linux-stable.git/include/asm-generic/vmlinux.lds.h, branch v5.4.201

module/ftrace: handle patchable-function-entry

2022-02-23T10:59:56+00:00

commit a1326b17ac03a9012cb3d01e434aacb4d67a416c upstream.

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: Mark Rutland 
Acked-by: Helge Deller 
Acked-by: Steven Rostedt (VMware) 
Reviewed-by: Ard Biesheuvel 
Reviewed-by: Torsten Duwe 
Tested-by: Amit Daniel Kachhap 
Tested-by: Sven Schnelle 
Tested-by: Torsten Duwe 
Cc: Ingo Molnar 
Cc: James E.J. Bottomley 
Cc: Jessica Yu 
Cc: linux-parisc@vger.kernel.org
Cc: Stephen Boyd 
Signed-off-by: Greg Kroah-Hartman

vmlinux.lds.h: Handle clang's module.{c,d}tor sections

2021-08-18T06:57:04+00:00

commit 848378812e40152abe9b9baf58ce2004f76fb988 upstream.

A recent change in LLVM causes module_{c,d}tor sections to appear when
CONFIG_K{A,C}SAN are enabled, which results in orphan section warnings
because these are not handled anywhere:

ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.asan.module_ctor) is being placed in '.text.asan.module_ctor'
ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.asan.module_dtor) is being placed in '.text.asan.module_dtor'
ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.tsan.module_ctor) is being placed in '.text.tsan.module_ctor'

Fangrui explains: "the function asan.module_ctor has the SHF_GNU_RETAIN
flag, so it is in a separate section even with -fno-function-sections
(default)".

Place them in the TEXT_TEXT section so that these technologies continue
to work with the newer compiler versions. All of the KASAN and KCSAN
KUnit tests continue to pass after this change.

Cc: stable@vger.kernel.org
Link: https://github.com/ClangBuiltLinux/linux/issues/1432
Link: https://github.com/llvm/llvm-project/commit/7b789562244ee941b7bf2cefeb3fc08a59a01865
Signed-off-by: Nathan Chancellor 
Reviewed-by: Nick Desaulniers 
Reviewed-by: Fangrui Song 
Acked-by: Marco Elver 
Signed-off-by: Kees Cook 
Link: https://lore.kernel.org/r/20210731023107.1932981-1-nathan@kernel.org
[nc: Resolve conflict due to lack of cf68fffb66d60]
Signed-off-by: Nathan Chancellor 
Signed-off-by: Greg Kroah-Hartman

vmlinux.lds.h: Avoid orphan section with !SMP

2021-06-16T09:59:44+00:00

commit d4c6399900364facd84c9e35ce1540b6046c345f upstream.

With x86_64_defconfig and the following configs, there is an orphan
section warning:

CONFIG_SMP=n
CONFIG_AMD_MEM_ENCRYPT=y
CONFIG_HYPERVISOR_GUEST=y
CONFIG_KVM=y
CONFIG_PARAVIRT=y

ld: warning: orphan section `.data..decrypted' from `arch/x86/kernel/cpu/vmware.o' being placed in section `.data..decrypted'
ld: warning: orphan section `.data..decrypted' from `arch/x86/kernel/kvm.o' being placed in section `.data..decrypted'

These sections are created with DEFINE_PER_CPU_DECRYPTED, which
ultimately turns into __PCPU_ATTRS, which in turn has a section
attribute with a value of PER_CPU_BASE_SECTION + the section name. When
CONFIG_SMP is not set, the base section is .data and that is not
currently handled in any linker script.

Add .data..decrypted to PERCPU_DECRYPTED_SECTION, which is included in
PERCPU_INPUT -> PERCPU_SECTION, which is include in the x86 linker
script when either CONFIG_X86_64 or CONFIG_SMP is unset, taking care of
the warning.

Fixes: ac26963a1175 ("percpu: Introduce DEFINE_PER_CPU_DECRYPTED")
Link: https://github.com/ClangBuiltLinux/linux/issues/1360
Reported-by: kernel test robot 
Signed-off-by: Nathan Chancellor 
Tested-by: Nick Desaulniers  # build
Signed-off-by: Kees Cook 
Link: https://lore.kernel.org/r/20210506001410.1026691-1-nathan@kernel.org
Signed-off-by: Greg Kroah-Hartman

vmlinux.lds.h: add DWARF v5 sections

2021-03-04T09:26:09+00:00

commit 3c4fa46b30c551b1df2fb1574a684f68bc22067c upstream.

We expect toolchains to produce these new debug info sections as part of
DWARF v5. Add explicit placements to prevent the linker warnings from
--orphan-section=warn.

Compilers may produce such sections with explicit -gdwarf-5, or based on
the implicit default version of DWARF when -g is used via DEBUG_INFO.
This implicit default changes over time, and has changed to DWARF v5
with GCC 11.

.debug_sup was mentioned in review, but without compilers producing it
today, let's wait to add it until it becomes necessary.

Cc: stable@vger.kernel.org
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1922707
Reported-by: Chris Murphy 
Suggested-by: Fangrui Song 
Reviewed-by: Nathan Chancellor 
Reviewed-by: Mark Wielaard 
Tested-by: Sedat Dilek 
Signed-off-by: Nick Desaulniers 
Signed-off-by: Masahiro Yamada 
Signed-off-by: Greg Kroah-Hartman

firmware_loader: align .builtin_fw to 8

2021-02-17T09:35:18+00:00

[ Upstream commit 793f49a87aae24e5bcf92ad98d764153fc936570 ]

arm64 references the start address of .builtin_fw (__start_builtin_fw)
with a pair of R_AARCH64_ADR_PREL_PG_HI21/R_AARCH64_LDST64_ABS_LO12_NC
relocations.  The compiler is allowed to emit the
R_AARCH64_LDST64_ABS_LO12_NC relocation because struct builtin_fw in
include/linux/firmware.h is 8-byte aligned.

The R_AARCH64_LDST64_ABS_LO12_NC relocation requires the address to be a
multiple of 8, which may not be the case if .builtin_fw is empty.
Unconditionally align .builtin_fw to fix the linker error.  32-bit
architectures could use ALIGN(4) but that would add unnecessary
complexity, so just use ALIGN(8).

Link: https://lkml.kernel.org/r/20201208054646.2913063-1-maskray@google.com
Link: https://github.com/ClangBuiltLinux/linux/issues/1204
Fixes: 5658c76 ("firmware: allow firmware files to be built into kernel image")
Signed-off-by: Fangrui Song 
Reported-by: kernel test robot 
Acked-by: Arnd Bergmann 
Reviewed-by: Nick Desaulniers 
Tested-by: Nick Desaulniers 
Tested-by: Douglas Anderson 
Acked-by: Nathan Chancellor 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

vmlinux.lds.h: Create section for protection against instrumentation

2021-02-17T09:35:16+00:00

[ Upstream commit 6553896666433e7efec589838b400a2a652b3ffa ]

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: Thomas Gleixner 
Reviewed-by: Alexandre Chartre 
Acked-by: Peter Zijlstra 
Link: https://lkml.kernel.org/r/20200505134100.075416272@linutronix.de
Signed-off-by: Sasha Levin

vmlinux.lds.h: Add PGO and AutoFDO input sections

2021-01-17T13:05:34+00:00

commit eff8728fe69880d3f7983bec3fb6cea4c306261f upstream.

Basically, consider .text.{hot|unlikely|unknown}.* part of .text, too.

When compiling with profiling information (collected via PGO
instrumentations or AutoFDO sampling), Clang will separate code into
.text.hot, .text.unlikely, or .text.unknown sections based on profiling
information. After D79600 (clang-11), these sections will have a
trailing `.` suffix, ie.  .text.hot., .text.unlikely., .text.unknown..

When using -ffunction-sections together with profiling infomation,
either explicitly (FGKASLR) or implicitly (LTO), code may be placed in
sections following the convention:
.text.hot., .text.unlikely., .text.unknown.
where , , and  are functions.  (This produces one section
per function; we generally try to merge these all back via linker script
so that we don't have 50k sections).

For the above cases, we need to teach our linker scripts that such
sections might exist and that we'd explicitly like them grouped
together, otherwise we can wind up with code outside of the
_stext/_etext boundaries that might not be mapped properly for some
architectures, resulting in boot failures.

If the linker script is not told about possible input sections, then
where the section is placed as output is a heuristic-laiden mess that's
non-portable between linkers (ie. BFD and LLD), and has resulted in many
hard to debug bugs.  Kees Cook is working on cleaning this up by adding
--orphan-handling=warn linker flag used in ARCH=powerpc to additional
architectures. In the case of linker scripts, borrowing from the Zen of
Python: explicit is better than implicit.

Also, ld.bfd's internal linker script considers .text.hot AND
.text.hot.* to be part of .text, as well as .text.unlikely and
.text.unlikely.*. I didn't see support for .text.unknown.*, and didn't
see Clang producing such code in our kernel builds, but I see code in
LLVM that can produce such section names if profiling information is
missing. That may point to a larger issue with generating or collecting
profiles, but I would much rather be safe and explicit than have to
debug yet another issue related to orphan section placement.

Reported-by: Jian Cai 
Suggested-by: Fāng-ruì Sòng 
Signed-off-by: Nick Desaulniers 
Signed-off-by: Kees Cook 
Signed-off-by: Ingo Molnar 
Tested-by: Luis Lozano 
Tested-by: Manoj Gupta 
Acked-by: Kees Cook 
Cc: linux-arch@vger.kernel.org
Cc: stable@vger.kernel.org
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=add44f8d5c5c05e08b11e033127a744d61c26aee
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=1de778ed23ce7492c523d5850c6c6dbb34152655
Link: https://reviews.llvm.org/D79600
Link: https://bugs.chromium.org/p/chromium/issues/detail?id=1084760
Link: https://lore.kernel.org/r/20200821194310.3089815-7-keescook@chromium.org

Debugged-by: Luis Lozano 
[nc: Resolve small conflict due to lack of NOINSTR_TEXT]
Signed-off-by: Nathan Chancellor 
Signed-off-by: Greg Kroah-Hartman

bpf: Prevent .BTF section elimination

2020-10-14T08:32:58+00:00

commit 65c204398928f9c79f1a29912b410439f7052635 upstream.

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: 90ceddcb4950 ("bpf: Support llvm-objcopy for vmlinux BTF")
Signed-off-by: Tony Ambardar 
Signed-off-by: Daniel Borkmann 
Acked-by: John Fastabend 
Acked-by: Andrii Nakryiko 
Link: https://lore.kernel.org/bpf/a635b5d3e2da044e7b51ec1315e8910fbce0083f.1600417359.git.Tony.Ambardar@gmail.com
Signed-off-by: Greg Kroah-Hartman

include/asm-generic/vmlinux.lds.h: align ro_after_init

2020-08-19T06:16:25+00:00

commit 7f897acbe5d57995438c831670b7c400e9c0dc00 upstream.

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.html

Signed-off-by: Romain Naour 
Signed-off-by: Andrew Morton 
Cc: Alan Modra 
Cc: Bin Meng 
Cc: Chen Zhou 
Cc: Geert Uytterhoeven 
Cc: John Paul Adrian Glaubitz 
Cc: Krzysztof Kozlowski 
Cc: Kuninori Morimoto 
Cc: Rich Felker 
Cc: Sam Ravnborg 
Cc: Yoshinori Sato 
Cc: Arnd Bergmann 
Cc: 
Link: https://marc.info/?l=linux-sh&m=158429470221261
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

x86, vmlinux.lds: Page-align end of ..page_aligned sections

2020-07-29T08:18:45+00:00

commit de2b41be8fcccb2f5b6c480d35df590476344201 upstream.

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: Joerg Roedel 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Kees Cook 
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20200721093448.10417-1-joro@8bytes.org
Signed-off-by: Greg Kroah-Hartman