region: Turn region_end() into an inclusive region_last()

The current region_end() implementation is susceptible to overflow
if the region is at the end of the addressable space. A common case
with the memory-mapped flash of x86 directly below the 32-bit limit.

Note: This patch also changes console output to inclusive limits.
IMO, to the better.

Change-Id: Ic4bd6eced638745b7e845504da74542e4220554a
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79946
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/commonlib/include/commonlib/region.h

@@ -124,15 +124,15 @@ static inline size_t region_sz(const struct region *r)
 	return r->size;
 }
 
-static inline size_t region_end(const struct region *r)
+static inline size_t region_last(const struct region *r)
 {
-	return region_offset(r) + region_sz(r);
+	return region_offset(r) + (region_sz(r) - 1);
 }
 
 static inline bool region_overlap(const struct region *r1, const struct region *r2)
 {
-	return (region_end(r1) > region_offset(r2)) &&
-	       (region_offset(r1) < region_end(r2));
+	return (region_last(r1) >= region_offset(r2)) &&
+	       (region_offset(r1) <= region_last(r2));
 }
 
 /* Helper to dynamically initialize region device. */
@@ -156,9 +156,9 @@ static inline size_t region_device_offset(const struct region_device *rdev)
 	return region_offset(region_device_region(rdev));
 }
 
-static inline size_t region_device_end(const struct region_device *rdev)
+static inline size_t region_device_last(const struct region_device *rdev)
 {
-	return region_end(region_device_region(rdev));
+	return region_last(region_device_region(rdev));
 }
 
 /* Memory map entire region device. Same semantics as rdev_mmap() above. */

src/commonlib/region.c

@@ -10,10 +10,10 @@ int region_is_subregion(const struct region *p, const struct region *c)
 	if (region_offset(c) < region_offset(p))
 		return 0;
 
-	if (region_end(c) > region_end(p))
+	if (region_last(c) > region_last(p))
 		return 0;
 
-	if (region_end(c) < region_offset(c))
+	if (region_last(c) < region_offset(c))
 		return 0;
 
 	return 1;

src/cpu/x86/smm/smm_module_loader.c

@@ -341,7 +341,7 @@ static void setup_smihandler_params(struct smm_runtime *mod_params,
 	}
 
 	for (int i = 0; i < loader_params->num_cpus; i++)
-		mod_params->save_state_top[i] = region_end(&cpus[i].ss);
+		mod_params->save_state_top[i] = region_last(&cpus[i].ss) + 1;
 
 	if (CONFIG(RUNTIME_CONFIGURABLE_SMM_LOGLEVEL))
 		mod_params->smm_log_level = mainboard_set_smm_log_level();
@@ -371,7 +371,7 @@ static void setup_smihandler_params(struct smm_runtime *mod_params,
 static void print_region(const char *name, const struct region region)
 {
 	printk(BIOS_DEBUG, "%-12s [0x%zx-0x%zx]\n", name, region_offset(&region),
-	       region_end(&region));
+	       region_last(&region));
 }
 
 /* STM + Handler + (Stub + Save state) * CONFIG_MAX_CPUS + stacks + page tables*/
@@ -482,7 +482,7 @@ int smm_load_module(const uintptr_t smram_base, const size_t smram_size,
 		return -1;
 
 	const struct region smram = region_create(smram_base, smram_size);
-	const uintptr_t smram_top = region_end(&smram);
+	const uintptr_t smram_top = region_last(&smram) + 1;
 
 	const size_t stm_size =
 		CONFIG(STM) ? CONFIG_MSEG_SIZE + CONFIG_BIOS_RESOURCE_LIST_SIZE : 0;

src/drivers/spi/winbond.c

@@ -374,7 +374,7 @@ static int winbond_get_write_protection(const struct spi_flash *flash,
 	}
 
 	printk(BIOS_DEBUG, "WINBOND: flash protected range 0x%08zx-0x%08zx\n",
-	       region_offset(&wp_region), region_end(&wp_region));
+	       region_offset(&wp_region), region_last(&wp_region));
 
 	return region_is_subregion(&wp_region, region);
 }
@@ -502,7 +502,7 @@ winbond_set_write_protection(const struct spi_flash *flash,
 	int ret;
 
 	/* Need to touch TOP or BOTTOM */
-	if (region_offset(region) != 0 && region_end(region) != flash->size)
+	if (region_offset(region) != 0 && region_last(region) != flash->size - 1)
 		return -1;
 
 	params = flash->part;
@@ -600,7 +600,7 @@ winbond_set_write_protection(const struct spi_flash *flash,
 		return ret;
 
 	printk(BIOS_DEBUG, "WINBOND: write-protection set to range "
-	       "0x%08zx-0x%08zx\n", region_offset(region), region_end(region));
+	       "0x%08zx-0x%08zx\n", region_offset(region), region_last(region));
 
 	return ret;
 }