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authorEyal Birger <eyal.birger@gmail.com>2022-08-24 21:10:43 +0300
committerAndrii Nakryiko <andrii@kernel.org>2022-08-25 21:49:14 +0300
commit0a0d55ef3e61d9f14e803cacb644fcc890f16774 (patch)
tree44b5afde26d144c2fe6132a7a74d74a70f21a876 /scripts
parent7184aef9c0f7a81db8fd18d183ee42481d89bf35 (diff)
downloadlinux-0a0d55ef3e61d9f14e803cacb644fcc890f16774.tar.xz
bpf/scripts: Assert helper enum value is aligned with comment order
The helper value is ABI as defined by enum bpf_func_id. As bpf_helper_defs.h is used for the userpace part, it must be consistent with this enum. Before this change the comments order was used by the bpf_doc script in order to set the helper values defined in the helpers file. When adding new helpers it is very puzzling when the userspace application breaks in weird places if the comment is inserted instead of appended - because the generated helper ABI is incorrect and shifted. This commit sets the helper value to the enum value. In addition it is currently the practice to have the comments appended and kept in the same order as the enum. As such, add an assertion validating the comment order is consistent with enum value. In case a different comments ordering is desired, this assertion can be lifted. Signed-off-by: Eyal Birger <eyal.birger@gmail.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reviewed-by: Quentin Monnet <quentin@isovalent.com> Link: https://lore.kernel.org/bpf/20220824181043.1601429-1-eyal.birger@gmail.com
Diffstat (limited to 'scripts')
-rwxr-xr-xscripts/bpf_doc.py39
1 files changed, 34 insertions, 5 deletions
diff --git a/scripts/bpf_doc.py b/scripts/bpf_doc.py
index f4f3e7ec6d44..d5c389df6045 100755
--- a/scripts/bpf_doc.py
+++ b/scripts/bpf_doc.py
@@ -50,6 +50,10 @@ class Helper(APIElement):
@desc: textual description of the helper function
@ret: description of the return value of the helper function
"""
+ def __init__(self, *args, **kwargs):
+ super().__init__(*args, **kwargs)
+ self.enum_val = None
+
def proto_break_down(self):
"""
Break down helper function protocol into smaller chunks: return type,
@@ -92,6 +96,7 @@ class HeaderParser(object):
self.commands = []
self.desc_unique_helpers = set()
self.define_unique_helpers = []
+ self.helper_enum_vals = {}
self.desc_syscalls = []
self.enum_syscalls = []
@@ -248,30 +253,54 @@ class HeaderParser(object):
break
def parse_define_helpers(self):
- # Parse the number of FN(...) in #define __BPF_FUNC_MAPPER to compare
- # later with the number of unique function names present in description.
+ # Parse FN(...) in #define __BPF_FUNC_MAPPER to compare later with the
+ # number of unique function names present in description and use the
+ # correct enumeration value.
# Note: seek_to(..) discards the first line below the target search text,
# resulting in FN(unspec) being skipped and not added to self.define_unique_helpers.
self.seek_to('#define __BPF_FUNC_MAPPER(FN)',
'Could not find start of eBPF helper definition list')
- # Searches for either one or more FN(\w+) defines or a backslash for newline
- p = re.compile('\s*(FN\(\w+\))+|\\\\')
+ # Searches for one FN(\w+) define or a backslash for newline
+ p = re.compile('\s*FN\((\w+)\)|\\\\')
fn_defines_str = ''
+ i = 1 # 'unspec' is skipped as mentioned above
while True:
capture = p.match(self.line)
if capture:
fn_defines_str += self.line
+ self.helper_enum_vals[capture.expand(r'bpf_\1')] = i
+ i += 1
else:
break
self.line = self.reader.readline()
# Find the number of occurences of FN(\w+)
self.define_unique_helpers = re.findall('FN\(\w+\)', fn_defines_str)
+ def assign_helper_values(self):
+ seen_helpers = set()
+ for helper in self.helpers:
+ proto = helper.proto_break_down()
+ name = proto['name']
+ try:
+ enum_val = self.helper_enum_vals[name]
+ except KeyError:
+ raise Exception("Helper %s is missing from enum bpf_func_id" % name)
+
+ # Enforce current practice of having the descriptions ordered
+ # by enum value.
+ seen_helpers.add(name)
+ desc_val = len(seen_helpers)
+ if desc_val != enum_val:
+ raise Exception("Helper %s comment order (#%d) must be aligned with its position (#%d) in enum bpf_func_id" % (name, desc_val, enum_val))
+
+ helper.enum_val = enum_val
+
def run(self):
self.parse_desc_syscall()
self.parse_enum_syscall()
self.parse_desc_helpers()
self.parse_define_helpers()
+ self.assign_helper_values()
self.reader.close()
###############################################################################
@@ -796,7 +825,7 @@ class PrinterHelpers(Printer):
comma = ', '
print(one_arg, end='')
- print(') = (void *) %d;' % len(self.seen_helpers))
+ print(') = (void *) %d;' % helper.enum_val)
print('')
###############################################################################