New patch to review for coreboot: 83a49f7 SMM: Add heap region and move C handler higher in region

[Stefan Reinauer]

Stefan Reinauer ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/1308

-gerrit

commit 83a49f79e7339b011063e346b9f96765b2805160
Author: Duncan Laurie 
Date:   Sat Jun 23 15:09:34 2012 -0700

SMM: Add heap region and move C handler higher in region

In order to support SPI and ELOG drivers the SMM region
    needs to be able to be larger than the previous allocation
    below 0x7400.  Now that we have support for 4M TSEG we do
    not need to live in this region.

This change adds a 16KB heap region abofe the save state area
    at TSEG+64KB and moves the C handler above this.

The heap region is then available for malloc and the C handler
    can grow to support flash and event log features.

While updating the memory map comment in assembly stub I also
    added a pause instruction to the cpu spin lock as this was
    added to the C code in latest upstream rebase.

Dump sympbols from smm.elf binary to see the new regions:

00010000 B _heap
    00014000 B _eheap
    00014000 T _smm_c_handler_start
    0001b240 T _smm_c_handler_end

Change-Id: I45f0ab4df1fdef3b626f877094a58587476ac634
    Signed-off-by: Duncan Laurie 
---
 src/cpu/x86/smm/smm_tseg.ld       |   45 +++++++++++++++++++++++-------------
 src/cpu/x86/smm/smmhandler_tseg.S |    9 +++++-
 2 files changed, 36 insertions(+), 18 deletions(-)

diff --git a/src/cpu/x86/smm/smm_tseg.ld b/src/cpu/x86/smm/smm_tseg.ld
index 016b5a0..6def972 100644
--- a/src/cpu/x86/smm/smm_tseg.ld
+++ b/src/cpu/x86/smm/smm_tseg.ld
@@ -10,6 +10,34 @@ SECTIONS
    .handler (.): {
    	/* Assembler stub */
    	*(.handler)
+	}
+
+	/* We are using the TSEG interleaved to stuff the SMM handlers
+	 * for all CPU cores in there. The jump table redirects the execution
+	 * to the actual SMM handler
+	 */
+	. = 0x8000 - (( CPUS - 1) * 0x400);
+	.jumptable : {
+		*(.jumptable)
+	}
+
+	/* Data used in early SMM TSEG handler. */
+	. = 0x8400;
+	.earlydata : {
+		*(.earlydata)
+	}
+
+	/* 16KB for the heap at 64KB */
+	. = 0x10000;
+	.heap : {
+		_heap = .;
+		. = 0x4000;
+		_eheap = .;
+	}
+
+	. = ALIGN(0x4000);
+	.smm_c_handler : {
+		_smm_c_handler_start = .;

/* C code of the SMM handler */
    	*(.text);
@@ -29,25 +57,10 @@ SECTIONS
    	 . = ALIGN(4);
    	*(.bss)
    	*(.sbss)
-
-		/* What is this? */
    	*(COMMON)
    	 . = ALIGN(4);
-	}

-	/* We are using the TSEG interleaved to stuff the SMM handlers
-	 * for all CPU cores in there. The jump table redirects the execution
-	 * to the actual SMM handler
-	 */
-	. = 0x8000 - (( CPUS - 1) * 0x400);
-	.jumptable : {
-		*(.jumptable)
-	}
-
-	/* Data used in early SMM TSEG handler. */
-	. = 0x8400;
-	.earlydata : {
-		*(.earlydata)
+		_smm_c_handler_end = .;
    }

/DISCARD/ : {
diff --git a/src/cpu/x86/smm/smmhandler_tseg.S b/src/cpu/x86/smm/smmhandler_tseg.S
index 8fdd75f..c61a611 100644
--- a/src/cpu/x86/smm/smmhandler_tseg.S
+++ b/src/cpu/x86/smm/smmhandler_tseg.S
@@ -20,7 +20,11 @@
  */

/*
- * +--------------------------------+ 0xffff
+ * +--------------------------------+
+ * | SMM Handler C Code             |
+ * +--------------------------------+ 0x14000
+ * | SMM Handler Heap               |
+ * +--------------------------------+ 0x10000
  * |  Save State Map Node 0         |
  * |  Save State Map Node 1         |
  * |  Save State Map Node 2         |
@@ -39,7 +43,7 @@
  * | ...                            |
  * +--------------------------------+ 0x7400
  * |                                |
- * | SMM Handler                    |
+ * | SMM Handler Assembly Stub      |
  * |                                |
  * +--------------------------------+ TSEG
  *
@@ -91,6 +95,7 @@ smm_handler_start:

/* If we did not get the lock, wait for release */
 wait_for_unlock:
+	pause
    addr32	movw (%ebx), %ax
    cmpw	$SMI_LOCKED, %ax
    je	wait_for_unlock