On Thu, Jan 28, 2016 at 07:19:34AM -0800, Kees Cook wrote:
> On Thu, Jan 28, 2016 at 7:04 AM, Geert Uytterhoeven
> <geert+renesas@xxxxxxxxx> wrote:
> > Hi Simon, Magnus,
> >
> > When CONFIG_ARM_KERNMEM_PERMS=y and CONFIG_DEBUG_RODATA=y, the kernel
> > crashes during system suspend:
> >
> > Freezing user space processes ... (elapsed 0.004 seconds) done.
> > Freezing remaining freezable tasks ... (elapsed 0.002 seconds)
> > done.
> > PM: suspend of devices complete after 111.948 msecs
> > PM: late suspend of devices complete after 1.086 msecs
> > PM: noirq suspend of devices complete after 11.576 msecs
> > Disabling non-boot CPUs ...
> > Kernel panic - not syncing: Attempted to kill the idle task!
> > 1014ec ---[ end Kernel panic - not syncing: Attempted to kill the idle task!
> > CPU0: stopping
> >
> > This happens because the shmobile assembler sources have several
> > variables that are written to in the .text section, while .text is
> > mapped read-only after kernel bootup if CONFIG_DEBUG_RODATA=y.
> >
> > This series fixes this by moving variables from .text to .data.
> > Note that there's still an issue with shmobile_boot_fn and
> > shmobile_boot_arg in arch/arm/mach-shmobile/headsmp.S.
> > So far I didn't manage to fix this (the code and data are copied to
> > SRAM on some SoCs). However, currently this are harmless, as these are
> > written during early kernel boot up only, before .text is marked
> > read-only.
> >
> > These issues were uncovered by "[PATCH v2] ARM: mm: flip priority of
> > CONFIG_DEBUG_RODATA". As that patch is planned for queue up (again)
> > soon, it may be a good idea to queue these fixes for v4.5, to avoid a
> > dependency with the arm tree.
> >
> > Tested hard on sh73a0/kzm9g, r8a7791/koelsch.
> > Tested lighter on emev2/kzm9d[*], r8a73a4/ape6evm, r8a7740/armadillo, and
> > r8a7779/marzen[*] ([*] = no remote resume).
> >
> > Thanks!
> >
> > Geert Uytterhoeven (2):
> > ARM: shmobile: Move shmobile_scu_base from .text to .data
> > ARM: shmobile: Move shmobile_smp_{mpidr,fn,arg}[] from .text to .data
> >
> > arch/arm/mach-shmobile/headsmp-scu.S | 6 ------
> > arch/arm/mach-shmobile/headsmp.S | 22 ++++++++++++++++------
> > arch/arm/mach-shmobile/platsmp-scu.c | 3 +++
> > 3 files changed, 19 insertions(+), 12 deletions(-)
>
> Thanks!
>
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
>
> And FWIW, I've now got the RODATA patch back in the patch queue, since
> we're at -rc1:
> http://www.arm.linux.org.uk/developer/patches/viewpatch.php?id=8501/1
And I'll be dropping it into linux-next for next week (iow, I'll commit
it tomorrow.)
Unfortunately, -rc1 broke some platforms, so Olof's builder isn't going
to get full coverage of it while building only my tree.
--
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
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