grub2/0159-powerpc-adjust-setting-of-prefix-for-signed-binary-c.patch

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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
($fwdevice)/grub2. This ends up being (ieee1275/disk)/grub2 and that
falls apart pretty quickly - there's no file-system on ieee1275/disk,
and it makes the search routine try things like
(ieee1275/disk,msdos2)(ieee1275/disk)/grub2 which also doesn't work.
Detect if we would be about to create (ieee1275/disk)/path and don't:
preserve a prefix of /path instead and hope the search later finds us.
Related: rhbz#1899864
Signed-off-by: Daniel Axtens <dja@axtens.net>
[rharwood@redhat.com: squash in fixup commit]
Signed-off-by: Robbie Harwood <rharwood@redhat.com>
---
grub-core/kern/main.c | 47 +++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 43 insertions(+), 4 deletions(-)
diff --git a/grub-core/kern/main.c b/grub-core/kern/main.c
index 353a62ef1e1..dbd4f596fbe 100644
--- a/grub-core/kern/main.c
+++ b/grub-core/kern/main.c
@@ -217,12 +217,51 @@ grub_set_prefix_and_root (void)
{
char *prefix_set;
- prefix_set = grub_xasprintf ("(%s)%s", device, path ? : "");
- if (prefix_set)
+#ifdef __powerpc__
+ /* We have to be careful here on powerpc-ieee1275 + signed grub. We
+ will have signed something with a prefix that doesn't have a device
+ because we cannot know in advance what partition we're on.
+
+ We will have had !device earlier, so we will have set device=fwdevice
+ However, we want to make sure we do not end up setting prefix to be
+ ($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);
}