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linux/scripts/genksyms/parse.y
Marco Elver 9ab55d7f24 genksyms: Ignore module scoped _Static_assert() 
The C11 _Static_assert() keyword may be used at module scope, and we
need to teach genksyms about it to not abort with an error. We currently
have a growing number of static_assert() (but also direct usage of
_Static_assert()) users at module scope:

	git grep -E '^_Static_assert\(|^static_assert\(' | grep -v '^tools' | wc -l
	135

More recently, when enabling CONFIG_MODVERSIONS with CONFIG_KCSAN, we
observe a number of warnings:

	WARNING: modpost: EXPORT symbol "<..all kcsan symbols..>" [vmlinux] [...]

When running a preprocessed source through 'genksyms -w' a number of
syntax errors point at usage of static_assert()s. In the case of
kernel/kcsan/encoding.h, new static_assert()s had been introduced which
used expressions that appear to cause genksyms to not even be able to
recover from the syntax error gracefully (as it appears was the case
previously).

Therefore, make genksyms ignore all _Static_assert() and the contained
expression. With the fix, usage of _Static_assert() no longer cause
"syntax error" all over the kernel, and the above modpost warnings for
KCSAN are gone, too.

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2020-12-21 13:57:08 +09:00

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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* C global declaration parser for genksyms.
* Copyright 1996, 1997 Linux International.
*
* New implementation contributed by Richard Henderson <rth@tamu.edu>
* Based on original work by Bjorn Ekwall <bj0rn@blox.se>
*
* This file is part of the Linux modutils.
*/
%{
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "genksyms.h"
static int is_typedef;
static int is_extern;
static char *current_name;
static struct string_list *decl_spec;
static void yyerror(const char *);
static inline void
remove_node(struct string_list **p)
{
struct string_list *node = *p;
*p = node->next;
free_node(node);
}
static inline void
remove_list(struct string_list **pb, struct string_list **pe)
{
struct string_list *b = *pb, *e = *pe;
*pb = e;
free_list(b, e);
}
/* Record definition of a struct/union/enum */
static void record_compound(struct string_list **keyw,
struct string_list **ident,
struct string_list **body,
enum symbol_type type)
{
struct string_list *b = *body, *i = *ident, *r;
if (i->in_source_file) {
remove_node(keyw);
(*ident)->tag = type;
remove_list(body, ident);
return;
}
r = copy_node(i); r->tag = type;
r->next = (*keyw)->next; *body = r; (*keyw)->next = NULL;
add_symbol(i->string, type, b, is_extern);
}
%}
%token ASM_KEYW
%token ATTRIBUTE_KEYW
%token AUTO_KEYW
%token BOOL_KEYW
%token BUILTIN_INT_KEYW
%token CHAR_KEYW
%token CONST_KEYW
%token DOUBLE_KEYW
%token ENUM_KEYW
%token EXTERN_KEYW
%token EXTENSION_KEYW
%token FLOAT_KEYW
%token INLINE_KEYW
%token INT_KEYW
%token LONG_KEYW
%token REGISTER_KEYW
%token RESTRICT_KEYW
%token SHORT_KEYW
%token SIGNED_KEYW
%token STATIC_KEYW
%token STATIC_ASSERT_KEYW
%token STRUCT_KEYW
%token TYPEDEF_KEYW
%token UNION_KEYW
%token UNSIGNED_KEYW
%token VOID_KEYW
%token VOLATILE_KEYW
%token TYPEOF_KEYW
%token VA_LIST_KEYW
%token EXPORT_SYMBOL_KEYW
%token ASM_PHRASE
%token ATTRIBUTE_PHRASE
%token TYPEOF_PHRASE
%token BRACE_PHRASE
%token BRACKET_PHRASE
%token EXPRESSION_PHRASE
%token STATIC_ASSERT_PHRASE
%token CHAR
%token DOTS
%token IDENT
%token INT
%token REAL
%token STRING
%token TYPE
%token OTHER
%token FILENAME
%%
declaration_seq:
declaration
| declaration_seq declaration
;
declaration:
{ is_typedef = 0; is_extern = 0; current_name = NULL; decl_spec = NULL; }
declaration1
{ free_list(*$2, NULL); *$2 = NULL; }
;
declaration1:
EXTENSION_KEYW TYPEDEF_KEYW { is_typedef = 1; } simple_declaration
{ $$ = $4; }
| TYPEDEF_KEYW { is_typedef = 1; } simple_declaration
{ $$ = $3; }
| simple_declaration
| function_definition
| asm_definition
| export_definition
| static_assert
| error ';' { $$ = $2; }
| error '}' { $$ = $2; }
;
simple_declaration:
decl_specifier_seq_opt init_declarator_list_opt ';'
{ if (current_name) {
struct string_list *decl = (*$3)->next;
(*$3)->next = NULL;
add_symbol(current_name,
is_typedef ? SYM_TYPEDEF : SYM_NORMAL,
decl, is_extern);
current_name = NULL;
}
$$ = $3;
}
;
init_declarator_list_opt:
/* empty */ { $$ = NULL; }
| init_declarator_list
;
init_declarator_list:
init_declarator
{ struct string_list *decl = *$1;
*$1 = NULL;
add_symbol(current_name,
is_typedef ? SYM_TYPEDEF : SYM_NORMAL, decl, is_extern);
current_name = NULL;
$$ = $1;
}
| init_declarator_list ',' init_declarator
{ struct string_list *decl = *$3;
*$3 = NULL;
free_list(*$2, NULL);
*$2 = decl_spec;
add_symbol(current_name,
is_typedef ? SYM_TYPEDEF : SYM_NORMAL, decl, is_extern);
current_name = NULL;
$$ = $3;
}
;
init_declarator:
declarator asm_phrase_opt attribute_opt initializer_opt
{ $$ = $4 ? $4 : $3 ? $3 : $2 ? $2 : $1; }
;
/* Hang on to the specifiers so that we can reuse them. */
decl_specifier_seq_opt:
/* empty */ { decl_spec = NULL; }
| decl_specifier_seq
;
decl_specifier_seq:
decl_specifier { decl_spec = *$1; }
| decl_specifier_seq decl_specifier { decl_spec = *$2; }
;
decl_specifier:
storage_class_specifier
{ /* Version 2 checksumming ignores storage class, as that
is really irrelevant to the linkage. */
remove_node($1);
$$ = $1;
}
| type_specifier
;
storage_class_specifier:
AUTO_KEYW
| REGISTER_KEYW
| STATIC_KEYW
| EXTERN_KEYW { is_extern = 1; $$ = $1; }
| INLINE_KEYW { is_extern = 0; $$ = $1; }
;
type_specifier:
simple_type_specifier
| cvar_qualifier
| TYPEOF_KEYW '(' parameter_declaration ')'
| TYPEOF_PHRASE
/* 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; $$ = $2; }
| UNION_KEYW IDENT
{ remove_node($1); (*$2)->tag = SYM_UNION; $$ = $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; }
| UNION_KEYW IDENT class_body
{ record_compound($1, $2, $3, SYM_UNION); $$ = $3; }
| ENUM_KEYW IDENT enum_body
{ record_compound($1, $2, $3, SYM_ENUM); $$ = $3; }
/*
* Anonymous enum definition. Tell add_symbol() to restart its counter.
*/
| ENUM_KEYW enum_body
{ add_symbol(NULL, SYM_ENUM, NULL, 0); $$ = $2; }
/* Anonymous s/u definitions. Nothing needs doing. */
| STRUCT_KEYW class_body { $$ = $2; }
| UNION_KEYW class_body { $$ = $2; }
;
simple_type_specifier:
CHAR_KEYW
| SHORT_KEYW
| INT_KEYW
| LONG_KEYW
| SIGNED_KEYW
| UNSIGNED_KEYW
| FLOAT_KEYW
| DOUBLE_KEYW
| VOID_KEYW
| BOOL_KEYW
| VA_LIST_KEYW
| BUILTIN_INT_KEYW
| TYPE { (*$1)->tag = SYM_TYPEDEF; $$ = $1; }
;
ptr_operator:
'*' cvar_qualifier_seq_opt
{ $$ = $2 ? $2 : $1; }
;
cvar_qualifier_seq_opt:
/* empty */ { $$ = NULL; }
| cvar_qualifier_seq
;
cvar_qualifier_seq:
cvar_qualifier
| cvar_qualifier_seq cvar_qualifier { $$ = $2; }
;
cvar_qualifier:
CONST_KEYW | VOLATILE_KEYW | ATTRIBUTE_PHRASE
| RESTRICT_KEYW
{ /* restrict has no effect in prototypes so ignore it */
remove_node($1);
$$ = $1;
}
;
declarator:
ptr_operator declarator { $$ = $2; }
| direct_declarator
;
direct_declarator:
IDENT
{ if (current_name != NULL) {
error_with_pos("unexpected second declaration name");
YYERROR;
} else {
current_name = (*$1)->string;
$$ = $1;
}
}
| TYPE
{ if (current_name != NULL) {
error_with_pos("unexpected second declaration name");
YYERROR;
} else {
current_name = (*$1)->string;
$$ = $1;
}
}
| direct_declarator '(' parameter_declaration_clause ')'
{ $$ = $4; }
| direct_declarator '(' error ')'
{ $$ = $4; }
| direct_declarator BRACKET_PHRASE
{ $$ = $2; }
| '(' declarator ')'
{ $$ = $3; }
;
/* Nested declarators differ from regular declarators in that they do
not record the symbols they find in the global symbol table. */
nested_declarator:
ptr_operator nested_declarator { $$ = $2; }
| direct_nested_declarator
;
direct_nested_declarator:
IDENT
| TYPE
| direct_nested_declarator '(' parameter_declaration_clause ')'
{ $$ = $4; }
| direct_nested_declarator '(' error ')'
{ $$ = $4; }
| direct_nested_declarator BRACKET_PHRASE
{ $$ = $2; }
| '(' nested_declarator ')'
{ $$ = $3; }
| '(' error ')'
{ $$ = $3; }
;
parameter_declaration_clause:
parameter_declaration_list_opt DOTS { $$ = $2; }
| parameter_declaration_list_opt
| parameter_declaration_list ',' DOTS { $$ = $3; }
;
parameter_declaration_list_opt:
/* empty */ { $$ = NULL; }
| parameter_declaration_list
;
parameter_declaration_list:
parameter_declaration
| parameter_declaration_list ',' parameter_declaration
{ $$ = $3; }
;
parameter_declaration:
decl_specifier_seq m_abstract_declarator
{ $$ = $2 ? $2 : $1; }
;
m_abstract_declarator:
ptr_operator m_abstract_declarator
{ $$ = $2 ? $2 : $1; }
| direct_m_abstract_declarator
;
direct_m_abstract_declarator:
/* empty */ { $$ = NULL; }
| IDENT
{ /* For version 2 checksums, we don't want to remember
private parameter names. */
remove_node($1);
$$ = $1;
}
/* This wasn't really a typedef name but an identifier that
shadows one. */
| TYPE
{ remove_node($1);
$$ = $1;
}
| direct_m_abstract_declarator '(' parameter_declaration_clause ')'
{ $$ = $4; }
| direct_m_abstract_declarator '(' error ')'
{ $$ = $4; }
| direct_m_abstract_declarator BRACKET_PHRASE
{ $$ = $2; }
| '(' m_abstract_declarator ')'
{ $$ = $3; }
| '(' error ')'
{ $$ = $3; }
;
function_definition:
decl_specifier_seq_opt declarator BRACE_PHRASE
{ struct string_list *decl = *$2;
*$2 = NULL;
add_symbol(current_name, SYM_NORMAL, decl, is_extern);
$$ = $3;
}
;
initializer_opt:
/* empty */ { $$ = NULL; }
| initializer
;
/* We never care about the contents of an initializer. */
initializer:
'=' EXPRESSION_PHRASE
{ remove_list($2, &(*$1)->next); $$ = $2; }
;
class_body:
'{' member_specification_opt '}' { $$ = $3; }
| '{' error '}' { $$ = $3; }
;
member_specification_opt:
/* empty */ { $$ = NULL; }
| member_specification
;
member_specification:
member_declaration
| member_specification member_declaration { $$ = $2; }
;
member_declaration:
decl_specifier_seq_opt member_declarator_list_opt ';'
{ $$ = $3; }
| error ';'
{ $$ = $2; }
;
member_declarator_list_opt:
/* empty */ { $$ = NULL; }
| member_declarator_list
;
member_declarator_list:
member_declarator
| member_declarator_list ',' member_declarator { $$ = $3; }
;
member_declarator:
nested_declarator attribute_opt { $$ = $2 ? $2 : $1; }
| IDENT member_bitfield_declarator { $$ = $2; }
| member_bitfield_declarator
;
member_bitfield_declarator:
':' EXPRESSION_PHRASE { $$ = $2; }
;
attribute_opt:
/* empty */ { $$ = NULL; }
| attribute_opt ATTRIBUTE_PHRASE
;
enum_body:
'{' enumerator_list '}' { $$ = $3; }
| '{' enumerator_list ',' '}' { $$ = $4; }
;
enumerator_list:
enumerator
| enumerator_list ',' enumerator
enumerator:
IDENT
{
const char *name = strdup((*$1)->string);
add_symbol(name, SYM_ENUM_CONST, NULL, 0);
}
| IDENT '=' EXPRESSION_PHRASE
{
const char *name = strdup((*$1)->string);
struct string_list *expr = copy_list_range(*$3, *$2);
add_symbol(name, SYM_ENUM_CONST, expr, 0);
}
asm_definition:
ASM_PHRASE ';' { $$ = $2; }
;
asm_phrase_opt:
/* empty */ { $$ = NULL; }
| ASM_PHRASE
;
export_definition:
EXPORT_SYMBOL_KEYW '(' IDENT ')' ';'
{ export_symbol((*$3)->string); $$ = $5; }
;
/* Ignore any module scoped _Static_assert(...) */
static_assert:
STATIC_ASSERT_PHRASE ';' { $$ = $2; }
;
%%
static void
yyerror(const char *e)
{
error_with_pos("%s", e);
}
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