alignchecker: fully parse structures #24365
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The alignchecker package takes BTF descriptions of structures and creates a map
with offsets. For example,
struct x {
u64 a;
u32 b;
u8 c;
u8 d;
};
will be converted to
{a: 0, b: 8, c: 12, d: 13}
These names are later used in Go struct definitions, so that we can check if they are properly aligned, e.g.:
type X struct {
A uint64 `align:"a"`
B uint32 `align:"b"`
C uint8 `align:"c"`
D uint8 `align:"d"`
}
If there are anonymous unions present, then their offsets will be stored as
$union0, $union1, etc., e.g.,
struct x {
union { u32 a; u32 b; };
union { u32 c; u32 d; };
u32 f;
};
will be converted to
{$union0: 0, $union1: 4, f: 8}
However, there's no way to refer to inner fields of unions, or to fields of
structures. Fix this by parsing BTFs recursively. After this change, e.g., the
following structure
struct x {
u32 a;
struct {
union {
u32 a;
u32 b;
};
u32 c;
};
u32 d;
};
will be converted to
{
a: 0,
$struct0: 4,
$struct0.$union0: 4,
$struct0.$union0.a: 4,
$struct0.$union0.b: 4,
$struct0.c: 8,
d: 12
}
Also fix a minor bug: previous code didn't check if an offset exists or not (it
was set to 0 by default). Patch two occurrences in code which were referencing
non-existing offset (it happened that the corresponding offsets were indeed 0).
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
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Build finished. |
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/test-1.16-4.19 |
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The test-1.16-4.19 is unrelated, so marking as ready to merge |
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The alignchecker package takes BTF descriptions of structures and creates a map with offsets. For example,
will be converted to
These names are later used in Go struct definitions, so that we can check if they are properly aligned, e.g.:
If there are anonymous unions present, then their offsets will be stored as $union0, $union1, etc., e.g.,
will be converted to
However, there's no way to refer to inner fields of unions, or to fields of structures. Fix this by parsing BTFs recursively. After this change, e.g., the following structure
will be converted to
Also fix a minor bug: previous code didn't check if an offset exists or not (it was set to 0 by default). Patch two occurrences in code which were referencing non-existing offset (it happened that the corresponding offsets were indeed 0).