mirror of
https://github.com/ringtailsoftware/uvm32.git
synced 2026-06-06 06:53:39 +00:00
Rework syscall ABI.
Syscalls now accept two parameters, allowing for things like "int count = read(buf, len)" Rather than providing safe signatures for syscalls, the user is now given helper functions to safely parse incoming values, c-strings and slices.
This commit is contained in:
Toby Jaffey
parent
f046a590c0
commit
76fba39a21
28 changed files with 543 additions and 537 deletions
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@ -1,13 +1,37 @@
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#include "config.h"
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#define MINIRV32_IMPLEMENTATION
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#include "uvm32.h"
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#include <stdio.h>
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#include <string.h>
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#ifndef UVM32_MEMORY_SIZE
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#error Define UVM32_MEMORY_SIZE
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#endif
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#define UVM32_NULL (void *)0
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// On an invalid operation, an error is set in uvm32_state_t, but a valid pointer still needs to be temporarily used
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static uint32_t garbage;
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#ifndef UVM32_MEMCPY
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#define UVM32_MEMCPY uvm32_memcpy
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void uvm32_memcpy(void *dst, const void *src, int len) {
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uint8_t *d = (uint8_t *)dst;
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const uint8_t *s = (const uint8_t *)src;
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while(len--) {
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*(d++) = *(s++);
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}
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}
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#endif
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#ifndef UVM32_MEMSET
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#define UVM32_MEMSET uvm32_memset
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void uvm32_memset(void *buf, int c, int len) {
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uint8_t *b = (uint8_t *)buf;
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while(len--) {
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*(b++) = c;
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}
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}
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#endif
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#include "mini-rv32ima.h"
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#define X(name) #name,
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@ -32,79 +56,85 @@ static void setStatus(uvm32_state_t *vmst, uvm32_status_t newStatus) {
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}
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static void setStatusErr(uvm32_state_t *vmst, uvm32_err_t err) {
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setStatus(vmst, UVM32_STATUS_ERROR);
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vmst->err = err;
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// if already in error state, stay in the first error state
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if (vmst->status != UVM32_STATUS_ERROR) {
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setStatus(vmst, UVM32_STATUS_ERROR);
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vmst->err = err;
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}
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}
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void uvm32_init(uvm32_state_t *vmst, const uvm32_mapping_t *mappings, uint32_t numMappings) {
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void uvm32_init(uvm32_state_t *vmst) {
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UVM32_MEMSET(vmst, 0x00, sizeof(uvm32_state_t));
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vmst->status = UVM32_STATUS_PAUSED;
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memset(vmst->memory, 0x00, UVM32_MEMORY_SIZE);
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// The core lives at the end of RAM.
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vmst->core = (struct MiniRV32IMAState*)(vmst->memory + UVM32_MEMORY_SIZE - sizeof(struct MiniRV32IMAState));
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vmst->core->pc = MINIRV32_RAM_IMAGE_OFFSET;
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vmst->core.pc = MINIRV32_RAM_IMAGE_OFFSET;
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// https://projectf.io/posts/riscv-cheat-sheet/
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// setup stack pointer
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// la sp, _sstack
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// addi sp,sp,-16
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vmst->core->regs[2] = (MINIRV32_RAM_IMAGE_OFFSET + UVM32_MEMORY_SIZE - sizeof(struct MiniRV32IMAState)) - 16;
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vmst->core->regs[10] = 0x00; //hart ID
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vmst->core->regs[11] = 0;
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vmst->core->extraflags |= 3; // Machine-mode.
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vmst->mappings = mappings;
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vmst->numMappings = numMappings;
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vmst->core.regs[2] = (MINIRV32_RAM_IMAGE_OFFSET + UVM32_MEMORY_SIZE) - 16;
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vmst->core.regs[10] = 0x00; //hart ID
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vmst->core.regs[11] = 0;
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vmst->core.extraflags |= 3; // Machine-mode.
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}
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bool uvm32_load(uvm32_state_t *vmst, uint8_t *rom, int len) {
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// RAM needs at least image then MiniRV32IMAState (core)
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if (len > UVM32_MEMORY_SIZE - sizeof(struct MiniRV32IMAState)) {
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if (len > UVM32_MEMORY_SIZE) {
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// too big
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return false;
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}
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memcpy(vmst->memory, rom, len);
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UVM32_MEMCPY(vmst->memory, rom, len);
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return true;
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}
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// Read C-string up to terminator and return len,ptr
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static void get_safeptr_terminated(uvm32_state_t *vmst, uint32_t addr, uint8_t terminator, uvm32_evt_syscall_buf_t *buf) {
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bool get_safeptr_null_terminated(uvm32_state_t *vmst, uint32_t addr, uvm32_evt_syscall_buf_t *buf) {
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uint32_t ptrstart = addr - MINIRV32_RAM_IMAGE_OFFSET;
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uint32_t p = ptrstart;
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if (p >= UVM32_MEMORY_SIZE) {
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setStatusErr(vmst, UVM32_ERR_MEM_RD);
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buf->ptr = NULL;
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buf->ptr = (uint8_t *)UVM32_NULL;
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buf->len = 0;
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return;
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return false;
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}
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while(vmst->memory[p] != terminator) {
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while(vmst->memory[p] != '\0') {
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p++;
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if (p >= UVM32_MEMORY_SIZE) {
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setStatusErr(vmst, UVM32_ERR_MEM_RD);
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buf->ptr = NULL;
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buf->ptr = (uint8_t *)UVM32_NULL;
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buf->len = 0;
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return;
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return false;
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}
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}
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buf->ptr = &vmst->memory[ptrstart];
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buf->len = p - ptrstart;
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return true;
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}
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#if 0
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static void get_safeptr(uvm32_state_t *vmst, uint32_t addr, uint32_t len, uvm32_evt_syscall_buf_t *buf) {
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bool get_safeptr(uvm32_state_t *vmst, uint32_t addr, uint32_t len, uvm32_evt_syscall_buf_t *buf) {
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uint32_t ptrstart = addr - MINIRV32_RAM_IMAGE_OFFSET;
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if (ptrstart + len >= UVM32_MEMORY_SIZE) {
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if ((ptrstart > UVM32_MEMORY_SIZE) || (ptrstart + len >= UVM32_MEMORY_SIZE)) {
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setStatusErr(vmst, UVM32_ERR_MEM_RD);
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buf->ptr = (uint8_t *)UVM32_NULL;
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buf->len = 0;
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return false;
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}
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buf->ptr = &vmst->memory[ptrstart];
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buf->len = len;
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return true;
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}
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#endif
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void uvm32_clearError(uvm32_state_t *vmst) {
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if (vmst->status == UVM32_STATUS_ERROR) {
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// vm is in an error state, but user wants to continue
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// most likely after UVM32_ERR_HUNG
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vmst->status = UVM32_STATUS_PAUSED;
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}
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}
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uint32_t uvm32_run(uvm32_state_t *vmst, uvm32_evt_t *evt, uint32_t instr_meter) {
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uint32_t num_instr = 0;
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// uvm32_evt_syscall_buf_t b;
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if (vmst->status != UVM32_STATUS_PAUSED) {
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setStatusErr(vmst, UVM32_ERR_NOTREADY);
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@ -118,59 +148,30 @@ uint32_t uvm32_run(uvm32_state_t *vmst, uvm32_evt_t *evt, uint32_t instr_meter)
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while(vmst->status == UVM32_STATUS_RUNNING) {
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uint64_t elapsedUs = 1;
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uint32_t ret;
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ret = MiniRV32IMAStep(vmst, vmst->core, vmst->memory, 0, elapsedUs, 1);
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ret = MiniRV32IMAStep(vmst, &vmst->core, vmst->memory, 0, elapsedUs, 1);
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if (3 == ret) {
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const uint32_t syscall = vmst->core->regs[17]; // a7
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uint32_t value = vmst->core->regs[10]; // a0
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bool syscall_valid = false;
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// Fetch registers used by syscall
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const uint32_t syscall = vmst->core.regs[17]; // a7
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// on exception we should jump to mtvec, but we handle directly
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// and skip over the ecall instruction
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vmst->core->pc += 4;
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vmst->core.pc += 4;
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switch(syscall) {
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// inbuilt syscalls
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case UVM32_SYSCALL_HALT:
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setStatus(vmst, UVM32_STATUS_ENDED);
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syscall_valid = true;
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break;
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case UVM32_SYSCALL_YIELD:
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vmst->ioevt.typ = UVM32_EVT_YIELD;
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setStatus(vmst, UVM32_STATUS_PAUSED);
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syscall_valid = true;
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break;
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// user defined syscalls
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default:
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// search in mappings
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for (int i=0;i<vmst->numMappings;i++) {
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if (syscall == vmst->mappings[i].syscall) {
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// setup ioevt.data according to mapping typ
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switch(vmst->mappings[i].typ) {
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case UVM32_SYSCALL_TYP_VOID:
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break;
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case UVM32_SYSCALL_TYP_U32_WR:
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vmst->ioevt.data.syscall.val.u32 = value;
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break;
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case UVM32_SYSCALL_TYP_BUF_TERMINATED_WR:
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get_safeptr_terminated(vmst, value, 0x00, &vmst->ioevt.data.syscall.val.buf);
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break;
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case UVM32_SYSCALL_TYP_U32_RD:
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// pass link to r1 for user function to update
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vmst->ioevt.data.syscall.val.u32p = &vmst->core->regs[11];
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break;
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}
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vmst->ioevt.typ = UVM32_EVT_SYSCALL;
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vmst->ioevt.data.syscall.code = vmst->mappings[i].code;
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vmst->ioevt.data.syscall.typ = vmst->mappings[i].typ;
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setStatus(vmst, UVM32_STATUS_PAUSED);
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syscall_valid = true;
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break; // stop searching
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}
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}
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// no mapping found
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if (!syscall_valid) {
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printf("BADSYS %08x halt=%08x YIELD=%08x\n", syscall, UVM32_SYSCALL_HALT, UVM32_SYSCALL_YIELD);
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setStatusErr(vmst, UVM32_ERR_BAD_SYSCALL);
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}
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// user defined syscalls
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vmst->ioevt.typ = UVM32_EVT_SYSCALL;
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vmst->ioevt.data.syscall.code = syscall;
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vmst->ioevt.data.syscall.ret = &vmst->core.regs[12]; // a2
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vmst->ioevt.data.syscall.params[0] = &vmst->core.regs[10]; // a0
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vmst->ioevt.data.syscall.params[1] = &vmst->core.regs[11]; // a1
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setStatus(vmst, UVM32_STATUS_PAUSED);
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break;
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}
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} else if (ret != 0) {
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@ -197,7 +198,7 @@ printf("BADSYS %08x halt=%08x YIELD=%08x\n", syscall, UVM32_SYSCALL_HALT, UVM32_
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// an event is ready
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if (vmst->status == UVM32_STATUS_PAUSED) {
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// send back the built up event
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memcpy(evt, &vmst->ioevt, sizeof(uvm32_evt_t));
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UVM32_MEMCPY(evt, &vmst->ioevt, sizeof(uvm32_evt_t));
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return num_instr;
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} else {
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if (vmst->status == UVM32_STATUS_ERROR) {
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@ -214,4 +215,54 @@ bool uvm32_hasEnded(const uvm32_state_t *vmst) {
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return vmst->status == UVM32_STATUS_ENDED;
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}
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static uint32_t *arg_to_ptr(uvm32_state_t *vmst, uvm32_evt_t *evt, uvm32_arg_t arg) {
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switch(arg) {
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case ARG0:
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return evt->data.syscall.params[0];
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break;
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case ARG1:
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return evt->data.syscall.params[1];
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break;
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case RET:
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return evt->data.syscall.ret;
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break;
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default:
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// if something invalid is passed to arg, we should never crash
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// return a pointer to something readable
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setStatusErr(vmst, UVM32_ERR_ARGS);
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garbage = 0;
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return &garbage;
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break;
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}
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}
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void uvm32_setval(uvm32_state_t *vmst, uvm32_evt_t *evt, uvm32_arg_t arg, uint32_t val) {
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*arg_to_ptr(vmst, evt, arg) = val;
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}
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uint32_t uvm32_getval(uvm32_state_t *vmst, uvm32_evt_t *evt, uvm32_arg_t arg) {
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return *arg_to_ptr(vmst, evt, arg);
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}
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const char *uvm32_getcstr(uvm32_state_t *vmst, uvm32_evt_t *evt, uvm32_arg_t arg) {
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uvm32_evt_syscall_buf_t scb;
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if (get_safeptr_null_terminated(vmst, uvm32_getval(vmst, evt, arg), &scb)) {
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return (const char *)scb.ptr; // we know the buffer in cpu memory is null terminated, so safe to pass back
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} else {
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setStatusErr(vmst, UVM32_ERR_MEM_RD);
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garbage = 0;
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return (const char *)&garbage;
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}
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}
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uvm32_evt_syscall_buf_t uvm32_getbuf(uvm32_state_t *vmst, uvm32_evt_t *evt, uvm32_arg_t argPtr, uvm32_arg_t argLen) {
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uvm32_evt_syscall_buf_t scb;
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if (!get_safeptr(vmst, uvm32_getval(vmst, evt, argPtr), uvm32_getval(vmst, evt, argLen), &scb)) {
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setStatusErr(vmst, UVM32_ERR_MEM_RD);
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garbage = 0;
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scb.ptr = (uint8_t *)&garbage;
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scb.len = 0;
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}
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return scb;
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}
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