[PATCH bpf-next v3 1/3] uapi/bpf: Add missing description and returns for helper documentation

[PATCH bpf-next v3 1/3] uapi/bpf: Add missing description and returns for helper documentation

[Usama Arif]

Both description and returns section will become mandatory
for helpers and syscalls in a later commit to generate man pages.

This commit also adds in the documentation that BPF_PROG_RUN is
an alias for BPF_PROG_TEST_RUN for anyone searching for the
syscall in the generated man pages.

Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
 include/uapi/linux/bpf.h       | 15 +++++++++++++++
 tools/include/uapi/linux/bpf.h | 15 +++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index b0383d371b9a..a9c96c21330a 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -330,6 +330,8 @@ union bpf_iter_link_info {
  *			*ctx_out*, *data_in* and *data_out* must be NULL.
  *			*repeat* must be zero.
  *
+ *		BPF_PROG_RUN is an alias for BPF_PROG_TEST_RUN.
+ *
  *	Return
  *		Returns zero on success. On error, -1 is returned and *errno*
  *		is set appropriately.
@@ -1775,6 +1777,8 @@ union bpf_attr {
  * 		0 on success, or a negative error in case of failure.
  *
  * u64 bpf_get_current_pid_tgid(void)
+ * 	Description
+ * 		Get the current pid and tgid.
  * 	Return
  * 		A 64-bit integer containing the current tgid and pid, and
  * 		created as such:
@@ -1782,6 +1786,8 @@ union bpf_attr {
  * 		*current_task*\ **->pid**.
  *
  * u64 bpf_get_current_uid_gid(void)
+ * 	Description
+ * 		Get the current uid and gid.
  * 	Return
  * 		A 64-bit integer containing the current GID and UID, and
  * 		created as such: *current_gid* **<< 32 \|** *current_uid*.
@@ -2256,6 +2262,8 @@ union bpf_attr {
  * 		The 32-bit hash.
  *
  * u64 bpf_get_current_task(void)
+ * 	Description
+ * 		Get the current task.
  * 	Return
  * 		A pointer to the current task struct.
  *
@@ -2369,6 +2377,8 @@ union bpf_attr {
  * 		indicate that the hash is outdated and to trigger a
  * 		recalculation the next time the kernel tries to access this
  * 		hash or when the **bpf_get_hash_recalc**\ () helper is called.
+ * 	Return
+ * 		void.
  *
  * long bpf_get_numa_node_id(void)
  * 	Description
@@ -2466,6 +2476,8 @@ union bpf_attr {
  * 		A 8-byte long unique number or 0 if *sk* is NULL.
  *
  * u32 bpf_get_socket_uid(struct sk_buff *skb)
+ * 	Description
+ * 		Get the owner UID of the socked associated to *skb*.
  * 	Return
  * 		The owner UID of the socket associated to *skb*. If the socket
  * 		is **NULL**, or if it is not a full socket (i.e. if it is a
@@ -3240,6 +3252,9 @@ union bpf_attr {
  * 		The id is returned or 0 in case the id could not be retrieved.
  *
  * u64 bpf_get_current_cgroup_id(void)
+ * 	Description
+ * 		Get the current cgroup id based on the cgroup within which
+ * 		the current task is running.
  * 	Return
  * 		A 64-bit integer containing the current cgroup id based
  * 		on the cgroup within which the current task is running.
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index b0383d371b9a..a9c96c21330a 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -330,6 +330,8 @@ union bpf_iter_link_info {
  *			*ctx_out*, *data_in* and *data_out* must be NULL.
  *			*repeat* must be zero.
  *
+ *		BPF_PROG_RUN is an alias for BPF_PROG_TEST_RUN.
+ *
  *	Return
  *		Returns zero on success. On error, -1 is returned and *errno*
  *		is set appropriately.
@@ -1775,6 +1777,8 @@ union bpf_attr {
  * 		0 on success, or a negative error in case of failure.
  *
  * u64 bpf_get_current_pid_tgid(void)
+ * 	Description
+ * 		Get the current pid and tgid.
  * 	Return
  * 		A 64-bit integer containing the current tgid and pid, and
  * 		created as such:
@@ -1782,6 +1786,8 @@ union bpf_attr {
  * 		*current_task*\ **->pid**.
  *
  * u64 bpf_get_current_uid_gid(void)
+ * 	Description
+ * 		Get the current uid and gid.
  * 	Return
  * 		A 64-bit integer containing the current GID and UID, and
  * 		created as such: *current_gid* **<< 32 \|** *current_uid*.
@@ -2256,6 +2262,8 @@ union bpf_attr {
  * 		The 32-bit hash.
  *
  * u64 bpf_get_current_task(void)
+ * 	Description
+ * 		Get the current task.
  * 	Return
  * 		A pointer to the current task struct.
  *
@@ -2369,6 +2377,8 @@ union bpf_attr {
  * 		indicate that the hash is outdated and to trigger a
  * 		recalculation the next time the kernel tries to access this
  * 		hash or when the **bpf_get_hash_recalc**\ () helper is called.
+ * 	Return
+ * 		void.
  *
  * long bpf_get_numa_node_id(void)
  * 	Description
@@ -2466,6 +2476,8 @@ union bpf_attr {
  * 		A 8-byte long unique number or 0 if *sk* is NULL.
  *
  * u32 bpf_get_socket_uid(struct sk_buff *skb)
+ * 	Description
+ * 		Get the owner UID of the socked associated to *skb*.
  * 	Return
  * 		The owner UID of the socket associated to *skb*. If the socket
  * 		is **NULL**, or if it is not a full socket (i.e. if it is a
@@ -3240,6 +3252,9 @@ union bpf_attr {
  * 		The id is returned or 0 in case the id could not be retrieved.
  *
  * u64 bpf_get_current_cgroup_id(void)
+ * 	Description
+ * 		Get the current cgroup id based on the cgroup within which
+ * 		the current task is running.
  * 	Return
  * 		A 64-bit integer containing the current cgroup id based
  * 		on the cgroup within which the current task is running.
-- 
2.25.1

[PATCH bpf-next v3 2/3] bpf/scripts: Make description and returns section for helpers/syscalls mandatory

[Usama Arif]

This  enforce a minimal formatting consistency for the documentation. The
description and returns missing for a few helpers have also been added.

Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>

---
v1->v3:
- Moved UAPI header changes to a seperate commit (suggested by
Andrii Nakryiko)
---
 scripts/bpf_doc.py | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/scripts/bpf_doc.py b/scripts/bpf_doc.py
index 5cf8ae2e72bd..20441e5d2d33 100755
--- a/scripts/bpf_doc.py
+++ b/scripts/bpf_doc.py
@@ -92,14 +92,14 @@ class HeaderParser(object):
 
     def parse_element(self):
         proto    = self.parse_symbol()
-        desc     = self.parse_desc()
-        ret      = self.parse_ret()
+        desc     = self.parse_desc(proto)
+        ret      = self.parse_ret(proto)
         return APIElement(proto=proto, desc=desc, ret=ret)
 
     def parse_helper(self):
         proto    = self.parse_proto()
-        desc     = self.parse_desc()
-        ret      = self.parse_ret()
+        desc     = self.parse_desc(proto)
+        ret      = self.parse_ret(proto)
         return Helper(proto=proto, desc=desc, ret=ret)
 
     def parse_symbol(self):
@@ -129,16 +129,15 @@ class HeaderParser(object):
         self.line = self.reader.readline()
         return capture.group(1)
 
-    def parse_desc(self):
+    def parse_desc(self, proto):
         p = re.compile(' \* ?(?:\t| {5,8})Description$')
         capture = p.match(self.line)
         if not capture:
-            # Helper can have empty description and we might be parsing another
-            # attribute: return but do not consume.
-            return ''
+            raise Exception("No description section found for " + proto)
         # Description can be several lines, some of them possibly empty, and it
         # stops when another subsection title is met.
         desc = ''
+        desc_present = False
         while True:
             self.line = self.reader.readline()
             if self.line == ' *\n':
@@ -147,21 +146,24 @@ class HeaderParser(object):
                 p = re.compile(' \* ?(?:\t| {5,8})(?:\t| {8})(.*)')
                 capture = p.match(self.line)
                 if capture:
+                    desc_present = True
                     desc += capture.group(1) + '\n'
                 else:
                     break
+
+        if not desc_present:
+            raise Exception("No description found for " + proto)
         return desc
 
-    def parse_ret(self):
+    def parse_ret(self, proto):
         p = re.compile(' \* ?(?:\t| {5,8})Return$')
         capture = p.match(self.line)
         if not capture:
-            # Helper can have empty retval and we might be parsing another
-            # attribute: return but do not consume.
-            return ''
+            raise Exception("No return section found for " + proto)
         # Return value description can be several lines, some of them possibly
         # empty, and it stops when another subsection title is met.
         ret = ''
+        ret_present = False
         while True:
             self.line = self.reader.readline()
             if self.line == ' *\n':
@@ -170,9 +172,13 @@ class HeaderParser(object):
                 p = re.compile(' \* ?(?:\t| {5,8})(?:\t| {8})(.*)')
                 capture = p.match(self.line)
                 if capture:
+                    ret_present = True
                     ret += capture.group(1) + '\n'
                 else:
                     break
+
+        if not ret_present:
+            raise Exception("No return found for " + proto)
         return ret
 
     def seek_to(self, target, help_message):
-- 
2.25.1

[PATCH bpf-next v3 3/3] bpf/scripts: Raise an exception if the correct number of sycalls are not generated

[Usama Arif]

Currently the syscalls rst and subsequently man page are auto-generated
using function documentation present in bpf.h. If the documentation for the
syscall is missing or doesn't follow a specific format, then that syscall
is not dumped in the auto-generated rst.

This patch checks the number of syscalls documented within the header file
with those present as part of the enum bpf_cmd and raises an Exception if
they don't match. It is not needed with the currently documented upstream
syscalls, but can help in debugging when developing new syscalls when
there might be missing or misformatted documentation.

The function helper_number_check is moved to the Printer parent
class and renamed to elem_number_check as all the most derived children
classes are using this function now.

Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>

---
v2->v3:
- Moved UAPI header changes to a seperate commit (suggested by
Andrii Nakryiko)

v1->v2:
- Removed debug prints and fixed formatting.
- Added in syscall documentation that BPF_PROG_RUN is an alias for
BPF_PROG_TEST_RUN (suggested by Quentin Monnet).
---
 scripts/bpf_doc.py | 86 +++++++++++++++++++++++++++++++---------------
 1 file changed, 59 insertions(+), 27 deletions(-)

diff --git a/scripts/bpf_doc.py b/scripts/bpf_doc.py
index 20441e5d2d33..096625242475 100755
--- a/scripts/bpf_doc.py
+++ b/scripts/bpf_doc.py
@@ -89,6 +89,8 @@ class HeaderParser(object):
         self.commands = []
         self.desc_unique_helpers = set()
         self.define_unique_helpers = []
+        self.desc_syscalls = []
+        self.enum_syscalls = []
 
     def parse_element(self):
         proto    = self.parse_symbol()
@@ -103,7 +105,7 @@ class HeaderParser(object):
         return Helper(proto=proto, desc=desc, ret=ret)
 
     def parse_symbol(self):
-        p = re.compile(' \* ?(.+)$')
+        p = re.compile(' \* ?(BPF\w+)$')
         capture = p.match(self.line)
         if not capture:
             raise NoSyscallCommandFound
@@ -181,26 +183,55 @@ class HeaderParser(object):
             raise Exception("No return found for " + proto)
         return ret
 
-    def seek_to(self, target, help_message):
+    def seek_to(self, target, help_message, discard_lines = 1):
         self.reader.seek(0)
         offset = self.reader.read().find(target)
         if offset == -1:
             raise Exception(help_message)
         self.reader.seek(offset)
         self.reader.readline()
-        self.reader.readline()
+        for _ in range(discard_lines):
+            self.reader.readline()
         self.line = self.reader.readline()
 
-    def parse_syscall(self):
+    def parse_desc_syscall(self):
         self.seek_to('* DOC: eBPF Syscall Commands',
                      'Could not find start of eBPF syscall descriptions list')
         while True:
             try:
                 command = self.parse_element()
                 self.commands.append(command)
+                self.desc_syscalls.append(command.proto)
+
             except NoSyscallCommandFound:
                 break
 
+    def parse_enum_syscall(self):
+        self.seek_to('enum bpf_cmd {',
+                     'Could not find start of bpf_cmd enum', 0)
+        # Searches for either one or more BPF\w+ enums
+        bpf_p = re.compile('\s*(BPF\w+)+')
+        # Searches for an enum entry assigned to another entry,
+        # for e.g. BPF_PROG_RUN = BPF_PROG_TEST_RUN, which is
+        # not documented hence should be skipped in check to
+        # determine if the right number of syscalls are documented
+        assign_p = re.compile('\s*(BPF\w+)\s*=\s*(BPF\w+)')
+        bpf_cmd_str = ''
+        while True:
+            capture = assign_p.match(self.line)
+            if capture:
+                # Skip line if an enum entry is assigned to another entry
+                self.line = self.reader.readline()
+                continue
+            capture = bpf_p.match(self.line)
+            if capture:
+                bpf_cmd_str += self.line
+            else:
+                break
+            self.line = self.reader.readline()
+        # Find the number of occurences of BPF\w+
+        self.enum_syscalls = re.findall('(BPF\w+)+', bpf_cmd_str)
+
     def parse_desc_helpers(self):
         self.seek_to('* Start of BPF helper function descriptions:',
                      'Could not find start of eBPF helper descriptions list')
@@ -234,7 +265,8 @@ class HeaderParser(object):
         self.define_unique_helpers = re.findall('FN\(\w+\)', fn_defines_str)
 
     def run(self):
-        self.parse_syscall()
+        self.parse_desc_syscall()
+        self.parse_enum_syscall()
         self.parse_desc_helpers()
         self.parse_define_helpers()
         self.reader.close()
@@ -266,6 +298,25 @@ class Printer(object):
             self.print_one(elem)
         self.print_footer()
 
+    def elem_number_check(self, desc_unique_elem, define_unique_elem, type, instance):
+        """
+        Checks the number of helpers/syscalls documented within the header file
+        description with those defined as part of enum/macro and raise an
+        Exception if they don't match.
+        """
+        nr_desc_unique_elem = len(desc_unique_elem)
+        nr_define_unique_elem = len(define_unique_elem)
+        if nr_desc_unique_elem != nr_define_unique_elem:
+            exception_msg = '''
+The number of unique %s in description (%d) doesn\'t match the number of unique %s defined in %s (%d)
+''' % (type, nr_desc_unique_elem, type, instance, nr_define_unique_elem)
+            if nr_desc_unique_elem < nr_define_unique_elem:
+                # Function description is parsed until no helper is found (which can be due to
+                # misformatting). Hence, only print the first missing/misformatted helper/enum.
+                exception_msg += '''
+The description for %s is not present or formatted correctly.
+''' % (define_unique_elem[nr_desc_unique_elem])
+            raise Exception(exception_msg)
 
 class PrinterRST(Printer):
     """
@@ -326,26 +377,6 @@ class PrinterRST(Printer):
 
         print('')
 
-def helper_number_check(desc_unique_helpers, define_unique_helpers):
-    """
-    Checks the number of functions documented within the header file
-    with those present as part of #define __BPF_FUNC_MAPPER and raise an
-    Exception if they don't match.
-    """
-    nr_desc_unique_helpers = len(desc_unique_helpers)
-    nr_define_unique_helpers = len(define_unique_helpers)
-    if nr_desc_unique_helpers != nr_define_unique_helpers:
-        helper_exception = '''
-The number of unique helpers in description (%d) doesn\'t match the number of unique helpers defined in __BPF_FUNC_MAPPER (%d)
-''' % (nr_desc_unique_helpers, nr_define_unique_helpers)
-        if nr_desc_unique_helpers < nr_define_unique_helpers:
-            # Function description is parsed until no helper is found (which can be due to
-            # misformatting). Hence, only print the first missing/misformatted function.
-            helper_exception += '''
-The description for %s is not present or formatted correctly.
-''' % (define_unique_helpers[nr_desc_unique_helpers])
-        raise Exception(helper_exception)
-
 class PrinterHelpersRST(PrinterRST):
     """
     A printer for dumping collected information about helpers as a ReStructured
@@ -355,7 +386,7 @@ class PrinterHelpersRST(PrinterRST):
     """
     def __init__(self, parser):
         self.elements = parser.helpers
-        helper_number_check(parser.desc_unique_helpers, parser.define_unique_helpers)
+        self.elem_number_check(parser.desc_unique_helpers, parser.define_unique_helpers, 'helper', '__BPF_FUNC_MAPPER')
 
     def print_header(self):
         header = '''\
@@ -529,6 +560,7 @@ class PrinterSyscallRST(PrinterRST):
     """
     def __init__(self, parser):
         self.elements = parser.commands
+        self.elem_number_check(parser.desc_syscalls, parser.enum_syscalls, 'syscall', 'bpf_cmd')
 
     def print_header(self):
         header = '''\
@@ -560,7 +592,7 @@ class PrinterHelpers(Printer):
     """
     def __init__(self, parser):
         self.elements = parser.helpers
-        helper_number_check(parser.desc_unique_helpers, parser.define_unique_helpers)
+        self.elem_number_check(parser.desc_unique_helpers, parser.define_unique_helpers, 'helper', '__BPF_FUNC_MAPPER')
 
     type_fwds = [
             'struct bpf_fib_lookup',
-- 
2.25.1

Re: [PATCH bpf-next v3 1/3] uapi/bpf: Add missing description and returns for helper documentation

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Wed, 19 Jan 2022 11:44:40 +0000 you wrote:
> Both description and returns section will become mandatory
> for helpers and syscalls in a later commit to generate man pages.
> 
> This commit also adds in the documentation that BPF_PROG_RUN is
> an alias for BPF_PROG_TEST_RUN for anyone searching for the
> syscall in the generated man pages.
> 
> [...]

Here is the summary with links:
  - [bpf-next,v3,1/3] uapi/bpf: Add missing description and returns for helper documentation
    https://git.kernel.org/bpf/bpf-next/c/e40fbbf0572c
  - [bpf-next,v3,2/3] bpf/scripts: Make description and returns section for helpers/syscalls mandatory
    https://git.kernel.org/bpf/bpf-next/c/f1f3f67fd8ed
  - [bpf-next,v3,3/3] bpf/scripts: Raise an exception if the correct number of sycalls are not generated
    https://git.kernel.org/bpf/bpf-next/c/0ba3929e5b3d

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html