[PATCH] badram filtering

[Robert Millan <rmh@aybabtu.com>]

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Hi,

This patch implements badram filtering in GRUB.  It's the same idea as in
http://rick.vanrein.org/linux/badram/ but applied to GRUB.

The badram module sits between loaders (or other users like lsmmap) and
filters the mmap entries, but only when user previously set the "badram"
variable (whose syntax is the same as the one in badram patch for Linux).

NOTE this won't affect loadees that get the memory map from BIOS instead
of from GRUB.  This means it currently works for Multiboot and for the
new/experimental Linux loader.

-- 
Robert Millan

  The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and
  how) you may access your data; but nobody's threatening your freedom: we
  still allow you to remove your data and not access it at all."

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2009-02-27  Robert Millan  <rmh@aybabtu.com>

	* conf/i386-pc.rmk (pkglib_MODULES): Add `badram.mod'.
	(badram_mod_SOURCES, badram_mod_CFLAGS)
	(badram_mod_LDFLAGS): New variables.
	* conf/i386-coreboot.rmk: Likewise.
	* conf/powerpc-ieee1275.rmk: Likewise.
	* conf/i386-ieee1275.rmk: Likewise.

	* lib/badram.c: New file.
	* include/grub/badram.h: New file.

	* commands/lsmmap.c (grub_cmd_lsmmap): Replace
	grub_machine_mmap_iterate() with grub_badram_mmap_iterate ().
	* loader/i386/linux.c (find_mmap_size, allocate_pages)
	(grub_linux32_boot): Likewise.
	* loader/i386/pc/multiboot.c (grub_get_multiboot_mmap_len)
	(grub_fill_multiboot_mmap): Likewise.

Index: conf/i386-pc.rmk
===================================================================
--- conf/i386-pc.rmk	(revision 2001)
+++ conf/i386-pc.rmk	(working copy)
@@ -370,6 +370,11 @@ lsmmap_mod_SOURCES = commands/lsmmap.c
 lsmmap_mod_CFLAGS = $(COMMON_CFLAGS)
 lsmmap_mod_LDFLAGS = $(COMMON_LDFLAGS)
 
+pkglib_MODULES += badram.mod
+badram_mod_SOURCES = lib/badram.c
+badram_mod_CFLAGS = $(COMMON_CFLAGS)
+badram_mod_LDFLAGS = $(COMMON_LDFLAGS)
+
 # For ata_pthru.mod.
 ata_pthru_mod_SOURCES = disk/ata_pthru.c
 ata_pthru_mod_CFLAGS = $(COMMON_CFLAGS)
Index: conf/i386-coreboot.rmk
===================================================================
--- conf/i386-coreboot.rmk	(revision 2001)
+++ conf/i386-coreboot.rmk	(working copy)
@@ -211,5 +211,10 @@ lsmmap_mod_SOURCES = commands/lsmmap.c
 lsmmap_mod_CFLAGS = $(COMMON_CFLAGS)
 lsmmap_mod_LDFLAGS = $(COMMON_LDFLAGS)
 
+pkglib_MODULES += badram.mod
+badram_mod_SOURCES = lib/badram.c
+badram_mod_CFLAGS = $(COMMON_CFLAGS)
+badram_mod_LDFLAGS = $(COMMON_LDFLAGS)
+
 include $(srcdir)/conf/i386.mk
 include $(srcdir)/conf/common.mk
Index: conf/powerpc-ieee1275.rmk
===================================================================
--- conf/powerpc-ieee1275.rmk	(revision 2001)
+++ conf/powerpc-ieee1275.rmk	(working copy)
@@ -181,5 +181,10 @@ lsmmap_mod_SOURCES = commands/lsmmap.c
 lsmmap_mod_CFLAGS = $(COMMON_CFLAGS)
 lsmmap_mod_LDFLAGS = $(COMMON_LDFLAGS)
 
+pkglib_MODULES += badram.mod
+badram_mod_SOURCES = lib/badram.c
+badram_mod_CFLAGS = $(COMMON_CFLAGS)
+badram_mod_LDFLAGS = $(COMMON_LDFLAGS)
+
 include $(srcdir)/conf/common.mk
 
Index: conf/i386-ieee1275.rmk
===================================================================
--- conf/i386-ieee1275.rmk	(revision 2001)
+++ conf/i386-ieee1275.rmk	(working copy)
@@ -210,5 +210,10 @@ lsmmap_mod_SOURCES = commands/lsmmap.c
 lsmmap_mod_CFLAGS = $(COMMON_CFLAGS)
 lsmmap_mod_LDFLAGS = $(COMMON_LDFLAGS)
 
+pkglib_MODULES += badram.mod
+badram_mod_SOURCES = lib/badram.c
+badram_mod_CFLAGS = $(COMMON_CFLAGS)
+badram_mod_LDFLAGS = $(COMMON_LDFLAGS)
+
 include $(srcdir)/conf/i386.mk
 include $(srcdir)/conf/common.mk
Index: lib/badram.c
===================================================================
--- lib/badram.c	(revision 0)
+++ lib/badram.c	(revision 0)
@@ -0,0 +1,127 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2009  Free Software Foundation, Inc.
+ *
+ *  GRUB 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 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/err.h>
+#include <grub/types.h>
+#include <grub/badram.h>
+#include <grub/mm.h>
+#include <grub/env.h>
+#include <grub/misc.h>
+#include <grub/machine/memory.h>
+
+#define CHUNK_SIZE	0x400
+
+struct badness
+{
+  grub_uint64_t addr;
+  grub_uint64_t mask;
+  struct badness *next;
+};
+
+static struct badness *badness;
+
+#define xor(a,b)	(((a) & ~(b)) | (~(a) & (b)))
+
+static int
+is_bad (grub_uint64_t page)
+{
+  struct badness *pat;
+  for (pat = badness; pat != NULL; pat = pat->next)
+    if ((xor (page, pat->addr) & pat->mask) == 0)
+      return 1;
+  return 0;
+}
+
+grub_err_t
+grub_badram_mmap_iterate (int NESTED_FUNC_ATTR (*hook) (grub_uint64_t, grub_uint64_t, grub_uint32_t))
+{
+  char *str;
+  grub_err_t ret;
+
+  str = grub_env_get ("badram");
+  if (! str)
+    return grub_machine_mmap_iterate (hook);
+
+  while (1)
+    {
+      struct badness *new;
+      grub_uint64_t addr, mask;
+      
+      /* Parse address and mask.  */
+      addr = grub_strtoull (str, &str, 16);
+      if (*str == ',')
+	str++;
+      mask = grub_strtoull (str, &str, 16);
+      if (*str == ',')
+	str++;
+
+      if (grub_errno == GRUB_ERR_BAD_NUMBER)
+	{
+	  grub_errno = 0;
+	  break;
+	}
+
+      /* When part of a page is tainted, we discard the whole of it.  There's
+	 no point in providing sub-page chunks.  */
+      mask &= ~(CHUNK_SIZE - 1);
+
+      new = grub_malloc (sizeof (struct badness));
+      new->addr = addr;
+      new->mask = mask;
+
+      /* Insert.  */
+      new->next = badness;
+      badness = new;
+    }
+
+  auto int NESTED_FUNC_ATTR badram_hook (grub_uint64_t, grub_uint64_t, grub_uint32_t);
+  int NESTED_FUNC_ATTR badram_hook (grub_uint64_t addr, grub_uint64_t size, grub_uint32_t type)
+  {
+    /* These define the start and end of each chunk of good pages.  */
+    grub_uint64_t start, end;
+
+    for (start = addr; 1; start = end)
+      {
+	/* Find a good page.  */
+	for (; is_bad (start); start += CHUNK_SIZE);
+	
+	/* Nothing left to use.  */
+	if (start >= addr + size)
+	  return 0;
+	
+	/* Find the last good page in this chunk.  */
+	for (end = start + CHUNK_SIZE; end < addr + size && ! is_bad (end); end += CHUNK_SIZE);
+	
+	/* Process what we found.  */
+	if (hook (start, end - start, type))
+	  return 1;
+      }
+  }
+
+  ret = grub_machine_mmap_iterate (badram_hook);
+
+  while (badness)
+    {
+      struct badness *p;
+      p = badness->next;
+      grub_free (badness);
+      badness = p;
+    }
+
+  return ret;
+}
Index: include/grub/badram.h
===================================================================
--- include/grub/badram.h	(revision 0)
+++ include/grub/badram.h	(revision 0)
@@ -0,0 +1,29 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2009  Free Software Foundation, Inc.
+ *
+ *  GRUB 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 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB 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 GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef GRUB_BADRAM_HEADER
+#define GRUB_BADRAM_HEADER	1
+
+#include <grub/symbol.h>
+#include <grub/types.h>
+#include <grub/err.h>
+
+grub_err_t EXPORT_FUNC(grub_badram_mmap_iterate)
+     (int NESTED_FUNC_ATTR (*hook) (grub_uint64_t, grub_uint64_t, grub_uint32_t));
+
+#endif
Index: commands/lsmmap.c
===================================================================
--- commands/lsmmap.c	(revision 2001)
+++ commands/lsmmap.c	(working copy)
@@ -1,6 +1,6 @@
 /*
  *  GRUB  --  GRand Unified Bootloader
- *  Copyright (C) 2008  Free Software Foundation, Inc.
+ *  Copyright (C) 2008,2009  Free Software Foundation, Inc.
  *
  *  GRUB is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -16,7 +16,7 @@
  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <grub/machine/memory.h>
+#include <grub/badram.h>
 #include <grub/normal.h>
 #include <grub/dl.h>
 #include <grub/arg.h>
@@ -34,7 +34,7 @@ grub_cmd_lsmmap (struct grub_arg_list *s
 		   addr, size, type);
       return 0;
     }
-  grub_machine_mmap_iterate (hook);
+  grub_badram_mmap_iterate (hook);
 
   return 0;
 }
Index: loader/i386/linux.c
===================================================================
--- loader/i386/linux.c	(revision 2001)
+++ loader/i386/linux.c	(working copy)
@@ -1,6 +1,6 @@
 /*
  *  GRUB  --  GRand Unified Bootloader
- *  Copyright (C) 2006,2007,2008  Free Software Foundation, Inc.
+ *  Copyright (C) 2006,2007,2008,2009  Free Software Foundation, Inc.
  *
  *  GRUB is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -20,6 +20,7 @@
 #include <grub/machine/machine.h>
 #include <grub/machine/memory.h>
 #include <grub/machine/loader.h>
+#include <grub/badram.h>
 #include <grub/file.h>
 #include <grub/disk.h>
 #include <grub/err.h>
@@ -102,7 +103,7 @@ find_mmap_size (void)
       return 0;
     }
   
-  grub_machine_mmap_iterate (hook);
+  grub_badram_mmap_iterate (hook);
   
   mmap_size = count * sizeof (struct grub_e820_mmap);
 
@@ -173,7 +174,7 @@ allocate_pages (grub_size_t prot_size)
 
       return 0;
     }
-  grub_machine_mmap_iterate (hook);
+  grub_badram_mmap_iterate (hook);
   if (! real_mode_mem)
     {
       grub_error (GRUB_ERR_OUT_OF_MEMORY, "cannot allocate real mode pages");
@@ -258,7 +259,7 @@ grub_linux32_boot (void)
     }
 
   e820_num = 0;
-  grub_machine_mmap_iterate (hook);
+  grub_badram_mmap_iterate (hook);
   params->mmap_size = e820_num;
 
   /* Hardware interrupts are not safe any longer.  */
Index: loader/i386/pc/multiboot.c
===================================================================
--- loader/i386/pc/multiboot.c	(revision 2001)
+++ loader/i386/pc/multiboot.c	(working copy)
@@ -32,6 +32,7 @@
 #include <grub/multiboot.h>
 #include <grub/machine/init.h>
 #include <grub/machine/memory.h>
+#include <grub/badram.h>
 #include <grub/elf.h>
 #include <grub/aout.h>
 #include <grub/file.h>
@@ -98,7 +99,7 @@ grub_get_multiboot_mmap_len (void)
       return 0;
     }
   
-  grub_machine_mmap_iterate (hook);
+  grub_badram_mmap_iterate (hook);
   
   return count * sizeof (struct grub_multiboot_mmap_entry);
 }
@@ -121,7 +122,7 @@ grub_fill_multiboot_mmap (struct grub_mu
       return 0;
     }
 
-  grub_machine_mmap_iterate (hook);
+  grub_badram_mmap_iterate (hook);
 }
 
 /* Check if BUFFER contains ELF32.  */