -rw------- 1 root root 560 Jul 22 01:42 /tmp/t
+
+**# bpftool prog dump jited tag 005a3d2123620c8b**
 
 ::
 
-    push   %rbp
-    mov    %rsp,%rbp
-    sub    $0x228,%rsp
-    sub    $0x28,%rbp
-    mov    %rbx,0x0(%rbp)
+    0:   push   %rbp
+    1:   mov    %rsp,%rbp
+    2:   sub    $0x228,%rsp
+    3:   sub    $0x28,%rbp
+    4:   mov    %rbx,0x0(%rbp)
 
 |
 | **# mount -t bpf none /sys/fs/bpf/**
 | **# bpftool prog pin id 10 /sys/fs/bpf/prog**
 | **# bpftool prog load ./my_prog.o /sys/fs/bpf/prog2**
 | **# ls -l /sys/fs/bpf/**
-|   -rw------- 1 root root 0 Jul 22 01:43 prog
-|   -rw------- 1 root root 0 Jul 22 01:44 prog2
 
-**# bpftool prog dum jited pinned /sys/fs/bpf/prog opcodes**
+::
+
+    -rw------- 1 root root 0 Jul 22 01:43 prog
+    -rw------- 1 root root 0 Jul 22 01:44 prog2
+
+**# bpftool prog dump jited pinned /sys/fs/bpf/prog opcodes**
 
 ::
 
-    push   %rbp
-    55
-    mov    %rsp,%rbp
-    48 89 e5
-    sub    $0x228,%rsp
-    48 81 ec 28 02 00 00
-    sub    $0x28,%rbp
-    48 83 ed 28
-    mov    %rbx,0x0(%rbp)
-    48 89 5d 00
+   0:   push   %rbp
+        55
+   1:   mov    %rsp,%rbp
+        48 89 e5
+   4:   sub    $0x228,%rsp
+        48 81 ec 28 02 00 00
+   b:   sub    $0x28,%rbp
+        48 83 ed 28
+   f:   mov    %rbx,0x0(%rbp)
+        48 89 5d 00
 
 |
 | **# bpftool prog load xdp1_kern.o /sys/fs/bpf/xdp1 type xdp map name rxcnt id 7**
 | **# bpftool prog show pinned /sys/fs/bpf/xdp1**
-|   9: xdp  name xdp_prog1  tag 539ec6ce11b52f98  gpl
-|       loaded_at 2018-06-25T16:17:31-0700  uid 0
-|       xlated 488B  jited 336B  memlock 4096B  map_ids 7
-| **# rm /sys/fs/bpf/xdp1**
-|
+
+::
+
+    9: xdp  name xdp_prog1  tag 539ec6ce11b52f98  gpl
+            loaded_at 2018-06-25T16:17:31-0700  uid 0
+            xlated 488B  jited 336B  memlock 4096B  map_ids 7
+
+**# rm /sys/fs/bpf/xdp1**
 
 SEE ALSO
 ========
diff --git a/tools/bpf/bpftool/common.c b/tools/bpf/bpftool/common.c
index 99e4027dde75..24582e8a96fb 100644
--- a/tools/bpf/bpftool/common.c
+++ b/tools/bpf/bpftool/common.c
@@ -28,7 +28,7 @@
 #define BPF_FS_MAGIC            0xcafe4a11
 #endif
 
-void p_err(const char *fmt, ...)
+void __printf(1, 2) p_err(const char *fmt, ...)
 {
         va_list ap;
 
@@ -46,7 +46,7 @@ void p_err(const char *fmt, ...)
         va_end(ap);
 }
 
-void p_info(const char *fmt, ...)
+void __printf(1, 2) p_info(const char *fmt, ...)
 {
         va_list ap;
 
diff --git a/tools/bpf/bpftool/json_writer.c b/tools/bpf/bpftool/json_writer.c
index a07d17918725..bff7ee026680 100644
--- a/tools/bpf/bpftool/json_writer.c
+++ b/tools/bpf/bpftool/json_writer.c
@@ -20,6 +20,7 @@
 #include <malloc.h>
 #include <inttypes.h>
 #include <stdint.h>
+#include <linux/compiler.h>
 
 #include "json_writer.h"
 
@@ -157,7 +158,8 @@ void jsonw_name(json_writer_t *self, const char *name)
                 putc(' ', self->out);
 }
 
-void jsonw_vprintf_enquote(json_writer_t *self, const char *fmt, va_list ap)
+void __printf(2, 0)
+jsonw_vprintf_enquote(json_writer_t *self, const char *fmt, va_list ap)
 {
         jsonw_eor(self);
         putc('"', self->out);
@@ -165,7 +167,7 @@ void jsonw_vprintf_enquote(json_writer_t *self, const char *fmt, va_list ap)
         putc('"', self->out);
 }
 
-void jsonw_printf(json_writer_t *self, const char *fmt, ...)
+void __printf(2, 3) jsonw_printf(json_writer_t *self, const char *fmt, ...)
 {
         va_list ap;
 
diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h
index d2beb88f0e2e..9487345b04a7 100644
--- a/tools/bpf/bpftool/main.h
+++ b/tools/bpf/bpftool/main.h
@@ -147,8 +147,8 @@ int prog_parse_fd(int *argc, char ***argv);
 int map_parse_fd(int *argc, char ***argv);
 int map_parse_fd_and_info(int *argc, char ***argv, void *info, __u32 *info_len);
 
-#ifdef HAVE_LIBBFD_SUPPORT
 struct bpf_prog_linfo;
+#ifdef HAVE_LIBBFD_SUPPORT
 void disasm_print_insn(unsigned char *image, ssize_t len, int opcodes,
                        const char *arch, const char *disassembler_options,
                        const struct btf *btf,
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index ee51279be9c7..2d1bb7d6ff51 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -32,7 +32,7 @@ static const char * const attach_type_strings[] = {
         [__MAX_BPF_ATTACH_TYPE] = NULL,
 };
 
-enum bpf_attach_type parse_attach_type(const char *str)
+static enum bpf_attach_type parse_attach_type(const char *str)
 {
         enum bpf_attach_type type;
 
@@ -798,7 +798,7 @@ struct map_replace {
         char *name;
 };
 
-int map_replace_compar(const void *p1, const void *p2)
+static int map_replace_compar(const void *p1, const void *p2)
 {
         const struct map_replace *a = p1, *b = p2;
 
diff --git a/tools/bpf/bpftool/xlated_dumper.c b/tools/bpf/bpftool/xlated_dumper.c
index 640ffe86a655..7073dbe1ff27 100644
--- a/tools/bpf/bpftool/xlated_dumper.c
+++ b/tools/bpf/bpftool/xlated_dumper.c
@@ -81,7 +81,7 @@ struct kernel_sym *kernel_syms_search(struct dump_data *dd,
                        sizeof(*dd->sym_mapping), kernel_syms_cmp) : NULL;
 }
 
-static void print_insn(void *private_data, const char *fmt, ...)
+static void __printf(2, 3) print_insn(void *private_data, const char *fmt, ...)
 {
         va_list args;
 
@@ -90,7 +90,7 @@ static void print_insn(void *private_data, const char *fmt, ...)
         va_end(args);
 }
 
-static void
+static void __printf(2, 3)
 print_insn_for_graph(void *private_data, const char *fmt, ...)
 {
         char buf[64], *p;
@@ -121,7 +121,8 @@ print_insn_for_graph(void *private_data, const char *fmt, ...)
         printf("%s", buf);
 }
 
-static void print_insn_json(void *private_data, const char *fmt, ...)
+static void __printf(2, 3)
+print_insn_json(void *private_data, const char *fmt, ...)
 {
         unsigned int l = strlen(fmt);
         char chomped_fmt[l];