2022-07-06 14:18:46

by James Hilliard

Subject: [PATCH] bpf/scripts: Generate GCC compatible helpers

The current bpf_helper_defs.h helpers are llvm specific and don't work
correctly with gcc.

Generate gcc compatible headers based on the format in bpf-helpers.h.

See:
https://github.com/gcc-mirror/gcc/blob/releases/gcc-12.1.0/gcc/config/bpf/bpf-helpers.h#L24-L27

Signed-off-by: James Hilliard <[email protected]>
---
scripts/bpf_doc.py | 43 ++++++++++++++++++++++++++-----------------
1 file changed, 26 insertions(+), 17 deletions(-)

diff --git a/scripts/bpf_doc.py b/scripts/bpf_doc.py
index a0ec321469bd..36fb400a5731 100755
--- a/scripts/bpf_doc.py
+++ b/scripts/bpf_doc.py
@@ -739,6 +739,24 @@ class PrinterHelpers(Printer):

seen_helpers = set()

+ def print_args(self, proto):
+ comma = ''
+ for i, a in enumerate(proto['args']):
+ t = a['type']
+ n = a['name']
+ if proto['name'] in self.overloaded_helpers and i == 0:
+ t = 'void'
+ n = 'ctx'
+ one_arg = '{}{}'.format(comma, self.map_type(t))
+ if n:
+ if a['star']:
+ one_arg += ' {}'.format(a['star'])
+ else:
+ one_arg += ' '
+ one_arg += '{}'.format(n)
+ comma = ', '
+ print(one_arg, end='')
+
def print_one(self, helper):
proto = helper.proto_break_down()

@@ -762,26 +780,17 @@ class PrinterHelpers(Printer):
print(' *{}{}'.format(' \t' if line else '', line))

print(' */')
+ print('#if __GNUC__ && !__clang__')
+ print('%s %s%s(' % (self.map_type(proto['ret_type']),
+ proto['ret_star'], proto['name']), end='')
+ self.print_args(proto)
+ print(') __attribute__((kernel_helper(%d)));' % len(self.seen_helpers))
+ print('#else')
print('static %s %s(*%s)(' % (self.map_type(proto['ret_type']),
proto['ret_star'], proto['name']), end='')
- comma = ''
- for i, a in enumerate(proto['args']):
- t = a['type']
- n = a['name']
- if proto['name'] in self.overloaded_helpers and i == 0:
- t = 'void'
- n = 'ctx'
- one_arg = '{}{}'.format(comma, self.map_type(t))
- if n:
- if a['star']:
- one_arg += ' {}'.format(a['star'])
- else:
- one_arg += ' '
- one_arg += '{}'.format(n)
- comma = ', '
- print(one_arg, end='')
-
+ self.print_args(proto)
print(') = (void *) %d;' % len(self.seen_helpers))
+ print('#endif')
print('')

###############################################################################
--
2.34.1

2022-07-06 17:22:52

by Daniel Borkmann

Subject: Re: [PATCH] bpf/scripts: Generate GCC compatible helpers

On 7/6/22 4:06 PM, James Hilliard wrote:
> The current bpf_helper_defs.h helpers are llvm specific and don't work
> correctly with gcc.
>
> Generate gcc compatible headers based on the format in bpf-helpers.h.
>
> See:
> https://github.com/gcc-mirror/gcc/blob/releases/gcc-12.1.0/gcc/config/bpf/bpf-helpers.h#L24-L27
>
> Signed-off-by: James Hilliard <[email protected]>

Please improve the commit description a bit with all the necessary context
around this, and perhaps also provide a small before/after extract around
the bpf-helpers.h. The github.com/gcc-mirror could stay as reference but all
details should be self-explanatory in commit description.

Thanks,
Daniel