commit 304ef4e8367244b547734143c792a2ab764831e8 upstream.

To allow debuggers to unwind through signal frames, we create a fake
stack unwinding prologue containing the link register and frame pointer
of the interrupted context. The signal frame is then offset by 16 bytes
to make room for the two saved registers which are pushed onto the frame
of the *interrupted* context, rather than placed directly above the
signal stack.

This doesn't work when an alternative signal stack is set up for a SEGV
handler, which is raised in response to RLIMIT_STACK being reached. In
this case, we try to push the unwinding prologue onto the full stack and
subsequently take a fault which we fail to resolve, causing setup_return
to return -EFAULT and handle_signal to force_sigsegv on the current task.

This patch fixes the problem by including the unwinding prologue as part
of the rt_sigframe definition, which is populated during setup_sigframe,
ensuring that it always ends up on the signal stack.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commit 149c24151e85 ("ARM: SMP: use a timing out completion for cpu
hotplug") modified arm's CPU up path to use completions. It seems that
we only got half of this patch for arm64, so add the missing call to
complete.

Reported-by: Jon Brawn <jon.brawn@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

struct user_fp does not exist for arm64, so use struct user_fpsimd_state
instead for the ELF core dumping definitions. Furthermore, since we use
regset-based core dumping, we do not need definitions for dump_task_regs
and dump_fpu.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

We currently use a fake event encoding (0xFF) to indicate CPU cycles so
that we don't waste an event counter and can target the hardware cycle
counter instead.

The problem with this approach is that the event space defined by the
architecture permits an implementation to allocate 0xFF for some other
event.

This patch uses the architected cycle counter encoding (0x11) so that
we avoid potentially clashing with event encodings on future CPU
implementations.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

If a debugger tries to zero a hardware debug control register, the
kernel will try to infer both the type and length of the breakpoint
in order to sanity-check against the requested regset type. This will
fail because the encoding will appear as a zero-length breakpoint.

This patch changes the control register setting so that disabled
breakpoints are treated as HW_BREAKPOINT_EMPTY and no further
sanity-checking is required.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

The user_hwdebug_state structure contains implicit padding to conform to
the alignment requirements of the AArch64 ABI (namely that aggregates
must be aligned to their most aligned member).

This patch fixes the ptrace functions operating on struct
user_hwdebug_state so that the padding is handled correctly.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

According to Documentation/arm64/booting.txt, the kernel image must be
loaded at a pre-defined offset from the start of RAM so that the kernel
can calculate PHYS_OFFSET based on this address. If the DT contains
memory blocks below this PHYS_OFFSET, report them and ignore the
corresponding memory range.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

With commit 576094b7 (time: Introduce new GENERIC_TIME_VSYSCALL) the old
update_vsyscall() prototype is no longer available. This patch updates
the arm64 port.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: John Stultz <john.stultz@linaro.org>

asm/mmu_context.h was included twice.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Pull arm64 uapi disintegration from Catalin Marinas:
 "UAPI headers for arm64 together with some clean-up to make it
  possible:
   - Do not export the COMPAT_* definitions to user
   - Simplify the compat unistd32.h definitions and remove the
     __SYSCALL_COMPAT guard
   - Disintegrate the arch/arm64/include/asm/* headers"

* tag 'arm64-uapi' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux-aarch64:
  UAPI: (Scripted) Disintegrate arch/arm64/include/asm
  arm64: Do not export the compat-specific definitions to the user
  arm64: Do not include asm/unistd32.h in asm/unistd.h
  arm64: Remove unused definitions from asm/unistd32.h