[prefix] Allow an initrd to be passed to iPXE

Allow an initrd (such as an embedded script) to be passed to iPXE when loaded as a .lkrn (or .iso) image. This allows an embedded script to be varied without recompiling iPXE. Signed-off-by: Michael Brown <mcb30@ipxe.org>
ipxe · Nov 12, 2011 · 27fdb95 · 27fdb95
1 parent 2422647
commit 27fdb95
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Showing 4 changed files with 262 additions and 124 deletions.
diff --git a/src/arch/i386/core/cmdline.c b/src/arch/i386/core/cmdline.c
diff --git a/src/arch/i386/core/runtime.c b/src/arch/i386/core/runtime.c
@@ -0,0 +1,249 @@
+/*
+ * Copyright (C) 2011 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+/** @file
+ *
+ * Command line and initrd passed to iPXE at runtime
+ *
+ */
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <assert.h>
+#include <ipxe/init.h>
+#include <ipxe/image.h>
+#include <ipxe/script.h>
+#include <ipxe/umalloc.h>
+#include <realmode.h>
+
+/** Command line physical address
+ *
+ * This can be set by the prefix.
+ */
+uint32_t __bss16 ( cmdline_phys );
+#define cmdline_phys __use_data16 ( cmdline_phys )
+
+/** initrd physical address
+ *
+ * This can be set by the prefix.
+ */
+uint32_t __bss16 ( initrd_phys );
+#define initrd_phys __use_data16 ( initrd_phys )
+
+/** initrd length
+ *
+ * This can be set by the prefix.
+ */
+uint32_t __bss16 ( initrd_len );
+#define initrd_len __use_data16 ( initrd_len )
+
+/** Internal copy of the command line */
+static char *cmdline_copy;
+
+/** Free command line image */
+static void cmdline_image_free ( struct refcnt *refcnt ) {
+	struct image *image = container_of ( refcnt, struct image, refcnt );
+
+	DBGC ( image, "RUNTIME freeing command line\n" );
+	free ( cmdline_copy );
+}
+
+/** Embedded script representing the command line */
+static struct image cmdline_image = {
+	.refcnt = REF_INIT ( cmdline_image_free ),
+	.name = "<CMDLINE>",
+	.type = &script_image_type,
+};
+
+/** Colour for debug messages */
+#define colour &cmdline_image
+
+/**
+ * Strip unwanted cruft from command line
+ *
+ * @v cmdline		Command line
+ * @v cruft		Initial substring of cruft to strip
+ */
+static void cmdline_strip ( char *cmdline, const char *cruft ) {
+	char *strip;
+	char *strip_end;
+
+	/* Find unwanted cruft, if present */
+	if ( ! ( strip = strstr ( cmdline, cruft ) ) )
+		return;
+
+	/* Strip unwanted cruft */
+	strip_end = strchr ( strip, ' ' );
+	if ( strip_end ) {
+		*strip_end = '\0';
+		DBGC ( colour, "RUNTIME stripping \"%s\"\n", strip );
+		strcpy ( strip, ( strip_end + 1 ) );
+	} else {
+		DBGC ( colour, "RUNTIME stripping \"%s\"\n", strip );
+		*strip = '\0';
+	}
+}
+
+/**
+ * Initialise command line
+ *
+ * @ret rc		Return status code
+ */
+static int cmdline_init ( void ) {
+	userptr_t cmdline_user;
+	char *cmdline;
+	size_t len;
+	int rc;
+
+	/* Do nothing if no command line was specified */
+	if ( ! cmdline_phys ) {
+		DBGC ( colour, "RUNTIME found no command line\n" );
+		return 0;
+	}
+	cmdline_user = phys_to_user ( cmdline_phys );
+	len = ( strlen_user ( cmdline_user, 0 ) + 1 /* NUL */ );
+
+	/* Allocate and copy command line */
+	cmdline_copy = malloc ( len );
+	if ( ! cmdline_copy ) {
+		DBGC ( colour, "RUNTIME could not allocate %zd bytes for "
+		       "command line\n", len );
+		rc = -ENOMEM;
+		goto err_alloc_cmdline_copy;
+	}
+	cmdline = cmdline_copy;
+	copy_from_user ( cmdline, cmdline_user, 0, len );
+	DBGC ( colour, "RUNTIME found command line \"%s\"\n", cmdline );
+
+	/* Strip unwanted cruft from the command line */
+	cmdline_strip ( cmdline, "BOOT_IMAGE=" );
+	cmdline_strip ( cmdline, "initrd=" );
+	while ( isspace ( *cmdline ) )
+		cmdline++;
+	DBGC ( colour, "RUNTIME using command line \"%s\"\n", cmdline );
+
+	/* Prepare and register image */
+	cmdline_image.data = virt_to_user ( cmdline );
+	cmdline_image.len = strlen ( cmdline );
+	if ( cmdline_image.len ) {
+		if ( ( rc = register_image ( &cmdline_image ) ) != 0 ) {
+			DBGC ( colour, "RUNTIME could not register command "
+			       "line: %s\n", strerror ( rc ) );
+			goto err_register_image;
+		}
+	}
+
+	/* Drop our reference to the image */
+	image_put ( &cmdline_image );
+
+	return 0;
+
+ err_register_image:
+	image_put ( &cmdline_image );
+ err_alloc_cmdline_copy:
+	return rc;
+}
+
+/**
+ * Initialise initrd
+ *
+ * @ret rc		Return status code
+ */
+static int initrd_init ( void ) {
+	struct image *image;
+	int rc;
+
+	/* Do nothing if no initrd was specified */
+	if ( ! initrd_phys ) {
+		DBGC ( colour, "RUNTIME found no initrd\n" );
+		return 0;
+	}
+	if ( ! initrd_len ) {
+		DBGC ( colour, "RUNTIME found empty initrd\n" );
+		return 0;
+	}
+	DBGC ( colour, "RUNTIME found initrd at [%x,%x)\n",
+	       initrd_phys, ( initrd_phys + initrd_len ) );
+
+	/* Allocate image */
+	image = alloc_image();
+	if ( ! image ) {
+		DBGC ( colour, "RUNTIME could not allocate image for "
+		       "initrd\n" );
+		goto err_alloc_image;
+	}
+	image_set_name ( image, "<INITRD>" );
+
+	/* Allocate and copy initrd content */
+	image->data = umalloc ( initrd_len );
+	if ( ! image->data ) {
+		DBGC ( colour, "RUNTIME could not allocate %zd bytes for "
+		       "initrd\n", initrd_len );
+		goto err_umalloc;
+	}
+	image->len = initrd_len;
+	memcpy_user ( image->data, 0, phys_to_user ( initrd_phys ), 0,
+		      initrd_len );
+
+	/* Register image */
+	if ( ( rc = register_image ( image ) ) != 0 ) {
+		DBGC ( colour, "RUNTIME could not register initrd: %s\n",
+		       strerror ( rc ) );
+		goto err_register_image;
+	}
+
+	/* Drop our reference to the image */
+	image_put ( image );
+
+	return 0;
+
+ err_register_image:
+ err_umalloc:
+	image_put ( image );
+ err_alloc_image:
+	return rc;
+}
+
+/**
+ * Initialise command line and initrd
+ *
+ */
+static void runtime_init ( void ) {
+	int rc;
+
+	/* Initialise command line */
+	if ( ( rc = cmdline_init() ) != 0 ) {
+		/* No way to report failure */
+		return;
+	}
+
+	/* Initialise initrd */
+	if ( ( rc = initrd_init() ) != 0 ) {
+		/* No way to report failure */
+		return;
+	}
+}
+
+/** Command line and initrd initialisation function */
+struct init_fn runtime_init_fn __init_fn ( INIT_NORMAL ) = {
+	.initialise = runtime_init,
+};
diff --git a/src/arch/i386/include/bits/errfile.h b/src/arch/i386/include/bits/errfile.h
@@ -15,6 +15,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define ERRFILE_biosint		( ERRFILE_ARCH | ERRFILE_CORE | 0x00040000 )
 #define ERRFILE_int13		( ERRFILE_ARCH | ERRFILE_CORE | 0x00050000 )
 #define ERRFILE_pxeparent	( ERRFILE_ARCH | ERRFILE_CORE | 0x00060000 )
+#define ERRFILE_runtime		( ERRFILE_ARCH | ERRFILE_CORE | 0x00070000 )
 
 #define ERRFILE_bootsector     ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x00000000 )
 #define ERRFILE_bzimage	       ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x00010000 )