lib/fmap: Add optional pre-RAM cache

This patch adds an optional pre-RAM cache for the FMAP which most
platforms should be able to use, complementing the recently added
post-RAM FMAP cache in CBMEM. vboot systems currently read the FMAP
about half a dozen times from flash in verstage, which will all be
coalesced into a single read with this patch. It will also help
future vboot improvements since when FMAP reads become "free" vboot
doesn't need to keep track of so much information separately.

In order to make sure we have a single, well-defined point where the new
cache is first initialized, eliminate the build-time hardcoding of the
CBFS section offsets, so that all CBFS accesses explicitly read the
FMAP.

Add FMAP_CACHEs to all platforms that can afford it (other than the
RISC-V things where I have no idea how they work), trying to take the
space from things that look like they were oversized anyway (pre-RAM
consoles and CBFS caches).

Change-Id: I2820436776ef620bdc4481b5cd4b6957764248ea
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36657
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Joel Kitching <kitching@google.com>

1 files changed, 89 insertions, 30 deletions

diff --git a/src/lib/fmap.c b/src/lib/fmap.c
index f3ff071766..4b4179c769 100644
--- a/src/lib/fmap.c
+++ b/src/lib/fmap.c
@@ -15,12 +15,13 @@
 
 #include <arch/early_variables.h>
 #include <boot_device.h>
+#include <cbmem.h>
 #include <console/console.h>
 #include <fmap.h>
 #include <commonlib/fmap_serialized.h>
 #include <stddef.h>
 #include <string.h>
-#include <cbmem.h>
+#include <symbols.h>
 
 #include "fmap_config.h"
 
@@ -31,26 +32,94 @@
 static int fmap_print_once CAR_GLOBAL;
 static struct mem_region_device fmap_cache CAR_GLOBAL;
 
+#define print_once(...) do { \
+		if (!car_get_var(fmap_print_once)) \
+			printk(__VA_ARGS__); \
+	} while (0)
+
+DECLARE_OPTIONAL_REGION(fmap_cache);
+
 uint64_t get_fmap_flash_offset(void)
 {
 	return FMAP_OFFSET;
 }
 
+static int check_signature(const struct fmap *fmap)
+{
+	return memcmp(fmap->signature, FMAP_SIGNATURE, sizeof(fmap->signature));
+}
+
+static void report(const struct fmap *fmap)
+{
+	print_once(BIOS_DEBUG, "FMAP: Found \"%s\" version %d.%d at %#x.\n",
+	       fmap->name, fmap->ver_major, fmap->ver_minor, FMAP_OFFSET);
+	print_once(BIOS_DEBUG, "FMAP: base = %#llx size = %#x #areas = %d\n",
+	       (long long)fmap->base, fmap->size, fmap->nareas);
+	car_set_var(fmap_print_once, 1);
+}
+
+static void setup_preram_cache(struct mem_region_device *cache_mrdev)
+{
+	if (!ENV_ROMSTAGE_OR_BEFORE) {
+		/* We get here if ramstage makes an FMAP access before calling
+		   cbmem_initialize(). We should avoid letting it come to that,
+		   so print a warning. */
+		print_once(BIOS_WARNING,
+			"WARNING: Post-RAM FMAP access too early for cache!\n");
+		return;
+	}
+
+	if (REGION_SIZE(fmap_cache) == 0) {
+		/* If you see this you really want to add an FMAP_CACHE to your
+		   memlayout, unless you absolutely can't affort the 2K. */
+		print_once(BIOS_NOTICE,
+			"NOTE: Running without FMAP_CACHE, should add it!\n");
+		return;
+	}
+
+	struct fmap *fmap = (struct fmap *)_fmap_cache;
+	if (!ENV_BOOTBLOCK) {
+		/* NOTE: This assumes that for all platforms running this code,
+		   the bootblock is the first stage and the bootblock will make
+		   at least one FMAP access (usually from finding CBFS). */
+		if (!check_signature(fmap))
+			goto register_cache;
+
+		printk(BIOS_ERR, "ERROR: FMAP cache corrupted?!\n");
+	}
+
+	/* In case we fail below, make sure the cache is invalid. */
+	memset(fmap->signature, 0, sizeof(fmap->signature));
+
+	boot_device_init();
+	const struct region_device *boot_rdev = boot_device_ro();
+	if (!boot_rdev)
+		return;
+
+	/* memlayout statically guarantees that the FMAP_CACHE is big enough. */
+	if (rdev_readat(boot_rdev, fmap, FMAP_OFFSET, FMAP_SIZE) != FMAP_SIZE)
+		return;
+	if (check_signature(fmap))
+		return;
+	report(fmap);
+
+register_cache:
+	mem_region_device_ro_init(cache_mrdev, fmap, FMAP_SIZE);
+}
+
 static int find_fmap_directory(struct region_device *fmrd)
 {
 	const struct region_device *boot;
 	struct fmap *fmap;
-	size_t fmap_size;
+	struct mem_region_device *cache;
 	size_t offset = FMAP_OFFSET;
 
-	if (cbmem_possibly_online() && !ENV_SMM) {
-		/* Try FMAP cache first */
-		const struct mem_region_device *cache;
-
-		cache = car_get_var_ptr(&fmap_cache);
-		if (region_device_sz(&cache->rdev))
-			return rdev_chain_full(fmrd, &cache->rdev);
-	}
+	/* Try FMAP cache first */
+	cache = car_get_var_ptr(&fmap_cache);
+	if (!region_device_sz(&cache->rdev))
+		setup_preram_cache(cache);
+	if (region_device_sz(&cache->rdev))
+		return rdev_chain_full(fmrd, &cache->rdev);
 
 	boot_device_init();
 	boot = boot_device_ro();
@@ -58,32 +127,22 @@ static int find_fmap_directory(struct region_device *fmrd)
 	if (boot == NULL)
 		return -1;
 
-	fmap_size = sizeof(struct fmap);
-
-	fmap = rdev_mmap(boot, offset, fmap_size);
+	fmap = rdev_mmap(boot, offset, sizeof(struct fmap));
 
 	if (fmap == NULL)
 		return -1;
 
-	if (memcmp(fmap->signature, FMAP_SIGNATURE, sizeof(fmap->signature))) {
+	if (check_signature(fmap)) {
 		printk(BIOS_DEBUG, "No FMAP found at %zx offset.\n", offset);
 		rdev_munmap(boot, fmap);
 		return -1;
 	}
 
-	if (!car_get_var(fmap_print_once)) {
-		printk(BIOS_DEBUG, "FMAP: Found \"%s\" version %d.%d at %zx.\n",
-		       fmap->name, fmap->ver_major, fmap->ver_minor, offset);
-		printk(BIOS_DEBUG, "FMAP: base = %llx size = %x #areas = %d\n",
-		       (long long)fmap->base, fmap->size, fmap->nareas);
-		car_set_var(fmap_print_once, 1);
-	}
-
-	fmap_size += fmap->nareas * sizeof(struct fmap_area);
+	report(fmap);
 
 	rdev_munmap(boot, fmap);
 
-	return rdev_chain(fmrd, boot, offset, fmap_size);
+	return rdev_chain(fmrd, boot, offset, FMAP_SIZE);
 }
 
 int fmap_locate_area_as_rdev(const char *name, struct region_device *area)
@@ -212,7 +271,7 @@ ssize_t fmap_overwrite_area(const char *name, const void *buffer, size_t size)
 	return rdev_writeat(&rdev, buffer, 0, size);
 }
 
-static void fmap_register_cache(int unused)
+static void fmap_register_cbmem_cache(int unused)
 {
 	const struct cbmem_entry *e;
 	struct mem_region_device *mdev;
@@ -232,7 +291,7 @@ static void fmap_register_cache(int unused)
  * The main reason to copy the FMAP into CBMEM is to make it available to the
  * OS on every architecture. As side effect use the CBMEM copy as cache.
  */
-static void fmap_setup_cache(int unused)
+static void fmap_setup_cbmem_cache(int unused)
 {
 	struct region_device fmrd;
 
@@ -255,9 +314,9 @@ static void fmap_setup_cache(int unused)
 	}
 
 	/* Finally advertise the cache for the current stage */
-	fmap_register_cache(unused);
+	fmap_register_cbmem_cache(unused);
 }
 
-ROMSTAGE_CBMEM_INIT_HOOK(fmap_setup_cache)
-RAMSTAGE_CBMEM_INIT_HOOK(fmap_register_cache)
-POSTCAR_CBMEM_INIT_HOOK(fmap_register_cache)
+ROMSTAGE_CBMEM_INIT_HOOK(fmap_setup_cbmem_cache)
+RAMSTAGE_CBMEM_INIT_HOOK(fmap_register_cbmem_cache)
+POSTCAR_CBMEM_INIT_HOOK(fmap_register_cbmem_cache)