[PATCH] lib: utils/fdt: Fix fdt_parse_isa_extensions() implementation

[Anup Patel]

Currently, the fdt_parse_isa_extensions() tries to parse the ISA
string once for each HART. This ISA string parsing can fail for
secondary HARTs if the FDT memory is already overwritten by the
supervisor OS.

To tackle this issue, we improve the fdt_parse_isa_extensions()
implementation to pre-parse ISA string for all HARTs during
cold boot.

Fixes: d72f5f17478d ("lib: utils: Add detection of Smepmp from ISA
string in FDT")
Signed-off-by: Anup Patel <apatel at ventanamicro.com>
---
 lib/utils/fdt/fdt_helper.c | 122 ++++++++++++++++++++++++-------------
 1 file changed, 79 insertions(+), 43 deletions(-)

diff --git a/lib/utils/fdt/fdt_helper.c b/lib/utils/fdt/fdt_helper.c
index 61a4100..c97f09d 100644
--- a/lib/utils/fdt/fdt_helper.c
+++ b/lib/utils/fdt/fdt_helper.c
@@ -314,54 +314,14 @@ int fdt_parse_timebase_frequency(void *fdt, unsigned long *freq)
 	return 0;
 }
 
-static int fdt_get_isa_string(void *fdt, unsigned int hartid,
-			const char **isa_string)
-{
-	int err, cpu_offset, cpus_offset, len;
-	u32 c_hartid;
-	const fdt32_t *val;
-
-	if (!fdt)
-		return SBI_EINVAL;
-
-	cpus_offset = fdt_path_offset(fdt, "/cpus");
-	if (cpus_offset < 0)
-		return cpus_offset;
-
-	fdt_for_each_subnode(cpu_offset, fdt, cpus_offset) {
-		err = fdt_parse_hart_id(fdt, cpu_offset, &c_hartid);
-		if (err)
-			continue;
-
-		if (!fdt_node_is_enabled(fdt, cpu_offset))
-			continue;
-
-		if (c_hartid == hartid) {
-			val = fdt_getprop(fdt, cpu_offset, "riscv,isa", &len);
-			if (val && len > 0) {
-				*isa_string = (const char *)val;
-				return 0;
-			}
-		}
-	}
-
-	return SBI_EINVAL;
-}
-
 #define RISCV_ISA_EXT_NAME_LEN_MAX	32
 
-int fdt_parse_isa_extensions(void *fdt, unsigned int hartid,
-			unsigned long *extensions)
+static unsigned long fdt_isa_bitmap_offset;
+
+static int fdt_parse_isa_one_hart(const char *isa, unsigned long *extensions)
 {
 	size_t i, j, isa_len;
 	char mstr[RISCV_ISA_EXT_NAME_LEN_MAX];
-	const char *isa = NULL;
-
-	if (fdt_get_isa_string(fdt, hartid, &isa))
-		return SBI_EINVAL;
-
-	if (!isa)
-		return SBI_EINVAL;
 
 	i = 0;
 	isa_len = strlen(isa);
@@ -424,6 +384,82 @@ int fdt_parse_isa_extensions(void *fdt, unsigned int hartid,
 	return 0;
 }
 
+static int fdt_parse_isa_all_harts(void *fdt)
+{
+	u32 hartid;
+	const fdt32_t *val;
+	unsigned long *hart_exts;
+	struct sbi_scratch *scratch;
+	int err, cpu_offset, cpus_offset, len;
+
+	if (!fdt || !fdt_isa_bitmap_offset)
+		return SBI_EINVAL;
+
+	cpus_offset = fdt_path_offset(fdt, "/cpus");
+	if (cpus_offset < 0)
+		return cpus_offset;
+
+	fdt_for_each_subnode(cpu_offset, fdt, cpus_offset) {
+		err = fdt_parse_hart_id(fdt, cpu_offset, &hartid);
+		if (err)
+			continue;
+
+		if (!fdt_node_is_enabled(fdt, cpu_offset))
+			continue;
+
+		val = fdt_getprop(fdt, cpu_offset, "riscv,isa", &len);
+		if (!val || len <= 0)
+			return SBI_ENOENT;
+
+		scratch = sbi_hartid_to_scratch(hartid);
+		if (!scratch)
+			return SBI_ENOENT;
+
+		hart_exts = sbi_scratch_offset_ptr(scratch,
+						   fdt_isa_bitmap_offset);
+		if (!hart_exts)
+			return SBI_ENOENT;
+
+		err = fdt_parse_isa_one_hart((const char *)val, hart_exts);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+int fdt_parse_isa_extensions(void *fdt, unsigned int hartid,
+			unsigned long *extensions)
+{
+	int rc, i;
+	unsigned long *hart_exts;
+	struct sbi_scratch *scratch;
+
+	if (!fdt_isa_bitmap_offset) {
+		fdt_isa_bitmap_offset = sbi_scratch_alloc_offset(
+					sizeof(*hart_exts) *
+					BITS_TO_LONGS(SBI_HART_EXT_MAX));
+		if (!fdt_isa_bitmap_offset)
+			return SBI_ENOMEM;
+
+		rc = fdt_parse_isa_all_harts(fdt);
+		if (rc)
+			return rc;
+	}
+
+	scratch = sbi_hartid_to_scratch(hartid);
+	if (!scratch)
+		return SBI_ENOENT;
+
+	hart_exts = sbi_scratch_offset_ptr(scratch, fdt_isa_bitmap_offset);
+	if (!hart_exts)
+		return SBI_ENOENT;
+
+	for (i = 0; i < BITS_TO_LONGS(SBI_HART_EXT_MAX); i++)
+		extensions[i] |= hart_exts[i];
+	return 0;
+}
+
 static int fdt_parse_uart_node_common(void *fdt, int nodeoffset,
 				      struct platform_uart_data *uart,
 				      unsigned long default_freq,
-- 
2.34.1