Systems with memory or disk constraints often reduce the kernel footprint
by configuring LD_DEAD_CODE_DATA_ELIMINATION. However, this can result in
removal of any BTF information.

Use the KEEP() macro to preserve the BTF data as done with other important
sections, while still allowing for smaller kernels.

Fixes: 90ceddcb ("bpf: Support llvm-objcopy for vmlinux BTF")
Signed-off-by: NTony Ambardar <Tony.Ambardar@gmail.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/a635b5d3e2da044e7b51ec1315e8910fbce0083f.1600417359.git.Tony.Ambardar@gmail.com

Since the patch [1], building the kernel using a toolchain built with
binutils 2.33.1 prevents booting a sh4 system under Qemu.  Apply the patch
provided by Alan Modra [2] that fix alignment of rodata.

[1] https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=ebd2263ba9a9124d93bbc0ece63d7e0fae89b40e
[2] https://www.sourceware.org/ml/binutils/2019-12/msg00112.htmlSigned-off-by: NRomain Naour <romain.naour@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Alan Modra <amodra@gmail.com>
Cc: Bin Meng <bin.meng@windriver.com>
Cc: Chen Zhou <chenzhou10@huawei.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Rich Felker <dalias@libc.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: <stable@vger.kernel.org>
Link: https://marc.info/?l=linux-sh&m=158429470221261Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

dyndbg populates its callsite info into __verbose section, change that
to a more specific and descriptive name, __dyndbg.

Also, per checkpatch:
  simplify __attribute(..) to __section(__dyndbg) declaration.

and 1 spelling fix, decriptor

Acked-by: <jbaron@akamai.com>
Signed-off-by: NJim Cromie <jim.cromie@gmail.com>
Link: https://lore.kernel.org/r/20200719231058.1586423-6-jim.cromie@gmail.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

On x86-32 the idt_table with 256 entries needs only 2048 bytes. It is
page-aligned, but the end of the .bss..page_aligned section is not
guaranteed to be page-aligned.

As a result, objects from other .bss sections may end up on the same 4k
page as the idt_table, and will accidentially get mapped read-only during
boot, causing unexpected page-faults when the kernel writes to them.

This could be worked around by making the objects in the page aligned
sections page sized, but that's wrong.

Explicit sections which store only page aligned objects have an implicit
guarantee that the object is alone in the page in which it is placed. That
works for all objects except the last one. That's inconsistent.

Enforcing page sized objects for these sections would wreckage memory
sanitizers, because the object becomes artificially larger than it should
be and out of bound access becomes legit.

Align the end of the .bss..page_aligned and .data..page_aligned section on
page-size so all objects places in these sections are guaranteed to have
their own page.

[ tglx: Amended changelog ]
Signed-off-by: NJoerg Roedel <jroedel@suse.de>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NKees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20200721093448.10417-1-joro@8bytes.org

Adding support to generate .BTF_ids section that will hold BTF
ID lists for verifier.

Adding macros that will help to define lists of BTF ID values
placed in .BTF_ids section. They are initially filled with zeros
(during compilation) and resolved later during the linking phase
by resolve_btfids tool.

Following defines list of one BTF ID value:

  BTF_ID_LIST(bpf_skb_output_btf_ids)
  BTF_ID(struct, sk_buff)

It also defines following variable to access the list:

  extern u32 bpf_skb_output_btf_ids[];

The BTF_ID_UNUSED macro defines 4 zero bytes. It's used when we
want to define 'unused' entry in BTF_ID_LIST, like:

  BTF_ID_LIST(bpf_skb_output_btf_ids)
  BTF_ID(struct, sk_buff)
  BTF_ID_UNUSED
  BTF_ID(struct, task_struct)
Suggested-by: NAndrii Nakryiko <andriin@fb.com>
Signed-off-by: NJiri Olsa <jolsa@kernel.org>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Tested-by: NAndrii Nakryiko <andriin@fb.com>
Acked-by: NAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200711215329.41165-4-jolsa@kernel.org

For some mysterious reason GCC-4.9 has a 64 byte section alignment for
structures, all other GCC versions (and Clang) tested (including 4.8
and 5.0) are fine with the 32 bytes alignment.

Getting this right is important for the new SCHED_DATA macro that
creates an explicitly ordered array of 'struct sched_class' in the
linker script and expect pointer arithmetic to work.

Fixes: c3a340f7 ("sched: Have sched_class_highest define by vmlinux.lds.h")
Reported-by: Nkernel test robot <lkp@intel.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200630144905.GX4817@hirez.programming.kicks-ass.net

Now that the sched_class descriptors are defined by the linker script, and
this needs to be aware of the existance of stop_sched_class when SMP is
enabled or not, as it is used as the "highest" priority when defined. Move
the declaration of sched_class_highest to the same location in the linker
script that inserts stop_sched_class, and this will also make it easier to
see what should be defined as the highest class, as this linker script
location defines the priorities as well.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20191219214558.682913590@goodmis.org

In order to make a micro optimization in pick_next_task(), the order of the
sched class descriptor address must be in the same order as their priority
to each other. That is:

 &idle_sched_class < &fair_sched_class < &rt_sched_class <
 &dl_sched_class < &stop_sched_class

In order to guarantee this order of the sched class descriptors, add each
one into their own data section and force the order in the linker script.
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/157675913272.349305.8936736338884044103.stgit@localhost.localdomain

Some code pathes, especially the low level entry code, must be protected
against instrumentation for various reasons:

 - Low level entry code can be a fragile beast, especially on x86.

 - With NO_HZ_FULL RCU state needs to be established before using it.

Having a dedicated section for such code allows to validate with tooling
that no unsafe functions are invoked.

Add the .noinstr.text section and the noinstr attribute to mark
functions. noinstr implies notrace. Kprobes will gain a section check
later.

Provide also a set of markers: instrumentation_begin()/end()

These are used to mark code inside a noinstr function which calls
into regular instrumentable text section as safe.

The instrumentation markers are only active when CONFIG_DEBUG_ENTRY is
enabled as the end marker emits a NOP to prevent the compiler from merging
the annotation points. This means the objtool verification requires a
kernel compiled with this option.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NAlexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200505134100.075416272@linutronix.de

In the x86 kernel, .exit.text and .exit.data sections are discarded at
runtime, not by the linker. Add RUNTIME_DISCARD_EXIT to generic DISCARDS
and define it in the x86 kernel linker script to keep them.

The sections are added before the DISCARD directive so document here
only the situation explicitly as this change doesn't have any effect on
the generated kernel. Also, other architectures like ARM64 will use it
too so generalize the approach with the RUNTIME_DISCARD_EXIT define.

 [ bp: Massage and extend commit message. ]
Signed-off-by: NH.J. Lu <hjl.tools@gmail.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NKees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200326193021.255002-1-hjl.tools@gmail.com

Simplify gen_btf logic to make it work with llvm-objcopy. The existing
'file format' and 'architecture' parsing logic is brittle and does not
work with llvm-objcopy/llvm-objdump.

'file format' output of llvm-objdump>=11 will match GNU objdump, but
'architecture' (bfdarch) may not.

.BTF in .tmp_vmlinux.btf is non-SHF_ALLOC. Add the SHF_ALLOC flag
because it is part of vmlinux image used for introspection. C code
can reference the section via linker script defined __start_BTF and
__stop_BTF. This fixes a small problem that previous .BTF had the
SHF_WRITE flag (objcopy -I binary -O elf* synthesized .data).

Additionally, `objcopy -I binary` synthesized symbols
_binary__btf_vmlinux_bin_start and _binary__btf_vmlinux_bin_stop (not
used elsewhere) are replaced with more commonplace __start_BTF and
__stop_BTF.

Add 2>/dev/null because GNU objcopy (but not llvm-objcopy) warns
"empty loadable segment detected at vaddr=0xffffffff81000000, is this intentional?"

We use a dd command to change the e_type field in the ELF header from
ET_EXEC to ET_REL so that lld will accept .btf.vmlinux.bin.o.  Accepting
ET_EXEC as an input file is an extremely rare GNU ld feature that lld
does not intend to support, because this is error-prone.

The output section description .BTF in include/asm-generic/vmlinux.lds.h
avoids potential subtle orphan section placement issues and suppresses
--orphan-handling=warn warnings.

Fixes: df786c9b ("bpf: Force .BTF section start to zero when dumping from vmlinux")
Fixes: cb0cc635 ("powerpc: Include .BTF section")
Reported-by: NNathan Chancellor <natechancellor@gmail.com>
Signed-off-by: NFangrui Song <maskray@google.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Tested-by: NStanislav Fomichev <sdf@google.com>
Tested-by: NAndrii Nakryiko <andriin@fb.com>
Reviewed-by: NStanislav Fomichev <sdf@google.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Acked-by: NAndrii Nakryiko <andriin@fb.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Link: https://github.com/ClangBuiltLinux/linux/issues/871
Link: https://lore.kernel.org/bpf/20200318222746.173648-1-maskray@google.com

The ftrace_graph_stub was created and points to ftrace_stub as a way to
assign the functon graph tracer function pointer to a stub function with a
different prototype than what ftrace_stub has and not trigger the C
verifier. The ftrace_graph_stub was created via the linker script
vmlinux.lds.h. Unfortunately, powerpc already uses the name
ftrace_graph_stub for its internal implementation of the function graph
tracer, and even though powerpc would still build, the change via the linker
script broke function tracer on powerpc from working.

By using the name ftrace_stub_graph, which does not exist anywhere else in
the kernel, this should not be a problem.

Link: https://lore.kernel.org/r/1573849732.5937.136.camel@lca.pw

Fixes: b83b43ff ("fgraph: Fix function type mismatches of ftrace_graph_return using ftrace_stub")
Reorted-by: NQian Cai <cai@lca.pw>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

The C compiler is allowing more checks to make sure that function pointers
are assigned to the correct prototype function. Unfortunately, the function
graph tracer uses a special name with its assigned ftrace_graph_return
function pointer that maps to a stub function used by the function tracer
(ftrace_stub). The ftrace_graph_return variable is compared to the
ftrace_stub in some archs to know if the function graph tracer is enabled or
not. This means we can not just simply create a new function stub that
compares it without modifying all the archs.

Instead, have the linker script create a function_graph_stub that maps to
ftrace_stub, and this way we can define the prototype for it to match the
prototype of ftrace_graph_return, and make the compiler checks all happy!

Link: http://lkml.kernel.org/r/20191015090055.789a0aed@gandalf.local.home

Cc: linux-sh@vger.kernel.org
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc:  Rich Felker <dalias@libc.org>
Reported-by: NSami Tolvanen <samitolvanen@google.com>
Signed-off-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>

When using patchable-function-entry, the compiler will record the
callsites into a section named "__patchable_function_entries" rather
than "__mcount_loc". Let's abstract this difference behind a new
FTRACE_CALLSITE_SECTION, so that architectures don't have to handle this
explicitly (e.g. with custom module linker scripts).

As parisc currently handles this explicitly, it is fixed up accordingly,
with its custom linker script removed. Since FTRACE_CALLSITE_SECTION is
only defined when DYNAMIC_FTRACE is selected, the parisc module loading
code is updated to only use the definition in that case. When
DYNAMIC_FTRACE is not selected, modules shouldn't have this section, so
this removes some redundant work in that case.

To make sure that this is keep up-to-date for modules and the main
kernel, a comment is added to vmlinux.lds.h, with the existing ifdeffery
simplified for legibility.

I built parisc generic-{32,64}bit_defconfig with DYNAMIC_FTRACE enabled,
and verified that the section made it into the .ko files for modules.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Acked-by: NHelge Deller <deller@gmx.de>
Acked-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: NTorsten Duwe <duwe@suse.de>
Tested-by: NAmit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: NSven Schnelle <svens@stackframe.org>
Tested-by: NTorsten Duwe <duwe@suse.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: linux-parisc@vger.kernel.org

Many architectures have an EXCEPTION_TABLE that needs to be only
readable. As such, it should live in RO_DATA. Create a macro to identify
this case for the architectures that can move EXCEPTION_TABLE into
RO_DATA.
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Acked-by: NWill Deacon <will@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: x86-ml <x86@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: https://lkml.kernel.org/r/20191029211351.13243-15-keescook@chromium.org

Rename RW_DATA_SECTION to RW_DATA. (Calling this a "section" is a lie,
since it's multiple sections and section flags cannot be applied to
the macro.)
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> # s390
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Will Deacon <will@kernel.org>
Cc: x86-ml <x86@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: https://lkml.kernel.org/r/20191029211351.13243-14-keescook@chromium.org

Finish renaming RO_DATA_SECTION to RO_DATA. (Calling this a "section"
is a lie, since it's multiple sections and section flags cannot be
applied to the macro.)
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> # s390
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Will Deacon <will@kernel.org>
Cc: x86-ml <x86@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: https://lkml.kernel.org/r/20191029211351.13243-13-keescook@chromium.org

There's no reason to keep the RODATA macro: replace the callers with
the expected RO_DATA macro.
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Will Deacon <will@kernel.org>
Cc: x86-ml <x86@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: https://lkml.kernel.org/r/20191029211351.13243-12-keescook@chromium.org

The .notes section should be non-executable read-only data. As such,
move it to the RO_DATA macro instead of being per-architecture defined.
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> # s390
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Will Deacon <will@kernel.org>
Cc: x86-ml <x86@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: https://lkml.kernel.org/r/20191029211351.13243-11-keescook@chromium.org

In preparation for moving NOTES into RO_DATA, make the Program Header
assignment restoration be part of the NOTES macro itself.
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> # s390
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Will Deacon <will@kernel.org>
Cc: x86-ml <x86@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: https://lkml.kernel.org/r/20191029211351.13243-10-keescook@chromium.org

In preparation for moving NOTES into RO_DATA, provide a mechanism for
architectures that want to emit a PT_NOTE Program Header to do so.
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> # s390
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-alpha@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-c6x-dev@linux-c6x.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-s390@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Will Deacon <will@kernel.org>
Cc: x86-ml <x86@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: https://lkml.kernel.org/r/20191029211351.13243-9-keescook@chromium.org

The lockdown module is intended to allow for kernels to be locked down
early in boot - sufficiently early that we don't have the ability to
kmalloc() yet. Add support for early initialisation of some LSMs, and
then add them to the list of names when we do full initialisation later.
Early LSMs are initialised in link order and cannot be overridden via
boot parameters, and cannot make use of kmalloc() (since the allocator
isn't initialised yet).

(Fixed by Stephen Rothwell to include a stub to fix builds when
!CONFIG_SECURITY)
Signed-off-by: NMatthew Garrett <mjg59@google.com>
Acked-by: NKees Cook <keescook@chromium.org>
Acked-by: NCasey Schaufler <casey@schaufler-ca.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NJames Morris <jmorris@namei.org>

Currently the governors are declared in their respective files but they
export their [un]register functions which in turn call the [un]register
governors core's functions. That implies a cyclic dependency which is
not desirable. There is a way to self-encapsulate the governors by letting
them to declare themselves in a __init section table.

Define the table in the asm generic linker description like the other
tables and provide the specific macros to deal with.
Reviewed-by: NAmit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: NZhang Rui <rui.zhang@intel.com>

This patch implements dynamic ftrace for PA-RISC. The required mcount
call sequences can get pretty long, so instead of patching the
whole call sequence out of the functions, we are using
-fpatchable-function-entry from gcc. This puts a configurable amount of
NOPS before/at the start of the function. Taking do_sys_open() as example,
which would look like this when the call is patched out:

1036b248:       08 00 02 40     nop
1036b24c:       08 00 02 40     nop
1036b250:       08 00 02 40     nop
1036b254:       08 00 02 40     nop

1036b258 <do_sys_open>:
1036b258:       08 00 02 40     nop
1036b25c:       08 03 02 41     copy r3,r1
1036b260:       6b c2 3f d9     stw rp,-14(sp)
1036b264:       08 1e 02 43     copy sp,r3
1036b268:       6f c1 01 00     stw,ma r1,80(sp)

When ftrace gets enabled for this function the kernel will patch these
NOPs to:

1036b248:       10 19 57 20     <address of ftrace>
1036b24c:       6f c1 00 80     stw,ma r1,40(sp)
1036b250:       48 21 3f d1     ldw -18(r1),r1
1036b254:       e8 20 c0 02     bv,n r0(r1)

1036b258 <do_sys_open>:
1036b258:       e8 3f 1f df     b,l,n .-c,r1
1036b25c:       08 03 02 41     copy r3,r1
1036b260:       6b c2 3f d9     stw rp,-14(sp)
1036b264:       08 1e 02 43     copy sp,r3
1036b268:       6f c1 01 00     stw,ma r1,80(sp)

So the first NOP in do_sys_open() will be patched to jump backwards into
some minimal trampoline code which pushes a stackframe, saves r1 which
holds the return address, loads the address of the real ftrace function,
and branches to that location. For 64 Bit things are getting a bit more
complicated (and longer) because we must make sure that the address of
ftrace location is 8 byte aligned, and the offset passed to ldd for
fetching the address is 8 byte aligned as well.

Note that gcc has a bug which misplaces the function label, and needs a
patch to make dynamic ftrace work. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90751 for details.
Signed-off-by: NSven Schnelle <svens@stackframe.org>
Signed-off-by: NHelge Deller <deller@gmx.de>

The SRCU for modules optimization (commit title "srcu: Allocate per-CPU
data for DEFINE_SRCU() in modules") introduced vmlinux linker entries
which is unused since it applies only to the built-in vmlinux. So remove
it to prevent any space usage due to the 8 byte alignment it added.
vmlinux.lds.h has no effect on module loading and is not used for
building the module object, so the changes were not needed in the first
place since the optimization is specific to modules.

Tested with SRCU torture_type and rcutorture. Put prints in module
loader to confirm it is able to find and initialize the srcu structures.

Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: kernel-team@android.com
Cc: paulmck@linux.vnet.ibm.com
Signed-off-by: NJoel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: NPaul E. McKenney <paulmck@linux.ibm.com>

Adding DEFINE_SRCU() or DEFINE_STATIC_SRCU() to a loadable module requires
that the size of the reserved region be increased, which is not something
we want to be doing all that often.  One approach would be to require
that loadable modules define an srcu_struct and invoke init_srcu_struct()
from their module_init function and cleanup_srcu_struct() from their
module_exit function.  However, this is more than a bit user unfriendly.

This commit therefore creates an ___srcu_struct_ptrs linker section,
and pointers to srcu_struct structures created by DEFINE_SRCU() and
DEFINE_STATIC_SRCU() within a module are placed into that module's
___srcu_struct_ptrs section.  The required init_srcu_struct() and
cleanup_srcu_struct() functions are then automatically invoked as needed
when that module is loaded and unloaded, thus allowing modules to continue
to use DEFINE_SRCU() and DEFINE_STATIC_SRCU() while avoiding the need
to increase the size of the reserved region.

Many of the algorithms and some of the code was cheerfully cherry-picked
from other code making use of linker sections, perhaps most notably from
tracepoints.  All bugs are nevertheless the sole property of the author.
Suggested-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
[ paulmck: Use __section() and use "default" in srcu_module_notify()'s
  "switch" statement as suggested by Joel Fernandes. ]
Signed-off-by: NPaul E. McKenney <paulmck@linux.ibm.com>
Tested-by: NJoel Fernandes (Google) <joel@joelfernandes.org>

Problem:

When a kernel module is compiled as a separate module, some important
information about the kernel module is available via .modinfo section of
the module.  In contrast, when the kernel module is compiled into the
kernel, that information is not available.

Information about built-in modules is necessary in the following cases:

1. When it is necessary to find out what additional parameters can be
passed to the kernel at boot time.

2. When you need to know which module names and their aliases are in
the kernel. This is very useful for creating an initrd image.

Proposal:

The proposed patch does not remove .modinfo section with module
information from the vmlinux at the build time and saves it into a
separate file after kernel linking. So, the kernel does not increase in
size and no additional information remains in it. Information is stored
in the same format as in the separate modules (null-terminated string
array). Because the .modinfo section is already exported with a separate
modules, we are not creating a new API.

It can be easily read in the userspace:

$ tr '\0' '\n' < modules.builtin.modinfo
ext4.softdep=pre: crc32c
ext4.license=GPL
ext4.description=Fourth Extended Filesystem
ext4.author=Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others
ext4.alias=fs-ext4
ext4.alias=ext3
ext4.alias=fs-ext3
ext4.alias=ext2
ext4.alias=fs-ext2
md_mod.alias=block-major-9-*
md_mod.alias=md
md_mod.description=MD RAID framework
md_mod.license=GPL
md_mod.parmtype=create_on_open:bool
md_mod.parmtype=start_dirty_degraded:int
...
Co-Developed-by: NGleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Signed-off-by: NGleb Fotengauer-Malinovskiy <glebfm@altlinux.org>
Signed-off-by: NAlexey Gladkov <gladkov.alexey@gmail.com>
Acked-by: NJessica Yu <jeyu@kernel.org>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

The reference to '__vermagic' is a relict from v2.5 times. And even
there it had a very short life time, from v2.5.59 (commit 1d411b80ee18
("Module Sanity Check") in the historic tree) to v2.5.69 (commit
67ac5b866bda ("[PATCH] complete modinfo section")).

Neither current kernels nor modules contain a '__vermagic' section any
more, so get rid of it.
Signed-off-by: NMathias Krause <minipli@googlemail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jessica Yu <jeyu@kernel.org>
Signed-off-by: NJessica Yu <jeyu@kernel.org>

The .orc_unwind section is a packed array of 6-byte structs.  It's
currently aligned to 6 bytes, which is causing warnings in the LLD
linker.

Six isn't a power of two, so it's not a valid alignment value.  The
actual alignment doesn't matter much because it's an array of packed
structs.  An alignment of two is sufficient.  In reality it always gets
aligned to four bytes because it comes immediately after the
4-byte-aligned .orc_unwind_ip section.

Fixes: ee9f8fce ("x86/unwind: Add the ORC unwinder")
Reported-by: NNick Desaulniers <ndesaulniers@google.com>
Reported-by: NDmitry Golovin <dima@golovin.in>
Reported-by: NSedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NSedat Dilek <sedat.dilek@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://github.com/ClangBuiltLinux/linux/issues/218
Link: https://lkml.kernel.org/r/d55027ee95fe73e952dcd8be90aebd31b0095c45.1551892041.git.jpoimboe@redhat.com

Enabling both CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y and
CONFIG_GCOV_PROFILE_ALL=y results in linker warnings:

  warning: orphan section `.data..LPBX1' being placed in
  section `.data..LPBX1'.

LD_DEAD_CODE_DATA_ELIMINATION adds compiler flag -fdata-sections. This
option causes GCC to create separate data sections for data objects,
including those generated by GCC internally for gcov profiling. The
names of these objects start with a dot (.LPBX0, .LPBX1), resulting in
section names starting with 'data..'.

As section names starting with 'data..' are used for specific purposes
in the Linux kernel, the linker script does not automatically include
them in the output data section, resulting in the "orphan section"
linker warnings.

Fix this by specifically including sections named "data..LPBX*" in the
data section.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Tested-by: NStephen Rothwell <sfr@canb.auug.org.au>
Tested-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NPeter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>

Enabling CONFIG_GCOV_PROFILE_ALL=y causes linker errors on ARM:

  `.text.exit' referenced in section `.ARM.exidx.text.exit':
  defined in discarded section `.text.exit'

  `.text.exit' referenced in section `.fini_array.00100':
  defined in discarded section `.text.exit'

And related errors on NDS32:

  `.text.exit' referenced in section `.dtors.65435':
  defined in discarded section `.text.exit'

The gcov compiler flags cause certain compiler versions to generate
additional destructor-related sections that are not yet handled by the
linker script, resulting in references between discarded and
non-discarded sections.

Since destructors are not used in the Linux kernel, fix this by
discarding these additional sections.
Reported-by: NArnd Bergmann <arnd@arndb.de>
Tested-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Reported-by: NGreentime Hu <green.hu@gmail.com>
Tested-by: NMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: NPeter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>

Since the struct lsm_info table is not an initcall, we can just move it
into INIT_DATA like all the other tables.
Signed-off-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NCasey Schaufler <casey@schaufler-ca.com>
Reviewed-by: NJohn Johansen <john.johansen@canonical.com>
Reviewed-by: NJames Morris <james.morris@microsoft.com>
Signed-off-by: NJames Morris <james.morris@microsoft.com>

In preparation for switching from initcall to just a regular set of
pointers in a section, rename the internal section name.
Signed-off-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NCasey Schaufler <casey@schaufler-ca.com>
Reviewed-by: NJames Morris <james.morris@microsoft.com>
Reviewed-by: NJohn Johansen <john.johansen@canonical.com>
Signed-off-by: NJames Morris <james.morris@microsoft.com>

Avoid copy/paste by defining SECURITY_INIT in terms of SECURITY_INITCALL.
Signed-off-by: NKees Cook <keescook@chromium.org>
Reviewed-by: NCasey Schaufler <casey@schaufler-ca.com>
Reviewed-by: NJames Morris <james.morris@microsoft.com>
Reviewed-by: NJohn Johansen <john.johansen@canonical.com>
Signed-off-by: NJames Morris <james.morris@microsoft.com>

The __jump_table sections emitted into the core kernel and into
each module consist of statically initialized references into
other parts of the code, and with the exception of entries that
point into init code, which are defused at post-init time, these
data structures are never modified.

So let's move them into the ro_after_init section, to prevent them
from being corrupted inadvertently by buggy code, or deliberately
by an attacker.
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NKees Cook <keescook@chromium.org>
Acked-by: NJessica Yu <jeyu@kernel.org>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Link: https://lkml.kernel.org/r/20180919065144.25010-9-ard.biesheuvel@linaro.org

This is unneeded since commit a6214385 ("vmlinux.lds.h: remove
no-op macro VMLINUX_SYMBOL()").
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Now that we use the driver core to stop deferred probe for missing
drivers, IOMMU_OF_DECLARE can be removed.

This is slightly less optimal than having a list of built-in drivers in
that we'll now defer probe twice before giving up. This shouldn't have a
significant impact on boot times as past discussions about deferred
probe have given no evidence of deferred probe having a substantial
impact.

Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Kukjin Kim <kgene@kernel.org>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Heiko Stuebner <heiko@sntech.de>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: iommu@lists.linux-foundation.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: linux-arm-msm@vger.kernel.org
Cc: linux-rockchip@lists.infradead.org
Cc: devicetree@vger.kernel.org
Acked-by: NWill Deacon <will.deacon@arm.com>
Acked-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Acked-by: NJoerg Roedel <jroedel@suse.de>
Signed-off-by: NRob Herring <robh@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

KEEP more tables, and add the function/data section wildcard to more
section selections.

This is a little ad-hoc at the moment, but kernel code should be moved
to consistently use .text..x (note: double dots) for explicit sections
and all references to it in the linker script can be made with
TEXT_MAIN, and similarly for other sections.

For now, let's see if major architectures move to enabling this option
then we can do some refactoring passes. Otherwise if it remains unused
or superseded by LTO, this may not be required.
Signed-off-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

Now that VMLINUX_SYMBOL() is no-op, clean up the linker script.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NSam Ravnborg <sam@ravnborg.org>

Commit 99492c39 ("earlycon: Fix __earlycon_table stride") tried to fix
__earlycon_table stride by forcing the earlycon_id struct alignment to 32
and asking the linker to 32-byte align the __earlycon_table symbol.  This
fix was based on commit 07fca0e5 ("tracing: Properly align linker
defined symbols") which tried a similar fix for the tracing subsystem.

However, this fix doesn't quite work because there is no guarantee that
gcc will place structures packed into an array format.  In fact, gcc 4.9
chooses to 64-byte align these structs by inserting additional padding
between the entries because it has no clue that they are supposed to be in
an array.  If we are unlucky, the linker will assign symbol
"__earlycon_table" to a 32-byte aligned address which does not correspond
to the 64-byte aligned contents of section "__earlycon_table".

To address this same problem, the fix to the tracing system was
subsequently re-implemented using a more robust table of pointers approach
by commits:
 3d56e331 ("tracing: Replace syscall_meta_data struct array with pointer array")
 65498646 ("tracepoints: Fix section alignment using pointer array")
 e4a9ea5e ("tracing: Replace trace_event struct array with pointer array")

Let's use this same "array of pointers to structs" approach for
EARLYCON_TABLE.

Fixes: 99492c39 ("earlycon: Fix __earlycon_table stride")
Signed-off-by: NDaniel Kurtz <djkurtz@chromium.org>
Suggested-by: NAaron Durbin <adurbin@chromium.org>
Reviewed-by: NRob Herring <robh@kernel.org>
Tested-by: NGuenter Roeck <groeck@chromium.org>
Reviewed-by: NGuenter Roeck <groeck@chromium.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>