Instead of using absolute addresses for both the exception location
and the fixup, use offsets relative to the exception table entry values.
Not only does this cut the size of the exception table in half, it is
also a prerequisite for KASLR, since absolute exception table entries
are subject to dynamic relocation, which is incompatible with the sorting
of the exception table that occurs at build time.

This patch also introduces the _ASM_EXTABLE preprocessor macro (which
exists on x86 as well) and its _asm_extable assembly counterpart, as
shorthands to emit exception table entries.
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

These functions/variables are not needed after booting, so mark them
as __init or __initdata.
Signed-off-by: NJisheng Zhang <jszhang@marvell.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

If the STXR instruction fails in the SWP emulation code, we leave *data
overwritten with the loaded value, therefore corrupting the data written
by a subsequent, successful attempt.

This patch re-jigs the code so that we only write back to *data once we
know that the update has happened.

Cc: <stable@vger.kernel.org>
Fixes: bd35a4ad ("arm64: Port SWP/SWPB emulation support from arm")
Reported-by: NShengjiu Wang <shengjiu.wang@freescale.com>
Reported-by: NVladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

'Privileged Access Never' is a new arm8.1 feature which prevents
privileged code from accessing any virtual address where read or write
access is also permitted at EL0.

This patch enables the PAN feature on all CPUs, and modifies {get,put}_user
helpers temporarily to permit access.

This will catch kernel bugs where user memory is accessed directly.
'Unprivileged loads and stores' using ldtrb et al are unaffected by PAN.
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NJames Morse <james.morse@arm.com>
[will: use ALTERNATIVE in asm and tidy up pan_enable check]
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Later patches need config_sctlr_el1 to set/clear bits in the sctlr_el1
register.

This patch moves this function into header a file.
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NJames Morse <james.morse@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Emulate deprecated 'setend' instruction for AArch32 bit tasks.

	setend [le/be] - Sets the endianness of EL0

On systems with CPUs which support mixed endian at EL0, the hardware
support for the instruction can be enabled by setting the SCTLR_EL1.SED
bit. Like the other emulated instructions it is controlled by an entry in
/proc/sys/abi/. For more information see :
	Documentation/arm64/legacy_instructions.txt

The instruction is emulated by setting/clearing the SPSR_EL1.E bit, which
will be reflected in the PSTATE.E in AArch32 context.

This patch also restores the native endianness for the execution of signal
handlers, since the process could have changed the endianness.

Note: All CPUs on the system must have mixed endian support at EL0. Once the
handler is registered, hotplugging a CPU which doesn't support mixed endian,
could lead to unexpected results/behavior in applications.
Signed-off-by: NSuzuki K. Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

As of now each insn_emulation has a cpu hotplug notifier that
enables/disables the CPU feature bit for the functionality. This
patch re-arranges the code, such that there is only one notifier
that runs through the list of registered emulation hooks and runs
their corresponding set_hw_mode.

We do nothing when a CPU is dying as we will set the appropriate bits
as it comes back online based on the state of the hooks.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NSuzuki K. Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Punit Agrawal <punit.agrawal@arm.com>
[catalin.marinas@arm.com: fix pr_warn compilation error]
[catalin.marinas@arm.com: remove unnecessary "insn" check]
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

update_insn_emulation_mode() returns 0 on success, so we should be
treating any non-zero values as failure, rather than the other way
around. Otherwise, writes to the sysctl file controlling the emulation
are ignored and immediately rolled back.
Reported-by: NGene Hackmann <ghackmann@google.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Introduce an event to trace the usage of emulated instructions. The
trace event is intended to help identify and encourage the migration
of legacy software using the emulation features.

Use this event to trace usage of swp and CP15 barrier emulation.
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NPunit Agrawal <punit.agrawal@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

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: NPunit Agrawal <punit.agrawal@arm.com>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

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: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NPunit Agrawal <punit.agrawal@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Typically, providing support for legacy instructions requires
emulating the behaviour of instructions whose encodings have become
undefined. If the instructions haven't been removed from the
architecture, there maybe an option in the implementation to turn
on/off the support for these instructions.

Create common infrastructure to support legacy instruction
emulation. In addition to emulation, also provide an option to support
hardware execution when supported. The default execution mode (one of
undef, emulate, hw exeuction) is dependent on the state of the
instruction (deprecated or obsolete) in the architecture and
can specified at the time of registering the instruction handlers. The
runtime state of the emulation can be controlled by writing to
individual nodes in sysctl. The expected default behaviour is
documented as part of this patch.
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NPunit Agrawal <punit.agrawal@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>