331 lines
9.3 KiB
Diff
331 lines
9.3 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Nicolas Frayer <nfrayer@redhat.com>
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Date: Fri, 31 Mar 2023 20:47:58 +0200
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Subject: [PATCH] emu: Add switch-root to grub-emu
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If the kernel running grub emu is the same as the one we want to
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boot, it makes sense that we just switch-root instead of kexec
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the same kernel again by doing grub2-emu --switch-root
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Signed-off-by: Nicolas Frayer <nfrayer@redhat.com>
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---
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grub-core/kern/emu/main.c | 5 +-
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grub-core/kern/emu/misc.c | 13 +++
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grub-core/loader/emu/linux.c | 209 +++++++++++++++++++++++++++++++++++++++++--
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include/grub/emu/exec.h | 2 +-
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include/grub/emu/misc.h | 2 +
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5 files changed, 223 insertions(+), 8 deletions(-)
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diff --git a/grub-core/kern/emu/main.c b/grub-core/kern/emu/main.c
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index 38c1576a2ef..61b3181775b 100644
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--- a/grub-core/kern/emu/main.c
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+++ b/grub-core/kern/emu/main.c
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@@ -108,6 +108,7 @@ static struct argp_option options[] = {
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{"verbose", 'v', 0, 0, N_("print verbose messages."), 0},
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{"hold", 'H', N_("SECS"), OPTION_ARG_OPTIONAL, N_("wait until a debugger will attach"), 0},
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{"kexec", 'X', 0, 0, N_("use kexec to boot Linux kernels via systemctl (pass twice to enable dangerous fallback to non-systemctl)."), 0},
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+ {"switch-root", 'W', 0, 0, N_("use switch-root to only switch root filesystem without restarting the kernel."), 0},
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{ 0, 0, 0, 0, 0, 0 }
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};
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@@ -168,7 +169,9 @@ argp_parser (int key, char *arg, struct argp_state *state)
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case 'X':
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grub_util_set_kexecute ();
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break;
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-
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+ case 'W':
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+ grub_util_set_switch_root ();
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+ break;
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case ARGP_KEY_ARG:
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{
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/* Too many arguments. */
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diff --git a/grub-core/kern/emu/misc.c b/grub-core/kern/emu/misc.c
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index d145e5796b3..7b9731b7efa 100644
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--- a/grub-core/kern/emu/misc.c
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+++ b/grub-core/kern/emu/misc.c
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@@ -40,6 +40,7 @@
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int verbosity;
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int kexecute;
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+int switchroot = 0;
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void
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grub_util_warn (const char *fmt, ...)
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@@ -231,3 +232,15 @@ grub_util_get_kexecute (void)
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{
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return kexecute;
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}
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+
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+void
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+grub_util_set_switch_root (void)
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+{
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+ switchroot = 1;
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+}
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+
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+int
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+grub_util_get_switch_root (void)
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+{
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+ return switchroot;
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+}
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diff --git a/grub-core/loader/emu/linux.c b/grub-core/loader/emu/linux.c
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index 7de3f7f8610..6feb0412c58 100644
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--- a/grub-core/loader/emu/linux.c
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+++ b/grub-core/loader/emu/linux.c
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@@ -15,7 +15,6 @@
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* You should have received a copy of the GNU General Public License
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* along with GRUB. If not, see <http://www.gnu.org/licenses/>.
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*/
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-
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#include <grub/loader.h>
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#include <grub/dl.h>
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#include <grub/command.h>
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@@ -33,6 +32,196 @@ static char *kernel_path;
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static char *initrd_path;
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static char *boot_cmdline;
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+static grub_err_t
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+grub_switch_root (void)
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+{
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+ char *tmp = NULL;
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+ char *options_cmd = NULL;
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+ char *options = NULL;
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+ char *subvol = NULL;
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+ char *root_uuid = NULL;
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+ char *kernel_release = NULL;
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+ grub_err_t rc = GRUB_ERR_NONE;
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+ const char *subvol_param = "subvol=";
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+ const char *kernel_release_prefix = "/boot/vmlinuz-";
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+ const char *root_prefix = "root=";
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+ const char *systemctl[] = {"systemctl", "--force", "switch-root", "/sysroot", NULL};
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+ const char *mountrootfs[] = {"mount", root_uuid, "/sysroot", options_cmd, options, NULL};
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+ const char *unamer[] = {"uname", "-r", NULL};
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+ char *uname_buf = NULL;
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+ int i = 0;
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+
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+ /* Extract the kernel release tag from kernel_path */
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+ if (!kernel_path)
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+ {
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+ rc = GRUB_ERR_BAD_ARGUMENT;
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+ grub_dprintf ("linux", "switch_root: No kernel_path found\n");
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+ goto out;
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+ }
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+
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+ if ((kernel_release = grub_xasprintf ("%s", (kernel_path + grub_strlen (kernel_release_prefix)))) == NULL)
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+ {
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+ grub_dprintf ("linux", "switch_root: Failed to allocate memory\n");
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+ rc = GRUB_ERR_BAD_ARGUMENT;
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+ goto out;
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+ }
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+
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+
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+ /* Check for kernel mismatch */
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+ /* Retrieve the current kernel relase tag */
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+ grub_util_exec_redirect (unamer, NULL, "/tmp/version");
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+
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+ grub_file_t f = grub_file_open ("/tmp/version", GRUB_FILE_TYPE_FS_SEARCH);
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+
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+ if (f == NULL)
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+ {
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+ grub_dprintf ("linux", "failed opening file.\n");
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+ rc = GRUB_ERR_FILE_NOT_FOUND;
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+ goto out;
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+ }
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+
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+ if ((uname_buf = grub_malloc (f->size)) == NULL)
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+ {
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+ grub_dprintf ("linux", "switch_root: Failed to allocate memory\n");
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+ rc = GRUB_ERR_OUT_OF_MEMORY;
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+ goto out;
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+ }
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+
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+ if (grub_file_read (f, uname_buf, f->size) < 0)
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+ {
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+ grub_dprintf ("linux", "switch_root: failed to read from file\n");
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+ rc = GRUB_ERR_FILE_READ_ERROR;
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+ goto out;
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+ }
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+
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+ grub_file_close (f);
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+
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+ if (grub_strstr (uname_buf, kernel_release) == NULL)
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+ {
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+ grub_dprintf ("linux", "switch_root: kernel mismatch, not performing switch-root ...\n");
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+ rc = GRUB_ERR_NO_KERNEL;
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+ goto out;
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+ }
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+
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+ /* Extract the root partition from boot_cmdline */
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+ if (!boot_cmdline)
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+ {
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+ rc = GRUB_ERR_BAD_ARGUMENT;
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+ goto out;
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+ }
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+
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+ tmp = grub_strdup (boot_cmdline);
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+
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+ if (tmp == NULL)
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+ {
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+ rc = GRUB_ERR_OUT_OF_MEMORY;
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+ goto out;
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+ }
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+
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+ if ((root_uuid = grub_strstr (tmp, root_prefix)) == NULL)
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+ {
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+ rc = GRUB_ERR_BAD_ARGUMENT;
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+ grub_dprintf ("linux", "switch_root: Can't find rootfs\n");
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+ goto out;
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+ }
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+
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+ root_uuid += grub_strlen (root_prefix);
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+
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+ while (root_uuid[i] != ' ' && root_uuid[i] != '\0')
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+ i++;
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+
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+ root_uuid[i] = '\0';
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+
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+ /* Allocate a new buffer holding root_uuid */
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+ root_uuid = grub_xasprintf ("%s", root_uuid);
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+
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+ if (root_uuid == NULL)
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+ {
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+ grub_dprintf ("linux", "switch_root: Failed to allocated memory\n");
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+ rc = GRUB_ERR_OUT_OF_MEMORY;
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+ goto out;
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+ }
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+
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+ /* Check for subvol parameter */
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+ grub_strcpy (tmp, boot_cmdline);
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+
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+ if ((subvol = grub_strstr(tmp, subvol_param)) != NULL)
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+ {
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+ i = 0;
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+
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+ while (subvol[i] != ' ' && subvol[i] != '\0')
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+ i++;
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+
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+ subvol[i] = '\0';
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+
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+ /* Allocate a new buffer holding subvol */
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+ subvol = grub_xasprintf("%s", subvol);
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+
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+ if (subvol == NULL)
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+ {
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+ grub_dprintf ("linux", "switch_root: Failed to allocated memory\n");
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+ rc = GRUB_ERR_OUT_OF_MEMORY;
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+ goto out;
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+ }
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+
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+ options_cmd = grub_xasprintf("%s", "-o");
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+ options = grub_xasprintf("%s", subvol);
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+ }
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+
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+ if (options == NULL)
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+ {
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+ mountrootfs[3] = NULL;
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+ }
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+ else
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+ {
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+ mountrootfs[3] = options_cmd;
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+ mountrootfs[4] = options;
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+ }
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+
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+ mountrootfs[1] = root_uuid;
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+
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+ grub_dprintf ("linux", "Executing:\n");
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+ grub_dprintf ("linux", "%s %s %s %s %s\n", mountrootfs[0], mountrootfs[1],
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+ mountrootfs[2], mountrootfs[3], mountrootfs[4]);
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+
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+ /* Mount the rootfs */
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+ rc = grub_util_exec (mountrootfs);
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+
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+ if (rc != GRUB_ERR_NONE)
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+ {
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+ grub_dprintf ("linux", "switch_root: Failed.\n");
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+ rc = GRUB_ERR_INVALID_COMMAND;
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+ goto out;
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+ }
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+
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+ grub_dprintf ("linux", "Done.\n");
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+
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+ grub_dprintf ("linux", "%s %s %s %s\n", systemctl[0], systemctl[1],
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+ systemctl[2], systemctl[3]);
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+
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+ /* Switch root */
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+ rc = grub_util_exec (systemctl);
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+
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+ if (rc != GRUB_ERR_NONE)
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+ {
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+ grub_dprintf ("linux", "switch_root: Failed.\n");
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+ rc = GRUB_ERR_INVALID_COMMAND;
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+ goto out;
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+ }
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+
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+ grub_dprintf ("linux", "Done.\n");
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+
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+out:
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+ grub_free (tmp);
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+ grub_free (options_cmd);
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+ grub_free (options);
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+ grub_free (subvol);
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+ grub_free (root_uuid);
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+ grub_free (uname_buf);
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+ grub_free (kernel_release);
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+ return rc;
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+}
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+
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static grub_err_t
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grub_linux_boot (void)
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{
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@@ -51,12 +240,20 @@ grub_linux_boot (void)
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else
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initrd_param = grub_xasprintf ("%s", "");
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- grub_dprintf ("linux", "%serforming 'kexec -la %s %s %s'\n",
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- (kexecute) ? "P" : "Not p",
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- kernel_path, initrd_param, boot_cmdline);
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+ if (grub_util_get_switch_root() == 1)
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+ {
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+ rc = grub_switch_root();
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+ if (rc != GRUB_ERR_NONE)
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+ grub_fatal (N_("Failed to execute switch_root\n"));
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+ }
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+ else if (kexecute)
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+ {
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+ grub_dprintf ("linux", "%serforming 'kexec -la %s %s %s'\n",
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+ (kexecute) ? "P" : "Not p",
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+ kernel_path, initrd_param, boot_cmdline);
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- if (kexecute)
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- rc = grub_util_exec (kexec);
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+ rc = grub_util_exec (kexec);
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+ }
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grub_free (initrd_param);
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diff --git a/include/grub/emu/exec.h b/include/grub/emu/exec.h
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index 1b61b4a2e5d..e82f13215e0 100644
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--- a/include/grub/emu/exec.h
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+++ b/include/grub/emu/exec.h
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@@ -36,7 +36,7 @@ grub_util_exec_redirect_all (const char *const *argv, const char *stdin_file,
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int
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EXPORT_FUNC(grub_util_exec) (const char *const *argv);
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int
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-grub_util_exec_redirect (const char *const *argv, const char *stdin_file,
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+EXPORT_FUNC(grub_util_exec_redirect) (const char *const *argv, const char *stdin_file,
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const char *stdout_file);
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int
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grub_util_exec_redirect_null (const char *const *argv);
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diff --git a/include/grub/emu/misc.h b/include/grub/emu/misc.h
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index 01056954b96..f3a712a8b2f 100644
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--- a/include/grub/emu/misc.h
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+++ b/include/grub/emu/misc.h
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@@ -59,6 +59,8 @@ void EXPORT_FUNC(grub_util_error) (const char *fmt, ...) __attribute__ ((format
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void EXPORT_FUNC(grub_util_set_kexecute) (void);
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int EXPORT_FUNC(grub_util_get_kexecute) (void) WARN_UNUSED_RESULT;
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+void EXPORT_FUNC(grub_util_set_switch_root) (void);
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+int EXPORT_FUNC(grub_util_get_switch_root) (void);
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grub_uint64_t EXPORT_FUNC (grub_util_get_cpu_time_ms) (void);
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