Add the 32-bit vdso Makefile to the vdso_install rule so that 'make
vdso_install' installs the 32-bit compat vdso when it is compiled.

Fixes: a7f71a2c ("arm64: compat: Add vDSO")
Signed-off-by: NStephen Boyd <swboyd@chromium.org>
Reviewed-by: NVincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: NWill Deacon <will@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20200818014950.42492-1-swboyd@chromium.orgSigned-off-by: NCatalin Marinas <catalin.marinas@arm.com>

TLBI RANGE feature instoduces new assembly instructions and only
support by binutils >= 2.30.  Add necessary Kconfig logic to allow
this to be enabled and pass '-march=armv8.4-a' to KBUILD_CFLAGS.
Signed-off-by: NZhenyu Ye <yezhenyu2@huawei.com>
Link: https://lore.kernel.org/r/20200715071945.897-3-yezhenyu2@huawei.comSigned-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Since commit 799c4341 ("kbuild: thin archives make default for
all archs"), core-y is passed to the linker with --whole-archive.
Hence, the whole of stub library is linked to vmlinux.

Use libs-y so that lib.a is passed after --no-whole-archive for
conditional linking.

The unused drivers/firmware/efi/libstub/relocate.o will be dropped
for ARCH=arm64.
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20200604022031.164207-1-masahiroy@kernel.orgSigned-off-by: NArd Biesheuvel <ardb@kernel.org>

TEXT_OFFSET was recently changed to 0x0, in preparation for its removal
at a later stage, and a warning is emitted into the kernel log when the
bootloader appears to have failed to take the TEXT_OFFSET image header
value into account.

Ironically, this warning itself fails to take TEXT_OFFSET into account,
and compares the kernel image's alignment modulo 2M against a hardcoded
value of 0x0, and so the warning will trigger spuriously when TEXT_OFFSET
randomization is enabled.

Given the intent to get rid of TEXT_OFFSET entirely, let's fix this
oversight by just removing support for TEXT_OFFSET randomization.
Signed-off-by: NArd Biesheuvel <ardb@kernel.org>
Acked-by: NMark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20200615101939.634391-1-ardb@kernel.orgSigned-off-by: NWill Deacon <will@kernel.org>

Reserve the x18 register from general allocation when SCS is enabled,
because the compiler uses the register to store the current task's
shadow stack pointer. Note that all external kernel modules must also be
compiled with -ffixed-x18 if the kernel has SCS enabled.
Signed-off-by: NSami Tolvanen <samitolvanen@google.com>
Reviewed-by: NNick Desaulniers <ndesaulniers@google.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Acked-by: NWill Deacon <will@kernel.org>
Signed-off-by: NWill Deacon <will@kernel.org>

$(AS) is not used anywhere in the kernel build, hence commit
aa824e0c ("kbuild: remove AS variable") killed it.

Remove the left-over code in arch/{arm,arm64}/Makefile.
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
Reviewed-by: NNathan Chancellor <natechancellor@gmail.com>
Acked-by: NWill Deacon <will@kernel.org>

When running with BTI enabled we need to ask the compiler to enable
generation of BTI landing pads beyond those generated as a result of
pointer authentication instructions being landing pads. Since the two
features are practically speaking unlikely to be used separately we
will make kernel mode BTI depend on pointer authentication in order
to simplify the Makefile.
Signed-off-by: NMark Brown <broonie@kernel.org>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20200506195138.22086-3-broonie@kernel.orgSigned-off-by: NWill Deacon <will@kernel.org>

Document the fact that we enable pointer authentication protection for
leaf functions since there is some narrow potential for ROP protection
benefits and little overhead has been observed.
Signed-off-by: NMark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20200506195138.22086-2-broonie@kernel.orgSigned-off-by: NWill Deacon <will@kernel.org>

TEXT_OFFSET on arm64 is a historical artifact from the early days of
the arm64 port where the boot protocol was basically 'copy this image
to the base of memory + 512k', giving us 512 KB of guaranteed BSS space
to put the swapper page tables. When the arm64 Image header was added in
v3.10, it already carried the actual value of TEXT_OFFSET, to allow the
bootloader to discover it dynamically rather than hardcode it to 512 KB.

Today, this memory window is not used for any particular purpose, and
it is simply handed to the page allocator at boot. The only reason it
still exists is because of the 512k misalignment it causes with respect
to the 2 MB aligned virtual base address of the kernel, which affects
the virtual addresses of all statically allocated objects in the kernel
image.

However, with the introduction of KASLR in v4.6, we added the concept of
relocatable kernels, which rewrite all absolute symbol references at
boot anyway, and so the placement of such kernels in the physical address
space is irrelevant, provided that the minimum segment alignment is
honoured (64 KB in most cases, 128 KB for 64k pages kernels with vmap'ed
stacks enabled). This makes 0x0 and 512 KB equally suitable values for
TEXT_OFFSET on the off chance that we are dealing with boot loaders that
ignore the value passed via the header entirely.

Considering that the distros as well as Android ship KASLR-capable
kernels today, and the fact that TEXT_OFFSET was discoverable from the
Image header from the very beginning, let's change this value to 0x0, in
preparation for removing it entirely at a later date.
Signed-off-by: NArd Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20200415082922.32709-1-ardb@kernel.orgSigned-off-by: NWill Deacon <will@kernel.org>

Drop the definition and export of GZFLAGS, which was never referenced
on arm64, and whose last recorded use in the ARM port (on which arm64
was based original) was removed by patch

  commit 5e89d379edb5ae08b57f39dd8d91697275245cbf [*]
  Author: Russell King <rmk@flint.arm.linux.org.uk>
  Date:   Wed Oct 16 14:32:17 2002 +0100

    [ARM] Convert ARM makefiles to new kbuild (Sam Ravnborg, Kai, rmk)

[*] git commit ID based on Thomas Gleixner's historical GIT repository at
    git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.gitSigned-off-by: NArd Biesheuvel <ardb@kernel.org>
Acked-by: NMark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20200415123049.25504-1-ardb@kernel.orgSigned-off-by: NWill Deacon <will@kernel.org>

Compilers with branch protection support can be configured to enable it by
default, it is likely that distributions will do this as part of deploying
branch protection system wide. As well as the slight overhead from having
some extra NOPs for unused branch protection features this can cause more
serious problems when the kernel is providing pointer authentication to
userspace but not built for pointer authentication itself. In that case our
switching of keys for userspace can affect the kernel unexpectedly, causing
pointer authentication instructions in the kernel to corrupt addresses.

To ensure that we get consistent and reliable behaviour always explicitly
initialise the branch protection mode, ensuring that the kernel is built
the same way regardless of the compiler defaults.

Fixes: 75031975 (arm64: add basic pointer authentication support)
Reported-by: NSzabolcs Nagy <szabolcs.nagy@arm.com>
Signed-off-by: NMark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
[catalin.marinas@arm.com: remove Kconfig option in favour of Makefile check]
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Compile all functions with two ptrauth instructions: PACIASP in the
prologue to sign the return address, and AUTIASP in the epilogue to
authenticate the return address (from the stack). If authentication
fails, the return will cause an instruction abort to be taken, followed
by an oops and killing the task.

This should help protect the kernel against attacks using
return-oriented programming. As ptrauth protects the return address, it
can also serve as a replacement for CONFIG_STACKPROTECTOR, although note
that it does not protect other parts of the stack.

The new instructions are in the HINT encoding space, so on a system
without ptrauth they execute as NOPs.

CONFIG_ARM64_PTR_AUTH now not only enables ptrauth for userspace and KVM
guests, but also automatically builds the kernel with ptrauth
instructions if the compiler supports it. If there is no compiler
support, we do not warn that the kernel was built without ptrauth
instructions.

GCC 7 and 8 support the -msign-return-address option, while GCC 9
deprecates that option and replaces it with -mbranch-protection. Support
both options.

Clang uses an external assembler hence this patch makes sure that the
correct parameters (-march=armv8.3-a) are passed down to help it recognize
the ptrauth instructions.

Ftrace function tracer works properly with Ptrauth only when
patchable-function-entry feature is present and is ensured by the
Kconfig dependency.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: NKees Cook <keescook@chromium.org>
Reviewed-by: Vincenzo Frascino <Vincenzo.Frascino@arm.com> # not co-dev parts
Co-developed-by: NVincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: NVincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com>
[Amit: Cover leaf function, comments, Ftrace Kconfig]
Signed-off-by: NAmit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Use the new 'as-instr' Kconfig macro to define CONFIG_BROKEN_GAS_INST
directly, making it available everywhere.
Signed-off-by: NVladimir Murzin <vladimir.murzin@arm.com>
[will: Drop redundant 'y if' logic]
Signed-off-by: NWill Deacon <will@kernel.org>

As the Kconfig syntax gained support for $(as-instr) tests, move the LSE
gas support detection from Makefile to the main arm64 Kconfig and remove
the additional CONFIG_AS_LSE definition and check.

Cc: Will Deacon <will@kernel.org>
Reviewed-by: NVladimir Murzin <vladimir.murzin@arm.com>
Tested-by: NVladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NWill Deacon <will@kernel.org>

This patch implements FTRACE_WITH_REGS for arm64, which allows a traced
function's arguments (and some other registers) to be captured into a
struct pt_regs, allowing these to be inspected and/or modified. This is
a building block for live-patching, where a function's arguments may be
forwarded to another function. This is also necessary to enable ftrace
and in-kernel pointer authentication at the same time, as it allows the
LR value to be captured and adjusted prior to signing.

Using GCC's -fpatchable-function-entry=N option, we can have the
compiler insert a configurable number of NOPs between the function entry
point and the usual prologue. This also ensures functions are AAPCS
compliant (e.g. disabling inter-procedural register allocation).

For example, with -fpatchable-function-entry=2, GCC 8.1.0 compiles the
following:

| unsigned long bar(void);
|
| unsigned long foo(void)
| {
|         return bar() + 1;
| }

... to:

| <foo>:
|         nop
|         nop
|         stp     x29, x30, [sp, #-16]!
|         mov     x29, sp
|         bl      0 <bar>
|         add     x0, x0, #0x1
|         ldp     x29, x30, [sp], #16
|         ret

This patch builds the kernel with -fpatchable-function-entry=2,
prefixing each function with two NOPs. To trace a function, we replace
these NOPs with a sequence that saves the LR into a GPR, then calls an
ftrace entry assembly function which saves this and other relevant
registers:

| mov	x9, x30
| bl	<ftrace-entry>

Since patchable functions are AAPCS compliant (and the kernel does not
use x18 as a platform register), x9-x18 can be safely clobbered in the
patched sequence and the ftrace entry code.

There are now two ftrace entry functions, ftrace_regs_entry (which saves
all GPRs), and ftrace_entry (which saves the bare minimum). A PLT is
allocated for each within modules.
Signed-off-by: NTorsten Duwe <duwe@suse.de>
[Mark: rework asm, comments, PLTs, initialization, commit message]
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Reviewed-by: NAmit Daniel Kachhap <amit.kachhap@arm.com>
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: NTorsten Duwe <duwe@suse.de>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Julien Thierry <jthierry@redhat.com>
Cc: Will Deacon <will@kernel.org>

CONFIG_COMPAT_VDSO is defined by passing '-DCONFIG_COMPAT_VDSO' to the
compiler when the generic compat vDSO code is in use. It's much cleaner
and simpler to expose this as a proper Kconfig option (like x86 does),
so do that and remove the bodge.
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NWill Deacon <will@kernel.org>

There's no need to export COMPATCC, so just define it locally in the
vdso32/Makefile, which is the only place where it is used.
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NWill Deacon <will@kernel.org>

Rather than force the use of GCC for the compat cross-compiler, instead
extract the target from CROSS_COMPILE_COMPAT and pass it to clang if the
main compiler is clang.
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NWill Deacon <will@kernel.org>

The .config file and the generated include/config/auto.conf can
end up out of sync after a set of commands since
CONFIG_CROSS_COMPILE_COMPAT_VDSO is not updated correctly.

The sequence can be reproduced as follows:

$ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- defconfig
[...]
$ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- menuconfig
[set CONFIG_CROSS_COMPILE_COMPAT_VDSO="arm-linux-gnueabihf-"]
$ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-

Which results in:

arch/arm64/Makefile:62: CROSS_COMPILE_COMPAT not defined or empty,
the compat vDSO will not be built

even though the compat vDSO has been built:

$ file arch/arm64/kernel/vdso32/vdso.so
arch/arm64/kernel/vdso32/vdso.so: ELF 32-bit LSB pie executable, ARM,
EABI5 version 1 (SYSV), dynamically linked,
BuildID[sha1]=c67f6c786f2d2d6f86c71f708595594aa25247f6, stripped

A similar case that involves changing the configuration parameter
multiple times can be reconducted to the same family of problems.

Remove the use of CONFIG_CROSS_COMPILE_COMPAT_VDSO altogether and
instead rely on the cross-compiler prefix coming from the environment
via CROSS_COMPILE_COMPAT, much like we do for the rest of the kernel.

Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: NWill Deacon <will@kernel.org>
Signed-off-by: NVincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: NWill Deacon <will@kernel.org>

The 'K' constraint is a documented AArch64 machine constraint supported
by GCC for matching integer constants that can be used with a 32-bit
logical instruction. Unfortunately, some released compilers erroneously
accept the immediate '4294967295' for this constraint, which is later
refused by GAS at assembly time. This had led us to avoid the use of
the 'K' constraint altogether.

Instead, detect whether the compiler is up to the job when building the
kernel and pass the 'K' constraint to our 32-bit atomic macros when it
appears to be supported.
Signed-off-by: NWill Deacon <will@kernel.org>

Use the standard obj-y form to specify the sub-directories under
arch/arm64/. No functional change intended.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NWill Deacon <will@kernel.org>

Currently, the timestamp of module linker scripts are not checked.
Add them to the dependency of modules so they are correctly rebuilt.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

KASAN_SHADOW_OFFSET is a constant that is supplied to gcc as a command
line argument and affects the codegen of the inline address sanetiser.

Essentially, for an example memory access:
    *ptr1 = val;
The compiler will insert logic similar to the below:
    shadowValue = *(ptr1 >> KASAN_SHADOW_SCALE_SHIFT + KASAN_SHADOW_OFFSET)
    if (somethingWrong(shadowValue))
        flagAnError();

This code sequence is inserted into many places, thus
KASAN_SHADOW_OFFSET is essentially baked into many places in the kernel
text.

If we want to run a single kernel binary with multiple address spaces,
then we need to do this with KASAN_SHADOW_OFFSET fixed.

Thankfully, due to the way the KASAN_SHADOW_OFFSET is used to provide
shadow addresses we know that the end of the shadow region is constant
w.r.t. VA space size:
    KASAN_SHADOW_END = ~0 >> KASAN_SHADOW_SCALE_SHIFT + KASAN_SHADOW_OFFSET

This means that if we increase the size of the VA space, the start of
the KASAN region expands into lower addresses whilst the end of the
KASAN region is fixed.

Currently the arm64 code computes KASAN_SHADOW_OFFSET at build time via
build scripts with the VA size used as a parameter. (There are build
time checks in the C code too to ensure that expected values are being
derived). It is sufficient, and indeed is a simplification, to remove
the build scripts (and build time checks) entirely and instead provide
KASAN_SHADOW_OFFSET values.

This patch removes the logic to compute the KASAN_SHADOW_OFFSET in the
arm64 Makefile, and instead we adopt the approach used by x86 to supply
offset values in kConfig. To help debug/develop future VA space changes,
the Makefile logic has been preserved in a script file in the arm64
Documentation folder.
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NSteve Capper <steve.capper@arm.com>
Signed-off-by: NWill Deacon <will@kernel.org>

In order to allow for a KASAN shadow that changes size at boot time, one
must fix the KASAN_SHADOW_END for both 48 & 52-bit VAs and "grow" the
start address. Also, it is highly desirable to maintain the same
function addresses in the kernel .text between VA sizes. Both of these
requirements necessitate us to flip the kernel address space halves s.t.
the direct linear map occupies the lower addresses.

This patch puts the direct linear map in the lower addresses of the
kernel VA range and everything else in the higher ranges.

We need to adjust:
 *) KASAN shadow region placement logic,
 *) KASAN_SHADOW_OFFSET computation logic,
 *) virt_to_phys, phys_to_virt checks,
 *) page table dumper.

These are all small changes, that need to take place atomically, so they
are bundled into this commit.

As part of the re-arrangement, a guard region of 2MB (to preserve
alignment for fixed map) is added after the vmemmap. Otherwise the
vmemmap could intersect with IS_ERR pointers.
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NSteve Capper <steve.capper@arm.com>
Signed-off-by: NWill Deacon <will@kernel.org>

Using an old .config in combination with "make oldconfig" can cause
an incorrect detection of the compat compiler:

$ grep CROSS_COMPILE_COMPAT .config
CONFIG_CROSS_COMPILE_COMPAT_VDSO=""

$ make oldconfig && make
arch/arm64/Makefile:58: gcc not found, check CROSS_COMPILE_COMPAT.
Stop.

Accordingly to the section 7.2 of the GNU Make manual "Syntax of
Conditionals", "When the value results from complex expansions of
variables and functions, expansions you would consider empty may
actually contain whitespace characters and thus are not seen as
empty. However, you can use the strip function to avoid interpreting
whitespace as a non-empty value."

Fix the issue adding strip to the CROSS_COMPILE_COMPAT string
evaluation.
Reported-by: NMatteo Croce <mcroce@redhat.com>
Tested-by: NMatteo Croce <mcroce@redhat.com>
Acked-by: NWill Deacon <will@kernel.org>
Signed-off-by: NVincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Add vDSO compat support to the arm64 build system.
Signed-off-by: NVincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NShijith Thotton <sthotton@marvell.com>
Tested-by: NAndre Przywara <andre.przywara@arm.com>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Huw Davies <huw@codeweavers.com>
Link: https://lkml.kernel.org/r/20190621095252.32307-16-vincenzo.frascino@arm.com

This is a GCC only option, which warns about ABI changes within GCC, so
unconditionally adding it breaks Clang with tons of:

warning: unknown warning option '-Wno-psabi' [-Wunknown-warning-option]

and link time failures:

ld.lld: error: undefined symbol: __efistub___stack_chk_guard
>>> referenced by arm-stub.c:73
(/home/nathan/cbl/linux/drivers/firmware/efi/libstub/arm-stub.c:73)
>>>               arm-stub.stub.o:(__efistub_install_memreserve_table)
in archive ./drivers/firmware/efi/libstub/lib.a

These failures come from the lack of -fno-stack-protector, which is
added via cc-option in drivers/firmware/efi/libstub/Makefile. When an
unknown flag is added to KBUILD_CFLAGS, clang will noisily warn that it
is ignoring the option like above, unlike gcc, who will just error.

$ echo "int main() { return 0; }" > tmp.c

$ clang -Wno-psabi tmp.c; echo $?
warning: unknown warning option '-Wno-psabi' [-Wunknown-warning-option]
1 warning generated.
0

$ gcc -Wsometimes-uninitialized tmp.c; echo $?
gcc: error: unrecognized command line option
‘-Wsometimes-uninitialized’; did you mean ‘-Wmaybe-uninitialized’?
1

For cc-option to work properly with clang and behave like gcc, -Werror
is needed, which was done in commit c3f0d0bc ("kbuild, LLVMLinux:
Add -Werror to cc-option to support clang").

$ clang -Werror -Wno-psabi tmp.c; echo $?
error: unknown warning option '-Wno-psabi'
[-Werror,-Wunknown-warning-option]
1

As a consequence of this, when an unknown flag is unconditionally added
to KBUILD_CFLAGS, it will cause cc-option to always fail and those flags
will never get added:

$ clang -Werror -Wno-psabi -fno-stack-protector tmp.c; echo $?
error: unknown warning option '-Wno-psabi'
[-Werror,-Wunknown-warning-option]
1

This can be seen when compiling the whole kernel as some warnings that
are normally disabled (see below) show up. The full list of flags
missing from drivers/firmware/efi/libstub are the following (gathered
from diffing .arm64-stub.o.cmd):

-fno-delete-null-pointer-checks
-Wno-address-of-packed-member
-Wframe-larger-than=2048
-Wno-unused-const-variable
-fno-strict-overflow
-fno-merge-all-constants
-fno-stack-check
-Werror=date-time
-Werror=incompatible-pointer-types
-ffreestanding
-fno-stack-protector

Use cc-disable-warning so that it gets disabled for GCC and does nothing
for Clang.

Fixes: ebcc5928 ("arm64: Silence gcc warnings about arch ABI drift")
Link: https://github.com/ClangBuiltLinux/linux/issues/511Reported-by: NQian Cai <cai@lca.pw>
Acked-by: NDave Martin <Dave.Martin@arm.com>
Reviewed-by: NNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: NNathan Chancellor <natechancellor@gmail.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Until recently, if KBUILD_DEFCONFIG was not set by the arch Makefile,
the default path arch/*/defconfig was used.

The last users of the default are gone by the following commits:

- Commit f3e20ad6 ("s390: move arch/s390/defconfig to
  arch/s390/configs/defconfig")

- Commit 986a1376 ("alpha: move arch/alpha/defconfig to
  arch/alpha/configs/defconfig")

Let's set arch/*/configs/defconfig as a new default. This saves
KBUILD_DEFCONFIG for some architectures.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>

Since GCC 9, the compiler warns about evolution of the
platform-specific ABI, in particular relating for the marshaling of
certain structures involving bitfields.

The kernel is a standalone binary, and of course nobody would be
so stupid as to expose structs containing bitfields as function
arguments in ABI.  (Passing a pointer to such a struct, however
inadvisable, should be unaffected by this change.  perf and various
drivers rely on that.)

So these warnings do more harm than good: turn them off.

We may miss warnings about future ABI drift, but that's too bad.
Future ABI breaks of this class will have to be debugged and fixed
the traditional way unless the compiler evolves finer-grained
diagnostics.
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Tag-based KASAN uses 1 shadow byte for 16 bytes of kernel memory, so it
requires 1/16th of the kernel virtual address space for the shadow memory.

This commit sets KASAN_SHADOW_SCALE_SHIFT to 4 when the tag-based KASAN
mode is enabled.

Link: http://lkml.kernel.org/r/308b6bd49f756bb5e533be93c6f085ba99b30339.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This enables the use of per-task stack canary values if GCC has
support for emitting the stack canary reference relative to the
value of sp_el0, which holds the task struct pointer in the arm64
kernel.

The $(eval) extends KBUILD_CFLAGS at the moment the make rule is
applied, which means asm-offsets.o (which we rely on for the offset
value) is built without the arguments, and everything built afterwards
has the options set.
Reviewed-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

readelf complains about the section layout of vmlinux when building
with CONFIG_RELOCATABLE=y (for KASLR):

  readelf: Warning: [21]: Link field (0) should index a symtab section.
  readelf: Warning: [21]: Info field (0) should index a relocatable section.

Also, it seems that our use of '-pie -shared' is contradictory, and
thus ambiguous. In general, the way KASLR is wired up at the moment
is highly tailored to how ld.bfd happens to implement (and conflate)
PIE executables and shared libraries, so given the current effort to
support other toolchains, let's fix some of these issues as well.

- Drop the -pie linker argument and just leave -shared. In ld.bfd,
  the differences between them are unclear (except for the ELF type
  of the produced image [0]) but lld chokes on seeing both at the
  same time.

- Rename the .rela output section to .rela.dyn, as is customary for
  shared libraries and PIE executables, so that it is not misidentified
  by readelf as a static relocation section (producing the warnings
  above).

- Pass the -z notext and -z norelro options to explicitly instruct the
  linker to permit text relocations, and to omit the RELRO program
  header (which requires a certain section layout that we don't adhere
  to in the kernel). These are the defaults for current versions of
  ld.bfd.

- Discard .eh_frame and .gnu.hash sections to avoid them from being
  emitted between .head.text and .text, screwing up the section layout.

These changes only affect the ELF image, and produce the same binary
image.

[0] b9dce7f1 ("arm64: kernel: force ET_DYN ELF type for ...")

Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Smith <peter.smith@linaro.org>
Tested-by: NNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

After 'a66649da arm64: fix vdso-offsets.h dependency' if
one will try to build .i file in case of external kernel module,
build fails complaining that prepare0 target is missing. This
issue came up with SystemTap when it tries to build variety
of .i files for its own generated kernel modules trying to
figure given kernel features/capabilities.

The issue is that prepare0 is defined in top level Makefile
only if KBUILD_EXTMOD is not defined. .i file rule depends
on prepare and in case KBUILD_EXTMOD defined top level Makefile
contains empty rule for prepare. But after mentioned commit
arch/arm64/Makefile would introduce dependency on prepare0
through its own prepare target.

Fix it to put proper ifdef KBUILD_EXTMOD around code introduced
by mentioned commit. It matches what top level Makefile does.
Acked-by: NKevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: NVictor Kamensky <kamensky@cisco.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

There is nothing arch specific about building dtb files other than their
location under /arch/*/boot/dts/. Keeping each arch aligned is a pain.
The dependencies and supported targets are all slightly different.
Also, a cross-compiler for each arch is needed, but really the host
compiler preprocessor is perfectly fine for building dtbs. Move the
build rules to a common location and remove the arch specific ones. This
is done in a single step to avoid warnings about overriding rules.

The build dependencies had been a mixture of 'scripts' and/or 'prepare'.
These pull in several dependencies some of which need a target compiler
(specifically devicetable-offsets.h) and aren't needed to build dtbs.
All that is really needed is dtc, so adjust the dependencies to only be
dtc.

This change enables support 'dtbs_install' on some arches which were
missing the target.
Acked-by: NWill Deacon <will.deacon@arm.com>
Acked-by: NPaul Burton <paul.burton@mips.com>
Acked-by: NLey Foon Tan <ley.foon.tan@intel.com>
Acked-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: linux-kbuild@vger.kernel.org
Cc: linux-snps-arc@lists.infradead.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: uclinux-h8-devel@lists.sourceforge.jp
Cc: linux-mips@linux-mips.org
Cc: nios2-dev@lists.rocketboards.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-xtensa@linux-xtensa.org
Signed-off-by: NRob Herring <robh@kernel.org>

Commit a0f97e06 ("kbuild: enable 'make CFLAGS=...' to add
additional options to CC") renamed CFLAGS to KBUILD_CFLAGS.

Commit 222d394d ("kbuild: enable 'make AFLAGS=...' to add
additional options to AS") renamed AFLAGS to KBUILD_AFLAGS.

Commit 06c5040c ("kbuild: enable 'make CPPFLAGS=...' to add
additional options to CPP") renamed CPPFLAGS to KBUILD_CPPFLAGS.

For some reason, LDFLAGS was not renamed.

Using a well-known variable like LDFLAGS may result in accidental
override of the variable.

Kbuild generally uses KBUILD_ prefixed variables for the internally
appended options, so here is one more conversion to sanitize the
naming convention.

I did not touch Makefiles under tools/ since the tools build system
is a different world.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: NPalmer Dabbelt <palmer@sifive.com>

Not all toolchains have the baremetal elf targets, RedHat/Fedora ones
in particular. So, probe for whether it's available and use the previous
(linux) targets if it isn't.
Reported-by: NLaura Abbott <labbott@redhat.com>
Tested-by: NLaura Abbott <labbott@redhat.com>
Acked-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Cc: Paul Kocialkowski <contact@paulk.fr>
Signed-off-by: NOlof Johansson <olof@lixom.net>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

This reverts commit 38fc4248.

Distributions such as Fedora and Debian do not package the ELF linker
scripts with their toolchains, resulting in kernel build failures such
as:

  |   CHK     include/generated/compile.h
  |   LD [M]  arch/arm64/crypto/sha512-ce.o
  | aarch64-linux-gnu-ld: cannot open linker script file ldscripts/aarch64elf.xr: No such file or directory
  | make[1]: *** [scripts/Makefile.build:530: arch/arm64/crypto/sha512-ce.o] Error 1
  | make: *** [Makefile:1029: arch/arm64/crypto] Error 2

Revert back to the linux targets for now, adding a comment to the Makefile
so we don't accidentally break this in the future.

Cc: Paul Kocialkowski <contact@paulk.fr>
Cc: <stable@vger.kernel.org>
Fixes: 38fc4248 ("arm64: Use aarch64elf and aarch64elfb emulation mode variants")
Tested-by: NKevin Hilman <khilman@baylibre.com>
Signed-off-by: NLaura Abbott <labbott@redhat.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Linking the ARM64 defconfig kernel with LLVM lld fails with the error:

  ld.lld: error: unknown argument: -p
  Makefile:1015: recipe for target 'vmlinux' failed

Without this flag, the ARM64 defconfig kernel successfully links with
lld and boots on Dragonboard 410c.

After digging through binutils source and changelogs, it turns out that
-p is only relevant to ancient binutils installations targeting 32-bit
ARM.  binutils accepts -p for AArch64 too, but it's always been
undocumented and silently ignored.  A comment in
ld/emultempl/aarch64elf.em explains that it's "Only here for backwards
compatibility".

Since this flag is a no-op on ARM64, we can safely drop it.
Acked-by: NWill Deacon <will.deacon@arm.com>
Reviewed-by: NNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: NGreg Hackmann <ghackmann@google.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

With the recent syntax extension, Kconfig is now able to evaluate the
compiler / toolchain capability.

However, accumulating flags to 'LD' is not compatible with the way
it works; 'LD' must be passed to Kconfig to call $(ld-option,...)
from Kconfig files.  If you tweak 'LD' in arch Makefile depending on
CONFIG_CPU_BIG_ENDIAN, this would end up with circular dependency
between Makefile and Kconfig.
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

The aarch64linux and aarch64linuxb emulation modes are not supported by
bare-metal toolchains and Linux using them forbids building the kernel
with these toolchains.

Since there is apparently no reason to target these emulation modes, the
more generic elf modes are used instead, allowing to build on bare-metal
toolchains as well as the already-supported ones.

Fixes: 3d6a7b99 ("arm64: ensure the kernel is compiled for LP64")

Cc: stable@vger.kernel.org
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NPaul Kocialkowski <contact@paulk.fr>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>