Loading modules far away from the kernel in memory is problematic
because the 'bl' instruction only has limited reach, and modules are not
built with PLTs. Instead of using the -mlong-calls option (which affects
all compiler emitted bl instructions, but not the ones in assembler),
this patch allocates some additional space at module load time, and
populates it with PLT like veneers when encountering relocations that
are out of range.
This should work with all relocations against symbols exported by the
kernel, including those resulting from GCC generated implicit function
calls for ftrace etc.
The module memory size increases by about 5% on average, regardless of
whether any PLT entries were actually needed. However, due to the page
based rounding that occurs when allocating module memory, the average
memory footprint increase is negligible.
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
It appears that gcc may put some code in ".text.unlikely" or
".text.hot" sections. Right now those aren't accounted for in unwind
tables. Add them.
I found some docs about this at:
http://gcc.gnu.org/onlinedocs/gcc-4.6.2/gcc.pdf
Without this, if you have slub_debug turned on, you can get messages
that look like this:
unwind: Index not found 7f008c50
Signed-off-by: Doug Anderson <dianders@chromium.org>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Use the mapping of Elf_[SPE]hdr, Elf_Addr, Elf_Sym, Elf_Dyn, Elf_Rel/Rela,
ELF_R_TYPE() and ELF_R_SYM() to either the 32-bit version or the 64-bit version
into asm-generic/module.h for all arches bar MIPS.
Also, use the generic definition mod_arch_specific where possible.
To this end, I've defined three new config bools:
(*) HAVE_MOD_ARCH_SPECIFIC
Arches define this if they don't want to use the empty generic
mod_arch_specific struct.
(*) MODULES_USE_ELF_RELA
Arches define this if their modules can contain RELA records. This causes
the Elf_Rela mapping to be emitted and allows apply_relocate_add() to be
defined by the arch rather than have the core emit an error message.
(*) MODULES_USE_ELF_REL
Arches define this if their modules can contain REL records. This causes
the Elf_Rel mapping to be emitted and allows apply_relocate() to be
defined by the arch rather than have the core emit an error message.
Note that it is possible to allow both REL and RELA records: m68k and mips are
two arches that do this.
With this, some arch asm/module.h files can be deleted entirely and replaced
with a generic-y marker in the arch Kbuild file.
Additionally, I have removed the bits from m32r and score that handle the
unsupported type of relocation record as that's now handled centrally.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This code can be removed now that MSM targets no longer need the 16-bit
offsets for P2V.
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Loading Thumb-2 modules into an ARM kernel or vice-versa isn't
guaranteed to work safely, since the kernel is not interworking-
aware everywhere.
This patch adds "thumb2" to the module vermagic when
CONFIG_THUMB2_KERNEL is enabled, to help avoid accidental loading
of modules into the wrong kernel.
Signed-off-by: Dave Martin <dave.martin@linaro.org>
Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
MSM's memory is aligned to 2MB, which is more than we can do with our
existing method as we're limited to the upper 8 bits. Extend this by
using two instructions to 16 bits, automatically selected when MSM is
enabled.
Acked-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This idea came from Nicolas, Eric Miao produced an initial version,
which was then rewritten into this.
Patch the physical to virtual translations at runtime. As we modify
the code, this makes it incompatible with XIP kernels, but allows us
to achieve this with minimal loss of performance.
As many translations are of the form:
physical = virtual + (PHYS_OFFSET - PAGE_OFFSET)
virtual = physical - (PHYS_OFFSET - PAGE_OFFSET)
we generate an 'add' instruction for __virt_to_phys(), and a 'sub'
instruction for __phys_to_virt(). We calculate at run time (PHYS_OFFSET
- PAGE_OFFSET) by comparing the address prior to MMU initialization with
where it should be once the MMU has been initialized, and place this
constant into the above add/sub instructions.
Once we have (PHYS_OFFSET - PAGE_OFFSET), we can calculate the real
PHYS_OFFSET as PAGE_OFFSET is a build-time constant, and save this for
the C-mode PHYS_OFFSET variable definition to use.
At present, we are unable to support Realview with Sparsemem enabled
as this uses a complex mapping function, and MSM as this requires a
constant which will not fit in our math instruction.
Add a module version magic string for this feature to prevent
incompatible modules being loaded.
Tested-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Tested-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
There's no need to keep pointers to the ELF sections available while
the module is loaded - we only need the section pointers while we're
finding and registering the unwind tables, which can all be done during
the finalize stage of loading.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Without these, exit functions cannot be stack-traced, so to speak.
This implies that module unloads that perform allocations (don't
laugh) will cause noisy warnings on the console when kmemleak is
enabled, as it presumes that all code's call chains are traceable.
Similarly, BUGs and WARN_ONs will give additional console spam.
Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The various sections are all dealt with similarly, so factor out
that common behaviour. (Incorporating Peter Huewe's fix.)
Cc: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This patch adds ELF section parsing for the unwinding tables in loadable
modules together with the PREL31 relocation symbol resolving.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Move platform independent header files to arch/arm/include/asm, leaving
those in asm/arch* and asm/plat* alone.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
