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