diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h index 318192c66fd8b5ed0c2cfec4f1564c59e905feae..0a62d2d684552da8c665d17632bc590e61b1dbc0 100644 --- a/arch/riscv/include/asm/csr.h +++ b/arch/riscv/include/asm/csr.h @@ -92,6 +92,7 @@ #define CSR_SATP 0x180 #define CSR_MSTATUS 0x300 +#define CSR_MISA 0x301 #define CSR_MIE 0x304 #define CSR_MTVEC 0x305 #define CSR_MSCRATCH 0x340 diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S index fc99730869466f6652007dec7db645dc36bf85da..64eb8beb228ee7884aeae462ee1939deabe296d5 100644 --- a/arch/riscv/kernel/head.S +++ b/arch/riscv/kernel/head.S @@ -11,6 +11,7 @@ #include <asm/thread_info.h> #include <asm/page.h> #include <asm/csr.h> +#include <asm/hwcap.h> #include <asm/image.h> __INIT @@ -51,12 +52,18 @@ _start_kernel: csrw CSR_IP, zero #ifdef CONFIG_RISCV_M_MODE + /* flush the instruction cache */ + fence.i + + /* Reset all registers except ra, a0, a1 */ + call reset_regs + /* * The hartid in a0 is expected later on, and we have no firmware * to hand it to us. */ csrr a0, CSR_MHARTID -#endif +#endif /* CONFIG_RISCV_M_MODE */ /* Load the global pointer */ .option push @@ -203,6 +210,85 @@ relocate: j .Lsecondary_park END(_start) +#ifdef CONFIG_RISCV_M_MODE +ENTRY(reset_regs) + li sp, 0 + li gp, 0 + li tp, 0 + li t0, 0 + li t1, 0 + li t2, 0 + li s0, 0 + li s1, 0 + li a2, 0 + li a3, 0 + li a4, 0 + li a5, 0 + li a6, 0 + li a7, 0 + li s2, 0 + li s3, 0 + li s4, 0 + li s5, 0 + li s6, 0 + li s7, 0 + li s8, 0 + li s9, 0 + li s10, 0 + li s11, 0 + li t3, 0 + li t4, 0 + li t5, 0 + li t6, 0 + csrw sscratch, 0 + +#ifdef CONFIG_FPU + csrr t0, CSR_MISA + andi t0, t0, (COMPAT_HWCAP_ISA_F | COMPAT_HWCAP_ISA_D) + bnez t0, .Lreset_regs_done + + li t1, SR_FS + csrs CSR_STATUS, t1 + fmv.s.x f0, zero + fmv.s.x f1, zero + fmv.s.x f2, zero + fmv.s.x f3, zero + fmv.s.x f4, zero + fmv.s.x f5, zero + fmv.s.x f6, zero + fmv.s.x f7, zero + fmv.s.x f8, zero + fmv.s.x f9, zero + fmv.s.x f10, zero + fmv.s.x f11, zero + fmv.s.x f12, zero + fmv.s.x f13, zero + fmv.s.x f14, zero + fmv.s.x f15, zero + fmv.s.x f16, zero + fmv.s.x f17, zero + fmv.s.x f18, zero + fmv.s.x f19, zero + fmv.s.x f20, zero + fmv.s.x f21, zero + fmv.s.x f22, zero + fmv.s.x f23, zero + fmv.s.x f24, zero + fmv.s.x f25, zero + fmv.s.x f26, zero + fmv.s.x f27, zero + fmv.s.x f28, zero + fmv.s.x f29, zero + fmv.s.x f30, zero + fmv.s.x f31, zero + csrw fcsr, 0 + /* note that the caller must clear SR_FS */ +#endif /* CONFIG_FPU */ +.Lreset_regs_done: + ret +END(reset_regs) +#endif /* CONFIG_RISCV_M_MODE */ + __PAGE_ALIGNED_BSS /* Empty zero page */ .balign PAGE_SIZE