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 <richard.yao@clusterhq.com>
Acked-by: Madhuri Yechuri <madhuriyechuri@clusterhq.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
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 <jbeulich@suse.com>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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.
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>
FreeBSD does not like <malloc.h> when __STDC__ is defined, use the standard
<stdlib.h> instead.
Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
We are having two kinds of problems with genksyms today: fake checksum
changes without actual ABI changes, and changes which we would rather like
to ignore (such as an additional field at the end of a structure that
modules are not supposed to touch, for example).
I have thought about ways to improve genksyms and compute checksums
differently to avoid those problems, but in the end I don't see a
fundamentally better way. So here are some genksyms patches for at least
making the checksums more easily manageable, if we cannot fully fix them.
In addition to the bugfixes (the first two patches), this allows genksyms
to track checksum changes and report why a checksum changed (third patch),
and to selectively ignore changes (fourth patch).
This patch:
Gcc __attribute__ definitions may occur repeatedly, e.g.,
static int foo __attribute__((__used__))
__attribute__((aligned (16)));
The genksyms parser does not understand this, and generates a syntax error.
Fix this case.
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>
Recently the __extension__ keyword has been introduced in the kernel.
Teach genksyms about this keyword so it can generate correct CRC for
exported symbols that uses a symbol marked __extension__.
For now only the typedef variant:
__extension__ typedef ...
is supported.
Later we may add more variants as needed.
This patch contains the actual source file changes. The
following patch will hold modifications to the generated
files (*_shipped) and only after the second patch the fix
has effect.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
This is a one-line change to parse.y.
To take advantage of this the scripts/genksyms/*_shipped files needs to
be rebuild - this is the next patch.
When a .c file contains:
DEFINE_PER_CPU(struct foo_s *, bar);
the .cpp output looks like:
__attribute__((__section__(".data.percpu"))) __typeof__(struct foo_s *) per_cpu__bar;
With the existing parse.y, the value inside the paranthesis of
__typeof__() does not evaluate as a type_specifier and therefore
per_cpu__bar does not get assigned a type for genksyms which results in
the EXPORT_PER_CPU_SYMBOL() not generating a CRC value.
I have compared the Modules.symvers with and without this
patch and for ia64's defconfig, the only change is:
Before 0x00000000 per_cpu____sn_nodepda vmlinux
After 0x9d3f3faa per_cpu____sn_nodepda vmlinux
per_cpu____sn_nodepda was the original source of my problems.
Signed-off-by: Robin Holt <holt@sgi.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
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!
