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 <patrick@coreboot.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79525
Reviewed-by: Martin L Roth <gaumless@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/src/lib/cbmem_stage_cache.c b/src/lib/cbmem_stage_cache.c
index b45c950..5e76fb0 100644
--- a/src/lib/cbmem_stage_cache.c
+++ b/src/lib/cbmem_stage_cache.c
@@ -21,14 +21,21 @@
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)
diff --git a/src/lib/program.ld b/src/lib/program.ld
index f406f9f..68bcab6 100644
--- a/src/lib/program.ld
+++ b/src/lib/program.ld
@@ -149,6 +149,15 @@
_eprogram = .;
RECORD_SIZE(program)
+/* The stage cache drops CONFIG_HEAP_SIZE bytes from the end of the in-memory
+ image of the ramstage, so ensure that when moving that many bytes backwards
+ from the program end, we're in the heap (or later), in some region that
+ doesn't contain initialized code or data. */
+#if ENV_RAMSTAGE
+_bogus = ASSERT(_eprogram - CONFIG_HEAP_SIZE >= _heap,
+ "HEAP_SIZE and heap misaligned");
+#endif
+
/* Discard the sections we don't need/want */
zeroptr = 0;