lib: Allow compiling without FP support

Currently, we mandate 'F' and 'D' extension in riscv_fp.h so that
misaligned load/store emulation has access to FP registers.

The above is too restrictive and we should certainly allow compilation
for soft-FP toolchains and explicit PLATFORM_RISCV_ISA not having 'F'
and 'D' extensions.

This patch extends riscv_fp.h and misaligned load/store emulation to
allow compiling OpenSBI without FP support.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

3 files changed, 16 insertions, 13 deletions

diff --git a/include/sbi/riscv_fp.h b/include/sbi/riscv_fp.h
index a8d4c51..a685884 100644
--- a/include/sbi/riscv_fp.h
+++ b/include/sbi/riscv_fp.h
@@ -73,10 +73,6 @@
 
 #define SET_FS_DIRTY() ((void)0)
 
-#else
-#error "Floating point emulation not supported.\n"
-#endif
-
 #define GET_F32_RS1(insn, regs) (GET_F32_REG(insn, 15, regs))
 #define GET_F32_RS2(insn, regs) (GET_F32_REG(insn, 20, regs))
 #define GET_F32_RS3(insn, regs) (GET_F32_REG(insn, 27, regs))
@@ -94,3 +90,5 @@
 #define GET_F64_RS2S(insn, regs) (GET_F64_REG(RVC_RS2S(insn), 0, regs))
 
 #endif
+
+#endif
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index 187b493..3be5b8a 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -52,8 +52,6 @@ static int fp_init(u32 hartid)
 {
 #ifdef __riscv_flen
 	int i;
-#else
-	unsigned long fd_mask;
 #endif
 
 	if (!misa_extension('D') && !misa_extension('F'))
@@ -66,11 +64,6 @@ static int fp_init(u32 hartid)
 	for (i = 0; i < 32; i++)
 		init_fp_reg(i);
 	csr_write(CSR_FCSR, 0);
-#else
-	fd_mask = (1 << ('F' - 'A')) | (1 << ('D' - 'A'));
-	csr_clear(CSR_MISA, fd_mask);
-	if (csr_read(CSR_MISA) & fd_mask)
-		return SBI_ENOTSUPP;
 #endif
 
 	return 0;
diff --git a/lib/sbi/sbi_misaligned_ldst.c b/lib/sbi/sbi_misaligned_ldst.c
index 7f911c3..1c4e5df 100644
--- a/lib/sbi/sbi_misaligned_ldst.c
+++ b/lib/sbi/sbi_misaligned_ldst.c
@@ -41,12 +41,14 @@ int sbi_misaligned_load_handler(u32 hartid, ulong mcause,
 	} else if ((insn & INSN_MASK_LWU) == INSN_MATCH_LWU) {
 		len = 4;
 #endif
+#ifdef __riscv_flen
 	} else if ((insn & INSN_MASK_FLD) == INSN_MATCH_FLD) {
 		fp  = 1;
 		len = 8;
 	} else if ((insn & INSN_MASK_FLW) == INSN_MATCH_FLW) {
 		fp  = 1;
 		len = 4;
+#endif
 	} else if ((insn & INSN_MASK_LH) == INSN_MATCH_LH) {
 		len   = 2;
 		shift = 8 * (sizeof(ulong) - len);
@@ -71,6 +73,7 @@ int sbi_misaligned_load_handler(u32 hartid, ulong mcause,
 		   ((insn >> SH_RD) & 0x1f)) {
 		len   = 4;
 		shift = 8 * (sizeof(ulong) - len);
+#ifdef __riscv_flen
 	} else if ((insn & INSN_MASK_C_FLD) == INSN_MATCH_C_FLD) {
 		fp   = 1;
 		len  = 8;
@@ -88,8 +91,10 @@ int sbi_misaligned_load_handler(u32 hartid, ulong mcause,
 		len = 4;
 #endif
 #endif
+#endif
 	} else
-		return SBI_EILL;
+		return sbi_trap_redirect(regs, scratch, regs->mepc,
+					 mcause, addr);
 
 	val.data_u64 = 0;
 	for (i = 0; i < len; i++) {
@@ -104,10 +109,12 @@ int sbi_misaligned_load_handler(u32 hartid, ulong mcause,
 
 	if (!fp)
 		SET_RD(insn, regs, val.data_ulong << shift >> shift);
+#ifdef __riscv_flen
 	else if (len == 8)
 		SET_F64_RD(insn, regs, val.data_u64);
 	else
 		SET_F32_RD(insn, regs, val.data_ulong);
+#endif
 
 	regs->mepc += INSN_LEN(insn);
 
@@ -132,12 +139,14 @@ int sbi_misaligned_store_handler(u32 hartid, ulong mcause,
 	} else if ((insn & INSN_MASK_SD) == INSN_MATCH_SD) {
 		len = 8;
 #endif
+#ifdef __riscv_flen
 	} else if ((insn & INSN_MASK_FSD) == INSN_MATCH_FSD) {
 		len	     = 8;
 		val.data_u64 = GET_F64_RS2(insn, regs);
 	} else if ((insn & INSN_MASK_FSW) == INSN_MATCH_FSW) {
 		len	       = 4;
 		val.data_ulong = GET_F32_RS2(insn, regs);
+#endif
 	} else if ((insn & INSN_MASK_SH) == INSN_MATCH_SH) {
 		len = 2;
 #ifdef __riscv_compressed
@@ -157,6 +166,7 @@ int sbi_misaligned_store_handler(u32 hartid, ulong mcause,
 		   ((insn >> SH_RD) & 0x1f)) {
 		len	       = 4;
 		val.data_ulong = GET_RS2C(insn, regs);
+#ifdef __riscv_flen
 	} else if ((insn & INSN_MASK_C_FSD) == INSN_MATCH_C_FSD) {
 		len	     = 8;
 		val.data_u64 = GET_F64_RS2S(insn, regs);
@@ -172,8 +182,10 @@ int sbi_misaligned_store_handler(u32 hartid, ulong mcause,
 		val.data_ulong = GET_F32_RS2C(insn, regs);
 #endif
 #endif
+#endif
 	} else
-		return SBI_EILL;
+		return sbi_trap_redirect(regs, scratch, regs->mepc,
+					 mcause, addr);
 
 	for (i = 0; i < len; i++) {
 		store_u8((void *)(addr + i), val.data_bytes[i],