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# Constants / Macros defined in Rust code:
# xscratch
# xstatus
# xepc
# xcause
# xtval
# XRET
.macro SAVE_ALL
# If coming from userspace, preserve the user stack pointer and load
# the kernel stack pointer. If we came from the kernel, sscratch
# will contain 0, and we should continue on the current stack.
csrrw sp, (xscratch), sp
bnez sp, _save_context
_restore_kernel_sp:
csrr sp, (xscratch)
# sscratch = previous-sp, sp = kernel-sp
_save_context:
# provide room for trap frame
addi sp, sp, -36 * 4
# save x registers except x2 (sp)
sw x1, 1*4(sp)
sw x3, 3*4(sp)
# tp(x4) = hartid. DON'T change.
# sw x4, 4*4(sp)
sw x5, 5*4(sp)
sw x6, 6*4(sp)
sw x7, 7*4(sp)
sw x8, 8*4(sp)
sw x9, 9*4(sp)
sw x10, 10*4(sp)
sw x11, 11*4(sp)
sw x12, 12*4(sp)
sw x13, 13*4(sp)
sw x14, 14*4(sp)
sw x15, 15*4(sp)
sw x16, 16*4(sp)
sw x17, 17*4(sp)
sw x18, 18*4(sp)
sw x19, 19*4(sp)
sw x20, 20*4(sp)
sw x21, 21*4(sp)
sw x22, 22*4(sp)
sw x23, 23*4(sp)
sw x24, 24*4(sp)
sw x25, 25*4(sp)
sw x26, 26*4(sp)
sw x27, 27*4(sp)
sw x28, 28*4(sp)
sw x29, 29*4(sp)
sw x30, 30*4(sp)
sw x31, 31*4(sp)
# get sp, sstatus, sepc, stval, scause
# set sscratch = 0
csrrw s0, (xscratch), x0
csrr s1, (xstatus)
csrr s2, (xepc)
csrr s3, (xtval)
csrr s4, (xcause)
# store sp, sstatus, sepc, sbadvaddr, scause
sw s0, 2*4(sp)
sw s1, 32*4(sp)
sw s2, 33*4(sp)
sw s3, 34*4(sp)
sw s4, 35*4(sp)
.endm
.macro RESTORE_ALL
lw s1, 32*4(sp) # s1 = sstatus
lw s2, 33*4(sp) # s2 = sepc
andi s0, s1, 1 << 8
bnez s0, _restore_context # back to S-mode? (sstatus.SPP = 1)
_save_kernel_sp:
addi s0, sp, 36*4
csrw (xscratch), s0 # sscratch = kernel-sp
_restore_context:
# restore sstatus, sepc
csrw (xstatus), s1
csrw (xepc), s2
# restore x registers except x2 (sp)
lw x1, 1*4(sp)
lw x3, 3*4(sp)
# lw x4, 4*4(sp)
lw x5, 5*4(sp)
lw x6, 6*4(sp)
lw x7, 7*4(sp)
lw x8, 8*4(sp)
lw x9, 9*4(sp)
lw x10, 10*4(sp)
lw x11, 11*4(sp)
lw x12, 12*4(sp)
lw x13, 13*4(sp)
lw x14, 14*4(sp)
lw x15, 15*4(sp)
lw x16, 16*4(sp)
lw x17, 17*4(sp)
lw x18, 18*4(sp)
lw x19, 19*4(sp)
lw x20, 20*4(sp)
lw x21, 21*4(sp)
lw x22, 22*4(sp)
lw x23, 23*4(sp)
lw x24, 24*4(sp)
lw x25, 25*4(sp)
lw x26, 26*4(sp)
lw x27, 27*4(sp)
lw x28, 28*4(sp)
lw x29, 29*4(sp)
lw x30, 30*4(sp)
lw x31, 31*4(sp)
# restore sp last
lw x2, 2*4(sp)
.endm
.section .text
.globl __alltraps
__alltraps:
SAVE_ALL
mv a0, sp
jal rust_trap
.globl __trapret
__trapret:
RESTORE_ALL
# return from supervisor call
XRET