Kernel library crate for xous
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#if __riscv_xlen == 64
# define STORE sd
# define LOAD ld
# define LOG_REGBYTES 3
#else
# define STORE sw
# define LOAD lw
# define LOG_REGBYTES 2
#endif
#define REGBYTES (1 << LOG_REGBYTES)
/*
Entry point of all programs (_start).
It initializes DWARF call frame information, the stack pointer, the
frame pointer (needed for closures to work in start_rust) and the global
pointer. Then it calls _start_rust.
*/
.section .text.init, "ax"
.global _start
_start:
.cfi_startproc
.cfi_undefined ra
csrw mie, 0
csrw mip, 0
li x1, 0
li x2, 0
li x3, 0
li x4, 0
li x5, 0
li x6, 0
li x7, 0
li x8, 0
li x9, 0
li x10,0
li x11,0
li x12,0
li x13,0
li x14,0
li x15,0
li x16,0
li x17,0
li x18,0
li x19,0
li x20,0
li x21,0
li x22,0
li x23,0
li x24,0
li x25,0
li x26,0
li x27,0
li x28,0
li x29,0
li x30,0
li x31,0
.option push
.option norelax
la gp, __global_pointer$
.option pop
#if !defined(SKIP_MULTICORE)
// Check hart id
csrr a2, mhartid
lui t0, %hi(_max_hart_id)
add t0, t0, %lo(_max_hart_id)
bgtu a2, t0, abort
#endif // SKIP_MULTICORE
// Allocate stacks
la sp, _estack
#if !defined(SKIP_MULTICORE)
lui t0, %hi(_hart_stack_size)
add t0, t0, %lo(_hart_stack_size)
mul t0, a2, t0
sub sp, sp, t0
#endif // SKIP_MULTICORE
// Set frame pointer
add s0, sp, zero
// Set trap handler
la t0, _start_trap
csrw mtvec, t0
jal zero, _start_rust
.cfi_endproc
/*
Trap entry point (_start_trap)
Saves caller saved registers ra, t0..6, a0..7, calls _start_trap_rust,
restores caller saved registers and then returns.
*/
.section .trap, "ax"
.global _start_trap
_start_trap:
addi sp, sp, -16*REGBYTES
STORE ra, 0*REGBYTES(sp)
STORE t0, 1*REGBYTES(sp)
STORE t1, 2*REGBYTES(sp)
STORE t2, 3*REGBYTES(sp)
STORE t3, 4*REGBYTES(sp)
STORE t4, 5*REGBYTES(sp)
STORE t5, 6*REGBYTES(sp)
STORE t6, 7*REGBYTES(sp)
STORE a0, 8*REGBYTES(sp)
STORE a1, 9*REGBYTES(sp)
STORE a2, 10*REGBYTES(sp)
STORE a3, 11*REGBYTES(sp)
STORE a4, 12*REGBYTES(sp)
STORE a5, 13*REGBYTES(sp)
STORE a6, 14*REGBYTES(sp)
STORE a7, 15*REGBYTES(sp)
jal ra, _start_trap_rust
LOAD ra, 0*REGBYTES(sp)
LOAD t0, 1*REGBYTES(sp)
LOAD t1, 2*REGBYTES(sp)
LOAD t2, 3*REGBYTES(sp)
LOAD t3, 4*REGBYTES(sp)
LOAD t4, 5*REGBYTES(sp)
LOAD t5, 6*REGBYTES(sp)
LOAD t6, 7*REGBYTES(sp)
LOAD a0, 8*REGBYTES(sp)
LOAD a1, 9*REGBYTES(sp)
LOAD a2, 10*REGBYTES(sp)
LOAD a3, 11*REGBYTES(sp)
LOAD a4, 12*REGBYTES(sp)
LOAD a5, 13*REGBYTES(sp)
LOAD a6, 14*REGBYTES(sp)
LOAD a7, 15*REGBYTES(sp)
addi sp, sp, 16*REGBYTES
mret
/* Make sure there is an abort when linking */
.section .text.init
.globl abort
abort:
j abort