Currently, modpost manages unresolved in a singly linked list; it adds
a new node to the head, and traverses the list from new to old.
Use a doubly linked list to keep the order in the symbol table in the
ELF file.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Add a small helper, sym_add_unresolved() to ease the further
refactoring.
Remove the 'weak' argument from alloc_symbol() because it is sensible
only for unresolved symbols.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Currently, modpost manages modules in a singly linked list; it adds
a new node to the head, and traverses the list from new to old.
It works, but the error messages are shown in the reverse order.
If you have a Makefile like this:
obj-m += foo.o bar.o
then, modpost shows error messages in bar.o, foo.o, in this order.
Use a doubly linked list to keep the order in modules.order; use
list_add_tail() for the node addition and list_for_each_entry() for
the list traverse.
Now that the kernel's list macros have been imported to modpost, I will
use them actively going forward.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Import include/linux/list.h to use convenient list macros in modpost.
I dropped kernel-space code such as {WRITE,READ}_ONCE etc. and unneeded
macros.
I also imported container_of() from include/linux/container_of.h and
type definitions from include/linux/types.h.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Currently, mod->gpl_compatible is tristate; it is set to -1 by default,
then to 1 or 0 when MODULE_LICENSE() is found.
Maybe, -1 was chosen to represent the 'unknown' license, but it is not
useful.
The current code:
if (!mod->gpl_compatible)
check_for_gpl_usage(exp->export, basename, exp->name);
... only cares whether gpl_compatible is zero or not.
Change it to a bool type with the initial value 'true', which has no
functional change.
The default value should be 'true' instead of 'false'.
Since commit 1d6cd39293 ("modpost: turn missing MODULE_LICENSE() into
error"), unknown module license is an error.
The error message, "missing MODULE_LICENSE()" is enough to explain the
issue. It is not sensible to show another message, "GPL-incompatible
module ... uses GPL-only symbol".
Add comments to explain this.
While I was here, I renamed gpl_compatible to is_gpl_compatible for
clarification, and also slightly refactored the code.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
There is no good reason to define struct namespace_list in modpost.h
struct module has pointers to struct namespace_list, but that does
not require the definition of struct namespace_list.
Move it to modpost.c.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Do not repeat the similar code.
It is simpler to do this in check_exports() instead of add_versions().
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
It took me a while to understand the intent of "exp->module == mod".
This code goes back to 2003. [1]
The commit is not in this git repository, and might be worth a little
explanation.
You can add EXPORT_SYMBOL() without having its definition in the same
file (but you need to put a declaration).
This is typical when EXPORT_SYMBOL() is added in a C file, but the
actual implementation is in a separate assembly file.
One example is arch/arm/kernel/armksyms.c
In the old days, EXPORT_SYMBOL() was only available in C files (but
this limitation does not exist any more). If you forget to add the
definition, this error occurs.
Add a separate, clearer message for this case. It should be an error
even if KBUILD_MODPOST_WARN is given.
[1]: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=2763b6bcb96e6a38a2fe31108fe5759ec5bcc80a
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
The description,
it may have already been added without a
CRC, in this case just update the CRC
... is no longer valid.
In the old days, this function was used to update the CRC as well.
Commit 040fcc819a ("kbuild: improved modversioning support for
external modules") started to use a separate function (sym_update_crc)
for updating the CRC.
The first part, "Add an exported symbol" is correct, but it is too
obvious from the function name. Drop this comment entirely.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
If an error occurs, modpost will fail anyway. Do not write out
any content (, which might be invalid).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Use snprintf() to avoid the potential buffer overflow, and also
check the return value to detect the too long path.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
It is allowed to add the same objects multiple times to obj-y / obj-m:
obj-y += foo.o foo.o foo.o
obj-m += bar.o bar.o bar.o
It is also allowed to add the same objects multiple times to a composite
module:
obj-m += foo.o
foo-y := foo1.o foo2.o foo2.o foo1.o
This flexibility is useful because the same object might be selected by
different CONFIG options, like this:
obj-m += foo.o
foo-y := foo1.o
foo-$(CONFIG_FOO_X) += foo2.o
foo-$(CONFIG_FOO_Y) += foo2.o
The duplicated objects are omitted at link time. It works naturally in
Makefiles because GNU Make removes duplication in $^ without changing
the order.
It is working well, almost...
A small flaw I notice is, *.mod contains duplication in such a case.
This is probably not a big deal. As far as I know, the only small
problem is scripts/mod/sumversion.c parses the same file multiple
times.
I am fixing this because I plan to reuse *.mod for other purposes,
where the duplication can be problematic.
The code change is quite simple. We already use awk to drop duplicated
lines in modules.order (see cmd_modules_order in the same file).
I copied the code, but changed RS to use spaces as record separators.
I also changed the file format to list one object per line.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The *.mod files have two lines; the first line lists the member objects
of the module, and the second line, if CONFIG_TRIM_UNUSED_KSYMS=y, lists
the undefined symbols.
Currently, we generate *.mod after constructing composite modules,
otherwise, we cannot compute the second line. No prerequisite is
required to print the first line.
They are orthogonal. Splitting them into separate commands will ease
further cleanups.
This commit splits the list of undefined symbols out to *.usyms files.
Previously, the list of undefined symbols ended up with a very long
line, but now it has one symbol per line.
Use sed like we did before commit 7d32358be8 ("kbuild: avoid split
lines in .mod files").
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
There are two call sites for sym_update_namespace().
When the symbol has no namespace, s->namespace is set to NULL,
but the conversion from "" to NULL is done in two different places.
[1] read_symbols()
This gets the namespace from __kstrtabns_<symbol>. If the symbol has
no namespace, sym_get_data(info, sym) returns the empty string "".
namespace_from_kstrtabns() converts it to NULL before it is passed to
sym_update_namespace().
[2] read_dump()
This gets the namespace from the dump file, *.symvers. If the symbol
has no namespace, the 'namespace' is the empty string "", which is
directly passed into sym_update_namespace(). The conversion from
"" to NULL is done in sym_update_namespace().
namespace_from_kstrtabns() exists only for creating this inconsistency.
Remove namespace_from_kstrtabns() so that sym_update_namespace() is
consistently passed with "" instead of NULL.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
These are initialized with zeros without explicit initializers.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
The assigned 'export' is only used when
if (strstarts(symname, "__ksymtab_"))
is met. The else-part of the assignment is the dead code.
Move the export_from_secname() call to where it is used.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
With commit 1743694eb2 ("modpost: stop symbol preloading for
modversion CRC") applied, now export_from_sec() is useless.
handle_symbol() is called for every symbol in the ELF.
When 'symname' does not start with "__ksymtab", export_from_sec() is
called, and the returned value is stored in 'export'.
It is used in the last part of handle_symbol():
if (strstarts(symname, "__ksymtab_")) {
name = symname + strlen("__ksymtab_");
sym_add_exported(name, mod, export);
}
'export' is used only when 'symname' starts with "__ksymtab_".
So, the value returned by export_from_sec() is never used.
Remove useless export_from_sec(). This makes further cleanups possible.
I put the temporary code:
export = export_unknown;
Otherwise, I would get the compiler warning:
warning: 'export' may be used uninitialized in this function [-Wmaybe-uninitialized]
This is apparently false positive because
if (strstarts(symname, "__ksymtab_")
... is a stronger condition than:
if (strstarts(symname, "__ksymtab")
Anyway, this part will be cleaned up by the next commit.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Pull x86 CET-IBT (Control-Flow-Integrity) support from Peter Zijlstra:
"Add support for Intel CET-IBT, available since Tigerlake (11th gen),
which is a coarse grained, hardware based, forward edge
Control-Flow-Integrity mechanism where any indirect CALL/JMP must
target an ENDBR instruction or suffer #CP.
Additionally, since Alderlake (12th gen)/Sapphire-Rapids, speculation
is limited to 2 instructions (and typically fewer) on branch targets
not starting with ENDBR. CET-IBT also limits speculation of the next
sequential instruction after the indirect CALL/JMP [1].
CET-IBT is fundamentally incompatible with retpolines, but provides,
as described above, speculation limits itself"
[1] https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/branch-history-injection.html
* tag 'x86_core_for_5.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits)
kvm/emulate: Fix SETcc emulation for ENDBR
x86/Kconfig: Only allow CONFIG_X86_KERNEL_IBT with ld.lld >= 14.0.0
x86/Kconfig: Only enable CONFIG_CC_HAS_IBT for clang >= 14.0.0
kbuild: Fixup the IBT kbuild changes
x86/Kconfig: Do not allow CONFIG_X86_X32_ABI=y with llvm-objcopy
x86: Remove toolchain check for X32 ABI capability
x86/alternative: Use .ibt_endbr_seal to seal indirect calls
objtool: Find unused ENDBR instructions
objtool: Validate IBT assumptions
objtool: Add IBT/ENDBR decoding
objtool: Read the NOENDBR annotation
x86: Annotate idtentry_df()
x86,objtool: Move the ASM_REACHABLE annotation to objtool.h
x86: Annotate call_on_stack()
objtool: Rework ASM_REACHABLE
x86: Mark __invalid_creds() __noreturn
exit: Mark do_group_exit() __noreturn
x86: Mark stop_this_cpu() __noreturn
objtool: Ignore extra-symbol code
objtool: Rename --duplicate to --lto
...
Pull Kbuild update for C11 language base from Masahiro Yamada:
"Kbuild -std=gnu11 updates for v5.18
Linus pointed out the benefits of C99 some years ago, especially
variable declarations in loops [1]. At that time, we were not ready
for the migration due to old compilers.
Recently, Jakob Koschel reported a bug in list_for_each_entry(), which
leaks the invalid pointer out of the loop [2]. In the discussion, we
agreed that the time had come. Now that GCC 5.1 is the minimum
compiler version, there is nothing to prevent us from going to
-std=gnu99, or even straight to -std=gnu11.
Discussions for a better list iterator implementation are ongoing, but
this patch set must land first"
[1] https://lore.kernel.org/all/CAHk-=wgr12JkKmRd21qh-se-_Gs69kbPgR9x4C+Es-yJV2GLkA@mail.gmail.com/
[2] https://lore.kernel.org/lkml/86C4CE7D-6D93-456B-AA82-F8ADEACA40B7@gmail.com/
* tag 'kbuild-gnu11-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
Kbuild: use -std=gnu11 for KBUILD_USERCFLAGS
Kbuild: move to -std=gnu11
Kbuild: use -Wdeclaration-after-statement
Kbuild: add -Wno-shift-negative-value where -Wextra is used
The kernel is moving from using `-std=gnu89` to `-std=gnu11`, permitting
the use of additional C11 features such as for-loop initial declarations.
One contentious aspect of C99 is that it permits mixed declarations and
code, and for now at least, it seems preferable to enforce that
declarations must come first.
These warnings were already enabled in the kernel itself, but not
for KBUILD_USERCFLAGS or the compat VDSO on arch/arm64, which uses
a separate set of CFLAGS.
This patch fixes an existing violation in modpost.c, which is not
reported because of the missing flag in KBUILD_USERCFLAGS:
| scripts/mod/modpost.c: In function ‘match’:
| scripts/mod/modpost.c:837:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]
| 837 | const char *endp = p + strlen(p) - 1;
| | ^~~~~
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
[arnd: don't add a duplicate flag to the default set, update changelog]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13.0.0 (x86-64)
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Currently with -mindirect-branch=thunk and -mfunction-return=thunk compiler
options expoline thunks are put into individual COMDAT group sections. s390
is the only architecture which has group sections and it has implications
for kpatch and objtool tools support.
Using -mindirect-branch=thunk-extern and -mfunction-return=thunk-extern
is an alternative, which comes with a need to generate all required
expoline thunks manually. Unfortunately modules area is too far away from
the kernel image, and expolines from the kernel image cannon be used.
But since all new distributions (except Debian) build kernels for machine
generations newer than z10, where "exrl" instruction is available, that
leaves only 16 expolines thunks possible.
Provide an option to build the kernel with
-mindirect-branch=thunk-extern and -mfunction-return=thunk-extern for
z10 or newer. This also requires to postlink expoline thunks into all
modules explicitly. Currently modules already contain most expolines
anyhow.
Unfortunately -mindirect-branch=thunk-extern and
-mfunction-return=thunk-extern options support is broken in gcc <= 11.2.
Additional compile test is required to verify proper gcc support.
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Co-developed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
