Messages in this thread | | | From | Junichi Nomura <> | Subject | Re: [PATCH v4] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel | Date | Thu, 11 Apr 2019 08:16:45 +0000 |
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On 4/11/19 5:09 PM, Borislav Petkov wrote: > On Wed, Apr 10, 2019 at 11:34:51PM +0000, Junichi Nomura wrote: >> But efi_get_rsdp_addr() needs to check whether the kernel was >> kexec booted to avoid accessing invalid EFI table address. >> efi_get_kexec_setup_data_addr() is the only method I know >> to check if it was kexec-booted. > > Your v3 had the right approach - you first check if you can get the > address as a kexec-ed kernel. If you do, you use that one and continue > the normal path. > > If you don't, you fall back to efi_get_rsdp_addr() and get it directly > from EFI. > > And then carve out the functionality you need to call multiple times in > helper functions like __efi_get_rsdp_addr(). > > Why doesn't that work anymore?
kexec_get_rsdp_addr() might fail on kexec-booted kernel, e.g. if the setup_data was invalid. In such a case, falling back to efi_get_rsdp_addr() will hit the problem of accessing invalid table pointer again.
-- Jun'ichi Nomura, NEC Corporation / NEC Solution Innovators, Ltd. | |