| Age | Commit message (Collapse) | Author |
|---|
|
This is currently a warning, but I think modpost should stop building
in this case.
If the same symbol is exported multiple times and we let it keep going,
the sanity check becomes difficult.
Only the legitimate case is that an external module overrides the
corresponding in-tree module to provide a different implementation
with the same interface.
Also, there exists an upstream example that exploits this feature.
$ make M=tools/testing/nvdimm
... builds tools/testing/nvdimm/libnvdimm.ko. This is a mocked module
that overrides the symbols from drivers/nvdimm/libnvdimm.ko.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
|
|
modpost dumps the exported symbols into Module.symvers, but currently
in random order because it iterates in the hash table.
Add a linked list of exported symbols in struct module, so we can
iterate on symbols per module.
This commit makes Module.symvers much more readable; the outer loop in
write_dump() iterates over the modules in the order of modules.order,
and the inner loop dumps symbols in each module.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
|
|
Use the doubly linked list to traverse the list in the added order.
This makes the code more consistent.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
|
|
This looks easier to understand (just because this is a pattern in
the kernel code). No functional change is intended.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
|
|
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>
|
|
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 1d6cd3929360 ("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>
|
|
Use 'bool' to clarify that the valid value is true or false.
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 040fcc819a2e ("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>
|
|
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 1743694eb235 ("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>
|
|
This log message was accidentally chopped off.
I was wondering why this happened, but checking the ML log, Mark
precisely followed my suggestion [1].
I just used "..." because I was too lazy to type the sentence fully.
Sorry for the confusion.
[1]: https://lore.kernel.org/all/CAK7LNAR6bXXk9-ZzZYpTqzFqdYbQsZHmiWspu27rtsFxvfRuVA@mail.gmail.com/
Fixes: 4a6795933a89 ("kbuild: modpost: Explicitly warn about unprototyped symbols")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
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
...
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
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
|
|
Masahiro-san deemed my kbuild changes to support whole module objtool
runs too terrible to live and gracefully provided an alternative.
Suggested-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/CAK7LNAQ2mYMnOKMQheVi+6byUFE3KEkjm1zcndNUfe0tORGvug@mail.gmail.com
|
|
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>
|
|
Similar as other architectures such as arm64, x86 and so on, use
offsets relative to the exception table entry values rather than
absolute addresses for both the exception locationand the fixup.
However, RISCV label difference will actually produce two relocations,
a pair of R_RISCV_ADD32 and R_RISCV_SUB32. Take below simple code for
example:
$ cat test.S
.section .text
1:
nop
.section __ex_table,"a"
.balign 4
.long (1b - .)
.previous
$ riscv64-linux-gnu-gcc -c test.S
$ riscv64-linux-gnu-readelf -r test.o
Relocation section '.rela__ex_table' at offset 0x100 contains 2 entries:
Offset Info Type Sym. Value Sym. Name + Addend
000000000000 000600000023 R_RISCV_ADD32 0000000000000000 .L1^B1 + 0
000000000000 000500000027 R_RISCV_SUB32 0000000000000000 .L0 + 0
The modpost will complain the R_RISCV_SUB32 relocation, so we need to
patch modpost.c to skip this relocation for .rela__ex_table section.
After this patch, the __ex_table section size of defconfig vmlinux is
reduced from 7072 Bytes to 3536 Bytes.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- Add -s option (strict mode) to merge_config.sh to make it fail when
any symbol is redefined.
- Show a warning if a different compiler is used for building external
modules.
- Infer --target from ARCH for CC=clang to let you cross-compile the
kernel without CROSS_COMPILE.
- Make the integrated assembler default (LLVM_IAS=1) for CC=clang.
- Add <linux/stdarg.h> to the kernel source instead of borrowing
<stdarg.h> from the compiler.
- Add Nick Desaulniers as a Kbuild reviewer.
- Drop stale cc-option tests.
- Fix the combination of CONFIG_TRIM_UNUSED_KSYMS and CONFIG_LTO_CLANG
to handle symbols in inline assembly.
- Show a warning if 'FORCE' is missing for if_changed rules.
- Various cleanups
* tag 'kbuild-v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (39 commits)
kbuild: redo fake deps at include/ksym/*.h
kbuild: clean up objtool_args slightly
modpost: get the *.mod file path more simply
checkkconfigsymbols.py: Fix the '--ignore' option
kbuild: merge vmlinux_link() between ARCH=um and other architectures
kbuild: do not remove 'linux' link in scripts/link-vmlinux.sh
kbuild: merge vmlinux_link() between the ordinary link and Clang LTO
kbuild: remove stale *.symversions
kbuild: remove unused quiet_cmd_update_lto_symversions
gen_compile_commands: extract compiler command from a series of commands
x86: remove cc-option-yn test for -mtune=
arc: replace cc-option-yn uses with cc-option
s390: replace cc-option-yn uses with cc-option
ia64: move core-y in arch/ia64/Makefile to arch/ia64/Kbuild
sparc: move the install rule to arch/sparc/Makefile
security: remove unneeded subdir-$(CONFIG_...)
kbuild: sh: remove unused install script
kbuild: Fix 'no symbols' warning when CONFIG_TRIM_UNUSD_KSYMS=y
kbuild: Switch to 'f' variants of integrated assembler flag
kbuild: Shuffle blank line to improve comment meaning
...
|
|
get_src_version() strips 'o' or 'lto.o' from the end of the object file
path (so, postfixlen is 1 or 5), then adds 'mod'.
If you look at the code closely, mod->name already holds the base path
with the extension stripped.
Most of the code changes made by commit 7ac204b545f2 ("modpost: lto:
strip .lto from module names") was actually unneeded.
sumversion.c does not need strends(), so it can get back local in
modpost.c again.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
Using asm goto in __WARN_FLAGS() and WARN_ON() allows more
flexibility to GCC.
For that add an entry to the exception table so that
program_check_exception() knowns where to resume execution
after a WARNING.
Here are two exemples. The first one is done on PPC32 (which
benefits from the previous patch), the second is on PPC64.
unsigned long test(struct pt_regs *regs)
{
int ret;
WARN_ON(regs->msr & MSR_PR);
return regs->gpr[3];
}
unsigned long test9w(unsigned long a, unsigned long b)
{
if (WARN_ON(!b))
return 0;
return a / b;
}
Before the patch:
000003a8 <test>:
3a8: 81 23 00 84 lwz r9,132(r3)
3ac: 71 29 40 00 andi. r9,r9,16384
3b0: 40 82 00 0c bne 3bc <test+0x14>
3b4: 80 63 00 0c lwz r3,12(r3)
3b8: 4e 80 00 20 blr
3bc: 0f e0 00 00 twui r0,0
3c0: 80 63 00 0c lwz r3,12(r3)
3c4: 4e 80 00 20 blr
0000000000000bf0 <.test9w>:
bf0: 7c 89 00 74 cntlzd r9,r4
bf4: 79 29 d1 82 rldicl r9,r9,58,6
bf8: 0b 09 00 00 tdnei r9,0
bfc: 2c 24 00 00 cmpdi r4,0
c00: 41 82 00 0c beq c0c <.test9w+0x1c>
c04: 7c 63 23 92 divdu r3,r3,r4
c08: 4e 80 00 20 blr
c0c: 38 60 00 00 li r3,0
c10: 4e 80 00 20 blr
After the patch:
000003a8 <test>:
3a8: 81 23 00 84 lwz r9,132(r3)
3ac: 71 29 40 00 andi. r9,r9,16384
3b0: 40 82 00 0c bne 3bc <test+0x14>
3b4: 80 63 00 0c lwz r3,12(r3)
3b8: 4e 80 00 20 blr
3bc: 0f e0 00 00 twui r0,0
0000000000000c50 <.test9w>:
c50: 7c 89 00 74 cntlzd r9,r4
c54: 79 29 d1 82 rldicl r9,r9,58,6
c58: 0b 09 00 00 tdnei r9,0
c5c: 7c 63 23 92 divdu r3,r3,r4
c60: 4e 80 00 20 blr
c70: 38 60 00 00 li r3,0
c74: 4e 80 00 20 blr
In the first exemple, we see GCC doesn't need to duplicate what
happens after the trap.
In the second exemple, we see that GCC doesn't need to emit a test
and a branch in the likely path in addition to the trap.
We've got some WARN_ON() in .softirqentry.text section so it needs
to be added in the OTHER_TEXT_SECTIONS in modpost.c
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/389962b1b702e3c78d169e59bcfac56282889173.1618331882.git.christophe.leroy@csgroup.eu
|
|
One common cause of modpost version generation failures is a failure to
prototype exported assembly functions - the tooling requires this for
exported functions even if they are not and should not be called from C
code in order to do the version mangling for symbols. Unfortunately the
error message is currently rather abstruse, simply saying that "version
generation failed" and even diving into the code doesn't directly show
what's going on since there's several steps between the problem and it
being observed.
Provide an explicit hint as to the likely cause of a version generation
failure to help anyone who runs into this in future more readily diagnose
and fix the problem.
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
Currently, clang LTO built vmlinux won't work with pahole.
LTO introduced cross-cu dwarf tag references and broke
current pahole model which handles one cu as a time.
The solution is to merge all cu's as one pahole cu as in [1].
We would like to do this merging only if cross-cu dwarf
references happens. The LTO build mode is a pretty good
indication for that.
In earlier version of this patch ([2]), clang flag
-grecord-gcc-switches is proposed to add to compilation flags
so pahole could detect "-flto" and then merging cu's.
This will increate the binary size of 1% without LTO though.
Arnaldo suggested to use a note to indicate the vmlinux
is built with LTO. Such a cheap way to get whether the vmlinux
is built with LTO or not helps pahole but is also useful
for tracing as LTO may inline/delete/demote global functions,
promote static functions, etc.
So this patch added an elfnote with a new type LINUX_ELFNOTE_LTO_INFO.
The owner of the note is "Linux".
With gcc 8.4.1 and clang trunk, without LTO, I got
$ readelf -n vmlinux
Displaying notes found in: .notes
Owner Data size Description
...
Linux 0x00000004 func
description data: 00 00 00 00
...
With "readelf -x ".notes" vmlinux", I can verify the above "func"
with type code 0x101.
With clang thin-LTO, I got the same as above except the following:
description data: 01 00 00 00
which indicates the vmlinux is built with LTO.
[1] https://lore.kernel.org/bpf/20210325065316.3121287-1-yhs@fb.com/
[2] https://lore.kernel.org/bpf/20210331001623.2778934-1-yhs@fb.com/
Suggested-by: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v12.0.0-rc4 (x86-64)
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
s/agorithm/algorithm/
s/criterias/criteria/
s/targetting/targeting/ ....two different places.
Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
Nathan reports that the mips defconfig emits the following warning:
WARNING: modpost: Symbol info of vmlinux is missing. Unresolved symbol check will be entirely skipped.
This false-positive happens when CONFIG_TRIM_UNUSED_KSYMS is enabled,
but no CONFIG option is set to 'm'.
Commit a0590473c5e6 ("nfs: fix PNFS_FLEXFILE_LAYOUT Kconfig default")
turned the last 'm' into 'y' for the mips defconfig, and uncovered
this issue.
In this case, the module feature itself is enabled, but we have no
module to build. As a result, CONFIG_TRIM_UNUSED_KSYMS drops all the
instances of EXPORT_SYMBOL. Then, modpost wrongly assumes vmlinux is
missing because vmlinux.symvers is empty. (As another false-positive
case, you can create a module that does not use any symbol of vmlinux).
The current behavior is to entirely suppress the unresolved symbol
warnings when vmlinux is missing just because there are too many.
I found the origin of this code in the historical git tree. [1]
If this is a matter of noisiness, I think modpost can display the
first 10 warnings, and the number of suppressed warnings at the end.
You will get a bit noisier logs when you run 'make modules' without
vmlinux, but such warnings are better to show because you never know
the resulting modules are actually loadable or not.
This commit changes the following:
- If any of input *.symver files is missing, pass -w option to let
the module build keep going with warnings instead of errors.
- If there are too many (10+) unresolved symbol warnings, show only
the first 10, and also the number of suppressed warnings.
[1]: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=1cc0e0529569bf6a94f6d49770aa6d4b599d2c46
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
The external module build shows the following warning if Module.symvers
is missing in the kernel tree.
WARNING: Symbol version dump "Module.symvers" is missing.
Modules may not have dependencies or modversions.
I think this is an important heads-up because the resulting modules may
not work as expected. This happens when you did not build the entire
kernel tree, for example, you might have prepared the minimal setups
for external modules by 'make defconfig && make modules_preapre'.
A problem is that 'make modules' creates Module.symvers even without
vmlinux. In this case, that warning is suppressed since Module.symvers
already exists in spite of its incomplete content.
The incomplete (i.e. invalid) Module.symvers should not be created.
This commit changes the second pass of modpost to dump symbols into
modules-only.symvers. The final Module.symvers is created by
concatenating vmlinux.symvers and modules-only.symvers if both exist.
Module.symvers is supposed to collect symbols from both vmlinux and
modules. It might be a bit confusing, and I am not quite sure if it
is an official interface, but presumably it is difficult to rename it
because some tools (e.g. kmod) parse it.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux
Pull module updates from Jessica Yu:
- Retire EXPORT_UNUSED_SYMBOL() and EXPORT_SYMBOL_GPL_FUTURE(). These
export types were introduced between 2006 - 2008. All the of the
unused symbols have been long removed and gpl future symbols were
converted to gpl quite a long time ago, and I don't believe these
export types have been used ever since. So, I think it should be safe
to retire those export types now (Christoph Hellwig)
- Refactor and clean up some aged code cruft in the module loader
(Christoph Hellwig)
- Build {,module_}kallsyms_on_each_symbol only when livepatching is
enabled, as it is the only caller (Christoph Hellwig)
- Unexport find_module() and module_mutex and fix the last module
callers to not rely on these anymore. Make module_mutex internal to
the module loader (Christoph Hellwig)
- Harden ELF checks on module load and validate ELF structures before
checking the module signature (Frank van der Linden)
- Fix undefined symbol warning for clang (Fangrui Song)
- Fix smatch warning (Dan Carpenter)
* tag 'modules-for-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux:
module: potential uninitialized return in module_kallsyms_on_each_symbol()
module: remove EXPORT_UNUSED_SYMBOL*
module: remove EXPORT_SYMBOL_GPL_FUTURE
module: move struct symsearch to module.c
module: pass struct find_symbol_args to find_symbol
module: merge each_symbol_section into find_symbol
module: remove each_symbol_in_section
module: mark module_mutex static
kallsyms: only build {,module_}kallsyms_on_each_symbol when required
kallsyms: refactor {,module_}kallsyms_on_each_symbol
module: use RCU to synchronize find_module
module: unexport find_module and module_mutex
drm: remove drm_fb_helper_modinit
powerpc/powernv: remove get_cxl_module
module: harden ELF info handling
module: Ignore _GLOBAL_OFFSET_TABLE_ when warning for undefined symbols
|
|
EXPORT_UNUSED_SYMBOL* is not actually used anywhere. Remove the
unused functionality as we generally just remove unused code anyway.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
|
|
As far as I can tell this has never been used at all, and certainly
not any time recently.
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
|
|
With LTO, everything is compiled into LLVM bitcode, so we have to link
each module into native code before modpost. Kbuild uses the .lto.o
suffix for these files, which also ends up in module information. This
change strips the unnecessary .lto suffix from the module name.
Suggested-by: Bill Wendling <morbo@google.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20201211184633.3213045-11-samitolvanen@google.com
|
|
Using EXPORT_SYMBOL*() on static functions is fundamentally wrong.
Modpost currently reports that as a warning, but clearly this is not a
pattern we should allow, and all in-tree occurences should have been
fixed by now. So, promote the warn() message to error() to make sure
this never happens again.
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Matthias Maennich <maennich@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
There is code that reports static EXPORT_SYMBOL a few lines below.
It is not a good idea to bail out here.
I renamed sec_mismatch_fatal to sec_mismatch_warn_only (with logical
inversion) to match to CONFIG_SECTION_MISMATCH_WARN_ONLY.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
Change fatal() to error() to continue running to report more possible
issues.
There is no difference in the fact that modpost will fail anyway.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
Do not create modules with no license tag.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
We have 3 log functions. fatal() is special because it lets modpost bail
out immediately. The difference between warn() and error() is the only
prefix parts ("WARNING:" vs "ERROR:").
In my understanding, the expected handling of error() is to propagate
the return code of the function to the exit code of modpost, as
check_exports() etc. already does. This is a good manner in general
because we should display as many error messages as possible in a
single run of modpost.
What is annoying about fatal() is that it kills modpost at the first
error. People would need to run Kbuild again and again until they fix
all errors.
But, unfortunately, people tend to do:
"This case should not be allowed. Let's replace warn() with fatal()."
One of the reasons is probably it is tedious to manually hoist the error
code to the main() function.
This commit refactors error() so any single call for it automatically
makes modpost return the error code.
I also added comments in modpost.h for warn(), error(), and fatal().
Please use fatal() only when you have a strong reason to do so.
For example:
- Memory shortage (i.e. malloc() etc. has failed)
- The ELF file is broken, and there is no point to continue parsing
- Something really odd has happened
For general coding errors, please use error().
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Quentin Perret <qperret@google.com>
|
|
The log function names, warn(), merror(), fatal() are inconsistent.
Commit 2a11665945d5 ("kbuild: distinguish between errors and warnings
in modpost") intentionally chose merror() to avoid the conflict with
the library function error(). See man page of error(3).
But, we are already causing the conflict with warn() because it is also
a library function. See man page of warn(3). err() would be a problem
for the same reason.
The common technique to work around name conflicts is to use macros.
For example:
/* in a header */
#define error(fmt, ...) __error(fmt, ##__VA_ARGS__)
#define warn(fmt, ...) __warn(fmt, ##__VA_ARGS__)
/* function definition */
void __error(const char *fmt, ...)
{
<our implementation>
}
void __warn(const char *fmt, ...)
{
<our implementation>
}
In this way, we can implement our own warn() and error(), still we can
include <error.h> and <err.h> with no problem.
And, commit 93c95e526a4e ("modpost: rework and consolidate logging
interface") already did that.
Since the log functions are all macros, we can use error() without
causing "conflicting types" errors.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
Use a more generic form for __section that requires quotes to avoid
complications with clang and gcc differences.
Remove the quote operator # from compiler_attributes.h __section macro.
Convert all unquoted __section(foo) uses to quoted __section("foo").
Also convert __attribute__((section("foo"))) uses to __section("foo")
even if the __attribute__ has multiple list entry forms.
Conversion done using the script at:
https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl
Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@gooogle.com>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Mention why we open-code strsep, so it is clear that it is intentional.
Fixes: 736bb11898ef ("modpost: remove use of non-standard strsep() in HOSTCC code")
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
strsep() is neither standard C nor POSIX and used outside
the kernel code here. Using it here requires that the
build host supports it out of the box which is e.g.
not true for a Darwin build host and using a cross-compiler.
This leads to:
scripts/mod/modpost.c:145:2: warning: implicit declaration of function 'strsep' [-Wimplicit-function-declaration]
return strsep(stringp, "\n");
^
and a segfault when running MODPOST.
See also: https://stackoverflow.com/a/7219504
So let's replace this by strchr() instead of using strsep().
It does not hurt kernel size or speed since this code is run
on the build host.
Fixes: ac5100f5432967 ("modpost: add read_text_file() and get_line() helpers")
Co-developed-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- fix warnings in 'make clean' for ARCH=um, hexagon, h8300, unicore32
- ensure to rebuild all objects when the compiler is upgraded
- exclude system headers from dependency tracking and fixdep processing
- fix potential bit-size mismatch between the kernel and BPF user-mode
helper
- add the new syntax 'userprogs' to build user-space programs for the
target architecture (the same arch as the kernel)
- compile user-space sample code under samples/ for the target arch
instead of the host arch
- make headers_install fail if a CONFIG option is leaked to user-space
- sanitize the output format of scripts/checkstack.pl
- handle ARM 'push' instruction in scripts/checkstack.pl
- error out before modpost if a module name conflict is found
- error out when multiple directories are passed to M= because this
feature is broken for a long time
- add CONFIG_DEBUG_INFO_COMPRESSED to support compressed debug info
- a lot of cleanups of modpost
- dump vmlinux symbols out into vmlinux.symvers, and reuse it in the
second pass of modpost
- do not run the second pass of modpost if nothing in modules is
updated
- install modules.builtin(.modinfo) by 'make install' as well as by
'make modules_install' because it is useful even when
CONFIG_MODULES=n
- add new command line variables, GZIP, BZIP2, LZOP, LZMA, LZ4, and XZ
to allow users to use alternatives such as pigz, pbzip2, etc.
* tag 'kbuild-v5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (96 commits)
kbuild: add variables for compression tools
Makefile: install modules.builtin even if CONFIG_MODULES=n
mksysmap: Fix the mismatch of '.L' symbols in System.map
kbuild: doc: rename LDFLAGS to KBUILD_LDFLAGS
modpost: change elf_info->size to size_t
modpost: remove is_vmlinux() helper
modpost: strip .o from modname before calling new_module()
modpost: set have_vmlinux in new_module()
modpost: remove mod->skip struct member
modpost: add mod->is_vmlinux struct member
modpost: remove is_vmlinux() call in check_for_{gpl_usage,unused}()
modpost: remove mod->is_dot_o struct member
modpost: move -d option in scripts/Makefile.modpost
modpost: remove -s option
modpost: remove get_next_text() and make {grab,release_}file static
modpost: use read_text_file() and get_line() for reading text files
modpost: avoid false-positive file open error
modpost: fix potential mmap'ed file overrun in get_src_version()
modpost: add read_text_file() and get_line() helpers
modpost: do not call get_modinfo() for vmlinux(.o)
...
|
|
Align with the mmap / munmap APIs.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
|
Now that is_vmlinux() is called only in new_module(), we can inline
the function call.
modname is the basename with '.o' is stripped. No need to compare it
with 'vmlinux.o'.
vmlinux is always located at the current working directory. No need
to strip the directory path.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
|
