From mboxrd@z Thu Jan 1 00:00:00 1970 From: Javier Martinez Canillas Subject: Re: [tpmdd-devel] [PATCH v2 2/3] efi: call get_event_log before ExitBootServices Date: Mon, 18 Sep 2017 14:49:00 +0200 Message-ID: References: <20170911100022.7251-1-tweek@google.com> <20170911100022.7251-3-tweek@google.com> <1f25ebdc-ab90-517f-b580-991a7cb5e25a@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Thiebaud Weksteen Cc: linux-efi@vger.kernel.org, Ard Biesheuvel , Matt Fleming , linux-kernel@vger.kernel.org, Matthew Garrett , Jason Gunthorpe , tpmdd-devel@lists.sourceforge.net, jarkko.sakkinen@linux.intel.com, Peter Jones List-Id: tpmdd-devel@lists.sourceforge.net On 09/18/2017 02:11 PM, Thiebaud Weksteen wrote: > On Thu, Sep 14, 2017 at 12:24 PM, Javier Martinez Canillas > wrote: >> On 09/11/2017 12:00 PM, Thiebaud Weksteen via tpmdd-devel wrote: [snip] >>> + >>> + if (status != EFI_SUCCESS) { >>> + efi_printk(sys_table_arg, >>> + "Unable to allocate memory for event log\n"); >>> + return; >>> + } >> >> If this fails or any previous error that will prevent the event log table + logs >> to be allocated, shouldn't tpm_read_log_efi() be notified somehow? Since AFAICT >> it will still try to access them even if the EFI allocate_pool did not succeed. >> > > The implicit part that covers this case is in > drivers/firmware/efi/efi.c. The match_config_table function will go > through all the installed configuration tables and only fill up the > associated member of the efi structure if it exists. In this case, > .tpm_log will remains at EFI_INVALID_TABLE_ADDR unless > efi_call_early(install_configuration_table, ...) is called. So no > further processing is to be expected should the allocation failed. > I see, missed that. Thanks a lot for the explanation. >>> + */ >>> +int __init efi_tpm_eventlog_init(void) >>> +{ >>> + struct linux_efi_tpm_eventlog *tbl; >>> + unsigned int tbl_size; >>> + >> >> The functions efi_retrieve_tpm2_eventlog_1_2() and tpm_read_log_efi() are using >> log_tbl as variable name, so I would use it here too for consistency. >> > > Done. > >>> + if (efi.tpm_log == EFI_INVALID_TABLE_ADDR) >>> + return 0; >>> + >>> + tbl = early_memremap(efi.tpm_log, sizeof(*tbl)); >>> + if (!tbl) { >>> + pr_err("Failed to map TPM Event Log table @ 0x%lx\n", >>> + efi.tpm_log); >>> + return -ENOMEM; >>> + } >>> + >> >> Same question than before, if this fails then the table + logs memory won't be >> reserved but tpm_read_log_efi() will still try to access it. I'm not sure what >> is the correct way to notify though, maybe setting efi.tpm_log to 0 and then in >> tpm_read_log_efi() check efi.tpm_log for 0 or EFI_INVALID_TABLE_ADDR instead? >> > > That's right. To keep it simple, it might be easier to just set > tpm_log to EFI_INVALID_TABLE_ADDR if that happens. Added in the next > version of the patch set. > Right. I wasn't sure if you wanted to distinguish between the two cases, but that is simpler indeed. Best regards, -- Javier Martinez Canillas Software Engineer - Desktop Hardware Enablement Red Hat