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96 lines
2.9 KiB
C
96 lines
2.9 KiB
C
#include "kernel.h"
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#include "ktypes.h"
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#include "ecall.h"
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#include "sched.h"
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#include "io.h"
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#include "malloc.h"
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#include "csr.h"
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void read_binary_table();
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void setup_mem_protection();
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// this array is populated when the memory image is built, therefore it should
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// resign in a section which is not overwritten with zeros on startup
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loaded_binary binary_table[PACKAGED_BINARY_COUNT] __attribute__ ((section(".data")));
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// access the memset function defined in boot.S
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extern void memset(unsigned int, void*, void*);
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// access linker symbols:
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extern byte* _end, _ftext;
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extern void init()
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{
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dbgln("Kernel started!", 15);
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// setup phsycial memory protection
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setup_mem_protection();
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// initialize scheduler
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scheudler_init();
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// initialize tabel for associating ecall codes with their handlers
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init_ecall_table();
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// read supplied binaries, this will call malloc_init with the memory layout
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// then it will create a new process for each loaded binary
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read_binary_table();
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// give control to the scheudler and start runnign user programs
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scheduler_run_next();
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}
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void read_binary_table()
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{
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char msg[28] = "found bin with id 0 at pos 0";
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struct malloc_info info = {
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.allocate_memory_end = (void*) END_OF_USABLE_MEM,
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.allocate_memory_start = (void*) 0
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};
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// calculate the end of loaded binaries
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for (int i = 0; i < PACKAGED_BINARY_COUNT; i++) {
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if (binary_table[i].binid == 0)
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break;
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if (DEBUGGING) {
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// print message
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msg[18] = (char) binary_table[i].binid + '0';
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msg[27] = (char) i + '0';
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dbgln(msg, 28);
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}
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info.allocate_memory_start = binary_table[i].bounds[1];
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}
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// initialize malloc
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malloc_init(&info);
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for (int i = 0; i < PACKAGED_BINARY_COUNT; i++) {
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if (binary_table[i].binid == 0)
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break;
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// create a new process for each binary found
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// it should have around 4kb stack
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optional_pcbptr res = create_new_process(binary_table + i);
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if (has_error(res)) {
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dbgln("Error creating initial process!", 31);
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}
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}
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}
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void setup_mem_protection()
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{
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// this pmp config uses Top-of-Range mode - read more in the privileged spec p.49
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// we disallow all access to 0x0-0x100 from user and machine mode
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// and all access to 0x100-kernel_end from user mode
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// to do this, we must first calculate the kernel bin length
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uint32 kernel_bin_len = ((uint32) &_end) - ((uint32) &_ftext);
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CSR_WRITE(CSR_PMPADDR, 0x100);
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CSR_WRITE(CSR_PMPADDR + 1, 0x100 + kernel_bin_len);
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// this contains two pmp configs:
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// fields: L A RWX
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// pmpcfg0: 0b1_00_01_000 <- disallow RWX from U and M mode
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// pmpcfg1: 0b0_00_01_000 <- disallow RWX from U mode
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// the resulint number is 0b0000100010001000, hex 0x888
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CSR_WRITE(CSR_PMPCFG, 0x888);
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}
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