amd64: introduce hook for custom preload metadata parsers

Add hooks to amd64 in order to have diverging implementations, since
on Xen PV the metadata is passed to the kernel in a different form.

Approbed by: gibbs
Sponsored by: Citrix Systems R&D

amd64/amd64/machdep.c:
 - Define init_ops for native.
 - Put native code inside of native_parse_preload_data hook.
 - Call the parse_preload_data in order to fill the metadata info.

x86/include/init.h:
 - Declare the init_ops struct.

x86/xen/pv.c:
 - Declare xen_init_ops that contains the Xen PV implementation of
   init_ops.
 - Implement the parse_preload_data for Xen PVH, the info is fetched
   from HYPERVISOR_start_info->cmd_line as provided by Xen.

1 files changed, 63 insertions, 0 deletions

diff --git a/sys/x86/xen/pv.c b/sys/x86/xen/pv.c
index 94985e3d1ad9..63dc39b92709 100644
--- a/sys/x86/xen/pv.c
+++ b/sys/x86/xen/pv.c
@@ -37,6 +37,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/lock.h>
 #include <sys/rwlock.h>
 #include <sys/boot.h>
+#include <sys/ctype.h>
 
 #include <vm/vm.h>
 #include <vm/vm_extern.h>
@@ -47,6 +48,8 @@ __FBSDID("$FreeBSD$");
 #include <vm/vm_pager.h>
 #include <vm/vm_param.h>
 
+#include <x86/init.h>
+
 #include <xen/xen-os.h>
 #include <xen/hypervisor.h>
 
@@ -55,6 +58,16 @@ extern u_int64_t hammer_time(u_int64_t, u_int64_t);
 /* Xen initial function */
 uint64_t hammer_time_xen(start_info_t *, uint64_t);
 
+/*--------------------------- Forward Declarations ---------------------------*/
+static caddr_t xen_pv_parse_preload_data(u_int64_t);
+
+/*-------------------------------- Global Data -------------------------------*/
+/* Xen init_ops implementation. */
+struct init_ops xen_init_ops = {
+	.parse_preload_data =	xen_pv_parse_preload_data,
+};
+
+/*-------------------------------- Xen PV init -------------------------------*/
 /*
  * First function called by the Xen PVH boot sequence.
  *
@@ -119,6 +132,56 @@ hammer_time_xen(start_info_t *si, uint64_t xenstack)
 	}
 	load_cr3(((uint64_t)&PT4[0]) - KERNBASE);
 
+	/* Set the hooks for early functions that diverge from bare metal */
+	init_ops = xen_init_ops;
+
 	/* Now we can jump into the native init function */
 	return (hammer_time(0, physfree));
 }
+
+/*-------------------------------- PV specific -------------------------------*/
+/*
+ * Functions to convert the "extra" parameters passed by Xen
+ * into FreeBSD boot options.
+ */
+static void
+xen_pv_set_env(void)
+{
+	char *cmd_line_next, *cmd_line;
+	size_t env_size;
+
+	cmd_line = HYPERVISOR_start_info->cmd_line;
+	env_size = sizeof(HYPERVISOR_start_info->cmd_line);
+
+	/* Skip leading spaces */
+	for (; isspace(*cmd_line) && (env_size != 0); cmd_line++)
+		env_size--;
+
+	/* Replace ',' with '\0' */
+	for (cmd_line_next = cmd_line; strsep(&cmd_line_next, ",") != NULL;)
+		;
+
+	init_static_kenv(cmd_line, env_size);
+}
+
+static void
+xen_pv_set_boothowto(void)
+{
+	int i;
+
+	/* get equivalents from the environment */
+	for (i = 0; howto_names[i].ev != NULL; i++) {
+		if (getenv(howto_names[i].ev) != NULL)
+			boothowto |= howto_names[i].mask;
+	}
+}
+
+static caddr_t
+xen_pv_parse_preload_data(u_int64_t modulep)
+{
+	/* Parse the extra boot information given by Xen */
+	xen_pv_set_env();
+	xen_pv_set_boothowto();
+
+	return (NULL);
+}