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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Daniel Axtens <dja@axtens.net>
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
($fwdevice)/grub2. This ends up being (ieee1275/disk)/grub2 and that
falls apart pretty quickly - there's no file-system on ieee1275/disk,
and it makes the search routine try things like
(ieee1275/disk,msdos2)(ieee1275/disk)/grub2 which also doesn't work.
Detect if we would be about to create (ieee1275/disk)/path and don't:
preserve a prefix of /path instead and hope the search later finds us.
Related: rhbz#1899864
Signed-off-by: Daniel Axtens <dja@axtens.net>
---
grub-core/kern/main.c | 38 +++++++++++++++++++++++++++++++++-----
1 file changed, 33 insertions(+), 5 deletions(-)
diff --git a/grub-core/kern/main.c b/grub-core/kern/main.c
index 0285e95a2bb..e809a5edec1 100644
--- a/grub-core/kern/main.c
+++ b/grub-core/kern/main.c
@@ -216,13 +216,41 @@ grub_set_prefix_and_root (void)
if (device)
{
char *prefix_set;
-
- prefix_set = grub_xasprintf ("(%s)%s", device, path ? : "");
- if (prefix_set)
+
+#ifdef __powerpc__
+ /* We have to be careful here on powerpc-ieee1275 + signed grub. We
+ will have signed something with a prefix that doesn't have a device
+ because we cannot know in advance what partition we're on.
+
+ We will have had !device earlier, so we will have set device=fwdevice
+ However, we want to make sure we do not end up setting prefix to be
+ ($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
+
+ So we only need to act if device = ieee1275/disk exactly.
+ */
+ if (grub_strncmp (device, "ieee1275/disk", 14) == 0)
+ 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);
}