[coreboot-gerrit] [S] Change in coreboot[main]: src/lib: Add memory/time saving special case for ramstage caching

[Patrick Georgi (Code Review)]

Patrick Georgi has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/79525?usp=email )

Change subject: src/lib: Add memory/time saving special case for ramstage caching
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src/lib: Add memory/time saving special case for ramstage caching

When caching the ramstage for suspend/resume, we copy the entire image
as it resides in RAM. The last part of that, CONFIG_HEAP_SIZE bytes, is
the heap that will be reinitialized when the ramstage is started again.

As such, copying doesn't make sense and complicates HEAP_SIZE
configuration (because it needs to fit the space-constrained cache
location) and costs time and space. Therefore, skip the heap.

Side notes:
- When building with ASAN, program.ld indicates that it will allocate
  some more space after the heap. This is not a problem, we just copy
  an ASAN-sized copy of the heap.
- Heap use is managed in src/lib/malloc with statically allocated
  variables. Because ramstage is cached before it's executed, these
  values will be reset to their compile-time default values, too.

Change-Id: I6553dc8b758196f2476af2e692c0421d0fa2b98e
Signed-off-by: Patrick Georgi 
---
M src/lib/cbmem_stage_cache.c
M src/lib/ext_stage_cache.c
2 files changed, 20 insertions(+), 5 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/25/79525/1

diff --git a/src/lib/cbmem_stage_cache.c b/src/lib/cbmem_stage_cache.c
index b45c950..65cb141 100644
--- a/src/lib/cbmem_stage_cache.c
+++ b/src/lib/cbmem_stage_cache.c
@@ -21,14 +21,22 @@
    meta->entry_addr = (uintptr_t)prog_entry(stage);
    meta->arg = (uintptr_t)prog_entry_arg(stage);

-	c = cbmem_add(CBMEM_ID_STAGEx_CACHE + stage_id, prog_size(stage));
+	unsigned int p_size = prog_size(stage);
+	if (stage_id == STAGE_RAMSTAGE) {
+		/* heap resides at the end of the image and will be
+		 * reinitialized, so it doesn't make sense to copy it around.
+		 */
+		p_size -= CONFIG_HEAP_SIZE;
+	}
+
+	c = cbmem_add(CBMEM_ID_STAGEx_CACHE + stage_id, p_size);
    if (c == NULL) {
    	printk(BIOS_ERR, "Can't add stage_cache %x to cbmem\n",
    			CBMEM_ID_STAGEx_CACHE + stage_id);
    	return;
    }

-	memcpy(c, prog_start(stage), prog_size(stage));
+	memcpy(c, prog_start(stage), p_size);
 }

void stage_cache_add_raw(int stage_id, const void *base, const size_t size)
diff --git a/src/lib/ext_stage_cache.c b/src/lib/ext_stage_cache.c
index a35ce37..462a635 100644
--- a/src/lib/ext_stage_cache.c
+++ b/src/lib/ext_stage_cache.c
@@ -59,8 +59,15 @@
    meta->entry_addr = (uintptr_t)prog_entry(stage);
    meta->arg = (uintptr_t)prog_entry_arg(stage);

-	e = imd_entry_add(imd, CBMEM_ID_STAGEx_CACHE + stage_id,
-				prog_size(stage));
+	unsigned int p_size = prog_size(stage);
+	if (stage_id == STAGE_RAMSTAGE) {
+		/* heap resides at the end of the image and will be
+		 * reinitialized, so it doesn't make sense to copy it around.
+		 */
+		p_size -= CONFIG_HEAP_SIZE;
+	}
+
+	e = imd_entry_add(imd, CBMEM_ID_STAGEx_CACHE + stage_id, p_size);

if (e == NULL) {
    	printk(BIOS_DEBUG, "Error: Can't add stage_cache %x to imd\n",
@@ -70,7 +77,7 @@

c = imd_entry_at(imd, e);

-	memcpy(c, prog_start(stage), prog_size(stage));
+	memcpy(c, prog_start(stage), p_size);
 }

void stage_cache_add_raw(int stage_id, const void *base, const size_t size)