On Tue, Mar 23, 2021 at 01:39:40PM -0700, Sami Tolvanen wrote:
> With CONFIG_CFI_CLANG, the compiler replaces function pointers with
> jump table addresses, which results in __pa_symbol returning the
> physical address of the jump table entry. As the jump table contains
> an immediate jump to an EL1 virtual address, this typically won't
> work as intended. Use __pa_function instead to get the address to
> cpu_resume.
>
> Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
> drivers/firmware/psci/psci.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
> index f5fc429cae3f..facd3cce3244 100644
> --- a/drivers/firmware/psci/psci.c
> +++ b/drivers/firmware/psci/psci.c
> @@ -326,7 +326,7 @@ static int psci_suspend_finisher(unsigned long state)
> {
> u32 power_state = state;
>
> - return psci_ops.cpu_suspend(power_state, __pa_symbol(cpu_resume));
> + return psci_ops.cpu_suspend(power_state, __pa_function(cpu_resume));
As mentioned on the patch adding __pa_function(), I'd prefer to keep the
whatever->phys conversion separate from the CFI removal, since we have a
number of distinct virtual address ranges with differing conversions to
phys, and I don't think it's clear that __pa_function() only works for
kernel symbols (rather than module addresses, linear map addresses,
etc).
Other than that, I'm happy in principle with wrapping this. I suspect
that for clarity we should add an intermediate variable, e.g.
| phys_addr_t pa_cpu_resume = pa_symbol(function_nocfi(cpu_resume));
| return psci_ops.cpu_suspend(power_state, pa_cpu_resume)
Thanks,
Mark.
> }
>
> int psci_cpu_suspend_enter(u32 state)
> @@ -345,7 +345,7 @@ int psci_cpu_suspend_enter(u32 state)
> static int psci_system_suspend(unsigned long unused)
> {
> return invoke_psci_fn(PSCI_FN_NATIVE(1_0, SYSTEM_SUSPEND),
> - __pa_symbol(cpu_resume), 0, 0);
> + __pa_function(cpu_resume), 0, 0);
> }
>
> static int psci_system_suspend_enter(suspend_state_t state)
> --
> 2.31.0.291.g576ba9dcdaf-goog
>
