[PATCH v2 5/6] RISC-V: Do no continue isa string parsing without correct XLEN

[Atish Patra]

The isa string should begin with either rv64 or rv32. Otherwise, it is
an incorrect isa string. Currently, the string parsing continues even if
it doesnot begin with current XLEN.

Fix this by checking if it found "rv64" or "rv32" in the beginning.

Signed-off-by: Atish Patra <atishp at rivosinc.com>
---
 arch/riscv/kernel/cpufeature.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 469b9739faf7..cca579bae8a0 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -84,6 +84,7 @@ void __init riscv_fill_hwcap(void)
 	for_each_of_cpu_node(node) {
 		unsigned long this_hwcap = 0;
 		uint64_t this_isa = 0;
+		char *temp;
 
 		if (riscv_of_processor_hartid(node) < 0)
 			continue;
@@ -93,6 +94,7 @@ void __init riscv_fill_hwcap(void)
 			continue;
 		}
 
+		temp = (char *)isa;
 #if IS_ENABLED(CONFIG_32BIT)
 		if (!strncmp(isa, "rv32", 4))
 			isa += 4;
@@ -100,6 +102,9 @@ void __init riscv_fill_hwcap(void)
 		if (!strncmp(isa, "rv64", 4))
 			isa += 4;
 #endif
+		/* The riscv,isa DT property must start with rv64 or rv32 */
+		if (temp == isa)
+			continue;
 		for (; *isa; ++isa) {
 			const char *ext = isa++;
 			const char *ext_end = isa;
-- 
2.30.2