Implement calls to rseq_signal_deliver, rseq_handle_notify_resume
and rseq_syscall so that we can select HAVE_RSEQ on arm64.
Acked-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Some code cares about the SPSR_ELx format for exceptions taken from
AArch32 to inspect or manipulate the SPSR_ELx value, which is already in
the SPSR_ELx format, and not in the AArch32 PSR format.

To separate these from cases where we care about the AArch32 PSR format,
migrate these cases to use the PSR_AA32_* definitions rather than
COMPAT_PSR_*.

There should be no functional change as a result of this patch.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

The SPSR_ELx format for exceptions taken from AArch32 is slightly
different to the AArch32 PSR format.

Map between the two in the compat ptrace code.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Fixes: 7206dc93 ("arm64: Expose Arm v8.4 features")
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Suzuki Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Currently valid_user_regs() treats SPSR_ELx.DIT as a RES0 bit, causing
it to be zeroed upon exception return, rather than preserved. Thus, code
relying on DIT will not function as expected, and may expose an
unexpected timing sidechannel.

Let's remove DIT from the set of RES0 bits, such that it is preserved.
At the same time, the related comment is updated to better describe the
situation, and to take into account the most recent documentation of
SPSR_ELx, in ARM DDI 0487C.a.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Fixes: 7206dc93 ("arm64: Expose Arm v8.4 features")
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Now that the kernel SVE support is reasonably mature, it is
excessive to default sve_max_vl to the invalid value -1 and then
sprinkle WARN_ON()s around the place to make sure it has been
initialised before use.  The cpufeatures code already runs pretty
early, and will ensure sve_max_vl gets initialised.

This patch initialises sve_max_vl to something sane that will be
supported by every SVE implementation, and removes most of the
sanity checks.

The checks in find_supported_vector_length() are retained for now.
If anything goes horribly wrong, we are likely to trip a check here
sooner or later.
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Having read_zcr_features() inline in cpufeature.h results in that
header requiring #includes which make it hard to include
<asm/fpsimd.h> elsewhere without triggering header inclusion
cycles.

This is not a hot-path function and arguably should not be in
cpufeature.h in the first place, so this patch moves it to
fpsimd.c, compiled conditionally if CONFIG_ARM64_SVE=y.

This allows some SVE-related #includes to be dropped from
cpufeature.h, which will ease future maintenance.

A couple of missing #includes of <asm/fpsimd.h> are exposed by this
change under arch/arm64/.  This patch adds the missing #includes as
necessary.

No functional change.
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

"make includecheck" detected few duplicated includes in arch/arm64.

This patch removes the double inclusions.
Signed-off-by: NVincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

It's possible for userspace to control idx. Sanitize idx when using it
as an array index.

Found by smatch.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

We transiently switch to KERNEL_DS in compat_ptrace_gethbpregs() and
compat_ptrace_sethbpregs(), but in either case this is pointless as we
don't perform any uaccess during this window.

let's rip out the redundant addr_limit manipulation.
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

When the hardend usercopy support was added for arm64, it was
concluded that all cases of usercopy into and out of thread_struct
were statically sized and so didn't require explicit whitelisting
of the appropriate fields in thread_struct.

Testing with usercopy hardening enabled has revealed that this is
not the case for certain ptrace regset manipulation calls on arm64.
This occurs because the sizes of usercopies associated with the
regset API are dynamic by construction, and because arm64 does not
always stage such copies via the stack: indeed the regset API is
designed to avoid the need for that by adding some bounds checking.

This is currently believed to affect only the fpsimd and TLS
registers.

Because the whitelisted fields in thread_struct must be contiguous,
this patch groups them together in a nested struct.  It is also
necessary to be able to determine the location and size of that
struct, so rather than making the struct anonymous (which would
save on edits elsewhere) or adding an anonymous union containing
named and unnamed instances of the same struct (gross), this patch
gives the struct a name and makes the necessary edits to code that
references it (noisy but simple).

Care is needed to ensure that the new struct does not contain
padding (which the usercopy hardening would fail to protect).

For this reason, the presence of tp2_value is made unconditional,
since a padding field would be needed there in any case.  This pads
up to the 16-byte alignment required by struct user_fpsimd_state.
Acked-by: NKees Cook <keescook@chromium.org>
Reported-by: NMark Rutland <mark.rutland@arm.com>
Fixes: 9e8084d3 ("arm64: Implement thread_struct whitelist for hardened usercopy")
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

In preparation for using a common representation of the FPSIMD
state for tasks and KVM vcpus, this patch separates out the "cpu"
field that is used to track the cpu on which the state was most
recently loaded.

This will allow common code to operate on task and vcpu contexts
without requiring the cpu field to be stored at the same offset
from the FPSIMD register data in both cases.  This should avoid the
need for messing with the definition of those parts of struct
vcpu_arch that are exposed in the KVM user ABI.

The resulting change is also convenient for grouping and defining
the set of thread_struct fields that are supposed to be accessible
to copy_{to,from}_user(), which includes user_fpsimd_state but
should exclude the cpu field.  This patch does not amend the
usercopy whitelist to match: that will be addressed in a subsequent
patch.
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
[will: inline fpsimd_flush_state for now]
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Using arm64_force_sig_info means that printing messages about unhandled
signals is dealt with for us, so use that in preference to force_sig_info
and remove any homebrew printing code.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

On lkml suggestions were made to split up such trivial typo fixes into per subsystem
patches:

  --- a/arch/x86/boot/compressed/eboot.c
  +++ b/arch/x86/boot/compressed/eboot.c
  @@ -439,7 +439,7 @@ setup_uga32(void **uga_handle, unsigned long size, u32 *width, u32 *height)
          struct efi_uga_draw_protocol *uga = NULL, *first_uga;
          efi_guid_t uga_proto = EFI_UGA_PROTOCOL_GUID;
          unsigned long nr_ugas;
  -       u32 *handles = (u32 *)uga_handle;;
  +       u32 *handles = (u32 *)uga_handle;
          efi_status_t status = EFI_INVALID_PARAMETER;
          int i;

This patch is the result of the following script:

  $ sed -i 's/;;$/;/g' $(git grep -E ';;$'  | grep "\.[ch]:"  | grep -vwE 'for|ia64' | cut -d: -f1 | sort | uniq)

... followed by manual review to make sure it's all good.

Splitting this up is just crazy talk, let's get over with this and just do it.
Reported-by: NPavel Machek <pavel@ucw.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

There are so many places that build struct siginfo by hand that at
least one of them is bound to get it wrong.  A handful of cases in the
kernel arguably did just that when using the errno field of siginfo to
pass no errno values to userspace.  The usage is limited to a single
si_code so at least does not mess up anything else.

Encapsulate this questionable pattern in a helper function so
that the userspace ABI is preserved.

Update all of the places that use this pattern to use the new helper
function.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

The siginfo structure has all manners of holes with the result that a
structure initializer is not guaranteed to initialize all of the bits.
As we have to copy the structure to userspace don't even try to use
a structure initializer.  Instead use clear_siginfo followed by initializing
selected fields.  This gives a guarantee that uninitialized kernel memory
is not copied to userspace.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

Instead of jumpping while !is_compat_task placee all of the code
inside of an if (is_compat_task) block.  This allows the int i
variable to be properly limited to the compat block no matter how the
rest of ptrace_hbptriggered changes.

In a following change a non-variable declaration will preceed
was made independent to ensure the code is easy to review.
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>

This patch defines and implements a new regset NT_ARM_SVE, which
describes a thread's SVE register state.  This allows a debugger to
manipulate the SVE state, as well as being included in ELF
coredumps for post-mortem debugging.

Because the regset size and layout are dependent on the thread's
current vector length, it is not possible to define a C struct to
describe the regset contents as is done for existing regsets.
Instead, and for the same reasons, NT_ARM_SVE is based on the
freeform variable-layout approach used for the SVE signal frame.

Additionally, to reduce debug overhead when debugging threads that
might or might not have live SVE register state, NT_ARM_SVE may be
presented in one of two different formats: the old struct
user_fpsimd_state format is embedded for describing the state of a
thread with no live SVE state, whereas a new variable-layout
structure is embedded for describing live SVE state.  This avoids a
debugger needing to poll NT_PRFPREG in addition to NT_ARM_SVE, and
allows existing userspace code to handle the non-SVE case without
too much modification.

For this to work, NT_ARM_SVE is defined with a fixed-format header
of type struct user_sve_header, which the recipient can use to
figure out the content, size and layout of the reset of the regset.
Accessor macros are defined to allow the vector-length-dependent
parts of the regset to be manipulated.
Signed-off-by: NAlan Hayward <alan.hayward@arm.com>
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Cc: Alex Bennée <alex.bennee@linaro.org>
Cc: Okamoto Takayuki <tokamoto@jp.fujitsu.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Before we add yet another stack to the kernel, it would be nice to
ensure that we consistently organise stack definitions and related
helper functions.

This patch moves the basic IRQ stack defintions to <asm/memory.h> to
live with their task stack counterparts. Helpers used for unwinding are
moved into <asm/stacktrace.h>, where subsequent patches will add helpers
for other stacks. Includes are fixed up accordingly.

This patch is a pure refactoring -- there should be no functional
changes as a result of this patch.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Reviewed-by: NWill Deacon <will.deacon@arm.com>
Tested-by: NLaura Abbott <labbott@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>

Our IRQ_STACK_PTR() and on_irq_stack() helpers both take a cpu argument,
used to generate a percpu address. In all cases, they are passed
{raw_,}smp_processor_id(), so this parameter is redundant.

Since {raw_,}smp_processor_id() use a percpu variable internally, this
approach means we generate a percpu offset to find the current cpu, then
use this to index an array of percpu offsets, which we then use to find
the current CPU's IRQ stack pointer. Thus, most of the work is
redundant.

Instead, we can consistently use raw_cpu_ptr() to generate the CPU's
irq_stack pointer by simply adding the percpu offset to the irq_stack
address, which is simpler in both respects.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will.deacon@arm.com>

The -1 "no syscall" value is written in various ways, shared with
the user ABI in some places, and generally obscure.

This patch attempts to make things a little more consistent and
readable by replacing all these uses with a single #define.  A
couple of symbolic helpers are provided to clarify the intent
further.

Because the in-syscall check in do_signal() is changed from >= 0 to
!= NO_SYSCALL by this patch, different behaviour may be observable
if syscallno is set to values less than -1 by a tracer.  However,
this is not different from the behaviour that is already observable
if a tracer sets syscallno to a value >= __NR_(compat_)syscalls.

It appears that this can cause spurious syscall restarting, but
that is not a new behaviour either, and does not appear harmful.
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

The upper 32 bits of the syscallno field in thread_struct are
handled inconsistently, being sometimes zero extended and sometimes
sign-extended.  In fact, only the lower 32 bits seem to have any
real significance for the behaviour of the code: it's been OK to
handle the upper bits inconsistently because they don't matter.

Currently, the only place I can find where those bits are
significant is in calling trace_sys_enter(), which may be
unintentional: for example, if a compat tracer attempts to cancel a
syscall by passing -1 to (COMPAT_)PTRACE_SET_SYSCALL at the
syscall-enter-stop, it will be traced as syscall 4294967295
rather than -1 as might be expected (and as occurs for a native
tracer doing the same thing).  Elsewhere, reads of syscallno cast
it to an int or truncate it.

There's also a conspicuous amount of code and casting to bodge
around the fact that although semantically an int, syscallno is
stored as a u64.

Let's not pretend any more.

In order to preserve the stp x instruction that stores the syscall
number in entry.S, this patch special-cases the layout of struct
pt_regs for big endian so that the newly 32-bit syscallno field
maps onto the low bits of the stored value.  This is not beautiful,
but benchmarking of the getpid syscall on Juno suggests indicates a
minor slowdown if the stp is split into an stp x and stp w.
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Now that compat_vfp_get() uses the regset API to copy the FPSCR
value out to userspace, compat_vfp_set() looks inconsistent.  In
particular, compat_vfp_set() will fail if called with kbuf != NULL
&& ubuf == NULL (which is valid usage according to the regset API).

This patch fixes compat_vfp_set() to use user_regset_copyin(),
similarly to compat_vfp_get().

This also squashes a sparse warning triggered by the cast that
drops __user when calling get_user().
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

compat_vfp_set() checks for userspace trying to write an excessive
amount of data to the regset.  However this check is conspicuous
for its absence from every other _set() in the arm64 ptrace
implementation.  In fact, the core ptrace_regset() already clamps
userspace's iov_len to the regset size before the individual regset
.{get,set}() methods get called.

This patch removes the redundant check.
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

If get_user() fails when reading the new FPSCR value from userspace
in compat_vfp_get(), then garbage* will be written to the task's
FPSR and FPCR registers.

This patch prevents this by checking the return from get_user()
first.

[*] Actually, zero, due to the behaviour of get_user() on error, but
that's still not what userspace expects.

Fixes: 478fcb2c ("arm64: Debugging support")
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

When reading current's user-writable TLS register (which occurs
when dumping core for native tasks), it is possible that userspace
has modified it since the time the task was last scheduled out.
The new TLS register value is not guaranteed to have been written
immediately back to thread_struct in this case.

As a result, a coredump can capture stale data for this register.
Reading the register for a stopped task via ptrace is unaffected.

For native tasks, this patch explicitly flushes the TPIDR_EL0
register back to thread_struct before dumping when operating on
current, thus ensuring that coredump contents are up to date.  For
compat tasks, the TLS register is not user-writable and so cannot
be out of sync, so no flush is required in compat_tls_get().
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

When reading the FPSIMD state of current (which occurs when dumping
core), it is possible that userspace has modified the FPSIMD
registers since the time the task was last scheduled out.  Such
changes are not guaranteed to be reflected immedately in
thread_struct.

As a result, a coredump can contain stale values for these
registers.  Reading the registers of a stopped task via ptrace is
unaffected.

This patch explicitly flushes the CPU state back to thread_struct
before dumping when operating on current, thus ensuring that
coredump contents are up to date.
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Currently, VFP registers are omitted from coredumps for compat
processes, due to a bug in the REGSET_COMPAT_VFP regset
implementation.

compat_vfp_get() needs to transfer non-contiguous data from
thread_struct.fpsimd_state, and uses put_user() to handle the
offending trailing word (FPSCR).  This fails when copying to a
kernel address (i.e., kbuf && !ubuf), which is what happens when
dumping core.  As a result, the ELF coredump core code silently
omits the NT_ARM_VFP note from the dump.

It would be possible to work around this with additional special
case code for the put_user(), but since user_regset_copyout() is
explicitly designed to handle this scenario it is cleaner to port
the put_user() to a user_regset_copyout() call, which this patch
does.
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

We are going to split <linux/sched/task_stack.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/task_stack.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/signal.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

We cannot preserve partial fields for hardware breakpoints, because
the values written by userspace to the hardware breakpoint
registers can't subsequently be recovered intact from the hardware.

So, just reject attempts to write incomplete fields with -EINVAL.

Cc: <stable@vger.kernel.org> # 3.7.x-
Fixes: 478fcb2c ("arm64: Debugging support")
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Acked-by: NWill Deacon <Will.Deacon@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Ensure that if userspace supplies insufficient data to
PTRACE_SETREGSET to fill all the registers, the thread's old
registers are preserved.

Cc: <stable@vger.kernel.org> # 4.3.x-
Fixes: 5d220ff9 ("arm64: Better native ptrace support for compat tasks")
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Acked-by: NWill Deacon <Will.Deacon@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Ensure that if userspace supplies insufficient data to
PTRACE_SETREGSET to fill all the registers, the thread's old
registers are preserved.

Cc: <stable@vger.kernel.org> # 3.19.x-
Fixes: 766a85d7 ("arm64: ptrace: add NT_ARM_SYSTEM_CALL regset")
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Acked-by: NWill Deacon <Will.Deacon@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Ensure that if userspace supplies insufficient data to
PTRACE_SETREGSET to fill all the registers, the thread's old
registers are preserved.

Cc: <stable@vger.kernel.org> # 3.7.x-
Fixes: 478fcb2c ("arm64: Debugging support")
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Acked-by: NWill Deacon <Will.Deacon@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

ARM64 hardware supports watchpoint at any double word aligned address.
However, it can select any consecutive bytes from offset 0 to 7 from that
base address. For example, if base address is programmed as 0x420030 and
byte select is 0x1C, then access of 0x420032,0x420033 and 0x420034 will
generate a watchpoint exception.

Currently, we do not have such modularity. We can only program byte,
halfword, word and double word access exception from any base address.

This patch adds support to overcome above limitations.
Signed-off-by: NPratyush Anand <panand@redhat.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Add HAVE_REGS_AND_STACK_ACCESS_API feature for arm64, including supporting
functions and defines.
Signed-off-by: NDavid A. Long <dave.long@linaro.org>
Acked-by: NMasami Hiramatsu <mhiramat@kernel.org>
[catalin.marinas@arm.com: Remove unused functions]
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Close the hole where ptrace can change a syscall out from under seccomp.
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org

Currently, if arch code wants to supply seccomp_data directly to
seccomp (which is generally much faster than having seccomp do it
using the syscall_get_xyz() API), it has to use the two-phase
seccomp hooks. Add it to the easy hooks, too.

Cc: linux-arch@vger.kernel.org
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NKees Cook <keescook@chromium.org>

We validate pstate using PSR_MODE32_BIT, which is part of the
user-provided pstate (and cannot be trusted). Also, we conflate
validation of AArch32 and AArch64 pstate values, making the code
difficult to reason about.

Instead, validate the pstate value based on the associated task. The
task may or may not be current (e.g. when using ptrace), so this must be
passed explicitly by callers. To avoid circular header dependencies via
sched.h, is_compat_task is pulled out of asm/ptrace.h.

To make the code possible to reason about, the AArch64 and AArch32
validation is split into separate functions. Software must respect the
RES0 policy for SPSR bits, and thus the kernel mirrors the hardware
policy (RAZ/WI) for bits as-yet unallocated. When these acquire an
architected meaning writes may be permitted (potentially with additional
validation).
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Cc: Dave Martin <dave.martin@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Make sure to clear out any ptrace singlestep state when a ptrace(2)
PTRACE_DETACH call is made on arm64 systems.

Otherwise, the previously ptraced task will die off with a SIGTRAP
signal if the debugger just previously singlestepped the ptraced task.

Cc: <stable@vger.kernel.org>
Signed-off-by: NJohn Blackwood <john.blackwood@ccur.com>
[will: added comment to justify why this is in the arch code]
Signed-off-by: NWill Deacon <will.deacon@arm.com>

The compat ptrace interface allows access to the TLS register, hardware
breakpoints and watchpoints, syscall number. However, a native task
using the native ptrace interface to debug compat tasks (e.g. multi-arch
gdb) only has access to the general and VFP register sets. The compat
ptrace interface cannot be accessed from a native task.

This patch adds a new user_aarch32_ptrace_view which contains the TLS,
hardware breakpoint/watchpoint and syscall number regsets in addition to
the existing GPR and VFP regsets. This view is backwards compatible with
the previous kernels. Core dumping of 32-bit tasks and compat ptrace are
not affected since the original user_aarch32_view is preserved.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Reported-by: NYao Qi <yao.qi@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>