linux.c32: make load_linux() support relocation

In the case where the preferred kernel locations are not available,
make load_linux() smart enough to be able to relocate the kernel if at
all possible.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

diff --git a/com32/include/syslinux/align.h b/com32/include/syslinux/align.h
new file mode 100644 (file)
index 0000000..5b01bf2
--- /dev/null
+++ b/com32/include/syslinux/align.h
@@ -0,0 +1,47 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   Copyright 2009 Intel Corporation; author H. Peter Anvin
+ *
+ *   Permission is hereby granted, free of charge, to any person
+ *   obtaining a copy of this software and associated documentation
+ *   files (the "Software"), to deal in the Software without
+ *   restriction, including without limitation the rights to use,
+ *   copy, modify, merge, publish, distribute, sublicense, and/or
+ *   sell copies of the Software, and to permit persons to whom
+ *   the Software is furnished to do so, subject to the following
+ *   conditions:
+ *
+ *   The above copyright notice and this permission notice shall
+ *   be included in all copies or substantial portions of the Software.
+ *
+ *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ *   OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * ----------------------------------------------------------------------- */
+
+#ifndef _SYSLINUX_ALIGN_H
+#define _SYSLINUX_ALIGN_H
+
+#include <stdint.h>
+
+static inline uintptr_t __align_down(uintptr_t __p, uintptr_t __a)
+{
+  return __p & ~(__a - 1);
+}
+static inline uintptr_t __align_up(uintptr_t __p, uintptr_t __a)
+{
+  return (__p + __a - 1) & ~(__a - 1);
+}
+
+#define ALIGN_UP(p,a) ((__typeof__(p))__align_up((uintptr_t)(p), (a)))
+#define ALIGN_DOWN(p,a) ((__typeof__(p))__align_down((uintptr_t)(p), (a)))
+#define ALIGN_UP_FOR(p,t) ALIGN_UP(p,sizeof(t))
+#define ALIGN_DOWN_FOR(p,t) ALIGN_DOWN(p,sizeof(t))
+
+#endif /* _SYSLINUX_ALIGN_H */

diff --git a/com32/lib/sys/argv.c b/com32/lib/sys/argv.c
index 0d16bfe..8b55d94 100644 (file)
--- a/com32/lib/sys/argv.c
+++ b/com32/lib/sys/argv.c
@@ -1,6 +1,6 @@
 /* ----------------------------------------------------------------------- *
  *
- *   Copyright 2004-2008 H. Peter Anvin - All Rights Reserved
+ *   Copyright 2004-2009 H. Peter Anvin - All Rights Reserved
  *
  *   Permission is hereby granted, free of charge, to any person
  *   obtaining a copy of this software and associated documentation
@@ -35,8 +35,7 @@
 #include <inttypes.h>
 #include <stddef.h>
 #include <stdio.h>
-
-#define ALIGN_UP(p,t)       ((t *)(((uintptr_t)(p) + (sizeof(t)-1)) & ~(sizeof(t)-1)))
+#include <syslinux/align.h>
 
 extern char _end[];         /* Symbol created by linker */
 void *__mem_end = &_end;     /* Global variable for use by malloc() */
@@ -75,7 +74,7 @@ int __parse_argv(char ***argv, const char *str)
   }
 
   /* Now create argv */
-  arg = ALIGN_UP(q,char *);
+  arg = ALIGN_UP_FOR(q, char *);
   *argv = arg;
   *arg++ = argv0;              /* argv[0] */
 

diff --git a/com32/lib/syslinux/load_linux.c b/com32/lib/syslinux/load_linux.c
index cca2efd..4f583cd 100644 (file)
--- a/com32/lib/syslinux/load_linux.c
+++ b/com32/lib/syslinux/load_linux.c
@@ -31,9 +31,11 @@
  * Load a Linux kernel (Image/zImage/bzImage).
  */
 
+#include <stdbool.h>
 #include <stdlib.h>
 #include <inttypes.h>
 #include <string.h>
+#include <syslinux/align.h>
 #include <syslinux/linux.h>
 #include <syslinux/bootrm.h>
 #include <syslinux/movebits.h>
@@ -159,6 +161,7 @@ int syslinux_boot_linux(void *kernel_buf, size_t kernel_size,
   struct syslinux_movelist *fraglist = NULL;
   struct syslinux_memmap *mmap = NULL;
   struct syslinux_memmap *amap = NULL;
+  bool ok;
 
   cmdline_size = strlen(cmdline)+1;
 
@@ -189,6 +192,9 @@ int syslinux_boot_linux(void *kernel_buf, size_t kernel_size,
   if (!memlimit || memlimit-1 > hdr.initrd_addr_max)
     memlimit = hdr.initrd_addr_max+1; /* Zero for no limit */
 
+  if (hdr.version < 0x0205)
+    hdr.relocatable_kernel = 0;
+
   if (hdr.version < 0x0206)
     hdr.cmdline_max_len = 256;
 
@@ -250,7 +256,79 @@ int syslinux_boot_linux(void *kernel_buf, size_t kernel_size,
 
   /* Place the kernel in memory */
 
+  /* First, find a suitable place for the protected-mode code */
+  if (syslinux_memmap_type(amap, prot_mode_base, prot_mode_size)
+      != SMT_FREE) {
+    const struct syslinux_memmap *mp;
+    if (!hdr.relocatable_kernel)
+      goto bail;               /* Can't relocate - no hope */
+
+    ok = false;
+    for (mp = amap; mp; mp = mp->next) {
+      addr_t start, end;
+      start = mp->start;
+      end = mp->next->start;
+
+      if (mp->type != SMT_FREE)
+       continue;
+
+      if (end <= prot_mode_base)
+       continue;               /* Only relocate upwards */
+
+      if (start <= prot_mode_base)
+       start = prot_mode_base;
+
+      start = ALIGN_UP(start, hdr.kernel_alignment);
+      if (start >= end)
+       continue;
+
+      /* The 3* here is a total fudge factor... it's supposed to
+        account for the fact that the kernel needs to be decompressed,
+        and then followed by the BSS and BRK regions.  This doesn't,
+        however, account for the fact that the kernel is decompressed
+        into a whole other place, either. */
+      if (end - start >= 3*prot_mode_size) {
+       prot_mode_base = start;
+       ok = true;
+       break;
+      }
+    }
+
+    if (!ok)
+      goto bail;
+  }
+
   /* Real mode code */
+  if (syslinux_memmap_type(amap, real_mode_base,
+                          cmdline_offset+cmdline_size) != SMT_FREE) {
+    const struct syslinux_memmap *mp;
+
+    ok = false;
+    for (mp = amap; mp; mp = mp->next) {
+      addr_t start, end;
+      start = mp->start;
+      end = mp->next->start;
+
+      if (mp->type != SMT_FREE)
+       continue;
+
+      if (start < real_mode_base)
+       start = real_mode_base; /* Lowest address we'll use */
+      if (end > 640*1024)
+       end = 640*1024;
+
+      start = ALIGN_UP(start, 16);
+      if (start >= end)
+       continue;
+
+      if (end - start >= cmdline_offset+cmdline_size) {
+       real_mode_base = start;
+       ok = true;
+       break;
+      }
+    }
+  }
+
   if (syslinux_add_movelist(&fraglist, real_mode_base, (addr_t)kernel_buf,
                            real_mode_size))
     goto bail;