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132 lines
2.6 KiB
132 lines
2.6 KiB
# 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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# XLENB
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# LOAD
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# STORE
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# TEST_BACK_TO_KERNEL
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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 * XLENB
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# save x registers except x2 (sp)
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STORE x1, 1
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STORE x3, 3
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# tp(x4) = hartid. DON'T change.
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# STORE x4, 4
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STORE x5, 5
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STORE x6, 6
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STORE x7, 7
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STORE x8, 8
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STORE x9, 9
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STORE x10, 10
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STORE x11, 11
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STORE x12, 12
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STORE x13, 13
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STORE x14, 14
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STORE x15, 15
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STORE x16, 16
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STORE x17, 17
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STORE x18, 18
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STORE x19, 19
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STORE x20, 20
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STORE x21, 21
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STORE x22, 22
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STORE x23, 23
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STORE x24, 24
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STORE x25, 25
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STORE x26, 26
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STORE x27, 27
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STORE x28, 28
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STORE x29, 29
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STORE x30, 30
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STORE x31, 31
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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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STORE s0, 2
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STORE s1, 32
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STORE s2, 33
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STORE s3, 34
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STORE s4, 35
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.endm
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.macro RESTORE_ALL
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LOAD s1, 32 # s1 = sstatus
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LOAD s2, 33 # s2 = sepc
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TEST_BACK_TO_KERNEL
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bnez s0, _restore_context # s0 = back to kernel?
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_save_kernel_sp:
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addi s0, sp, 36*XLENB
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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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LOAD x1, 1
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LOAD x3, 3
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# LOAD x4, 4
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LOAD x5, 5
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LOAD x6, 6
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LOAD x7, 7
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LOAD x8, 8
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LOAD x9, 9
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LOAD x10, 10
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LOAD x11, 11
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LOAD x12, 12
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LOAD x13, 13
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LOAD x14, 14
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LOAD x15, 15
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LOAD x16, 16
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LOAD x17, 17
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LOAD x18, 18
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LOAD x19, 19
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LOAD x20, 20
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LOAD x21, 21
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LOAD x22, 22
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LOAD x23, 23
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LOAD x24, 24
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LOAD x25, 25
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LOAD x26, 26
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LOAD x27, 27
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LOAD x28, 28
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LOAD x29, 29
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LOAD x30, 30
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LOAD x31, 31
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# restore sp last
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LOAD x2, 2
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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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