1 files changed, 33 insertions, 10 deletions

diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 694267d1fe81..93e45560af30 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -9,6 +9,7 @@
 #include <linux/bitmap.h>
 #include <linux/ctype.h>
 #include <linux/libfdt.h>
+#include <linux/log2.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <asm/alternative.h>
@@ -68,21 +69,38 @@ bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
 }
 EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);
 
+static bool riscv_isa_extension_check(int id)
+{
+	switch (id) {
+	case RISCV_ISA_EXT_ZICBOM:
+		if (!riscv_cbom_block_size) {
+			pr_err("Zicbom detected in ISA string, but no cbom-block-size found\n");
+			return false;
+		} else if (!is_power_of_2(riscv_cbom_block_size)) {
+			pr_err("cbom-block-size present, but is not a power-of-2\n");
+			return false;
+		}
+		return true;
+	}
+
+	return true;
+}
+
 void __init riscv_fill_hwcap(void)
 {
 	struct device_node *node;
 	const char *isa;
 	char print_str[NUM_ALPHA_EXTS + 1];
 	int i, j, rc;
-	static unsigned long isa2hwcap[256] = {0};
+	unsigned long isa2hwcap[26] = {0};
 	unsigned long hartid;
 
-	isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
-	isa2hwcap['m'] = isa2hwcap['M'] = COMPAT_HWCAP_ISA_M;
-	isa2hwcap['a'] = isa2hwcap['A'] = COMPAT_HWCAP_ISA_A;
-	isa2hwcap['f'] = isa2hwcap['F'] = COMPAT_HWCAP_ISA_F;
-	isa2hwcap['d'] = isa2hwcap['D'] = COMPAT_HWCAP_ISA_D;
-	isa2hwcap['c'] = isa2hwcap['C'] = COMPAT_HWCAP_ISA_C;
+	isa2hwcap['i' - 'a'] = COMPAT_HWCAP_ISA_I;
+	isa2hwcap['m' - 'a'] = COMPAT_HWCAP_ISA_M;
+	isa2hwcap['a' - 'a'] = COMPAT_HWCAP_ISA_A;
+	isa2hwcap['f' - 'a'] = COMPAT_HWCAP_ISA_F;
+	isa2hwcap['d' - 'a'] = COMPAT_HWCAP_ISA_D;
+	isa2hwcap['c' - 'a'] = COMPAT_HWCAP_ISA_C;
 
 	elf_hwcap = 0;
 
@@ -189,15 +207,20 @@ void __init riscv_fill_hwcap(void)
 #define SET_ISA_EXT_MAP(name, bit)						\
 			do {							\
 				if ((ext_end - ext == sizeof(name) - 1) &&	\
-				     !memcmp(ext, name, sizeof(name) - 1))	\
+				     !memcmp(ext, name, sizeof(name) - 1) &&	\
+				     riscv_isa_extension_check(bit))		\
 					set_bit(bit, this_isa);			\
 			} while (false)						\
 
 			if (unlikely(ext_err))
 				continue;
 			if (!ext_long) {
-				this_hwcap |= isa2hwcap[(unsigned char)(*ext)];
-				set_bit(*ext - 'a', this_isa);
+				int nr = *ext - 'a';
+
+				if (riscv_isa_extension_check(nr)) {
+					this_hwcap |= isa2hwcap[nr];
+					set_bit(nr, this_isa);
+				}
 			} else {
 				SET_ISA_EXT_MAP("sscofpmf", RISCV_ISA_EXT_SSCOFPMF);
 				SET_ISA_EXT_MAP("svpbmt", RISCV_ISA_EXT_SVPBMT);