[Devel] [PATCH vz10 20/32] ve: compile the per-Container VDSO copies only on x86

[Konstantin Khorenko <khorenko@virtuozzo.com>]

From: Eva Kurchatova <eva.kurchatova@virtuozzo.com>

Every Container gets its own copy of the VDSO images so that the Linux
version code inside them can be patched to whatever the Container's
os_release says.  All of that is built on vdso_image_64 / vdso_image_32,
which exist on x86 only, while kernel/ve/ve.c is generic code - so the
file does not compile on an architecture without them, User Mode Linux
being the one we now want for KUnit:

  kernel/ve/ve.c: error: 'vdso_image_64' undeclared here
                  (not in a function)

Guard the ve0 initializer, copy_vdso()/ve_free_vdso() and their callers
with CONFIG_X86, and give ve_free_vdso() a no-op stub so the error path of
ve_create() stays as it is.  Its err_vdso label stays reachable either
way, since ve_mount_devtmpfs() jumps to it too.  A Container on an
architecture without a patchable VDSO simply keeps the host's.

Feature: mm: vdso virtualization
https://virtuozzo.atlassian.net/browse/VSTOR-134732
Signed-off-by: Eva Kurchatova <eva.kurchatova@virtuozzo.com>
Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
---
 kernel/ve/ve.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/kernel/ve/ve.c b/kernel/ve/ve.c
index 73d1c3b4873e..3a9f3841fe55 100644
--- a/kernel/ve/ve.c
+++ b/kernel/ve/ve.c
@@ -85,8 +85,10 @@ struct ve_struct ve0 = {
 	.meminfo_val		= VE_MEMINFO_SYSTEM,
 	.umh_running_helpers    = ATOMIC_INIT(0),
 	.umh_helpers_waitq      = __WAIT_QUEUE_HEAD_INITIALIZER(ve0.umh_helpers_waitq),
+#ifdef CONFIG_X86
 	.vdso_64		= (struct vdso_image*)&vdso_image_64,
 	.vdso_32		= (struct vdso_image*)&vdso_image_32,
+#endif
 };
 EXPORT_SYMBOL(ve0);
 
@@ -675,6 +677,7 @@ u64 ve_get_uptime(struct ve_struct *ve)
 }
 EXPORT_SYMBOL(ve_get_uptime);
 
+#ifdef CONFIG_X86
 static int copy_vdso(struct vdso_image **vdso_dst, const struct vdso_image *vdso_src)
 {
 	struct vdso_image *vdso;
@@ -712,6 +715,9 @@ static void ve_free_vdso(struct ve_struct *ve)
 		kfree(ve->vdso_32);
 	}
 }
+#else
+static inline void ve_free_vdso(struct ve_struct *ve) { }
+#endif
 
 static struct cgroup_subsys_state *ve_create(struct cgroup_subsys_state *parent_css)
 {
@@ -758,6 +764,7 @@ static struct cgroup_subsys_state *ve_create(struct cgroup_subsys_state *parent_
 	if (err)
 		goto err_log;
 
+#ifdef CONFIG_X86
 	err = copy_vdso(&ve->vdso_64, &vdso_image_64);
 	if (err)
 		goto err_vdso;
@@ -765,6 +772,7 @@ static struct cgroup_subsys_state *ve_create(struct cgroup_subsys_state *parent_
 	err = copy_vdso(&ve->vdso_32, &vdso_image_32);
 	if (err)
 		goto err_vdso;
+#endif
 
 	err = ve_mount_devtmpfs(ve);
 	if (err)
@@ -1158,8 +1166,10 @@ static ssize_t ve_os_release_write(struct kernfs_open_file *of, char *buf,
 
 	if (sscanf(buf, "%d.%d.%d", &n1, &n2, &n3) == 3) {
 		new_version = ((n1 << 16) + (n2 << 8)) + n3;
+#ifdef CONFIG_X86
 		*((int *)(ve->vdso_64->data + ve->vdso_64->sym_linux_version_code)) = new_version;
 		*((int *)(ve->vdso_32->data + ve->vdso_32->sym_linux_version_code)) = new_version;
+#endif
 	}
 
 	down_write(&uts_sem);
-- 
2.47.1