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    Subject[PATCH v2 04/43] arm64: RME: Handle Granule Protection Faults (GPFs)
    Date
    If the host attempts to access granules that have been delegated for use
    in a realm these accesses will be caught and will trigger a Granule
    Protection Fault (GPF).

    A fault during a page walk signals a bug in the kernel and is handled by
    oopsing the kernel. A non-page walk fault could be caused by user space
    having access to a page which has been delegated to the kernel and will
    trigger a SIGBUS to allow debugging why user space is trying to access a
    delegated page.

    Signed-off-by: Steven Price <steven.price@arm.com>
    ---
    arch/arm64/mm/fault.c | 29 ++++++++++++++++++++++++-----
    1 file changed, 24 insertions(+), 5 deletions(-)

    diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
    index 8251e2fea9c7..91da0f446dd9 100644
    --- a/arch/arm64/mm/fault.c
    +++ b/arch/arm64/mm/fault.c
    @@ -765,6 +765,25 @@ static int do_tag_check_fault(unsigned long far, unsigned long esr,
    return 0;
    }

    +static int do_gpf_ptw(unsigned long far, unsigned long esr, struct pt_regs *regs)
    +{
    + const struct fault_info *inf = esr_to_fault_info(esr);
    +
    + die_kernel_fault(inf->name, far, esr, regs);
    + return 0;
    +}
    +
    +static int do_gpf(unsigned long far, unsigned long esr, struct pt_regs *regs)
    +{
    + const struct fault_info *inf = esr_to_fault_info(esr);
    +
    + if (!is_el1_instruction_abort(esr) && fixup_exception(regs))
    + return 0;
    +
    + arm64_notify_die(inf->name, regs, inf->sig, inf->code, far, esr);
    + return 0;
    +}
    +
    static const struct fault_info fault_info[] = {
    { do_bad, SIGKILL, SI_KERNEL, "ttbr address size fault" },
    { do_bad, SIGKILL, SI_KERNEL, "level 1 address size fault" },
    @@ -802,11 +821,11 @@ static const struct fault_info fault_info[] = {
    { do_alignment_fault, SIGBUS, BUS_ADRALN, "alignment fault" },
    { do_bad, SIGKILL, SI_KERNEL, "unknown 34" },
    { do_bad, SIGKILL, SI_KERNEL, "unknown 35" },
    - { do_bad, SIGKILL, SI_KERNEL, "unknown 36" },
    - { do_bad, SIGKILL, SI_KERNEL, "unknown 37" },
    - { do_bad, SIGKILL, SI_KERNEL, "unknown 38" },
    - { do_bad, SIGKILL, SI_KERNEL, "unknown 39" },
    - { do_bad, SIGKILL, SI_KERNEL, "unknown 40" },
    + { do_gpf_ptw, SIGKILL, SI_KERNEL, "Granule Protection Fault at level 0" },
    + { do_gpf_ptw, SIGKILL, SI_KERNEL, "Granule Protection Fault at level 1" },
    + { do_gpf_ptw, SIGKILL, SI_KERNEL, "Granule Protection Fault at level 2" },
    + { do_gpf_ptw, SIGKILL, SI_KERNEL, "Granule Protection Fault at level 3" },
    + { do_gpf, SIGBUS, SI_KERNEL, "Granule Protection Fault not on table walk" },
    { do_bad, SIGKILL, SI_KERNEL, "level -1 address size fault" },
    { do_bad, SIGKILL, SI_KERNEL, "unknown 42" },
    { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level -1 translation fault" },
    --
    2.34.1

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