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genksyms: fix syntax error for attribute after 'struct'

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A longstanding issue with genksyms is that it has hidden syntax errors.

When a syntax error occurs, yyerror() is called. However,
error_with_pos() is a no-op unless the -w option is provided.

You can observe syntax errors by manually passing the -w option.

For example, with CONFIG_MODVERSIONS=y on v6.13-rc1:

    $ make -s KCFLAGS=-D__GENKSYMS__ arch/x86/kernel/cpu/mshyperv.i
    $ cat arch/x86/kernel/cpu/mshyperv.i | scripts/genksyms/genksyms -w
        [ snip ]
    ./arch/x86/include/asm/svm.h:122: syntax error

The syntax error occurs in the following code in arch/x86/include/asm/svm.h:

    struct __attribute__ ((__packed__)) vmcb_control_area {
            [ snip ]
    };

The issue arises from __attribute__ immediately after the 'struct'
keyword.

This commit allows the 'struct' keyword to be followed by attributes.

The lexer must be adjusted because dont_want_brace_phase should not be
decremented while processing attributes.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
This commit is contained in:
Masahiro Yamada 2025-01-14 00:00:52 +09:00
parent 2ac068cb0b
commit 82db1c2910
2 changed files with 11 additions and 6 deletions
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7
scripts/genksyms/lex.l
View file

@ -438,7 +438,12 @@ fini:
if (suppress_type_lookup > 0)
--suppress_type_lookup;
if (dont_want_brace_phrase > 0)
/*
* __attribute__() can be placed immediately after the 'struct' keyword.
* e.g.) struct __attribute__((__packed__)) foo { ... };
*/
if (token != ATTRIBUTE_PHRASE && dont_want_brace_phrase > 0)
--dont_want_brace_phrase;
yylval = &next_node->next;

10
scripts/genksyms/parse.y
View file

@ -234,16 +234,16 @@ type_specifier:
/* References to s/u/e's defined elsewhere. Rearrange things
so that it is easier to expand the definition fully later. */
| STRUCT_KEYW IDENT
{ remove_node($1); (*$2)->tag = SYM_STRUCT; $$ = $2; }
| STRUCT_KEYW attribute_opt IDENT
{ remove_node($1); (*$3)->tag = SYM_STRUCT; $$ = $3; }
| UNION_KEYW IDENT
{ remove_node($1); (*$2)->tag = SYM_UNION; $$ = $2; }
| ENUM_KEYW IDENT
{ remove_node($1); (*$2)->tag = SYM_ENUM; $$ = $2; }
/* Full definitions of an s/u/e. Record it. */
| STRUCT_KEYW IDENT class_body
{ record_compound($1, $2, $3, SYM_STRUCT); $$ = $3; }
| STRUCT_KEYW attribute_opt IDENT class_body
{ record_compound($1, $3, $4, SYM_STRUCT); $$ = $4; }
| UNION_KEYW IDENT class_body
{ record_compound($1, $2, $3, SYM_UNION); $$ = $3; }
| ENUM_KEYW IDENT enum_body
@ -254,7 +254,7 @@ type_specifier:
| ENUM_KEYW enum_body
{ add_symbol(NULL, SYM_ENUM, NULL, 0); $$ = $2; }
/* Anonymous s/u definitions. Nothing needs doing. */
| STRUCT_KEYW class_body { $$ = $2; }
| STRUCT_KEYW attribute_opt class_body { $$ = $3; }
| UNION_KEYW class_body { $$ = $2; }
;