Hi, On 20-06-18 09:49, Ard Biesheuvel wrote:
On 19 June 2018 at 21:50, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:Commit 79832f0b5f71 ("efi/libstub/tpm: Initialize pointer variables to zero for mixed mode") fixes a problem with the tpm code on mixed mode (64 bit kernel on 32 bit UEFI), where 64-bit pointer variables are not fully initialized by the 32-bit EFI code. The same problem applies to the efi_physical_addr_t variables which are written by the get_event_log EFI call. This commit initializes these to 0 to, to ensure the upper 32 bits are 0 in mixed mode. This fixes recent kernels sometimes hanging during early boot on mixed mode UEFI systems.efi_physical_addr_t is always a 64-bit type, regardless of mixed mode, so this smells like buggy firmware.
That is true. I would not be surprised if this is buggy firmware, this is the infamous Insyde firmware for Bay Trail devices which is weird and special in many ways as it was first written to bring up Android and then modified to run Windows later (I think / it seems). At least the DSDT tables have Android and Windows specific bits and some firmware-s have a setup switch to select which bits get activated, while others try to autodetect which OS they are going to boot. Anyways I will do a v2 with a fixed commit message taking into account that efi_physical_addr_t is always a 64-bit type.
Is the issue 100% reproducible?
Without this change my Asus T100TA boots about once every other time, maybe even worse like once every 3 boots. When it does not boot most of the time it hangs in early boot (before the efifb driver initializes), sometimes it hangs only for a minute or 2 and then reboots. With this change it boots 10 out 10 times, both after a power off + wait 10 sec + on and on regular reboots. Regards, Hans
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> --- drivers/firmware/efi/libstub/tpm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/firmware/efi/libstub/tpm.c b/drivers/firmware/efi/libstub/tpm.c index caa37a6dd9d4..a90b0b8fc69a 100644 --- a/drivers/firmware/efi/libstub/tpm.c +++ b/drivers/firmware/efi/libstub/tpm.c @@ -64,7 +64,7 @@ static void efi_retrieve_tpm2_eventlog_1_2(efi_system_table_t *sys_table_arg) efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID; efi_guid_t linux_eventlog_guid = LINUX_EFI_TPM_EVENT_LOG_GUID; efi_status_t status; - efi_physical_addr_t log_location, log_last_entry; + efi_physical_addr_t log_location = 0, log_last_entry = 0; struct linux_efi_tpm_eventlog *log_tbl = NULL; unsigned long first_entry_addr, last_entry_addr; size_t log_size, last_entry_size; -- 2.17.1
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