[PATCH] lib: utils: Mark only the largest region as reserved in FDT

[Himanshu Chauhan]

In commit 230278dcf, RX and RW regions were marked separately.
When the RW region grows (e.g. with more harts) and it isn't a
power-of-two, sbi_domain_memregion_init will upgrade the region
to the next power-of-two. This will make RX and RW both start
at the same base address, like so (with 64 harts):
Domain0 Region01 : 0x0000000080000000-0x000000008001ffff M: (R,X) S/U: ()
Domain0 Region02 : 0x0000000080000000-0x00000000800fffff M: (R,W) S/U: ()

This doesn't break the permission enforcement because of static
priorities in PMP but makes the kernel complain about the regions
overlapping each other. Like so:
[    0.000000] OF: reserved mem: OVERLAP DETECTED!
[    0.000000] mmode_resv0 at 80000000 (0x0000000080000000--0x0000000080020000) \
	overlaps with mmode_resv1 at 80000000 (0x0000000080000000--0x0000000080100000)

To fix this warning, among the multiple regions having same base
address but different sizes, add only the largest region as reserved
region during fdt fixup.

Fixes: 230278dcf (lib: sbi: Add separate entries for firmware RX and RW regions)

Signed-off-by: Himanshu Chauhan <hchauhan at ventanamicro.com>
---
 lib/utils/fdt/fdt_fixup.c | 34 ++++++++++++++++++++++++++++++----
 1 file changed, 30 insertions(+), 4 deletions(-)

diff --git a/lib/utils/fdt/fdt_fixup.c b/lib/utils/fdt/fdt_fixup.c
index 42692cc..4085762 100644
--- a/lib/utils/fdt/fdt_fixup.c
+++ b/lib/utils/fdt/fdt_fixup.c
@@ -1,3 +1,4 @@
+
 // SPDX-License-Identifier: BSD-2-Clause
 /*
  * fdt_fixup.c - Flat Device Tree parsing helper routines
@@ -14,6 +15,7 @@
 #include <sbi/sbi_hart.h>
 #include <sbi/sbi_scratch.h>
 #include <sbi/sbi_string.h>
+#include <sbi/sbi_error.h>
 #include <sbi_utils/fdt/fdt_fixup.h>
 #include <sbi_utils/fdt/fdt_pmu.h>
 #include <sbi_utils/fdt/fdt_helper.h>
@@ -200,8 +202,10 @@ int fdt_reserved_memory_fixup(void *fdt)
 	struct sbi_domain_memregion *reg;
 	struct sbi_domain *dom = sbi_domain_thishart_ptr();
 	struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
+	unsigned long filtered_base[PMP_COUNT] = { 0 };
+	unsigned char filtered_order[PMP_COUNT] = { 0 };
 	unsigned long addr, size;
-	int err, parent, i;
+	int err, parent, i, j;
 	int na = fdt_address_cells(fdt, 0);
 	int ns = fdt_size_cells(fdt, 0);
 
@@ -266,11 +270,33 @@ int fdt_reserved_memory_fixup(void *fdt)
 		if (reg->flags & SBI_DOMAIN_MEMREGION_SU_EXECUTABLE)
 			continue;
 
+		if (i > PMP_COUNT) {
+			sbi_printf("%s: Too many memory regions to fixup.\n",
+				   __func__);
+			return SBI_ENOSPC;
+		}
+ 
 		addr = reg->base;
-		size = 1UL << reg->order;
-		fdt_resv_memory_update_node(fdt, addr, size, i, parent,
-			(sbi_hart_pmp_count(scratch)) ? false : true);
+		for (j = 0; j < i; j++) {
+			if (addr == filtered_base[j]
+			    && filtered_order[j] < reg->order) {
+				filtered_order[j] = reg->order;
+				goto next_entry;
+			}
+		}
+
+		filtered_base[i] = reg->base;
+		filtered_order[i] = reg->order;
 		i++;
+	next_entry:
+	}
+
+	for (j = 0; j < i; j++) {
+		addr = filtered_base[j];
+		size = 1UL << filtered_order[j];
+		fdt_resv_memory_update_node(fdt, addr, size, j, parent,
+					    (sbi_hart_pmp_count(scratch))
+					    ? false : true);
 	}
 
 	return 0;
-- 
2.39.1