+# See LICENSE for license details.
+
#include "encoding.h"
- .data
- .globl _heapend
- .globl environ
-_heapend:
- .word 0
-environ:
- .word 0
+#if __riscv_xlen == 64
+# define LREG ld
+# define SREG sd
+# define REGBYTES 8
+#else
+# define LREG lw
+# define SREG sw
+# define REGBYTES 4
+#endif
- .text
+ .section ".text.init"
.globl _start
-
_start:
+ la t0, trap_entry
+ csrw mtvec, t0
+
li x1, 0
li x2, 0
li x3, 0
li x30,0
li x31,0
-#ifdef __riscv64
- li a0, SR_U64 | SR_S64
- csrs status, a0
+ # enable FPU and accelerator if present
+ li t0, MSTATUS_FS | MSTATUS_XS
+ csrs mstatus, t0
+
+ # make sure XLEN agrees with compilation choice
+ li t0, 1
+ slli t0, t0, 31
+#if __riscv_xlen == 64
+ bgez t0, 1f
+#else
+ bltz t0, 1f
#endif
+ li a0, 1
+ sw a0, tohost, t0
+1:
- # enable fp and accelerator
- li a0, SR_EF | SR_EA
- csrs status, a0
-
- ## if that didn't stick, we don't have an FPU, so don't initialize it
- csrr t0, status
- and t0, t0, SR_EF
+#ifdef __riscv_flen
+ # initialize FPU if we have one
+ andi t0, t0, 1 << ('f' - 'a')
beqz t0, 1f
fssr x0
fmv.s.x f29,x0
fmv.s.x f30,x0
fmv.s.x f31,x0
+#endif
+
1:
- la t0, trap_entry
- csrw evec, t0
+ # initialize global pointer
+ la gp, _gp
la tp, _end + 63
and tp, tp, -64
- # get core id and number of cores
- csrr a0, hartid
- lw a1, 4(zero)
+ # get core id
+ csrr a0, mhartid
+ # for now, assume only 1 core
+ li a1, 1
+1:bgeu a0, a1, 1b
- # give each core a 1KB TLS and a 127KB stack
+ # give each core 128KB of stack + TLS
#define STKSHIFT 17
sll a2, a0, STKSHIFT
add tp, tp, a2
add sp, a0, 1
sll sp, sp, STKSHIFT
add sp, sp, tp
- add tp, tp, 1024
- jal _init
- unimp
+ j _init
+ .align 2
trap_entry:
- csrw sup0, t0
- csrw sup1, t1
- la t0, uarch_insn
- lw t0, (t0)
- csrr t1, epc
- and t1, t1, ~3
- lw t1, (t1)
- and t1, t1, t0
- beq t1, t0, handle_uarch_insn
-
- # a trap occurred that shouldn't have.
- li t0, 1337
- csrw tohost, t0
-1:j 1b
-
-handle_uarch_insn:
- # we trapped on an illegal uarch-specific CSR. just skip over it.
- csrr t1, epc
- add t1, t1, 4
- csrw epc, t1
- csrr t0, sup0
- csrr t1, sup1
- sret
-
-uarch_insn:
- csrr x0, uarch0
+ addi sp, sp, -272
+
+ SREG x1, 1*REGBYTES(sp)
+ SREG x2, 2*REGBYTES(sp)
+ SREG x3, 3*REGBYTES(sp)
+ SREG x4, 4*REGBYTES(sp)
+ SREG x5, 5*REGBYTES(sp)
+ SREG x6, 6*REGBYTES(sp)
+ SREG x7, 7*REGBYTES(sp)
+ SREG x8, 8*REGBYTES(sp)
+ SREG x9, 9*REGBYTES(sp)
+ SREG x10, 10*REGBYTES(sp)
+ SREG x11, 11*REGBYTES(sp)
+ SREG x12, 12*REGBYTES(sp)
+ SREG x13, 13*REGBYTES(sp)
+ SREG x14, 14*REGBYTES(sp)
+ SREG x15, 15*REGBYTES(sp)
+ SREG x16, 16*REGBYTES(sp)
+ SREG x17, 17*REGBYTES(sp)
+ SREG x18, 18*REGBYTES(sp)
+ SREG x19, 19*REGBYTES(sp)
+ SREG x20, 20*REGBYTES(sp)
+ SREG x21, 21*REGBYTES(sp)
+ SREG x22, 22*REGBYTES(sp)
+ SREG x23, 23*REGBYTES(sp)
+ SREG x24, 24*REGBYTES(sp)
+ SREG x25, 25*REGBYTES(sp)
+ SREG x26, 26*REGBYTES(sp)
+ SREG x27, 27*REGBYTES(sp)
+ SREG x28, 28*REGBYTES(sp)
+ SREG x29, 29*REGBYTES(sp)
+ SREG x30, 30*REGBYTES(sp)
+ SREG x31, 31*REGBYTES(sp)
+
+ csrr a0, mcause
+ csrr a1, mepc
+ mv a2, sp
+ jal handle_trap
+ csrw mepc, a0
+
+ # Remain in M-mode after eret
+ li t0, MSTATUS_MPP
+ csrs mstatus, t0
+
+ LREG x1, 1*REGBYTES(sp)
+ LREG x2, 2*REGBYTES(sp)
+ LREG x3, 3*REGBYTES(sp)
+ LREG x4, 4*REGBYTES(sp)
+ LREG x5, 5*REGBYTES(sp)
+ LREG x6, 6*REGBYTES(sp)
+ LREG x7, 7*REGBYTES(sp)
+ LREG x8, 8*REGBYTES(sp)
+ LREG x9, 9*REGBYTES(sp)
+ LREG x10, 10*REGBYTES(sp)
+ LREG x11, 11*REGBYTES(sp)
+ LREG x12, 12*REGBYTES(sp)
+ LREG x13, 13*REGBYTES(sp)
+ LREG x14, 14*REGBYTES(sp)
+ LREG x15, 15*REGBYTES(sp)
+ LREG x16, 16*REGBYTES(sp)
+ LREG x17, 17*REGBYTES(sp)
+ LREG x18, 18*REGBYTES(sp)
+ LREG x19, 19*REGBYTES(sp)
+ LREG x20, 20*REGBYTES(sp)
+ LREG x21, 21*REGBYTES(sp)
+ LREG x22, 22*REGBYTES(sp)
+ LREG x23, 23*REGBYTES(sp)
+ LREG x24, 24*REGBYTES(sp)
+ LREG x25, 25*REGBYTES(sp)
+ LREG x26, 26*REGBYTES(sp)
+ LREG x27, 27*REGBYTES(sp)
+ LREG x28, 28*REGBYTES(sp)
+ LREG x29, 29*REGBYTES(sp)
+ LREG x30, 30*REGBYTES(sp)
+ LREG x31, 31*REGBYTES(sp)
+
+ addi sp, sp, 272
+ mret
+
+.section ".tdata.begin"
+.globl _tdata_begin
+_tdata_begin:
+
+.section ".tdata.end"
+.globl _tdata_end
+_tdata_end:
+
+.section ".tbss.end"
+.globl _tbss_end
+_tbss_end:
+
+.section ".tohost","aw",@progbits
+.align 6
+.globl tohost
+tohost: .dword 0
+.align 6
+.globl fromhost
+fromhost: .dword 0