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Diffstat (limited to 'arch/riscv/kernel/head.S')
-rw-r--r--arch/riscv/kernel/head.S112
1 files changed, 106 insertions, 6 deletions
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 72f89b7590dd..84a6f0a4b120 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
@@ -47,8 +48,22 @@ ENTRY(_start)
.global _start_kernel
_start_kernel:
/* Mask all interrupts */
- csrw CSR_SIE, zero
- csrw CSR_SIP, zero
+ csrw CSR_IE, zero
+ 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 /* CONFIG_RISCV_M_MODE */
/* Load the global pointer */
.option push
@@ -61,7 +76,7 @@ _start_kernel:
* floating point in kernel space
*/
li t0, SR_FS
- csrc CSR_SSTATUS, t0
+ csrc CSR_STATUS, t0
#ifdef CONFIG_SMP
li t0, CONFIG_NR_CPUS
@@ -94,8 +109,10 @@ clear_bss_done:
la sp, init_thread_union + THREAD_SIZE
mv a0, s1
call setup_vm
+#ifdef CONFIG_MMU
la a0, early_pg_dir
call relocate
+#endif /* CONFIG_MMU */
/* Restore C environment */
la tp, init_task
@@ -106,6 +123,7 @@ clear_bss_done:
call parse_dtb
tail start_kernel
+#ifdef CONFIG_MMU
relocate:
/* Relocate return address */
li a1, PAGE_OFFSET
@@ -116,7 +134,7 @@ relocate:
/* Point stvec to virtual address of intruction after satp write */
la a2, 1f
add a2, a2, a1
- csrw CSR_STVEC, a2
+ csrw CSR_TVEC, a2
/* Compute satp for kernel page tables, but don't load it yet */
srl a2, a0, PAGE_SHIFT
@@ -138,7 +156,7 @@ relocate:
1:
/* Set trap vector to spin forever to help debug */
la a0, .Lsecondary_park
- csrw CSR_STVEC, a0
+ csrw CSR_TVEC, a0
/* Reload the global pointer */
.option push
@@ -156,12 +174,13 @@ relocate:
sfence.vma
ret
+#endif /* CONFIG_MMU */
.Lsecondary_start:
#ifdef CONFIG_SMP
/* Set trap vector to spin forever to help debug */
la a3, .Lsecondary_park
- csrw CSR_STVEC, a3
+ csrw CSR_TVEC, a3
slli a3, a0, LGREG
la a1, __cpu_up_stack_pointer
@@ -181,9 +200,11 @@ relocate:
beqz tp, .Lwait_for_cpu_up
fence
+#ifdef CONFIG_MMU
/* Enable virtual memory and relocate to virtual address */
la a0, swapper_pg_dir
call relocate
+#endif
tail smp_callin
#endif
@@ -195,6 +216,85 @@ 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