This add the kbuild infrastructure that will allow architectures to emit
vmlinux symbol CRCs as 32-bit offsets to another location in the kernel
where the actual value is stored. This works around problems with CRCs
being mistaken for relocatable symbols on kernels that self relocate at
runtime (i.e., powerpc with CONFIG_RELOCATABLE=y)

For the kbuild side of things, this comes down to the following:

 - introducing a Kconfig symbol MODULE_REL_CRCS

 - adding a -R switch to genksyms to instruct it to emit the CRC symbols
   as references into the .rodata section

 - making modpost distinguish such references from absolute CRC symbols
   by the section index (SHN_ABS)

 - making kallsyms disregard non-absolute symbols with a __crc_ prefix
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This catches the failing ceph CRC on with:

    LD      vmlinux.o
    MODPOST vmlinux.o
  WARNING: EXPORT symbol "ceph_monc_do_statfs" [vmlinux] version
  generation failed, symbol will not be versioned.

When the modules referring to exported symbols are built, there is an
existing warning for missing CRC, but it's not always the case such
any such module will be built, and in any case it is useful to get a
warning at the source.

This gets a little verbose with CONFIG_DEBUG_SECTION_MISMATCH,
producing a warning with each object linked, but I didn't think
that warranted extra complexity to avoid.
Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NMichal Marek <mmarek@suse.com>

valgrind complains that memory is not freed after allocation
with realloc() called from main() and write_dump().

So let us free the allocated memory properly.
Signed-off-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Link: http://lkml.kernel.org/r/1470166981-6461-1-git-send-email-xypron.glpk@gmx.deSigned-off-by: NJessica Yu <jeyu@redhat.com>

When doing an nmi backtrace of many cores, most of which are idle, the
output is a little overwhelming and very uninformative.  Suppress
messages for cpus that are idling when they are interrupted and just
emit one line, "NMI backtrace for N skipped: idling at pc 0xNNN".

We do this by grouping all the cpuidle code together into a new
.cpuidle.text section, and then checking the address of the interrupted
PC to see if it lies within that section.

This commit suitably tags x86 and tile idle routines, and only adds in
the minimal framework for other architectures.

Link: http://lkml.kernel.org/r/1472487169-14923-5-git-send-email-cmetcalf@mellanox.comSigned-off-by: NChris Metcalf <cmetcalf@mellanox.com>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org> [arm]
Tested-by: NPetr Mladek <pmladek@suse.com>
Cc: Aaron Tomlin <atomlin@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

PowerPC64 uses the symbol .TOC. much as other targets use
_GLOBAL_OFFSET_TABLE_. It identifies the value of the GOT pointer (or in
powerpc parlance, the TOC pointer). Global offset tables are generally
local to an executable or shared library, or in the kernel, module. Thus
it does not make sense for a module to resolve a relocation against
.TOC. to the kernel's .TOC. value. A module has its own .TOC., and
indeed the powerpc64 module relocation processing ignores the kernel
value of .TOC. and instead calculates a module-local value.

This patch removes code involved in exporting the kernel .TOC., tweaks
modpost to ignore an undefined .TOC., and the module loader to twiddle
the section symbol so that .TOC. isn't seen as undefined.

Note that if the kernel was compiled with -msingle-pic-base then ELFv2
would not have function global entry code setting up r2. In that case
the module call stubs would need to be modified to set up r2 using the
kernel .TOC. value, requiring some of this code to be reinstated.

mpe: Furthermore a change in binutils master (not yet released) causes
the current way we handle the TOC to no longer work when building with
MODVERSIONS=y and RELOCATABLE=n. The symptom is that modules can not be
loaded due to there being no version found for TOC.

Cc: stable@vger.kernel.org # 3.16+
Signed-off-by: NAlan Modra <amodra@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

In our ARC toolchain the default linker script includes special
sections used for code and data located in special fast memory.
To avoid warnings we add these sections i.e. .cmem* and .fmt_slot*
to white list.
Signed-off-by: NNoam Camus <noamc@ezchip.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

The section mismatch warning can be easy to miss during the kernel build
process. Allow it to be marked as fatal to be easily caught and prevent
bugs from slipping in.

Setting CONFIG_SECTION_MISMATCH_WARN_ONLY=y causes these warnings to be
non-fatal, since there are a number of section mismatches when using
allmodconfig on some architectures, and we do not want to break these
builds by default.
Signed-off-by: NNicolas Boichat <drinkcat@chromium.org>
Change-Id: Ic346706e3297c9f0d790e3552aa94e5cff9897a6
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Module symbols have a limited length, but currently the build system
allows the build finishing even if the driver code contains a too long
symbol name, which eventually overflows the modversion_info[] item.
The compiler may catch at compiling *.mod.c like
  CC      xxx.mod.o
  xxx.mod.c:18:16: warning: initializer-string for array of chars is too long
but it's merely a warning.

This patch adds the check of the symbol length in modpost and stops
the build properly.

Currently MODULE_NAME_LEN is defined in modpost.c instead of referring
to the definition in kernel header because including linux/module.h is
messy and we must cover cross-compilation.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

The tilegx and tilepro compilers use .coldtext for their unlikely
executed text section name, so an __attribute__((cold)) function
will (when compiled with higher optimization levels) land in
the .coldtext section.

Modify modpost to add .coldtext to the set of OTHER_TEXT_SECTIONS
so we don't get warnings about referencing such a section in an
__ex_table block, and then also modify arch/tile/lib/memcpy_user_64.c
so that it uses plain ".coldtext" instead of ".coldtext.memcpy".
The latter naming is a relic of an earlier use of -ffunction-sections,
which we no longer use by default.
Signed-off-by: NChris Metcalf <cmetcalf@ezchip.com>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>

Currently an allyesconfig build [gcc-4.9.1] can generate the following:

   WARNING: vmlinux.o(.text.unlikely+0x3864): Section mismatch in
   reference from the function cpumask_empty.constprop.3() to the
   variable .init.data:nmi_ipi_mask

which comes from the cpumask_empty usage in arch/x86/kernel/nmi_selftest.c.

Normally we would not see a symbol entry for cpumask_empty since it is:

	static inline bool cpumask_empty(const struct cpumask *srcp)

however in this case, the variant of the symbol gets emitted when GCC does
constant propagation optimization.

Fix things up so that any locally optimized constprop variants don't warn
when accessing variables that live in the __init sections.
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Currently the match() function supports a leading * to match any
prefix and a trailing * to match any suffix.  However there currently
is not a combination of both that can be used to target matches of
whole families of functions that share a common substring.

Here we expand the *foo and foo* match to also support *foo* with
the goal of targeting compiler generated symbol names that contain
strings like ".constprop." and ".isra."
Signed-off-by: NPaul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Trying to match the SHT_NUL section isn't useful and causes build failures
on parisc and mn10300 since the addition of section strict white-listing
and __ex_table sanitizing.
Signed-off-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Reported-by: NGuenter Roeck <linux@roeck-us.net>
Fixes: 050e57fd ("modpost: add strict white-listing when referencing....")
Fixes: 52dc0595 ("modpost: handle relocations mismatch in __ex_table.")
Tested-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

As Guenter pointed out, we were never really calculating the extable entry
size because the pointer arithmetic was simply wrong.  We want to check
we're handling the second relocation in __ex_table to infer an entry size,
but we were using (void*) pointers instead of Elf_Rel[a]* ones.

This fixes the problem by moving that check in the caller (since we can
deal with different types of relocations) and add is_second_extable_reloc()
to make the whole thing more readable.
Signed-off-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Reported-by: NGuenter Roeck <linux@roeck-us.net>
CC: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

As Guenter pointed out, we want to assert that extable_entry_size has been
discovered and not the other way around.  Moreover, this sanity check is
only valid when we're not dealing with the first relocation in __ex_table,
since we have not discovered the extable entry size at that point.

This was leading to a divide-by-zero on some architectures and make the
build fail.
Signed-off-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Reported-by: NGuenter Roeck <linux@roeck-us.net>
CC: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

52dc0595 introduced OTHER_TEXT_SECTIONS for identifying what
sections could validly have __ex_table entries.  Unfortunately, it
wasn't tested with -ffunction-sections, which some architectures
use.
Reported-by: Nkbuild test robot <fengguang.wu@intel.com>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

32-bit and 64-bit ARM use these sections to store executable code, so
they must be whitelisted in modpost's table of valid text sections.
Signed-off-by: NThierry Reding <treding@nvidia.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

struct section_check is used as a generic way of describing what
relocations are authorized/forbidden when running modpost.  This commit
tries to describe how each field is used.
Signed-off-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (Fixed "mist"ake)

__ex_table is a simple table section where each entry is a pair of
addresses - the first address is an address which can fault in kernel
space, and the second address points to where the kernel should jump to
when handling that fault.  This is how copy_from_user() does not crash the
kernel if userspace gives a borked pointer for example.

If one of these addresses point to a non-executable section, something is
seriously wrong since it either means the kernel will never fault from
there or it will not be able to jump to there.  As both cases are serious
enough, we simply error out in these cases so the build fails and the
developper has to fix the issue.

In case the section is executable, but it isn't referenced in our list of
authorized sections to point to from __ex_table, we just dump a warning
giving more information about it.  We do this in case the new section is
executable but isn't supposed to be executed by the kernel.  This happened
with .altinstr_replacement, which is executable but is only used to copy
instructions from - we should never have our instruction pointer pointing
in .altinstr_replacement.  Admitedly, a proper fix in that case would be to
just set .altinstr_replacement NX, but we need to warn about future cases
like this.
Signed-off-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (added long casts)

Signed-off-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Signed-off-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

This will be useful when we want to have special handlers which need to go
through more hops to print useful information to the user.
Signed-off-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

sched.text and .kprobes.text should behave exactly like .text with regards
to how we should warn about referencing sections which might get discarded
at runtime.
Signed-off-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Prints a warning when a section references a section outside a strict
white-list.  This will be useful to print a warning if __ex_table
references a non-executable section.
Signed-off-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Similar to ARM, AArch64 is generating $x and $d syms... which isn't
terribly helpful when looking at %pF output and the like. Filter those
out in kallsyms, modpost and when looking at module symbols.

Seems simplest since none of these check EM_ARM anyway, to just add it
to the strchr used, rather than trying to make things overly
complicated.

initcall_debug improves:
dmesg_before.txt: initcall $x+0x0/0x154 [sg] returned 0 after 26331 usecs
dmesg_after.txt: initcall init_sg+0x0/0x154 [sg] returned 0 after 15461 usecs
Signed-off-by: NKyle McMartin <kyle@redhat.com>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Avoid the variable length array (vla), just use PATH_MAX instead.
This not only makes this code clang friedly, it also leads to a
code size reduction:

   text    data     bss     dec     hex filename
  51765    2224   12416   66405   10365 scripts/mod/modpost.old
  51677    2224   12416   66317   1030d scripts/mod/modpost.new
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Internally used symbols of modpost don't need to be externally visible;
make them static. Also constify the string arrays so they resist in the
r/o section instead of being runtime writable.

Those changes lead to a small size reduction as can be seen below:

   text    data     bss     dec     hex filename
  51381    2640   12416   66437   10385 scripts/mod/modpost.old
  51765    2224   12416   66405   10365 scripts/mod/modpost.new
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

For several years, the pattern "foo$" has effectively been treated as
equivalent to "foo" due to a bug in the (misnamed) helper
number_prefix(). This hasn't been observed to cause any problems, so
remove the broken $ functionality and change all foo$ patterns to foo.
Signed-off-by: NRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

The scripts/mod/modpost.c triggers the following warning:

scripts/mod/modpost.c: In function ‘remove_dot’:
scripts/mod/modpost.c:1710:10: warning: ignoring return value of ‘strtoul’, declared with attribute warn_unused_result [-Wunused-result]

The remove_dot function that calls strtoul does not care about the
numeric value of the string that is parsed but only looks for the
end of the numeric sequence.  As such, it's equivalent to just skip
over all digits.
Signed-off-by: NMichal Nazarewicz <mina86@mina86.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Signed-off-by: NMasahiro Yamada <yamada.m@jp.panasonic.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

Signed-off-by: NPaul Bolle <pebolle@tiscali.nl>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Function read_dump() memory maps the input via grab_file(), but fails to call
the corresponding unmap function. Add the missing call to release_file().
Detected by Coverity: CID 1192419
Signed-off-by: NChristian Engelmayer <cengelma@gmx.at>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Add processing for normally encountered thumb relocation types so that
section mismatches will be detected.

Comment from Rusty Russell follows:

Happiest for this to go through an ARM tree, so:
Signed-off-by: NDavid A. Long <dave.long@linaro.org>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

- Don't warn about LTO marker symbols. modpost runs before
the linker, so the module is not necessarily LTOed yet.
- Don't complain about .gnu.lto* sections
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1391846481-31491-13-git-send-email-ak@linux.intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

LTO turns all global symbols effectively into statics. This
has the side effect that they all have a .NUMBER postfix to make
them unique. In modpost drop this postfix because it confuses
it.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1391846481-31491-8-git-send-email-ak@linux.intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

This reference is discarded, but can cause warnings when it refers to
exit. Ignore for now.

This is a workaround and can be removed once we get rid of
-fno-toplevel-reorder
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1391846481-31491-7-git-send-email-ak@linux.intel.comSigned-off-by: NH. Peter Anvin <hpa@linux.intel.com>

GCC 4.8 now generates out-of-line vr save/restore functions when
optimizing for size.  They are needed for the raid6 altivec support.
Signed-off-by: NAndreas Schwab <schwab@linux-m68k.org>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

For some reason I managed to trick gcc into create CRC symbols that are
not absolute anymore, but weak.

Make modpost handle this case.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Andi's change in e0f244c6 ("asmlinkage, module: Make ksymtab and
kcrctab symbols and __this_module __visible") make the crc appear
first in the symbol table.

modpost creates an entry when it sees the CRC, then when it sees the
actual symbol, it complains that it's seen it before.  The preloaded
flag already exists for the equivalent case where we loaded from
Module.symvers, so use that.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Tested-by: The Awesome Power Of linux-next
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Make the ksymtab symbols for EXPORT_SYMBOL visible.
This prevents the LTO compiler from adding a .NUMBER prefix,
which avoids various problems in later export processing.

Cc: rusty@rustcorp.com.au
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Commit ea4054a2 (modpost: handle huge numbers of modules) added
support for building a large number of modules.

Unfortunately, the commit changed the semantics of the makefile: Instead of
passing only existing object files to modpost, make now passes all expected
object files. If make was started with option -i, this results in a modpost
error if a single file failed to build.

Example with the current btrfs build falure on m68k:

fs/btrfs/btrfs.o: No such file or directory
make[1]: [__modpost] Error 1 (ignored)

This error is followed by lots of errors such as:

m68k-linux-gcc: error: arch/m68k/emu/nfcon.mod.c: No such file or directory
m68k-linux-gcc: fatal error: no input files
compilation terminated.
make[1]: [arch/m68k/emu/nfcon.mod.o] Error 1 (ignored)

This doesn't matter much for normal builds, but it is annoying for builds
started with "make -i" due to the large number of secondary errors.
Those errors unnececessarily clog any error log and make it difficult
to find the real errors in the build.

Fix the problem by adding a new parameter '-n' to modpost. If this parameter
is specified, modpost reports but ignores missing object files.

With this patch, error output from above problem is (with make -i):

m68k-linux-ld: cannot find fs/btrfs/ioctl.o: No such file or directory
make[2]: [fs/btrfs/btrfs.o] Error 1 (ignored)
...
fs/btrfs/btrfs.o: No such file or directory (ignored)

Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Michael Marek <mmarek@suse.cz>
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>