[coreboot-gerrit] New patch to review for coreboot: 6a7dfb2 cbmem utility: compatibility with older coreboot versions

Stefan Reinauer (stefan.reinauer@coreboot.org) gerrit at coreboot.org
Mon Nov 18 23:04:36 CET 2013

Stefan Reinauer (stefan.reinauer at coreboot.org) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/4139


commit 6a7dfb2ec77be337a29f08e3f2179d8010fd2125
Author: Stefan Reinauer <reinauer at chromium.org>
Date:   Fri Apr 19 14:22:29 2013 -0700

    cbmem utility: compatibility with older coreboot versions
    Commit b8ad224 changed the memory address in lb_cbmem_ref coreboot
    table entries from a pointer to a uint64_t. This change was introduced
    to make the cbmem utility work on both 32bit and 64bit userland.
    Unfortunately, this broke the cbmem utility running on older versions
    of coreboot because they were still providing a 32bit only field for
    the address while the cbmem utility would now take the following 4
    bytes as upper 32bits of a pointer that can obviously not be
    mmapped. This change checks if the size of the lb_cbmem_ref structure
    provided by coreboot is smaller than expected, and if so, ignore the
    upper 32bit of the address read.
    Signed-off-by: Stefan Reinauer <reinauer at google.com>
    Change-Id: If4c8e9b72b2a38c961c11d7071b728e61e5f1d18
    Commit-Queue: Stefan Reinauer <reinauer at google.com>
    Tested-by: Stefan Reinauer <reinauer at google.com>
    Reviewed-by: Aaron Durbin <adurbin at chromium.org>
 util/cbmem/cbmem.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/util/cbmem/cbmem.c b/util/cbmem/cbmem.c
index 74e0fd4..e05a72a 100644
--- a/util/cbmem/cbmem.c
+++ b/util/cbmem/cbmem.c
@@ -22,6 +22,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <inttypes.h>
 #include <getopt.h>
 #include <errno.h>
 #include <fcntl.h>
@@ -128,6 +129,25 @@ static struct lb_cbmem_ref timestamps;
 static struct lb_cbmem_ref console;
 static struct lb_memory_range cbmem;
+/* This is a work-around for a nasty problem introduced by initially having
+ * pointer sized entries in the lb_cbmem_ref structures. This caused problems
+ * on 64bit x86 systems because coreboot is 32bit on those systems.
+ * When the problem was found, it was corrected, but there are a lot of
+ * systems out there with a firmware that does not produce the right
+ * lb_cbmem_ref structure. Hence we try to autocorrect this issue here.
+ */
+static struct lb_cbmem_ref parse_cbmem_ref(struct lb_cbmem_ref *cbmem_ref)
+	struct lb_cbmem_ref ret;
+	ret = *cbmem_ref;
+	if (cbmem_ref->size < sizeof(*cbmem_ref))
+		ret.cbmem_addr = (uint32_t)ret.cbmem_addr;
+	return ret;
 static int parse_cbtable(u64 address)
 	int i, found = 0;
@@ -184,12 +204,12 @@ static int parse_cbtable(u64 address)
 				debug("    Found timestamp table.\n");
-				timestamps = *(struct lb_cbmem_ref *) lbr_p;
+				timestamps = parse_cbmem_ref((struct lb_cbmem_ref *) lbr_p);
 				debug("    Found cbmem console.\n");
-				console = *(struct lb_cbmem_ref *) lbr_p;
+				console = parse_cbmem_ref((struct lb_cbmem_ref *) lbr_p);
 			case LB_TAG_FORWARD: {

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