arm64: Remove duplicate inclusion of mmu_context.h in smp.c

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>
arm64: Select MODULES_USE_ELF_RELA

With commit 786d35d4 (make most arch asm/module.h files use
asm-generic/module.h) arm64 needs to enable MODULES_USE_ELF_RELA for
loadable modules.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Will Deacon <Will.Deacon@arm.com>
arm64: Fix the update_vsyscall() prototype

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>
arm64: Ignore memory blocks below PHYS_OFFSET

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>
arm64: No need to set the x0-x2 registers in start_thread()

For historical reasons, ARM used to set r0-r2 in start_thread() to the
first values on the user stack when starting a new user application. The
same logic has been inherited in AArch64. The x0 register is overridden
by the sys_execve() return value so it's always zero on success. The x1
and x2 registers are ignored by AArch64 and EABI AArch32 applications,
so we can safely remove the register setting for both native and compat
user space.

This also fixes a potential fault with the kernel accessing user space
stack directly.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
arm64: ptrace: make structure padding explicit for debug registers

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>
arm64: ptrace: use HW_BREAKPOINT_EMPTY type for disabled breakpoints

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>
arm64: fix alignment padding in assembly code

An interesting effect of using the generic version of linkage.h
is that the padding is defined in terms of x86 NOPs, which can have
even more interesting effects when the assembly code looks like this:

ENTRY(func1)
	mov	x0, xzr
ENDPROC(func1)
	// fall through
ENTRY(func2)
	mov	x0, #1
	ret
ENDPROC(func2)

Admittedly, the code is not very nice. But having code from another
architecture doesn't look completely sane either.

The fix is to add arm64's version of linkage.h, which causes the insertion
of proper AArch64 NOPs.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux-aarch64

Pull arm64 fixes from Catalin Marinas:
 "Main changes:
   - AArch64 Linux compilation fixes following 3.7-rc1 changes
     (MODULES_USE_ELF_RELA, update_vsyscall() prototype)
   - Unnecessary register setting in start_thread() (thanks to Al Viro)
   - ptrace fixes"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux-aarch64:
  arm64: fix alignment padding in assembly code
  arm64: ptrace: use HW_BREAKPOINT_EMPTY type for disabled breakpoints
  arm64: ptrace: make structure padding explicit for debug registers
  arm64: No need to set the x0-x2 registers in start_thread()
  arm64: Ignore memory blocks below PHYS_OFFSET
  arm64: Fix the update_vsyscall() prototype
  arm64: Select MODULES_USE_ELF_RELA
  arm64: Remove duplicate inclusion of mmu_context.h in smp.c