77 lines
1.8 KiB
C
77 lines
1.8 KiB
C
// TODO: CHECK/REPLACE/UPDATE OLD CODE (this file is based on xv6)
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#include "types.h"
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#include "param.h"
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#include "memlayout.h"
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#include "riscv.h"
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#include "defs.h"
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#include "sched.h"
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void main();
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void timerinit();
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// entry.S needs one stack per CPU.
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/*TODO __attribute__ ((aligned (16))) char stack0[4096 * NCPU]; */
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uint64 stack0[512*SCHED_CORE_MAX];
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// entry.S jumps here in machine mode on stack0.
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void
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start()
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{
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//consputc(65);
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// set M Previous Privilege mode to Supervisor, for mret.
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unsigned long x = r_mstatus();
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x &= ~MSTATUS_MPP_MASK;
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x |= MSTATUS_MPP_S;
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w_mstatus(x);
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// set M Exception Program Counter to main, for mret.
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// requires gcc -mcmodel=medany
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w_mepc((uint64)(&main));
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// disable paging for now.
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w_satp(0);
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// delegate all interrupts and exceptions to supervisor mode.
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w_medeleg(0xffff);
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w_mideleg(0xffff);
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w_sie(r_sie() | SIE_SEIE | SIE_STIE | SIE_SSIE);
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// configure Physical Memory Protection to give supervisor mode
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// access to all of physical memory.
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w_pmpaddr0(0x3fffffffffffffull);
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w_pmpcfg0(0xf);
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// ask for clock interrupts.
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timerinit();
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// keep each CPU's hartid in its tp register, for SCHED_CORE_THISNUMBER_NOINTERRUPTS().
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int _id = r_mhartid();
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sched_cputhreadpointer_set(_id);
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// switch to supervisor mode and jump to main().
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#ifdef _ZCC
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__asm {
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mret
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};
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#else
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asm volatile("mret");
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#endif
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}
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// ask each hart to generate timer interrupts.
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void
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timerinit()
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{
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// enable supervisor-mode timer interrupts.
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w_mie(r_mie() | MIE_STIE);
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// enable the sstc extension (i.e. stimecmp).
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w_menvcfg(r_menvcfg() | (1L << 63));
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// allow supervisor to use stimecmp and time.
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w_mcounteren(r_mcounteren() | 2);
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// ask for the very first timer interrupt.
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w_stimecmp(r_time() + 1000000);
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}
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