linux-toradex.git/scripts/genksyms/parse.y, branch v5.17-rc7

genksyms: Ignore module scoped _Static_assert()

2020-12-21T04:57:08+00:00

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 
Acked-by: Nick Desaulniers 
Signed-off-by: Masahiro Yamada

genksyms: convert to SPDX License Identifier for lex.l and parse.y

2019-09-14T02:40:13+00:00

I used the C comment style (/* ... */) for the flex and bison files
as in Kconfig (scripts/kconfig/{lexer.l,parser.y})

Signed-off-by: Masahiro Yamada

genksyms: Teach parser about 128-bit built-in types

2019-06-23T18:43:03+00:00

__uint128_t crops up in a few files that export symbols to modules, so
teach genksyms about it and the other GCC built-in 128-bit integer types
so that we don't end up skipping the CRC generation for some symbols due
to the parser failing to spot them:

  | WARNING: EXPORT symbol "kernel_neon_begin" [vmlinux] version
  |          generation failed, symbol will not be versioned.
  | ld: arch/arm64/kernel/fpsimd.o: relocation R_AARCH64_ABS32 against
  |     `__crc_kernel_neon_begin' can not be used when making a shared
  |     object
  | ld: arch/arm64/kernel/fpsimd.o:(.data+0x0): dangerous relocation:
  |     unsupported relocation

Reported-by: Arnd Bergmann 
Signed-off-by: Will Deacon 
Signed-off-by: Masahiro Yamada

genksyms: Fix segfault with invalid declarations

2017-01-05T12:00:54+00:00

Do not try to recover too early and segfault when parsing invalid
declarations such as

echo 'int (int);' | scripts/genksyms/genksyms
echo 'int a, (int);' | scripts/genksyms/genksyms
echo 'extern void *__inline_memcpy((void *), (const void *), (__kernel_size_t));' | scripts/genksyms/genksyms

The last one was a real-life bug with
include/asm-generic/asm-prototypes.h on x86_64.

Reported-and-tested-by: Borislav Petkov 
Signed-off-by: Michal Marek

kbuild/genksyms: handle va_list type

2016-11-29T14:53:19+00:00

genksyms currently does not handle va_list. Add the __builtin_va_list
keyword as a type. This reduces the amount of syntax errors thrown,
but so far no export symbol has a type with a va_list argument, so
there is currently no bug in the end result.

Note: this patch does not regenerate shipped parser files.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michal Marek

genksyms: Duplicate function pointer type definitions segfault

2015-08-20T12:55:55+00:00

I noticed that genksyms will segfault when it sees duplicate function
pointer type declaration when I placed the same function pointer
definition in two separate headers in a local branch as an intermediate
step of some refactoring. This can be reproduced by piping the following
minimal test case into `genksyms -r /dev/null` or alternatively, putting
it into a C file attempting a build:

typedef int (*f)();
typedef int (*f)();

Attaching gdb to genksyms to understand this failure is useless without
changing CFLAGS to emit debuginfo. Once you have debuginfo, you will
find that the failure is that `char *s` was NULL and the program
executed `while(*s)`. At which point, further debugging requires
familiarity with compiler front end / parser development.

What happens is that flex identifies the first instance of the token "f"
as IDENT and the yacc parser adds it to the symbol table. On the second
instance, flex will identify "f" as TYPE, which triggers an error case
in the yacc parser. Given that TYPE would have been IDENT had it not
been in the symbol table, the the segmentaion fault could be avoided by
treating TYPE as IDENT in the affected rule.

Some might consider placing identical function pointer type declarations
in different headers to be poor style might consider a failure to be
beneficial. However, failing through a segmentation fault makes the
cause non-obvious and can waste the time of anyone who encounters it.

Signed-off-by: Richard Yao 
Acked-by: Madhuri Yechuri 
Signed-off-by: Michal Marek

genksyms: fix typeof() handling

2014-04-03T23:20:52+00:00

Recent increased use of typeof() throughout the tree resulted in a
number of symbols (25 in a typical distro config of ours) not getting a
proper CRC calculated for them anymore, due to the parser in genksyms
not coping with several of these uses (interestingly in the majority of
[if not all] cases the problem is due to the use of typeof() in code
preceding a certain export, not in the declaration/definition of the
exported function/object itself; I wasn't able to find a way to address
this more general parser shortcoming).

The use of parameter_declaration is a little more relaxed than would be
ideal (permitting not just a bare type specification, but also one with
identifier), but since the same code is being passed through an actual
compiler, there's no apparent risk of allowing through any broken code.

Otoh using parameter_declaration instead of the ad hoc
"decl_specifier_seq '*'" / "decl_specifier_seq" pair allows all types to
be handled rather than just plain ones and pointers to plain ones.

Signed-off-by: Jan Beulich 
Cc: Michal Marek 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

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: Minor parser cleanup

2011-10-11T09:59:19+00:00

Move the identical logic for recording a struct/union/enum definition to
a function.

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