After commit 07919126ec ("netfilter: annotate NAT helper hook pointers
with __rcu"), genksyms fails to parse the __rcu annotation when building
with CONFIG_DEBUG_INFO_BTF=y, CONFIG_PAHOLE_HAS_BTF_TAG=y, and a version
of clang that supports btf_type_tag.
$ clang --version | head -1
ClangBuiltLinux clang version 22.1.0 (https://github.com/llvm/llvm-project.git 4434dabb69916856b824f68a64b029c67175e532)
$ cat kernel/configs/repro.config
CONFIG_BPF_SYSCALL=y
CONFIG_MODVERSIONS=y
# CONFIG_DEBUG_INFO_NONE is not set
CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
CONFIG_DEBUG_INFO_BTF=y
$ make -skj"$(nproc)" ARCH=x86_64 LLVM=1 mrproper defconfig repro.config all
WARNING: modpost: EXPORT symbol "nf_nat_ftp_hook" [vmlinux] version generation failed, symbol will not be versioned.
...
WARNING: modpost: EXPORT symbol "nf_nat_irc_hook" [vmlinux] version generation failed, symbol will not be versioned.
...
genksyms falls over parsing the __rcu attribute in the declarator:
# Kernel reproducer
$ make -skj"$(nproc)" ARCH=x86_64 KCFLAGS=-D__GENKSYMS__ LLVM=1 net/netfilter/nf_conntrack_ftp.i
$ scripts/genksyms/genksyms -w <net/netfilter/nf_conntrack_ftp.i &| rg 'syntax error'
include/linux/netfilter/nf_conntrack_ftp.h:29: syntax error
net/netfilter/nf_conntrack_ftp.c:46: syntax error
# Trivial reproducer
$ cat test.c
int (*func)(void *foo, int bar);
int (__attribute__((btf_type_tag("rcu"))) *func_with_attr)(void *foo, int bar);
$ scripts/genksyms/genksyms -w <test.c
<stdin>:2: syntax error
Optionally allow an attribute to precede a declarator to resolve this
error and properly generate symbol versions.
Fixes: 07919126ec ("netfilter: annotate NAT helper hook pointers with __rcu")
Link: https://patch.msgid.link/20260225-genksyms-fix-attribute-declarator-v1-1-1b21478663fb@kernel.org
Tested-by: Nicolas Schier <nsc@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Enumeration constants read from a symbol reference file can incorrectly
affect new enumeration constants parsed from an actual input file.
Example:
$ cat test.c
enum { E_A, E_B, E_MAX };
struct bar { int mem[E_MAX]; };
int foo(struct bar *a) {}
__GENKSYMS_EXPORT_SYMBOL(foo);
$ cat test.c | ./scripts/genksyms/genksyms -T test.0.symtypes
#SYMVER foo 0x070d854d
$ cat test.0.symtypes
E#E_MAX 2
s#bar struct bar { int mem [ E#E_MAX ] ; }
foo int foo ( s#bar * )
$ cat test.c | ./scripts/genksyms/genksyms -T test.1.symtypes -r test.0.symtypes
<stdin>:4: warning: foo: modversion changed because of changes in enum constant E_MAX
#SYMVER foo 0x9c9dfd81
$ cat test.1.symtypes
E#E_MAX ( 2 ) + 3
s#bar struct bar { int mem [ E#E_MAX ] ; }
foo int foo ( s#bar * )
The __add_symbol() function includes logic to handle the incrementation of
enumeration values, but this code is also invoked when reading a reference
file. As a result, the variables last_enum_expr and enum_counter might be
incorrectly set after reading the reference file, which later affects
parsing of the actual input.
Fix the problem by splitting the logic for the incrementation of
enumeration values into a separate function process_enum() and call it from
__add_symbol() only when processing non-reference data.
Fixes: e37ddb8250 ("genksyms: Track changes to enum constants")
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
A longstanding issue with genksyms is that it has hidden syntax errors.
For example, genksyms fails to parse the following valid code:
int x, __attribute__((__section__(".init.data")))y;
Here, only 'y' is annotated by the attribute, although I am not aware
of actual uses of this pattern in the kernel tree.
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.
$ echo 'int x, __attribute__((__section__(".init.data")))y;' | scripts/genksyms/genksyms -w
<stdin>:1: syntax error
This commit allows attributes to be placed between a comma and
init_declarator.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
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, genksyms fails to parse the following code in
arch/arm64/lib/xor-neon.c:
static inline uint64x2_t eor3(uint64x2_t p, uint64x2_t q, uint64x2_t r)
{
[ snip ]
}
The syntax error occurs because genksyms does not recognize the
uint64x2_t keyword.
This commit adds support for builtin types described in Arm Neon
Intrinsics Reference.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
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__ fs/lockd/svc.i
$ cat fs/lockd/svc.i | scripts/genksyms/genksyms -w
[ snip ]
./include/net/addrconf.h:35: syntax error
The syntax error occurs in the following code in include/net/addrconf.h:
union __packed {
[ snip ]
};
The issue arises from __packed, which is defined as
__attribute__((__packed__)), immediately after the 'union' keyword.
This commit allows the 'union' keyword to be followed by attributes.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
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>
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__ kernel/module/main.i
$ cat kernel/module/main.i | scripts/genksyms/genksyms -w
[ snip ]
kernel/module/main.c:97: syntax error
The syntax error occurs in the following code in kernel/module/main.c:
static void __mod_update_bounds(enum mod_mem_type type __maybe_unused, void *base,
unsigned int size, struct mod_tree_root *tree)
{
[ snip ]
}
The issue arises from __maybe_unused, which is defined as
__attribute__((__unused__)).
This commit allows direct_abstract_declarator to be followed with
attributes.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
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__ drivers/acpi/prmt.i
$ cat drivers/acpi/prmt.i | scripts/genksyms/genksyms -w
[ snip ]
drivers/acpi/prmt.c:56: syntax error
The syntax error occurs in the following code in drivers/acpi/prmt.c:
struct prm_handler_info {
[ snip ]
efi_status_t (__efiapi *handler_addr)(u64, void *);
[ snip ]
};
The issue arises from __efiapi, which is defined as either
__attribute__((ms_abi)) or __attribute__((regparm(0))).
This commit allows nested_declarator to be prefixed with attributes.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
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__ init/main.i
$ cat init/main.i | scripts/genksyms/genksyms -w
[ snip ]
./include/linux/efi.h:1225: syntax error
The syntax error occurs in the following code in include/linux/efi.h:
efi_status_t
efi_call_acpi_prm_handler(efi_status_t (__efiapi *handler_addr)(u64, void *),
u64 param_buffer_addr, void *context);
The issue arises from __efiapi, which is defined as either
__attribute__((ms_abi)) or __attribute__((regparm(0))).
This commit allows abstract_declarator to be prefixed with attributes.
To avoid conflicts, I tweaked the rule for decl_specifier_seq. Due to
this change, a standalone attribute cannot become decl_specifier_seq.
Otherwise, I do not know how to resolve the conflicts.
The following code, which was previously accepted by genksyms, will now
result in a syntax error:
void my_func(__attribute__((unused))x);
I do not think it is a big deal because GCC also fails to parse it.
$ echo 'void my_func(__attribute__((unused))x);' | gcc -c -x c -
<stdin>:1:37: error: unknown type name 'x'
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
The __attribute__ keyword can appear in more contexts than 'const' or
'volatile'.
To avoid grammatical conflicts with future changes, ATTRIBUTE_PHRASE
should not be reduced into type_qualifier.
No functional changes are intended.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
I believe the missing action here is a bug.
For rules with no explicit action, the following default is used:
{ $$ = $1; }
However, in this case, $1 is the value of attribute_opt itself. As a
result, the value of attribute_opt is always NULL.
The following test code demonstrates inconsistent behavior.
int x __attribute__((__aligned__(4)));
int y __attribute__((__aligned__(4))) = 0;
The attribute is recorded only when followed by an initializer.
This commit adds the correct action to propagate the value of the
ATTRIBUTE_PHRASE token.
With this change, the attribute in the example above is consistently
recorded for both 'x' and 'y'.
[Before]
$ cat <<EOF | scripts/genksyms/genksyms -d
int x __attribute__((__aligned__(4)));
int y __attribute__((__aligned__(4))) = 0;
EOF
Defn for type0 x == <int x >
Defn for type0 y == <int y __attribute__ ( ( __aligned__ ( 4 ) ) ) >
Hash table occupancy 2/4096 = 0.000488281
[After]
$ cat <<EOF | scripts/genksyms/genksyms -d
int x __attribute__((__aligned__(4)));
int y __attribute__((__aligned__(4))) = 0;
EOF
Defn for type0 x == <int x __attribute__ ( ( __aligned__ ( 4 ) ) ) >
Defn for type0 y == <int y __attribute__ ( ( __aligned__ ( 4 ) ) ) >
Hash table occupancy 2/4096 = 0.000488281
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
Similar to the previous commit, this change makes the parser logic a
little more accurate.
Currently, genksyms accepts the following invalid code:
struct foo {
int (*callback)(int)(int)(int);
};
A direct-declarator should not recursively absorb multiple
( parameter-type-list ) constructs.
In the example above, (*callback) should be followed by at most one
(int).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
While there is no more grammatical ambiguity in genksyms, the parser
logic is still inaccurate.
For example, genksyms accepts the following invalid C code:
void my_func(int ()(int));
This should result in a syntax error because () cannot be reduced to
<direct-abstract-declarator>.
( <abstract-declarator> ) can be reduced, but <abstract-declarator>
must not be empty in the following grammar from K&R [1]:
<direct-abstract-declarator> ::= ( <abstract-declarator> )
| {<direct-abstract-declarator>}? [ {<constant-expression>}? ]
| {<direct-abstract-declarator>}? ( {<parameter-type-list>}? )
Furthermore, genksyms accepts the following weird code:
void my_func(int (*callback)(int)(int)(int));
The parser allows <direct-abstract-declarator> to recursively absorb
multiple ( {<parameter-type-list>}? ), but this behavior is incorrect.
In the example above, (*callback) should be followed by at most one
(int).
[1]: https://cs.wmich.edu/~gupta/teaching/cs4850/sumII06/The%20syntax%20of%20C%20in%20Backus-Naur%20form.htm
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
This workaround was introduced for suppressing the reduce/reduce conflict
warnings because the %expect-rr directive, which is applicable only to GLR
parsers, cannot be used for genksyms.
Since there are no longer any conflicts, this Makefile hack is now
unnecessary.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
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: 3 shift/reduce conflicts [-Wconflicts-sr]
scripts/genksyms/parse.y: note: rerun with option '-Wcounterexamples' to generate conflict counterexamples
The ambiguity arises when decl_specifier_seq is followed by '(' because
the following two interpretations are possible:
- decl_specifier_seq direct_abstract_declarator '(' parameter_declaration_clause ')'
- decl_specifier_seq '(' abstract_declarator ')'
This issue occurs because the current parser allows an empty string to
be reduced to direct_abstract_declarator, which is incorrect.
K&R [1] explains the correct grammar:
<parameter-declaration> ::= {<declaration-specifier>}+ <declarator>
| {<declaration-specifier>}+ <abstract-declarator>
| {<declaration-specifier>}+
<abstract-declarator> ::= <pointer>
| <pointer> <direct-abstract-declarator>
| <direct-abstract-declarator>
<direct-abstract-declarator> ::= ( <abstract-declarator> )
| {<direct-abstract-declarator>}? [ {<constant-expression>}? ]
| {<direct-abstract-declarator>}? ( {<parameter-type-list>}? )
This commit resolves all remaining conflicts.
We need to consider the difference between the following two examples:
[Example 1] ( <abstract-declarator> ) can become <direct-abstract-declarator>
void my_func(int (foo));
... is equivalent to:
void my_func(int foo);
[Example 2] ( <parameter-type-list> ) can become <direct-abstract-declarator>
typedef int foo;
void my_func(int (foo));
... is equivalent to:
void my_func(int (*callback)(int));
Please note that the function declaration is identical in both examples,
but the preceding typedef creates the distinction. I introduced a new
term, open_paren, to enable the type lookup immediately after the '('
token. Without this, we cannot distinguish between [Example 1] and
[Example 2].
[1]: https://cs.wmich.edu/~gupta/teaching/cs4850/sumII06/The%20syntax%20of%20C%20in%20Backus-Naur%20form.htm
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Nicolas Schier <n.schier@avm.de>
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>
Currently, 'unsigned long' is used for intermediate variables when
calculating CRCs.
The size of 'long' differs depending on the architecture: it is 32 bits
on 32-bit architectures and 64 bits on 64-bit architectures.
The CRC values generated by genksyms represent the compatibility of
exported symbols. Therefore, reproducibility is important. In other
words, we need to ensure that the output is the same when the kernel
source is identical, regardless of whether genksyms is running on a
32-bit or 64-bit build machine.
Fortunately, the output from genksyms is not affected by the build
machine's architecture because only the lower 32 bits of the
'unsigned long' variables are used.
To make it even clearer that the CRC calculation is independent of
the build machine's architecture, this commit explicitly uses the
fixed-width type, uint32_t.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
free_list() must be called before returning from this for-loop.
Swap 'break' and the combination of free_list() and 'return'.
This reduces the code and minimizes the risk of introducing memory
leaks in future changes.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
To improve readability, reduce the indentation as follows:
- Use 'continue' earlier when the symbol does not match
- flip !sym->is_declared to flatten the if-else chain
No functional changes are intended.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Nathan Chancellor
Petr PavluandMasahiro Yamada
Uros BizjakandIngo Molnar