com32: merge all memory map discovery to one file

Merge the memory map discovery for malloc and the memory map discovery
for memmap into one file that scans memory and invokes a callback.

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

1 files changed, 153 insertions, 0 deletions

diff --git a/com32/lib/syslinux/memscan.c b/com32/lib/syslinux/memscan.c
new file mode 100644
index 00000000..a5661e31
--- /dev/null
+++ b/com32/lib/syslinux/memscan.c
@@ -0,0 +1,153 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   Copyright 2007-2009 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
+ *   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.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * memscan.c
+ *
+ * Query the system for free memory
+ */
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+#include <com32.h>
+
+#include <syslinux/memscan.h>
+
+struct e820_entry {
+  uint64_t start;
+  uint64_t len;
+  uint32_t type;
+  uint32_t extattr;
+};
+
+int syslinux_scan_memory(scan_memory_callback callback, void *data)
+{
+  static com32sys_t ireg, zireg;
+  com32sys_t oreg;
+  struct e820_entry *e820buf = __com32.cs_bounce;
+  uint64_t start, len, maxlen;
+  int memfound = 0;
+  int rv;
+
+  /* Use INT 12h to get DOS memory above 0x7c00 */
+  __intcall(0x12, &zireg, &oreg);
+  if (oreg.eax.w[0] > 2 && oreg.eax.w[0] <= 640) {
+    addr_t dosmem = (oreg.eax.w[0] << 10) - 0x504;
+    rv = callback(data, 0x504, dosmem, true);
+    if (rv)
+      return rv;
+  }
+
+  /* First try INT 15h AX=E820h */
+  ireg.eax.l    = 0xe820;
+  ireg.edx.l    = 0x534d4150;
+  ireg.ebx.l    = 0;
+  ireg.ecx.l    = sizeof(*e820buf);
+  ireg.es       = SEG(e820buf);
+  ireg.edi.w[0] = OFFS(e820buf);
+  memset(e820buf, 0, sizeof *e820buf);
+  /* Set this in case the BIOS doesn't, but doesn't change %ecx to match. */
+  e820buf->extattr = 1;
+
+  do {
+    __intcall(0x15, &ireg, &oreg);
+
+    if ((oreg.eflags.l & EFLAGS_CF) ||
+	(oreg.eax.l != 0x534d4150) ||
+	(oreg.ecx.l < 20))
+      break;
+
+    if (oreg.ecx.l < 24)
+      e820buf->extattr = 1;	/* Enabled, normal */
+
+    if (!(e820buf->extattr & 1))
+      continue;
+
+    start = e820buf->start;
+    len = e820buf->len;
+
+    if (start < 0x100000000ULL) {
+      /* Don't rely on E820 being valid for low memory.  Doing so
+	 could mean stuff like overwriting the PXE stack even when
+	 using "keeppxe", etc. */
+      if (start < 0x100000ULL) {
+	if (len > 0x100000ULL-start)
+	  len -= 0x100000ULL-start;
+	else
+	  len = 0;
+	start = 0x100000ULL;
+      }
+
+      maxlen = 0x100000000ULL-start;
+      if (len > maxlen)
+	len = maxlen;
+
+      if (len) {
+	rv = callback(data, (addr_t)start, (addr_t)len, e820buf->type == 1);
+	if (rv)
+	  return rv;
+	memfound = 1;
+      }
+    }
+
+    ireg.ebx.l = oreg.ebx.l;
+  } while (oreg.ebx.l);
+
+  if (memfound)
+    return 0;
+
+  /* Next try INT 15h AX=E801h */
+  ireg.eax.w[0] = 0xe801;
+  __intcall(0x15, &ireg, &oreg);
+
+  if (!(oreg.eflags.l & EFLAGS_CF) && oreg.ecx.w[0]) {
+    rv = callback(data, (addr_t)1 << 20, oreg.ecx.w[0] << 10, true);
+    if (rv)
+      return rv;
+
+    if (oreg.edx.w[0]) {
+      rv = callback(data, (addr_t)16 << 20, oreg.edx.w[0] << 16, true);
+      if (rv)
+	return rv;
+    }
+
+    return 0;
+  }
+
+  /* Finally try INT 15h AH=88h */
+  ireg.eax.w[0] = 0x8800;
+  if (!(oreg.eflags.l & EFLAGS_CF) && oreg.eax.w[0]) {
+    rv = callback(data, (addr_t)1 << 20, oreg.ecx.w[0] << 10, true);
+    if (rv)
+      return rv;
+  }
+
+  return 0;
+}