ARCH_SUPPORTS_DEBUG_PAGEALLOC provides a hook to map and unmap
pages for debugging purposes. This requires memory be mapped
with PAGE_SIZE mappings since breaking down larger mappings
at runtime will lead to TLB conflicts. Check if debug_pagealloc
is enabled at runtime and if so, map everyting with PAGE_SIZE
pages. Implement the functions to actually map/unmap the
pages at runtime.
Reviewed-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: NMark Rutland <mark.rutland@arm.com>
Tested-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NLaura Abbott <labbott@fedoraproject.org>
[catalin.marinas@arm.com: static annotation block_mappings_allowed() and #ifdef]
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

The range of set_memory_* is currently restricted to the module address
range because of difficulties in breaking down larger block sizes.
vmalloc maps PAGE_SIZE pages so it is safe to use as well. Update the
function ranges and add a comment explaining why the range is restricted
the way it is.
Suggested-by: NLaura Abbott <labbott@fedoraproject.org>
Acked-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Calling apply_to_page_range with an empty range results in a BUG_ON
from the core code. This can be triggered by trying to load the st_drv
module with CONFIG_DEBUG_SET_MODULE_RONX enabled:

  kernel BUG at mm/memory.c:1874!
  Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
  Modules linked in:
  CPU: 3 PID: 1764 Comm: insmod Not tainted 4.5.0-rc1+ #2
  Hardware name: ARM Juno development board (r0) (DT)
  task: ffffffc9763b8000 ti: ffffffc975af8000 task.ti: ffffffc975af8000
  PC is at apply_to_page_range+0x2cc/0x2d0
  LR is at change_memory_common+0x80/0x108

This patch fixes the issue by making change_memory_common (called by the
set_memory_* functions) a NOP when numpages == 0, therefore avoiding the
erroneous call to apply_to_page_range and bringing us into line with x86
and s390.

Cc: <stable@vger.kernel.org>
Reviewed-by: NLaura Abbott <labbott@redhat.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NMika Penttilä <mika.penttila@nextfour.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

The <linux/mm.h> already provides the PAGE_ALIGNED macro. Let's
use this macro instead of IS_ALIGNED and passing PAGE_SIZE directly.
Signed-off-by: NAlexander Kuleshov <kuleshovmail@gmail.com>
Acked-by: NLaura Abbott <laura@labbott.name>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

This effectively unexports set_memory_ro and set_memory_rw functions from
commit 11d91a77 ("arm64: Add CONFIG_DEBUG_SET_MODULE_RONX support").

No module user of those is in mainline kernel and we explicitly do not want
modules to use these functions, as they i.e. RO-protect eBPF (interpreted and
JIT'ed) images from malicious modifications/bugs.

Outside of eBPF scope, I believe also other set_memory_* functions should
be unexported on arm64 due to non-existant mainline module user. Laura
mentioned that they have some uses for modules doing set_memory_*, but
none that are in mainline and it's unclear if they would ever get there.
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NAlexei Starovoitov <ast@plumgrid.com>
Acked-by: NLaura Abbott <lauraa@codeaurora.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

The set_memory_* functions currently only support module
addresses. The addresses are validated using is_module_addr.
That function is special though and relies on internal state
in the module subsystem to work properly. At the time of
module initialization and calling set_memory_*, it's too early
for is_module_addr to work properly so it always returns
false. Rather than be subject to the whims of the module state,
just bounds check against the module virtual address range.
Signed-off-by: NLaura Abbott <lauraa@codeaurora.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

The start address needs to be actually updated after it
is detected to be unaligned. Adjust it and the end address
properly.
Reported-by: NZi Shen Lim <zlim.lnx@gmail.com>
Reviewed-by: NZi Shen Lim <zlim.lnx@gmail.com>
Signed-off-by: NLaura Abbott <lauraa@codeaurora.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

In a similar fashion to other architecture, add the infrastructure
and Kconfig to enable DEBUG_SET_MODULE_RONX support. When
enabled, module ranges will be marked read-only/no-execute as
appropriate.
Signed-off-by: NLaura Abbott <lauraa@codeaurora.org>
[will: fixed off-by-one in module end check]
Signed-off-by: NWill Deacon <will.deacon@arm.com>