| Message ID | 20210305093958.187358-2-ardb@kernel.org |
|---|---|
| State | Accepted |
| Commit | 9e9888a0fe97b9501a40f717225d2bef7100a2c1 |
| Headers | show |
| Series | use RT_PROPERTIES table to implement efi=novamap | expand |
On Fri, Mar 05, 2021 at 10:39:58AM +0100, Ard Biesheuvel wrote: > The EFI_RT_PROPERTIES_TABLE contains a mask of runtime services that are > available after ExitBootServices(). This mostly does not concern the EFI > stub at all, given that it runs before that. However, there is one call > that is made at runtime, which is the call to SetVirtualAddressMap() > (which is not even callable at boot time to begin with) > > So add the missing handling of the RT_PROP table to ensure that we only > call SetVirtualAddressMap() if it is not being advertised as unsupported > by the firmware. > > Signed-off-by: Ard Biesheuvel <ardb@kernel.org> On Lenovo Yoga C630 laptop: Tested-by: Shawn Guo <shawn.guo@linaro.org> It's a great help to dropping 'efi=novamap' kernel cmdline, which is a very nice thing for distros to support Snapdragon laptops. Thanks much, Ard! Shawn
diff --git a/drivers/firmware/efi/libstub/efi-stub.c b/drivers/firmware/efi/libstub/efi-stub.c index ec2f3985bef3..26e69788f27a 100644 --- a/drivers/firmware/efi/libstub/efi-stub.c +++ b/drivers/firmware/efi/libstub/efi-stub.c @@ -96,6 +96,18 @@ static void install_memreserve_table(void) efi_err("Failed to install memreserve config table!\n"); } +static u32 get_supported_rt_services(void) +{ + const efi_rt_properties_table_t *rt_prop_table; + u32 supported = EFI_RT_SUPPORTED_ALL; + + rt_prop_table = get_efi_config_table(EFI_RT_PROPERTIES_TABLE_GUID); + if (rt_prop_table) + supported &= rt_prop_table->runtime_services_supported; + + return supported; +} + /* * EFI entry point for the arm/arm64 EFI stubs. This is the entrypoint * that is described in the PE/COFF header. Most of the code is the same @@ -250,6 +262,10 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, (prop_tbl->memory_protection_attribute & EFI_PROPERTIES_RUNTIME_MEMORY_PROTECTION_NON_EXECUTABLE_PE_DATA); + /* force efi_novamap if SetVirtualAddressMap() is unsupported */ + efi_novamap |= !(get_supported_rt_services() & + EFI_RT_SUPPORTED_SET_VIRTUAL_ADDRESS_MAP); + /* hibernation expects the runtime regions to stay in the same place */ if (!IS_ENABLED(CONFIG_HIBERNATION) && !efi_nokaslr && !flat_va_mapping) { /*
The EFI_RT_PROPERTIES_TABLE contains a mask of runtime services that are available after ExitBootServices(). This mostly does not concern the EFI stub at all, given that it runs before that. However, there is one call that is made at runtime, which is the call to SetVirtualAddressMap() (which is not even callable at boot time to begin with) So add the missing handling of the RT_PROP table to ensure that we only call SetVirtualAddressMap() if it is not being advertised as unsupported by the firmware. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- drivers/firmware/efi/libstub/efi-stub.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)