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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 <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
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Use macros provided by hashtable.h
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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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 <linux/export.h>
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 <masahiroy@kernel.org>
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This is only used in yylex() in lex.l
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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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 <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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 <nicolas.iooss_linux@m4x.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
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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.
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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 <constant> <value>. 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 <mmarek@suse.cz>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
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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 <mmarek@suse.cz>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
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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 <agruen@suse.de>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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Sometimes it is preferable to avoid changes of exported symbol checksums
(to avoid breaking externally provided modules). When a checksum change
occurs, it can be hard to figure out what caused this change: underlying
types may have changed, or additional type information may simply have
become available at the point where a symbol is exported.
Add a new --reference option to genksyms which allows it to report why
checksums change, based on the type information dumps it creates with the
--dump-types flag. Genksyms will read in such a dump from a previous run,
and report which symbols have changed (and why).
The behavior can be controlled for an entire build as follows: If
KBUILD_SYMTYPES is set, genksyms uses --dump-types to produce *.symtypes
dump files. If any *.symref files exist, those will be used as the
reference to check against. If KBUILD_PRESERVE is set, checksum changes
will fail the build.
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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Here is a patch that adds a new -T option to genksyms for generating dumps of
the type definition that makes up the symbol version hashes. This allows to
trace modversion changes back to what caused them. The dump format is the
name of the type defined, followed by its definition (which is almost C):
s#list_head struct list_head { s#list_head * next , * prev ; }
The s#, u#, e#, and t# prefixes stand for struct, union, enum, and typedef.
The exported symbols do not define types, and thus do not have an x# prefix:
nfs4_acl_get_whotype int nfs4_acl_get_whotype ( char * , t#u32 )
The symbol type defintion of a single file can be generated with:
make fs/jbd/journal.symtypes
If KBUILD_SYMTYPES is defined, all the *.symtypes of all object files that
export symbols are generated.
The single *.symtypes files can be combined into a single file after a kernel
build with a script like the following:
for f in $(find -name '*.symtypes' | sort); do
f=${f#./}
echo "/* ${f%.symtypes}.o */"
cat $f
echo
done \
| sed -e '\:UNKNOWN:d' \
-e 's:[,;] }:}:g' \
-e 's:\([[({]\) :\1:g' \
-e 's: \([])},;]\):\1:g' \
-e 's: $::' \
$f \
| awk '
/^.#/ { if (defined[$1] == $0) {
print $1
next
}
defined[$1] = $0
}
{ print }
'
When the kernel ABI changes, diffing individual *.symtype files, or the
combined files, against each other will show which symbol changes caused the
ABI changes. This can save a tremendous amount of time.
Dump the types that make up modversions
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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o remove all inlines
o declare everything static which is only used by genksyms.c
o delete unused functions
o delete unused variables
o delete unused stuff in genksyms.h
o properly ident genksyms.h
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
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