From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Mon, 19 Jul 2021 14:35:55 +1000 Subject: [PATCH] powerpc: adjust setting of prefix for signed binary case On RHEL-signed powerpc grub, we sign a grub with -p /grub2 and expect that there's a boot partition. Unfortunately grub_set_prefix_and_root tries to convert this to ($fwdevice)/grub2. This ends up being (ieee1275/disk)/grub2 and that falls apart pretty quickly - there's no file-system on ieee1275/disk, and it makes the search routine try things like (ieee1275/disk,msdos2)(ieee1275/disk)/grub2 which also doesn't work. Detect if we would be about to create (ieee1275/disk)/path and don't: preserve a prefix of /path instead and hope the search later finds us. Related: rhbz#1899864 Signed-off-by: Daniel Axtens [rharwood@redhat.com: squash in fixup commit] Signed-off-by: Robbie Harwood --- grub-core/kern/main.c | 49 ++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 44 insertions(+), 5 deletions(-) diff --git a/grub-core/kern/main.c b/grub-core/kern/main.c index b573be665..3fc340147 100644 --- a/grub-core/kern/main.c +++ b/grub-core/kern/main.c @@ -216,13 +216,52 @@ grub_set_prefix_and_root (void) if (device) { char *prefix_set; - - prefix_set = grub_xasprintf ("(%s)%s", device, path ? : ""); - if (prefix_set) + +#ifdef __powerpc__ + /* We have to be careful here on powerpc-ieee1275 + signed grub. We + will have signed something with a prefix that doesn't have a device + because we cannot know in advance what partition we're on. + + We will have had !device earlier, so we will have set device=fwdevice + However, we want to make sure we do not end up setting prefix to be + ($fwdevice)/path, because we will then end up trying to boot or search + based on a prefix of (ieee1275/disk)/path, which will not work because + it's missing a partition. + + Also: + - You can end up with a device with an FS directly on it, without + a partition, e.g. ieee1275/cdrom. + + - powerpc-ieee1275 + grub-install sets e.g. prefix=(,gpt2)/path, + which will have now been extended to device=$fwdisk,partition + and path=/path + + - PowerVM will give us device names like + ieee1275//vdevice/v-scsi@3000006c/disk@8100000000000000 + and we don't want to try to encode some sort of truth table about + what sorts of paths represent disks with partition tables and those + without partition tables. + + So we act unless there is a comma in the device, which would indicate + a partition has already been specified. + + (If we only have a path, the code in normal to discover config files + will try both without partitions and then with any partitions so we + will cover both CDs and HDs.) + */ + if (grub_strchr (device, ',') == NULL) + grub_env_set ("prefix", path); + else +#endif { - grub_env_set ("prefix", prefix_set); - grub_free (prefix_set); + prefix_set = grub_xasprintf ("(%s)%s", device, path ? : ""); + if (prefix_set) + { + grub_env_set ("prefix", prefix_set); + grub_free (prefix_set); + } } + grub_env_set ("root", device); }