RISC-V: Do no continue isa string parsing without correct XLEN

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.

Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 3455fdfd680e0d836a7bdc87bc3d975ed4a61c64..a43c08af5f4b37e3d360492ed64710a552c55d5a 100644 (file)
--- 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;
                DECLARE_BITMAP(this_isa, RISCV_ISA_EXT_MAX);
+               const char *temp;
 
                if (riscv_of_processor_hartid(node) < 0)
                        continue;
@@ -93,6 +94,7 @@ void __init riscv_fill_hwcap(void)
                        continue;
                }
 
+               temp = 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;
                bitmap_zero(this_isa, RISCV_ISA_EXT_MAX);
                for (; *isa; ++isa) {
                        const char *ext = isa++;