arm64: insn: Add encoders for LDRSB/LDRSH/LDRSW

To support BPF sign-extend load instructions, add encoders for
LDRSB/LDRSH/LDRSW.

LDRSB/LDRSH/LDRSW (immediate) is encoded as follows:

3 2 2 2 2 1 0 0
0 7 6 4 2 0 5 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sz|1 1 1|0|0 1|opc| imm12 | Rn | Rt |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

LDRSB/LDRSH/LDRSW (register) is encoded as follows:

3 2 2 2 2 2 1 1 1 1 0 0
0 7 6 4 2 1 6 3 2 0 5 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sz|1 1 1|0|0 0|opc|1| Rm | opt |S|1 0| Rn | Rt |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

where:

- sz
indicates whether 8-bit, 16-bit or 32-bit data is to be loaded

- opc
opc[1] (bit 23) is always 1 and opc[0] == 1 indicates regsize
is 32-bit. Since BPF signed load instructions always exend the
sign bit to bit 63 regardless of whether it loads an 8-bit,
16-bit or 32-bit data. So only 64-bit register size is required.
That is, it's sufficient to set field opc fixed to 0x2.

- opt
Indicates whether to sign extend the offset register Rm and the
effective bits of Rm. We set opt to 0x7 (SXTX) since we'll use
Rm as a sgined 64-bit value in BPF.

- S
Optional only when opt field is 0x3 (LSL)

In short, the above fields are encoded to the values listed below.

sz opc opt S
LDRSB (immediate) 0x0 0x2 na na
LDRSH (immediate) 0x1 0x2 na na
LDRSW (immediate) 0x2 0x2 na na
LDRSB (register) 0x0 0x2 0x7 0
LDRSH (register) 0x1 0x2 0x7 0
LDRSW (register) 0x2 0x2 0x7 0

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Florent Revest <revest@chromium.org>
Acked-by: Florent Revest <revest@chromium.org>
Link: https://lore.kernel.org/bpf/20230815154158.717901-2-xukuohai@huaweicloud.com

arm64: insn: Add helpers for BTI

In subsequent patches we'd like to check whether an instruction is a
BTI. In preparation for this, add basic instruction helpers for BTI
instructions.

Per ARM DDI 0487H.a section C6.2.41, BTI is encoded in binary as
follows, MSB to LSB:

1101 0101 000 0011 0010 0100 xx01 1111

Where the `xx` bits encode J/C/JC:

00 : (omitted)
01 : C
10 : J
11 : JC

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230123134603.1064407-6-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arm64: insn: always inline hint generation

All users of aarch64_insn_gen_hint() (e.g. aarch64_insn_gen_nop()) pass
a constant argument and generate a constant value. Some of those users
are noinstr code (e.g. for alternatives patching).

For noinstr code it is necessary to either inline these functions or to
ensure the out-of-line versions are noinstr.

Since in all cases these are generating a constant, make them
__always_inline.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Link: https://lore.kernel.org/r/20221114135928.3000571-5-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

arm64: insn: simplify insn group identification

The only code which needs to check for an entire instruction group is
the aarch64_insn_is_steppable() helper function used by kprobes, which
must not be instrumented, and only needs to check for the "Branch,
exception generation and system instructions" class.

Currently we have an out-of-line helper in insn.c which must be marked
as __kprobes, which indexes a table with some bits extracted from the
instruction. In aarch64_insn_is_steppable() we then need to compare the
result with an expected enum value.

It would be simpler to have a predicate for this, as with the other
aarch64_insn_is_*() helpers, which would be always inlined to prevent
inadvertent instrumentation, and would permit better code generation.

This patch adds a predicate function for this instruction group using
the existing __AARCH64_INSN_FUNCS() helpers, and removes the existing
out-of-line helper. As the only class we currently care about is the
branch+exception+sys class, I have only added helpers for this, and left
the other classes unimplemented for now.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Link: https://lore.kernel.org/r/20221114135928.3000571-4-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

arm64: insn: always inline predicates

We have a number of aarch64_insn_*() predicates which are used in code
which is not instrumentation safe (e.g. alternatives patching, kprobes).
Some of those are marked with __kprobes, but most are not, and are
implemented out-of-line in insn.c.

This patch moves the predicates to insn.h and marks them with
__always_inline. This is ensures that they will respect the
instrumentation requirements of their caller which they will be inlined
into.

At the same time, I've formatted each of the functions consistently as a
list, to make them easier to read and update in future.

Other than preventing unwanted instrumentation, there should be no
functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Link: https://lore.kernel.org/r/20221114135928.3000571-3-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

arm64: insn: remove aarch64_insn_gen_prefetch()

There are no users of aarch64_insn_gen_prefetch(), and which encodes a
PRFM (immediate) with a hard-coded offset of 0.

Remove it for now; we can always restore it with tests if we need it in
future.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Link: https://lore.kernel.org/r/20221114135928.3000571-2-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

arm64: Add LDR (literal) instruction

Add LDR (literal) instruction to load data from address relative to PC.
This instruction will be used to implement long jump from bpf prog to
bpf trampoline in the follow-up patch.

The instruction encoding:

3 2 2 2 0 0
0 7 6 4 5 0
+-----+-------+---+-----+-------------------------------------+--------+
| 0 x | 0 1 1 | 0 | 0 0 | imm19 | Rt |
+-----+-------+---+-----+-------------------------------------+--------+

for 32-bit, variant x == 0; for 64-bit, x == 1.

branch_imm_common() is used to check the distance between pc and target
address, since it's reused by this patch and LDR (literal) is not a branch
instruction, rename it to label_imm_common().

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/bpf/20220711150823.2128542-3-xukuohai@huawei.com

arm64, insn: Add ldr/str with immediate offset

This patch introduces ldr/str with immediate offset support to simplify
the JIT implementation of BPF LDX/STX instructions on arm64. Although
arm64 ldr/str immediate is available in pre-index, post-index and
unsigned offset forms, the unsigned offset form is sufficient for BPF,
so this patch only adds this type.

Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220321152852.2334294-2-xukuohai@huawei.com

arm64: insn: add encoders for atomic operations

It is a preparation patch for eBPF atomic supports under arm64. eBPF
needs support atomic[64]_fetch_add, atomic[64]_[fetch_]{and,or,xor} and
atomic[64]_{xchg|cmpxchg}. The ordering semantics of eBPF atomics are
the same with the implementations in linux kernel.

Add three helpers to support LDCLR/LDEOR/LDSET/SWP, CAS and DMB
instructions. STADD/STCLR/STEOR/STSET are simply encoded as aliases for
LDADD/LDCLR/LDEOR/LDSET with XZR as the destination register, so no extra
helper is added. atomic_fetch_add() and other atomic ops needs support for
STLXR instruction, so extend enum aarch64_insn_ldst_type to do that.

LDADD/LDEOR/LDSET/SWP and CAS instructions are only available when LSE
atomics is enabled, so just return AARCH64_BREAK_FAULT directly in
these newly-added helpers if CONFIG_ARM64_LSE_ATOMICS is disabled.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20220217072232.1186625-3-houtao1@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>

arm64: Use the clearbhb instruction in mitigations

Future CPUs may implement a clearbhb instruction that is sufficient
to mitigate SpectreBHB. CPUs that implement this instruction, but
not CSV2.3 must be affected by Spectre-BHB.

Add support to use this instruction as the BHB mitigation on CPUs
that support it. The instruction is in the hint space, so it will
be treated by a NOP as older CPUs.

Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>

arm64: insn: avoid circular include dependency

Nathan reports that when building with CONFIG_LTO_CLANG_THIN=y, the
build fails due to BUILD_BUG_ON() not being defined before its uss in
<asm/insn.h>.

The problem is that with LTO, we patch READ_ONCE(), and <asm/rwonce.h>
includes <asm/insn.h>, creating a circular include chain:

<linux/build_bug.h>
<linux/compiler.h>
<asm/rwonce.h>
<asm/alternative-macros.h>
<asm/insn.h>
<linux/build-bug.h>

... and so when <asm/insn.h> includes <linux/build_bug.h>, none of the
BUILD_BUG* definitions have happened yet.

To avoid this, let's move AARCH64_INSN_SIZE into a header without any
dependencies, such that it can always be safely included. At the same
time, avoid including <asm/alternative.h> in <asm/insn.h>, which should
no longer be necessary (and doesn't make sense when insn.h is consumed
by userspace).

Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210621080830.GA37068@C02TD0UTHF1T.local
Fixes: 3e00e39d9dad ("arm64: insn: move AARCH64_INSN_SIZE into <asm/insn.h>")
Signed-off-by: Will Deacon <will@kernel.org>

arm64: insn: move AARCH64_INSN_SIZE into <asm/insn.h>

For histroical reasons, we define AARCH64_INSN_SIZE in
<asm/alternative-macros.h>, but it would make more sense to do so in
<asm/insn.h>. Let's move it into <asm/insn.h>, and add the necessary
include directives for this.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210609102301.17332-3-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

arm64: insn: decouple patching from insn code

Currently, <asm/insn.h> includes <asm/patching.h>. We intend that
<asm/insn.h> will be usable from userspace, so it doesn't make sense to
include headers for kernel-only features such as the patching routines,
and we'd intended to restrict <asm/insn.h> to instruction encoding
details.

Let's decouple the patching code from <asm/insn.h>, and explicitly
include <asm/patching.h> where it is needed. Since <asm/patching.h>
isn't included from assembly, we can drop the __ASSEMBLY__ guards.

At the same time, sort the kprobes includes so that it's easier to see
what is and isn't incldued.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210609102301.17332-2-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

arm64: insn: Add load/store decoding helpers

Provide some function to group different load/store instructions.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Link: https://lore.kernel.org/r/20210303170536.1838032-9-jthierry@redhat.com
Signed-off-by: Will Deacon <will@kernel.org>

arm64: insn: Add some opcodes to instruction decoder

Add decoding capability for some instructions that objtool will need
to decode.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Link: https://lore.kernel.org/r/20210303170536.1838032-8-jthierry@redhat.com
Signed-off-by: Will Deacon <will@kernel.org>

arm64: insn: Add barrier encodings

Create necessary functions to encode/decode aarch64 barrier
instructions.

DSB needs special case handling as it has multiple encodings.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Link: https://lore.kernel.org/r/20210303170536.1838032-7-jthierry@redhat.com
[will: Don't reject DSB #4]
Signed-off-by: Will Deacon <will@kernel.org>

arm64: insn: Add SVE instruction class

SVE has been public for some time now. Let the decoder acknowledge
its existence.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Link: https://lore.kernel.org/r/20210303170536.1838032-6-jthierry@redhat.com
Signed-off-by: Will Deacon <will@kernel.org>

arm64: Move aarch32 condition check functions

The functions to check condition flags for aarch32 execution is only
used to emulate aarch32 instructions. Move them from the instruction
encoding/decoding code to the trap handling files.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Link: https://lore.kernel.org/r/20210303170536.1838032-3-jthierry@redhat.com
[will: leave aarch32_opcode_cond_checks where it is]
Signed-off-by: Will Deacon <will@kernel.org>

Signed-off-by: Will Deacon <will@kernel.org>

arm64: Move patching utilities out of instruction encoding/decoding

Files insn.[c|h] containt some functions used for instruction patching.
In order to reuse the instruction encoder/decoder, move the patching
utilities to their own file.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Link: https://lore.kernel.org/r/20210303170536.1838032-2-jthierry@redhat.com
[will: Include patching.h in insn.h to fix header mess; add __ASSEMBLY__ guards]
Signed-off-by: Will Deacon <will@kernel.org>

Signed-off-by: Will Deacon <will@kernel.org>

arm64: alternatives: Split up alternative.h

asm/alternative.h contains both the macros needed to use alternatives,
as well the type definitions and function prototypes for applying them.

Split the header in two, so that alternatives can be used from core
header files such as linux/compiler.h without the risk of circular
includes

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

arm64: kprobe: add checks for ARMv8.3-PAuth combined instructions

Currently the ARMv8.3-PAuth combined branch instructions (braa, retaa
etc.) are not simulated for out-of-line execution with a handler. Hence the
uprobe of such instructions leads to kernel warnings in a loop as they are
not explicitly checked and fall into INSN_GOOD categories. Other combined
instructions like LDRAA and LDRBB can be probed.

The issue of the combined branch instructions is fixed by adding
group definitions of all such instructions and rejecting their probes.
The instruction groups added are br_auth(braa, brab, braaz and brabz),
blr_auth(blraa, blrab, blraaz and blrabz), ret_auth(retaa and retab) and
eret_auth(eretaa and eretab).

Warning log:
WARNING: CPU: 0 PID: 156 at arch/arm64/kernel/probes/uprobes.c:182 uprobe_single_step_handler+0x34/0x50
Modules linked in:
CPU: 0 PID: 156 Comm: func Not tainted 5.9.0-rc3 #188
Hardware name: Foundation-v8A (DT)
pstate: 804003c9 (Nzcv DAIF +PAN -UAO BTYPE=--)
pc : uprobe_single_step_handler+0x34/0x50
lr : single_step_handler+0x70/0xf8
sp : ffff800012af3e30
x29: ffff800012af3e30 x28: ffff000878723b00
x27: 0000000000000000 x26: 0000000000000000
x25: 0000000000000000 x24: 0000000000000000
x23: 0000000060001000 x22: 00000000cb000022
x21: ffff800012065ce8 x20: ffff800012af3ec0
x19: ffff800012068d50 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000
x15: 0000000000000000 x14: 0000000000000000
x13: 0000000000000000 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000000
x9 : ffff800010085c90 x8 : 0000000000000000
x7 : 0000000000000000 x6 : ffff80001205a9c8
x5 : ffff80001205a000 x4 : ffff80001233db80
x3 : ffff8000100a7a60 x2 : 0020000000000003
x1 : 0000fffffffff008 x0 : ffff800012af3ec0
Call trace:
uprobe_single_step_handler+0x34/0x50
single_step_handler+0x70/0xf8
do_debug_exception+0xb8/0x130
el0_sync_handler+0x138/0x1b8
el0_sync+0x158/0x180

Fixes: 74afda4016a7 ("arm64: compile the kernel with ptrauth return address signing")
Fixes: 04ca3204fa09 ("arm64: enable pointer authentication")
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Link: https://lore.kernel.org/r/20200914083656.21428-2-amit.kachhap@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

arm64: insn: Provide a better name for aarch64_insn_is_nop()

The current aarch64_insn_is_nop() has exactly one caller which uses it
solely to identify if the instruction is a HINT that can safely be stepped,
requiring us to list things that aren't NOPs and make things more confusing
than they need to be. Rename the function to reflect the actual usage and
make things more clear.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20200504131326.18290-3-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

arm64: insn: Add constants for new HINT instruction decode

Add constants for decoding newer instructions defined in the HINT space.
Since we are now decoding both the op2 and CRm fields rename the enum as
well; this is compatible with what the existing users are doing.

Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20200504131326.18290-2-broonie@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

arm64: insn: add encoder for MOV (register)

For FTRACE_WITH_REGS, we're going to want to generate a MOV (register)
instruction as part of the callsite intialization. As MOV (register) is
an alias for ORR (shifted register), we can generate this with
aarch64_insn_gen_logical_shifted_reg(), but it's somewhat verbose and
difficult to read in-context.

Add a aarch64_insn_gen_move_reg() wrapper for this case so that we can
write callers in a more straightforward way.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Torsten Duwe <duwe@suse.de>
Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Tested-by: Torsten Duwe <duwe@suse.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 234

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details you should have received a copy of the gnu general
public license along with this program if not see http www gnu org
licenses

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 503 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Enrico Weigelt <info@metux.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arm64: insn: Add BUILD_BUG_ON() for invalid masks

Detect invalid instruction masks at build time. Some versions of GCC can
warn about the situation, but not all of them, it seems.

Suggested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: insn: Fix ldadd instruction encoding

GCC 8.1.0 reports that the ldadd instruction encoding, recently added to
insn.c, doesn't match the mask and couldn't possibly be identified:

linux/arch/arm64/include/asm/insn.h: In function 'aarch64_insn_is_ldadd':
linux/arch/arm64/include/asm/insn.h:280:257: warning: bitwise comparison always evaluates to false [-Wtautological-compare]

Bits [31:30] normally encode the size of the instruction (1 to 8 bytes)
and the current instruction value only encodes the 4- and 8-byte
variants. At the moment only the BPF JIT needs this instruction, and
doesn't require the 1- and 2-byte variants, but to be consistent with
our other ldr and str instruction encodings, clear the size field in the
insn value.

Fixes: 34b8ab091f9ef57a ("bpf, arm64: use more scalable stadd over ldxr / stxr loop in xadd")
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Reported-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

bpf, arm64: use more scalable stadd over ldxr / stxr loop in xadd

Since ARMv8.1 supplement introduced LSE atomic instructions back in 2016,
lets add support for STADD and use that in favor of LDXR / STXR loop for
the XADD mapping if available. STADD is encoded as an alias for LDADD with
XZR as the destination register, therefore add LDADD to the instruction
encoder along with STADD as special case and use it in the JIT for CPUs
that advertise LSE atomics in CPUID register. If immediate offset in the
BPF XADD insn is 0, then use dst register directly instead of temporary
one.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

arm64/insn: add support for emitting ADR/ADRP instructions

Add support for emitting ADR and ADRP instructions so we can switch
over our PLT generation code in a subsequent patch.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: insn: Don't fallback on nosync path for general insn patching

Patching kernel instructions at runtime requires other CPUs to undergo
a context synchronisation event via an explicit ISB or an IPI in order
to ensure that the new instructions are visible. This is required even
for "hotpatch" instructions such as NOP and BL, so avoid optimising in
this case and always go via stop_machine() when performing general
patching.

ftrace isn't quite as strict, so it can continue to call the nosync
code directly.

Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64; insn: Add encoder for the EXTR instruction

Add an encoder for the EXTR instruction, which also implements the ROR
variant (where Rn == Rm).

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arm64: insn: Add encoder for bitwise operations using literals

We lack a way to encode operations such as AND, ORR, EOR that take
an immediate value. Doing so is quite involved, and is all about
reverse engineering the decoding algorithm described in the
pseudocode function DecodeBitMasks().

This has been tested by feeding it all the possible literal values
and comparing the output with that of GAS.

Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arm64: insn: Add N immediate encoding

We're missing the a way to generate the encoding of the N immediate,
which is only a single bit used in a number of instruction that take
an immediate.

Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arm64: Prevent cpu hotplug rwsem recursion

The text patching functions which are invoked from jump_label and kprobes
code are protected against cpu hotplug at the call sites.

Use stop_machine_cpuslocked() to avoid recursion on the cpu hotplug
rwsem. stop_machine_cpuslocked() contains a lockdep assertion to catch any
unprotected callers.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20170524081549.197070135@linutronix.de

bpf, arm64: implement jiting of BPF_XADD

This work adds BPF_XADD for BPF_W/BPF_DW to the arm64 JIT and therefore
completes JITing of all BPF instructions, meaning we can thus also remove
the 'notyet' label and do not need to fall back to the interpreter when
BPF_XADD is used in a program!

This now also brings arm64 JIT in line with x86_64, s390x, ppc64, sparc64,
where all current eBPF features are supported.

BPF_W example from test_bpf:

.u.insns_int = {
BPF_ALU32_IMM(BPF_MOV, R0, 0x12),
BPF_ST_MEM(BPF_W, R10, -40, 0x10),
BPF_STX_XADD(BPF_W, R10, R0, -40),
BPF_LDX_MEM(BPF_W, R0, R10, -40),
BPF_EXIT_INSN(),
},

[...]
00000020: 52800247 mov w7, #0x12 // #18
00000024: 928004eb mov x11, #0xffffffffffffffd8 // #-40
00000028: d280020a mov x10, #0x10 // #16
0000002c: b82b6b2a str w10, [x25,x11]
// start of xadd mapping:
00000030: 928004ea mov x10, #0xffffffffffffffd8 // #-40
00000034: 8b19014a add x10, x10, x25
00000038: f9800151 prfm pstl1strm, [x10]
0000003c: 885f7d4b ldxr w11, [x10]
00000040: 0b07016b add w11, w11, w7
00000044: 880b7d4b stxr w11, w11, [x10]
00000048: 35ffffab cbnz w11, 0x0000003c
// end of xadd mapping:
[...]

BPF_DW example from test_bpf:

.u.insns_int = {
BPF_ALU32_IMM(BPF_MOV, R0, 0x12),
BPF_ST_MEM(BPF_DW, R10, -40, 0x10),
BPF_STX_XADD(BPF_DW, R10, R0, -40),
BPF_LDX_MEM(BPF_DW, R0, R10, -40),
BPF_EXIT_INSN(),
},

[...]
00000020: 52800247 mov w7, #0x12 // #18
00000024: 928004eb mov x11, #0xffffffffffffffd8 // #-40
00000028: d280020a mov x10, #0x10 // #16
0000002c: f82b6b2a str x10, [x25,x11]
// start of xadd mapping:
00000030: 928004ea mov x10, #0xffffffffffffffd8 // #-40
00000034: 8b19014a add x10, x10, x25
00000038: f9800151 prfm pstl1strm, [x10]
0000003c: c85f7d4b ldxr x11, [x10]
00000040: 8b07016b add x11, x11, x7
00000044: c80b7d4b stxr w11, x11, [x10]
00000048: 35ffffab cbnz w11, 0x0000003c
// end of xadd mapping:
[...]

Tested on Cavium ThunderX ARMv8, test suite results after the patch:

No JIT: [ 3751.855362] test_bpf: Summary: 311 PASSED, 0 FAILED, [0/303 JIT'ed]
With JIT: [ 3573.759527] test_bpf: Summary: 311 PASSED, 0 FAILED, [303/303 JIT'ed]

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

arm64: Add helper to decode register from instruction

Add a helper to extract the register field from a given
instruction.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: insn: Add helpers for adrp offsets

Adds helpers for decoding/encoding the PC relative addresses for adrp.
This will be used for handling dynamic patching of 'adrp' instructions
in alternative code patching.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: Kprobes with single stepping support

Add support for basic kernel probes(kprobes) and jump probes
(jprobes) for ARM64.

Kprobes utilizes software breakpoint and single step debug
exceptions supported on ARM v8.

A software breakpoint is placed at the probe address to trap the
kernel execution into the kprobe handler.

ARM v8 supports enabling single stepping before the break exception
return (ERET), with next PC in exception return address (ELR_EL1). The
kprobe handler prepares an executable memory slot for out-of-line
execution with a copy of the original instruction being probed, and
enables single stepping. The PC is set to the out-of-line slot address
before the ERET. With this scheme, the instruction is executed with the
exact same register context except for the PC (and DAIF) registers.

Debug mask (PSTATE.D) is enabled only when single stepping a recursive
kprobe, e.g.: during kprobes reenter so that probed instruction can be
single stepped within the kprobe handler -exception- context.
The recursion depth of kprobe is always 2, i.e. upon probe re-entry,
any further re-entry is prevented by not calling handlers and the case
counted as a missed kprobe).

Single stepping from the x-o-l slot has a drawback for PC-relative accesses
like branching and symbolic literals access as the offset from the new PC
(slot address) may not be ensured to fit in the immediate value of
the opcode. Such instructions need simulation, so reject
probing them.

Instructions generating exceptions or cpu mode change are rejected
for probing.

Exclusive load/store instructions are rejected too. Additionally, the
code is checked to see if it is inside an exclusive load/store sequence
(code from Pratyush).

System instructions are mostly enabled for stepping, except MSR/MRS
accesses to "DAIF" flags in PSTATE, which are not safe for
probing.

This also changes arch/arm64/include/asm/ptrace.h to use
include/asm-generic/ptrace.h.

Thanks to Steve Capper and Pratyush Anand for several suggested
Changes.

Signed-off-by: Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com>
Signed-off-by: David A. Long <dave.long@linaro.org>
Signed-off-by: Pratyush Anand <panand@redhat.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arm64: add conditional instruction simulation support

Cease using the arm32 arm_check_condition() function and replace it with
a local version for use in deprecated instruction support on arm64. Also
make the function table used by this available for future use by kprobes
and/or uprobes.

This function is derived from code written by Sandeepa Prabhu.

Signed-off-by: Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com>
Signed-off-by: David A. Long <dave.long@linaro.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arm64: Add more test functions to insn.c

Certain instructions are hard to execute correctly out-of-line (as in
kprobes). Test functions are added to insn.[hc] to identify these. The
instructions include any that use PC-relative addressing, change the PC,
or change interrupt masking. For efficiency and simplicity test
functions are also added for small collections of related instructions.

Signed-off-by: David A. Long <dave.long@linaro.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arm64: insn: Add aarch64_{get,set}_branch_offset

In order to deal with branches located in alternate sequences,
but pointing to the main kernel text, it is required to extract
the relative displacement encoded in the instruction, and to be
able to update said instruction with a new offset (once it is
known).

For this, we introduce three new helpers:
- aarch64_insn_is_branch_imm is a predicate indicating if the
instruction is an immediate branch
- aarch64_get_branch_offset returns a signed value representing
the byte offset encoded in a branch instruction
- aarch64_set_branch_offset takes an instruction and an offset,
and returns the corresponding updated instruction.

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arm64: insn: Add aarch64_insn_decode_immediate

Patching an instruction sometimes requires extracting the immediate
field from this instruction. To facilitate this, and avoid
potential duplication of code, add aarch64_insn_decode_immediate
as the reciprocal to aarch64_insn_encode_immediate.

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: insn: fix compare-and-branch encodings

Fix cbz/cbnz having the mask offset by a bit, and add encodings for
tbz/tbnz so that all branch forms are represented.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Zi Shen Lim <zlim.lnx@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: Emulate CP15 Barrier instructions

The CP15 barrier instructions (CP15ISB, CP15DSB and CP15DMB) are
deprecated in the ARMv7 architecture, superseded by ISB, DSB and DMB
instructions respectively. Some implementations may provide the
ability to disable the CP15 barriers by disabling the CP15BEN bit in
SCTLR_EL1. If not enabled, the encodings for these instructions become
undefined.

To support legacy software using these instructions, this patch
register hooks to -
* emulate CP15 barriers and warn the user about their use
* toggle CP15BEN in SCTLR_EL1

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: Port SWP/SWPB emulation support from arm

The SWP instruction was deprecated in the ARMv6 architecture. The
ARMv7 multiprocessing extensions mandate that SWP/SWPB instructions
are treated as undefined from reset, with the ability to enable them
through the System Control Register SW bit. With ARMv8, the option to
enable these instructions through System Control Register was dropped
as well.

To support legacy applications using these instructions, port the
emulation of the SWP and SWPB instructions from the arm port to arm64.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: Add support for hooks to handle undefined instructions

Add support to register hooks for undefined instructions. The handlers
will be called when the undefined instruction and the processor state
(as contained in pstate) match criteria used at registration.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_logical_shifted_reg()

Introduce function to generate logical (shifted register)
instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_data3()

Introduce function to generate data-processing (3 source) instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_data2()

Introduce function to generate data-processing (2 source) instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_data1()

Introduce function to generate data-processing (1 source) instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_add_sub_shifted_reg()

Introduce function to generate add/subtract (shifted register)
instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_movewide()

Introduce function to generate move wide (immediate) instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_bitfield()

Introduce function to generate bitfield instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_add_sub_imm()

Introduce function to generate add/subtract (immediate) instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_load_store_pair()

Introduce function to generate load/store pair instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_load_store_reg()

Introduce function to generate load/store (register offset)
instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_cond_branch_imm()

Introduce function to generate conditional branch (immediate)
instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_branch_reg()

Introduce function to generate unconditional branch (register)
instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_comp_branch_imm()

Introduce function to generate compare & branch (immediate)
instructions.

Signed-off-by: Zi Shen Lim <zlim.lnx@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: add __ASSEMBLY__ in asm/insn.h

Since insn.h is indirectly included in asm/entry-ftrace.S,
we need to exclude some declarations by __ASSEMBLY__.

Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arm64: introduce aarch64_insn_gen_{nop|branch_imm}() helper functions

Introduce aarch64_insn_gen_{nop|branch_imm}() helper functions, which
will be used to implement jump label on ARM64.

Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arm64: move encode_insn_immediate() from module.c to insn.c

Function encode_insn_immediate() will be used by other instruction
manipulate related functions, so move it into insn.c and rename it
as aarch64_insn_encode_immediate().

Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arm64: introduce interfaces to hotpatch kernel and module code

Introduce three interfaces to patch kernel and module code:
aarch64_insn_patch_text_nosync():
patch code without synchronization, it's caller's responsibility
to synchronize all CPUs if needed.
aarch64_insn_patch_text_sync():
patch code and always synchronize with stop_machine()
aarch64_insn_patch_text():
patch code and synchronize with stop_machine() if needed

Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arm64: introduce basic aarch64 instruction decoding helpers

Introduce basic aarch64 instruction decoding helper
aarch64_get_insn_class() and aarch64_insn_hotpatch_safe().

Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>