lib: Add error detection for misa_extension

Add assertions for misa_extension to prevent incoming illegal
characters.

Signed-off-by: Xiang Wang <merle@hardenedlinux.org>
Reviewed-by: Anup Patel <anup.patel@wdc.com>

diff --git a/include/sbi/riscv_asm.h b/include/sbi/riscv_asm.h
index 04502e1..c3d5985 100644 (file)
--- a/include/sbi/riscv_asm.h
+++ b/include/sbi/riscv_asm.h
@@ -159,8 +159,16 @@ void csr_write_num(int csr_num, unsigned long val);
                __asm__ __volatile__("wfi" ::: "memory"); \
        } while (0)
 
-/* Determine CPU extension, return non-zero support */
-int misa_extension(char ext);
+
+/* determine CPU extension, return non-zero support */
+int misa_extension_imp(char ext);
+
+#define misa_extension(c)\
+({\
+       _Static_assert(((c >= 'A') && (c <= 'Z')),\
+               "The parameter of misa_extension must be [A-Z]");\
+       misa_extension_imp(c);\
+})
 
 /* Get MXL field of misa, return -1 on error */
 int misa_xlen(void);
@@ -170,7 +178,7 @@ static inline void misa_string(char *out, unsigned int out_sz)
        unsigned long i;
 
        for (i = 0; i < 26; i++) {
-               if (misa_extension('A' + i)) {
+               if (misa_extension_imp('A' + i)) {
                        *out = 'A' + i;
                        out++;
                }

diff --git a/lib/sbi/riscv_asm.c b/lib/sbi/riscv_asm.c
index d16e32a..7b612d4 100644 (file)
--- a/lib/sbi/riscv_asm.c
+++ b/lib/sbi/riscv_asm.c
@@ -12,7 +12,8 @@
 #include <sbi/sbi_error.h>
 #include <sbi/sbi_platform.h>
 
-int misa_extension(char ext)
+/* determine CPU extension, return non-zero support */
+int misa_extension_imp(char ext)
 {
        unsigned long misa = csr_read(CSR_MISA);