Since commit 7b4537199a ("kbuild: link symbol CRCs at final link,
removing CONFIG_MODULE_REL_CRCS"), module versioning is broken on
some architectures. Loading a module fails with "disagrees about
version of symbol module_layout".
On such architectures (e.g. ARCH=sparc build with sparc64_defconfig),
modpost shows a warning, like follows:
WARNING: modpost: EXPORT symbol "_mcount" [vmlinux] version generation failed, symbol will not be versioned.
Is "_mcount" prototyped in <asm/asm-prototypes.h>?
Previously, it was a harmless warning (CRC check was just skipped),
but now wrong CRCs are used for comparison because invalid CRCs are
just skipped.
$ sparc64-linux-gnu-nm -n vmlinux
[snip]
0000000000c2cea0 r __ksymtab__kstrtol
0000000000c2ceb8 r __ksymtab__kstrtoul
0000000000c2ced0 r __ksymtab__local_bh_enable
0000000000c2cee8 r __ksymtab__mcount
0000000000c2cf00 r __ksymtab__printk
0000000000c2cf18 r __ksymtab__raw_read_lock
0000000000c2cf30 r __ksymtab__raw_read_lock_bh
[snip]
0000000000c53b34 D __crc__kstrtol
0000000000c53b38 D __crc__kstrtoul
0000000000c53b3c D __crc__local_bh_enable
0000000000c53b40 D __crc__printk
0000000000c53b44 D __crc__raw_read_lock
0000000000c53b48 D __crc__raw_read_lock_bh
Please notice __crc__mcount is missing here.
When the module subsystem looks up a CRC that comes after, it results
in reading out a wrong address. For example, when __crc__printk is
needed, the module subsystem reads 0xc53b44 instead of 0xc53b40.
All CRC entries must be output for correct index accessing. Invalid
CRCs will be unused, but are needed to keep the one-to-one mapping
between __ksymtab_* and __crc_*.
The best is to fix all modpost warnings, but several warnings are still
remaining on less popular architectures.
Fixes: 7b4537199a ("kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS")
Reported-by: matoro <matoro_mailinglist_kernel@matoro.tk>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: matoro <matoro_mailinglist_kernel@matoro.tk>
- Remove the support for -O3 (CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3)
- Fix error of rpm-pkg cross-builds
- Support riscv for checkstack tool
- Re-enable -Wformwat warnings for Clang
- Clean up modpost, Makefiles, and misc scripts
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Merge tag 'kbuild-v5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- Remove the support for -O3 (CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3)
- Fix error of rpm-pkg cross-builds
- Support riscv for checkstack tool
- Re-enable -Wformwat warnings for Clang
- Clean up modpost, Makefiles, and misc scripts
* tag 'kbuild-v5.20' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (30 commits)
modpost: remove .symbol_white_list field entirely
modpost: remove unneeded .symbol_white_list initializers
modpost: add PATTERNS() helper macro
modpost: shorten warning messages in report_sec_mismatch()
Revert "Kbuild, lto, workaround: Don't warn for initcall_reference in modpost"
modpost: use more reliable way to get fromsec in section_rel(a)()
modpost: add array range check to sec_name()
modpost: refactor get_secindex()
kbuild: set EXIT trap before creating temporary directory
modpost: remove unused Elf_Sword macro
Makefile.extrawarn: re-enable -Wformat for clang
kbuild: add dtbs_prepare target
kconfig: Qt5: tell the user which packages are required
modpost: use sym_get_data() to get module device_table data
modpost: drop executable ELF support
checkstack: add riscv support for scripts/checkstack.pl
kconfig: shorten the temporary directory name for cc-option
scripts: headers_install.sh: Update config leak ignore entries
kbuild: error out if $(INSTALL_MOD_PATH) contains % or :
kbuild: error out if $(KBUILD_EXTMOD) contains % or :
...
It is not so useful to have symbol whitelists in arrays. With this
over-engineering, the code is difficult to follow.
Let's do it more directly, and collect the relevant code to one place.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The ->symbol_white_list field is referenced in secref_whitelist(),
only when 'fromsec' is data_sections.
/* Check for pattern 2 */
if (match(tosec, init_exit_sections) &&
match(fromsec, data_sections) &&
match(fromsym, mismatch->symbol_white_list))
return 0;
If .fromsec is not data sections, the .symbol_white_list member is
not used by anyone.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This will be useful to define a NULL-terminated array inside a function
call.
Currently, string arrays passed to match() are defined in separate
places:
static const char *const init_sections[] = { ALL_INIT_SECTIONS, NULL };
static const char *const text_sections[] = { ALL_TEXT_SECTIONS, NULL };
static const char *const optim_symbols[] = { "*.constprop.*", NULL };
...
/* Check for pattern 5 */
if (match(fromsec, text_sections) &&
match(tosec, init_sections) &&
match(fromsym, optim_symbols))
return 0;
With the new helper macro, you can list the patterns directly in the
function call, like this:
/* Check for pattern 5 */
if (match(fromsec, PATTERNS(ALL_TEXT_SECTIONS)) &&
match(tosec, PATTERNS(ALL_INIT_SECTIONS)) &&
match(fromsym, PATTERNS("*.contprop.*")))
return 0;
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Each section mismatch results in long warning messages. Too much.
Make each warning fit in one line, and remove a lot of messy code.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This reverts commit 77ab21adae.
Even after 8 years later, GCC LTO has not been upstreamed. Also, it said
"This is a workaround". If this is needed in the future, it should be
added in a proper way.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Jiri Slaby <jirislaby@kernel.org>
The section name of Rel and Rela starts with ".rel" and ".rela"
respectively (but, I do not know whether this is specification or
convention).
For example, ".rela.text" holds relocation entries applied to the
".text" section.
So, the code chops the ".rel" or ".rela" prefix to get the name of
the section to which the relocation applies.
However, I do not like to skip 4 or 5 bytes blindly because it is
potential memory overrun.
The ELF specification provides a more reliable way to do this.
- The sh_info field holds extra information, whose interpretation
depends on the section type
- If the section type is SHT_REL or SHT_RELA, the sh_info field holds
the section header index of the section to which the relocation
applies.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The section index is always positive, so the argument, secindex, should
be unsigned.
Also, inserted the array range check.
If sym->st_shndx is a special section index (between SHN_LORESERVE and
SHN_HIRESERVE), there is no corresponding section header.
For example, if a symbol specifies an absolute value, sym->st_shndx is
SHN_ABS (=0xfff1).
The current users do not cause the out-of-range access of
info->sechddrs[], but it is better to avoid such a pitfall.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
SPECIAL() is only used in get_secindex(). Squash it.
Make the code more readable with more comments.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Commit 9ad21c3f3e ("kbuild: try harder to find symbol names in
modpost") added Elf_Sword (in a wrong way), but did not use it at all.
BTW, the current code looks weird.
The fix for the 32-bit part would be:
Elf64_Sword --> Elf32_Sword
(inconsistet prefix, Elf32_ vs Elf64_)
The fix for the 64-bit part would be:
Elf64_Sxword --> Elf64_Sword
(the size is different between Sword and Sxword)
Note:
Elf32_Sword == Elf64_Sword == int32_t
Elf32_Sxword == Elf64_Sxword == int64_t
Anyway, let's drop unused code instead of fixing it.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
This KUnit update for Linux 5.20-rc1 consists of several fixes and an
important feature to discourage running KUnit tests on production
systems. Running tests on a production system could leave the system
in a bad state. This new feature adds:
- adds a new taint type, TAINT_TEST to signal that a test has been run.
This should discourage people from running these tests on production
systems, and to make it easier to tell if tests have been run
accidentally (by loading the wrong configuration, etc.)
- several documentation and tool enhancements and fixes.
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Merge tag 'linux-kselftest-kunit-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest
Pull KUnit updates from Shuah Khan:
"This consists of several fixes and an important feature to discourage
running KUnit tests on production systems. Running tests on a
production system could leave the system in a bad state.
Summary:
- Add a new taint type, TAINT_TEST to signal that a test has been
run.
This should discourage people from running these tests on
production systems, and to make it easier to tell if tests have
been run accidentally (by loading the wrong configuration, etc)
- Several documentation and tool enhancements and fixes"
* tag 'linux-kselftest-kunit-5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest: (29 commits)
Documentation: KUnit: Fix example with compilation error
Documentation: kunit: Add CLI args for kunit_tool
kcsan: test: Add a .kunitconfig to run KCSAN tests
kunit: executor: Fix a memory leak on failure in kunit_filter_tests
clk: explicitly disable CONFIG_UML_PCI_OVER_VIRTIO in .kunitconfig
mmc: sdhci-of-aspeed: test: Use kunit_test_suite() macro
nitro_enclaves: test: Use kunit_test_suite() macro
thunderbolt: test: Use kunit_test_suite() macro
kunit: flatten kunit_suite*** to kunit_suite** in .kunit_test_suites
kunit: unify module and builtin suite definitions
selftest: Taint kernel when test module loaded
module: panic: Taint the kernel when selftest modules load
Documentation: kunit: fix example run_kunit func to allow spaces in args
Documentation: kunit: Cleanup run_wrapper, fix x-ref
kunit: test.h: fix a kernel-doc markup
kunit: tool: Enable virtio/PCI by default on UML
kunit: tool: make --kunitconfig repeatable, blindly concat
kunit: add coverage_uml.config to enable GCOV on UML
kunit: tool: refactor internal kconfig handling, allow overriding
kunit: tool: introduce --qemu_args
...
Use sym_get_data() to replace the long code.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Since commit 269a535ca9 ("modpost: generate vmlinux.symvers and
reuse it for the second modpost"), modpost only parses relocatable
files (ET_REL).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
This reverts commit 4d10c223ba.
Commit 37744feebc ("sh: remove sh5 support") removed the sh64 support
entirely.
Note:
.cranges was only used for sh64 ever.
Commit 211dc24b8744 ("Remove sh5 and sh64 support") in binutils-gdb
already removed the relevant code.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Taint the kernel with TAINT_TEST whenever a test module loads, by adding
a new "TEST" module property, and setting it for all modules in the
tools/testing directory. This property can also be set manually, for
tests which live outside the tools/testing directory with:
MODULE_INFO(test, "Y");
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Aaron Tomlin <atomlin@redhat.com>
Acked-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Since commit f02e8a6596 ("module: Sort exported symbols"),
EXPORT_SYMBOL* is placed in the individual section ___ksymtab(_gpl)+<sym>
(3 leading underscores instead of 2).
Since then, modpost cannot detect the bad combination of EXPORT_SYMBOL
and __init/__exit.
Fix the .fromsec field.
Fixes: f02e8a6596 ("module: Sort exported symbols")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
- Fix build regressions for parisc, csky, nios2, openrisc
- Simplify module builds for CONFIG_LTO_CLANG and CONFIG_X86_KERNEL_IBT
- Remove arch/parisc/nm, which was presumably a workaround for old tools
- Check the odd combination of EXPORT_SYMBOL and 'static' precisely
- Make external module builds robust against "too long argument error"
- Support j, k keys for moving the cursor in nconfig
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Merge tag 'kbuild-v5.19-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull more Kbuild updates from Masahiro Yamada:
- Fix build regressions for parisc, csky, nios2, openrisc
- Simplify module builds for CONFIG_LTO_CLANG and CONFIG_X86_KERNEL_IBT
- Remove arch/parisc/nm, which was presumably a workaround for old
tools
- Check the odd combination of EXPORT_SYMBOL and 'static' precisely
- Make external module builds robust against "too long argument error"
- Support j, k keys for moving the cursor in nconfig
* tag 'kbuild-v5.19-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (25 commits)
kbuild: Allow to select bash in a modified environment
scripts: kconfig: nconf: make nconfig accept jk keybindings
modpost: use fnmatch() to simplify match()
modpost: simplify mod->name allocation
kbuild: factor out the common objtool arguments
kbuild: move vmlinux.o link to scripts/Makefile.vmlinux_o
kbuild: clean .tmp_* pattern by make clean
kbuild: remove redundant cleanups in scripts/link-vmlinux.sh
kbuild: rebuild multi-object modules when objtool is updated
kbuild: add cmd_and_savecmd macro
kbuild: make *.mod rule robust against too long argument error
kbuild: make built-in.a rule robust against too long argument error
kbuild: check static EXPORT_SYMBOL* by script instead of modpost
parisc: remove arch/parisc/nm
kbuild: do not create *.prelink.o for Clang LTO or IBT
kbuild: replace $(linked-object) with CONFIG options
kbuild: do not try to parse *.cmd files for objects provided by compiler
kbuild: replace $(if A,A,B) with $(or A,B) in scripts/Makefile.modpost
modpost: squash if...else-if in find_elf_symbol2()
modpost: reuse ARRAY_SIZE() macro for section_mismatch()
...
Replace the own implementation for wildcard (glob) matching with
a function call to fnmatch().
Also, change the return type to 'bool'.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
mod->name is set to the ELF filename with the suffix ".o" stripped.
The current code calls strdup() and free() to manipulate the string,
but a simpler approach is to pass new_module() with the name length
subtracted by 2.
Also, check if the passed filename ends with ".o" before stripping it.
The current code blindly chops the suffix:
tmp[strlen(tmp) - 2] = '\0'
It will cause buffer under-run if strlen(tmp) < 2;
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Here is the large set of char, misc, and other driver subsystem updates
for 5.19-rc1. The merge request for this has been delayed as I wanted
to get lots of linux-next testing due to some late arrivals of changes
for the habannalabs driver.
Highlights of this merge are:
- habanalabs driver updates for new hardware types and fixes and
other updates
- IIO driver tree merge which includes loads of new IIO drivers
and cleanups and additions
- PHY driver tree merge with new drivers and small updates to
existing ones
- interconnect driver tree merge with fixes and updates
- soundwire driver tree merge with some small fixes
- coresight driver tree merge with small fixes and updates
- mhi bus driver tree merge with lots of updates and new device
support
- firmware driver updates
- fpga driver updates
- lkdtm driver updates (with a merge conflict, more on that
below)
- extcon driver tree merge with small updates
- lots of other tiny driver updates and fixes and cleanups, full
details in the shortlog.
All of these have been in linux-next for almost 2 weeks with no reported
problems.
Note, there are 3 merge conflicts when merging this with your tree:
- MAINTAINERS, should be easy to resolve
- drivers/slimbus/qcom-ctrl.c, should be straightforward
resolution
- drivers/misc/lkdtm/stackleak.c, not an easy resolution. This
has been noted in the linux-next tree for a while, and
resolved there, here's a link to the resolution that Stephen
came up with and that Kees says is correct:
https://lore.kernel.org/r/20220509185344.3fe1a354@canb.auug.org.au
I will be glad to provide a merge point that contains these resolutions
if that makes things any easier for you.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'char-misc-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char / misc / other smaller driver subsystem updates from Greg KH:
"Here is the large set of char, misc, and other driver subsystem
updates for 5.19-rc1. The merge request for this has been delayed as I
wanted to get lots of linux-next testing due to some late arrivals of
changes for the habannalabs driver.
Highlights of this merge are:
- habanalabs driver updates for new hardware types and fixes and
other updates
- IIO driver tree merge which includes loads of new IIO drivers and
cleanups and additions
- PHY driver tree merge with new drivers and small updates to
existing ones
- interconnect driver tree merge with fixes and updates
- soundwire driver tree merge with some small fixes
- coresight driver tree merge with small fixes and updates
- mhi bus driver tree merge with lots of updates and new device
support
- firmware driver updates
- fpga driver updates
- lkdtm driver updates (with a merge conflict, more on that below)
- extcon driver tree merge with small updates
- lots of other tiny driver updates and fixes and cleanups, full
details in the shortlog.
All of these have been in linux-next for almost 2 weeks with no
reported problems"
* tag 'char-misc-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (387 commits)
habanalabs: use separate structure info for each error collect data
habanalabs: fix missing handle shift during mmap
habanalabs: remove hdev from hl_ctx_get args
habanalabs: do MMU prefetch as deferred work
habanalabs: order memory manager messages
habanalabs: return -EFAULT on copy_to_user error
habanalabs: use NULL for eventfd
habanalabs: update firmware header
habanalabs: add support for notification via eventfd
habanalabs: add topic to memory manager buffer
habanalabs: handle race in driver fini
habanalabs: add device memory scrub ability through debugfs
habanalabs: use unified memory manager for CB flow
habanalabs: unified memory manager new code for CB flow
habanalabs/gaudi: set arbitration timeout to a high value
habanalabs: add put by handle method to memory manager
habanalabs: hide memory manager page shift
habanalabs: Add separate poll interval value for protocol
habanalabs: use get_task_pid() to take PID
habanalabs: add prefetch flag to the MAP operation
...
The 'static' specifier and EXPORT_SYMBOL() are an odd combination.
Commit 15bfc2348d ("modpost: check for static EXPORT_SYMBOL*
functions") tried to detect it, but this check has false negatives.
Here is the sample code.
Makefile:
obj-y += foo1.o foo2.o
foo1.c:
#include <linux/export.h>
static void foo(void) {}
EXPORT_SYMBOL(foo);
foo2.c:
void foo(void) {}
foo1.c exports the static symbol 'foo', but modpost cannot catch it
because it is fooled by foo2.c, which has a global symbol with the
same name.
s->is_static is cleared if a global symbol with the same name is found
somewhere, but EXPORT_SYMBOL() and the global symbol do not necessarily
belong to the same compilation unit.
This check should be done per compilation unit, but I do not know how
to do it in modpost. modpost runs against vmlinux.o or modules, which
merges multiple objects, then forgets their origin.
modpost cannot parse individual objects because they may not be ELF but
LLVM IR when CONFIG_LTO_CLANG=y.
Add a simple bash script to parse the output from ${NM}. This works for
CONFIG_LTO_CLANG=y because llvm-nm can dump symbols of LLVM IR files.
Revert 15bfc2348d.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
When CONFIG_LTO_CLANG=y, additional intermediate *.prelink.o is created
for each module. Also, objtool is postponed until LLVM IR is converted
to ELF.
CONFIG_X86_KERNEL_IBT works in a similar way to postpone objtool until
objects are merged together.
This commit stops generating *.prelink.o, so the build flow will look
similar with/without LTO.
The following figures show how the LTO build currently works, and
how this commit is changing it.
Current build flow
==================
[1] single-object module
$(LD)
$(CC) +objtool $(LD)
foo.c --------------------> foo.o -----> foo.prelink.o -----> foo.ko
(LLVM IR) (ELF) | (ELF)
|
foo.mod.o --/
(LLVM IR)
[2] multi-object module
$(LD)
$(CC) $(AR) +objtool $(LD)
foo1.c -----> foo1.o -----> foo.o -----> foo.prelink.o -----> foo.ko
| (archive) (ELF) | (ELF)
foo2.c -----> foo2.o --/ |
(LLVM IR) foo.mod.o --/
(LLVM IR)
One confusion is that foo.o in multi-object module is an archive
despite of its suffix.
New build flow
==============
[1] single-object module
Since there is only one object, there is no need to keep the LLVM IR.
Use $(CC)+$(LD) to generate an ELF object in one build rule. When LTO
is disabled, $(LD) is unneeded because $(CC) produces an ELF object.
$(CC)+$(LD)+objtool $(LD)
foo.c ----------------------------> foo.o ---------> foo.ko
(ELF) | (ELF)
|
foo.mod.o --/
(LLVM IR)
[2] multi-object module
Previously, $(AR) was used to combine LLVM IR files into an archive,
but there was no technical reason to do so. Use $(LD) to merge them
into a single ELF object.
$(LD)
$(CC) +objtool $(LD)
foo1.c ---------> foo1.o ---------> foo.o ---------> foo.ko
| (ELF) | (ELF)
foo2.c ---------> foo2.o ----/ |
(LLVM IR) foo.mod.o --/
(LLVM IR)
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
if ((addr - sym->st_value) < distance) {
distance = addr - sym->st_value;
near = sym;
} else if ((addr - sym->st_value) == distance) {
near = sym;
}
is equivalent to:
if (addr - sym->st_value <= distance) {
distance = addr - sym->st_value;
near = sym;
}
(The else-if block can overwrite 'distance' with the same value).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Move ARRAY_SIZE() from file2alias.c to modpost.h to reuse it in
section_mismatch().
Also, move the variable 'check' inside the for-loop.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
check_sec_ref() does not use the first parameter 'mod'.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
The return value of is_arm_mapping_symbol() is unpredictable when "$"
is passed in.
strchr(3) says:
The strchr() and strrchr() functions return a pointer to the matched
character or NULL if the character is not found. The terminating null
byte is considered part of the string, so that if c is specified as
'\0', these functions return a pointer to the terminator.
When str[1] is '\0', strchr("axtd", str[1]) is not NULL, and str[2] is
referenced (i.e. buffer overrun).
Test code
---------
char str1[] = "abc";
char str2[] = "ab";
strcpy(str1, "$");
strcpy(str2, "$");
printf("test1: %d\n", is_arm_mapping_symbol(str1));
printf("test2: %d\n", is_arm_mapping_symbol(str2));
Result
------
test1: 0
test2: 1
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
With the `-z unique-symbol` linker flag or any similar mechanism,
it is possible to trigger the following:
ERROR: modpost: "param_set_uint.0" [vmlinux] is a static EXPORT_SYMBOL
The reason is that for now the condition from remove_dot():
if (m && (s[n + m] == '.' || s[n + m] == 0))
which was designed to test if it's a dot or a '\0' after the suffix
is never satisfied.
This is due to that `s[n + m]` always points to the last digit of a
numeric suffix, not on the symbol next to it (from a custom debug
print added to modpost):
param_set_uint.0, s[n + m] is '0', s[n + m + 1] is '\0'
So it's off-by-one and was like that since 2014.
Fix this for the sake of any potential upcoming features, but don't
bother stable-backporting, as it's well hidden -- apart from that
LD flag, it can be triggered only with GCC LTO which never landed
upstream.
Fixes: fcd38ed0ff ("scripts: modpost: fix compilation warning")
Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
include/{linux,asm-generic}/export.h defines a weak symbol, __crc_*
as a placeholder.
Genksyms writes the version CRCs into the linker script, which will be
used for filling the __crc_* symbols. The linker script format depends
on CONFIG_MODULE_REL_CRCS. If it is enabled, __crc_* holds the offset
to the reference of CRC.
It is time to get rid of this complexity.
Now that modpost parses text files (.*.cmd) to collect all the CRCs,
it can generate C code that will be linked to the vmlinux or modules.
Generate a new C file, .vmlinux.export.c, which contains the CRCs of
symbols exported by vmlinux. It is compiled and linked to vmlinux in
scripts/link-vmlinux.sh.
Put the CRCs of symbols exported by modules into the existing *.mod.c
files. No additional build step is needed for modules. As before,
*.mod.c are compiled and linked to *.ko in scripts/Makefile.modfinal.
No linker magic is used here. The new C implementation works in the
same way, whether CONFIG_RELOCATABLE is enabled or not.
CONFIG_MODULE_REL_CRCS is no longer needed.
Previously, Kbuild invoked additional $(LD) to update the CRCs in
objects, but this step is unneeded too.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nicolas Schier <nicolas@fjasle.eu>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
Currently, CONFIG_MODVERSIONS needs extra link to embed the symbol
versions into ELF objects. Then, modpost extracts the version CRCs
from them.
The following figures show how it currently works, and how I am trying
to change it.
Current implementation
======================
|----------|
embed CRC -------------------------->| final |
$(CC) $(LD) / |---------| | link for |
-----> *.o -------> *.o -->| modpost | | vmlinux |
/ / | |-- *.mod.c -->| or |
/ genksyms / |---------| | module |
*.c ------> *.symversions |----------|
Genksyms outputs the calculated CRCs in the form of linker script
(*.symversions), which is used by $(LD) to update the object.
If CONFIG_LTO_CLANG=y, the build process is much more complex. Embedding
the CRCs is postponed until the LLVM bitcode is converted into ELF,
creating another intermediate *.prelink.o.
However, this complexity is unneeded. There is no reason why we must
embed version CRCs in objects so early.
There is final link stage for vmlinux (scripts/link-vmlinux.sh) and
modules (scripts/Makefile.modfinal). We can link CRCs at the very last
moment.
New implementation
==================
|----------|
--------------------------------------->| final |
$(CC) / |---------| | link for |
-----> *.o ---->| | | vmlinux |
/ | modpost |--- .vmlinux.export.c -->| or |
/ genksyms | |--- *.mod.c ------------>| module |
*.c ------> *.cmd -->|---------| |----------|
Pass the symbol versions to modpost as separate text data, which are
available in *.cmd files.
This commit changes modpost to extract CRCs from *.cmd files instead of
from ELF objects.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
find_symbol() returns the first symbol found in the hash table. This
table is global, so it may return a symbol from an unexpected module.
There is a case where we want to search for a symbol with a given name
in a specified module.
Add sym_find_with_module(), which receives the module pointer as the
second argument. It is equivalent to find_module() if NULL is passed
as the module pointer.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
There were more EXPORT_SYMBOL types in the past. The following commits
removed unused ones.
- f1c3d73e97 ("module: remove EXPORT_SYMBOL_GPL_FUTURE")
- 367948220f ("module: remove EXPORT_UNUSED_SYMBOL*")
There are 3 remaining in enum export, but export_unknown does not make
any sense because we never expect such a situation like "we do not know
how it was exported".
If the symbol name starts with "__ksymtab_", but the section name
does not start with "___ksymtab+" or "___ksymtab_gpl+", it is not an
exported symbol.
It occurs when a variable starting with "__ksymtab_" is directly defined:
int __ksymtab_foo;
Presumably, there is no practical issue for using such a weird variable
name (but there is no good reason for doing so, either).
Anyway, that is not an exported symbol. Setting export_unknown is not
the right thing to do. Do not call sym_add_exported() in this case.
With pointless export_unknown removed, the export type finally becomes
boolean (either EXPORT_SYMBOL or EXPORT_SYMBOL_GPL).
I renamed the field name to is_gpl_only. EXPORT_SYMBOL_GPL sets it true.
Only GPL-compatible modules can use it.
I removed the orphan comment, "How a symbol is exported", which is
unrelated to sec_mismatch_count. It is about enum export.
See commit bd5cbcedf4 ("kbuild: export-type enhancement to modpost.c")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Nathan Chancellor <nathan@kernel.org>
This is a remnant of commit 6543becf26 ("mod/file2alias: make
modalias generation safe for cross compiling").
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
A later commit will add more code to this list_for_each_entry loop.
Before that, move the loop body into a separate helper function.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Nathan Chancellor <nathan@kernel.org>
add_intree_flag(), add_retpoline(), and add_staging_flag() are small
enough to be merged into add_header().
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Tested-by: Nathan Chancellor <nathan@kernel.org>
new_symbol() does two things; allocate a new symbol and register it
to the hash table.
Using a separate function for each is easier to understand.
Replace new_symbol() with hash_add_symbol(). Remove the second parameter
of alloc_symbol().
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Currently, sym_add_exported() does not allocate a symbol if the same
name symbol already exists in the hash table.
This does not reflect the real use cases. You can let an external
module override the in-tree one. In this case, the external module
will export the same name symbols as the in-tree one. However,
modpost simply ignores those symbols, then Module.symvers for the
external module loses its symbols.
sym_add_exported() should allocate a new symbol.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
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>
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>
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>
Masahiro Yamada
Linus Torvalds
David Gow
Alexander Lobakin