linux-toradex.git/scripts/genksyms/genksyms.h, branch v7.0-rc2

genksyms: fix 6 shift/reduce conflicts and 5 reduce/reduce conflicts

2025-01-18T00:11:38+00:00

The genksyms parser has ambiguities in its grammar, which are currently
suppressed by a workaround in scripts/genksyms/Makefile.

Building genksyms with W=1 generates the following warnings:

    YACC    scripts/genksyms/parse.tab.[ch]
  scripts/genksyms/parse.y: warning: 9 shift/reduce conflicts [-Wconflicts-sr]
  scripts/genksyms/parse.y: warning: 5 reduce/reduce conflicts [-Wconflicts-rr]
  scripts/genksyms/parse.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples

The comment in the parser describes the current problem:

    /* This wasn't really a typedef name but an identifier that
       shadows one.  */

Consider the following simple C code:

    typedef int foo;
    void my_func(foo foo) {}

In the function parameter list (foo foo), the first 'foo' is a type
specifier (typedef'ed as 'int'), while the second 'foo' is an identifier.

However, the lexer cannot distinguish between the two. Since 'foo' is
already typedef'ed, the lexer returns TYPE for both instances, instead
of returning IDENT for the second one.

To support shadowed identifiers, TYPE can be reduced to either a
simple_type_specifier or a direct_abstract_declarator, which creates
a grammatical ambiguity.

Without analyzing the grammar context, it is very difficult to resolve
this correctly.

This commit introduces a flag, dont_want_type_specifier, which allows
the parser to inform the lexer whether an identifier is expected. When
dont_want_type_specifier is true, the type lookup is suppressed, and
the lexer returns IDENT regardless of any preceding typedef.

After this commit, only 3 shift/reduce conflicts will remain.

Signed-off-by: Masahiro Yamada 
Acked-by: Nicolas Schier

genksyms: use generic macros for hash table implementation

2025-01-10T14:01:22+00:00

Use macros provided by hashtable.h

Signed-off-by: Masahiro Yamada

genksyms: fix memory leak when the same symbol is read from *.symref file

2025-01-10T14:01:22+00:00

When a symbol that is already registered is read again from *.symref
file, __add_symbol() removes the previous one from the hash table without
freeing it.

[Test Case]

  $ cat foo.c
  #include 
  void foo(void);
  void foo(void) {}
  EXPORT_SYMBOL(foo);

  $ cat foo.symref
  foo void foo ( void )
  foo void foo ( void )

When a symbol is removed from the hash table, it must be freed along
with its ->name and ->defn members. However, sym->name cannot be freed
because it is sometimes shared with node->string, but not always. If
sym->name and node->string share the same memory, free(sym->name) could
lead to a double-free bug.

To resolve this issue, always assign a strdup'ed string to sym->name.

Fixes: 64e6c1e12372 ("genksyms: track symbol checksum changes")
Signed-off-by: Masahiro Yamada

genksyms: make source_file a local variable in lexer

2021-02-16T03:01:44+00:00

This is only used in yylex() in lex.l

Signed-off-by: Masahiro Yamada

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156

2019-05-30T18:26:35+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version this program is distributed in the
  hope that it will be useful but without any warranty without even
  the implied warranty of merchantability or fitness for a particular
  purpose see the gnu general public license for more details you
  should have received a copy of the gnu general public license along
  with this program if not write to the free software foundation inc
  59 temple place suite 330 boston ma 02111 1307 usa

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 1334 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Reviewed-by: Richard Fontana 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de
Signed-off-by: Greg Kroah-Hartman

genksyms: add printf format attribute to error_with_pos()

2017-06-05T16:22:48+00:00

When compiling with -Wsuggest-attribute=format in HOSTCFLAGS, gcc
complains that error_with_pos() may be declared with a printf format
attribute:

    scripts/genksyms/genksyms.c:726:3: warning: function might be
    possible candidate for ‘gnu_printf’ format attribute
    [-Wsuggest-attribute=format]
       vfprintf(stderr, fmt, args);
       ^~~~~~~~

This would allow catching printf-format errors at compile time in
callers to error_with_pos(). Add this attribute.

Signed-off-by: Nicolas Iooss 
Signed-off-by: Masahiro Yamada

genksyms: Do not expand internal types

2011-10-11T10:00:39+00:00

Consider structures, unions and enums defined in the source file as
internal and do not expand them. This way, changes to e.g. struct
serial_private in drivers/tty/serial/8250_pci.c will not affect the
checksum of the pciserial_* exports.

genksyms: Track changes to enum constants

2011-03-17T14:13:56+00:00

Enum constants can be used as array sizes; if the enum itself does not
appear in the symbol expansion, a change in the enum constant will go
unnoticed. Example patch that changes the ABI but does not change the
checksum with current genksyms:

| enum e {
|	E1,
|	E2,
|+	E3,
|	E_MAX
| };
|
| struct s {
|	int a[E_MAX];
| }
|
| int f(struct s *s) { ... }
| EXPORT_SYMBOL(f)

Therefore, remember the value of each enum constant and
expand each occurence to  . The value is not actually
computed, but instead an expression in the form
(last explicitly assigned value) + N
is used. This avoids having to parse and semantically understand whole
of C.

Note: The changes won't take effect until the lexer and parser are
rebuilt by the next patch.

Signed-off-by: Michal Marek 
Acked-by: Sam Ravnborg

genksyms: simplify usage of find_symbol()

2011-03-17T14:13:55+00:00

Allow searching for symbols of an exact type. The lexer does this and a
subsequent patch will add one more usage.

Signed-off-by: Michal Marek 
Acked-by: Sam Ravnborg

genksyms: allow to ignore symbol checksum changes

2008-12-03T21:33:12+00:00

This adds an "override" keyword for use in *.symvers / *.symref files.
When a symbol is overridden, the symbol's old definition will be used for
computing checksums instead of the new one, preserving the previous
checksum.  (Genksyms will still warn about the change.)

This is meant to allow distributions to hide minor actual as well as fake
ABI changes.  (For example, when extra type information becomes available
because additional headers are included, this may change checksums even
though none of the types used have actully changed.)

This approach also allows to get rid of "#ifdef __GENKSYMS__" hacks in the
code, which are currently used in some vendor kernels to work around
checksum changes.

Signed-off-by: Andreas Gruenbacher 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Sam Ravnborg