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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2026 Richard QIn
*/
#include "common/types.h"
#include "kernel/riscv.h"
#include "kernel/proc.h"
#include "kernel/mm.h"
#include "kernel/elf.h"
#include "fs/fs.h"
#include "lib/string.h"
#include "drivers/uart.h"
#include "kernel/trap.h"
#include "drivers/uart.h"
extern char trampoline[];
// RAII: Page Table Resource Management
class VmGuard
{
public:
uint64 *pagetable = nullptr;
uint64 sz = 0;
VmGuard() : pagetable(VM::uvmcreate()) {}
~VmGuard()
{
if (pagetable)
{
VM::uvmfree(pagetable, sz);
}
}
// Copying is prohibited
VmGuard(const VmGuard &) = delete;
VmGuard &operator=(const VmGuard &) = delete;
// Submit resources: Ownership transfer, destructor no longer releases
uint64 *commit()
{
uint64 *pt = pagetable;
pagetable = nullptr;
return pt;
}
};
// RAII: Inode Lock Management
class InodeGuard
{
public:
Inode *ip;
InodeGuard(Inode *i) : ip(i)
{
if (ip)
VFS::ilock(ip);
}
~InodeGuard()
{
if (ip)
{
VFS::iunlockput(ip); // Automatically unlock and release references
}
}
// Copying is prohibited
InodeGuard(const InodeGuard &) = delete;
InodeGuard &operator=(const InodeGuard &) = delete;
};
// laod segment
static int loadseg(uint64 *pagetable, uint64 va, Inode *ip, uint64 offset, uint64 sz)
{
for (uint64 i = 0; i < sz; i += PGSIZE)
{
uint64 pa = VM::walkaddr(pagetable, va + i);
if (pa == 0)
return -1;
uint64 n = PGSIZE - (va + i) % PGSIZE;
if (i + n > sz)
n = sz - i;
// Read physical address (isUser=0)
if (ip->read((char *)(pa + (va + i) % PGSIZE), offset + i, n, 0) != (int)n)
return -1;
}
return 0;
}
namespace Exec
{
int exec(char *path, char **argv)
{
// Get Inode
Inode *raw_ip = VFS::namei(path);
if (!raw_ip)
return -1;
InodeGuard iguard(raw_ip);
// Get ELF head
struct elfhdr elf;
if (raw_ip->read((char *)&elf, 0, sizeof(elf), 0) != sizeof(elf))
return -1;
if (elf.magic != ELF_MAGIC)
return -1;
// Create new pagetable
VmGuard vm_guard;
if (!vm_guard.pagetable)
return -1;
// Load Program Segment
struct proghdr ph;
for (int i = 0; i < elf.phnum; i++)
{
uint64 off = elf.phoff + i * sizeof(ph);
if (raw_ip->read((char *)&ph, off, sizeof(ph), 0) != sizeof(ph))
return -1;
if (ph.type != ELF_PROG_LOAD)
continue;
if (ph.memsz < ph.filesz)
return -1;
if (ph.vaddr + ph.memsz < ph.vaddr)
return -1;
uint64 sz1 = VM::uvmalloc(vm_guard.pagetable, vm_guard.sz, ph.vaddr + ph.memsz, PTE_W | PTE_X | PTE_R | PTE_U);
if (sz1 == 0)
return -1;
vm_guard.sz = sz1;
if (loadseg(vm_guard.pagetable, ph.vaddr, raw_ip, ph.off, ph.filesz) < 0)
return -1;
}
// Prepare user stack
uint64 sz = PGROUNDUP(vm_guard.sz);
const int stack_data_pages = 16;
const int stack_total_pages = stack_data_pages + 1;
uint64 sz1 = VM::uvmalloc(vm_guard.pagetable, sz, sz + stack_total_pages * PGSIZE, PTE_W | PTE_R | PTE_U);
if (sz1 == 0)
return -1;
vm_guard.sz = sz1;
VM::uvmunmap(vm_guard.pagetable, sz, 1, 0); // protected pagetable
uint64 sp = sz1;
uint64 stackbase = sp - stack_data_pages * PGSIZE;
uint64 ustack[32];
uint64 argc = 0;
// Push parameter string
for (; argv[argc]; argc++)
{
if (argc >= 31)
return -1;
sp -= strlen(argv[argc]) + 1;
sp -= sp % 16;
if (sp < stackbase)
return -1;
if (VM::copyout(vm_guard.pagetable, sp, argv[argc], strlen(argv[argc]) + 1) < 0)
return -1;
ustack[argc] = sp;
}
ustack[argc] = 0;
// Push into parameter array
sp -= (argc + 1) * sizeof(uint64);
sp -= sp % 16;
if (sp < stackbase)
return -1;
if (VM::copyout(vm_guard.pagetable, sp, (char *)ustack, (argc + 1) * sizeof(uint64)) < 0)
return -1;
// Commit Changes
struct Proc *p = myproc();
if (VM::mappages(vm_guard.pagetable, TRAPFRAME, PGSIZE, (uint64)p->tf, PTE_R | PTE_W) < 0)
return -1;
uint64 oldsz = p->sz;
uint64 *oldpagetable = p->pagetable;
// setup Trapframe
p->tf->a0 = argc;
p->tf->a1 = sp;
p->tf->sp = sp;
p->tf->epc = elf.entry;
// update process name
char *s = path, *last = path;
while (*s)
{
if (*s == '/')
last = s + 1;
s++;
}
// memmove(p->name, last, sizeof(p->name));
size_t len = 0;
while (last[len] && len < sizeof(p->name) - 1)
{
p->name[len] = last[len];
len++;
}
p->name[len] = '\0';
// change pagetable
p->pagetable = vm_guard.commit();
p->sz = vm_guard.sz;
// release old pagetable
VM::uvmfree(oldpagetable, oldsz);
asm volatile("fence.i");
return 0; // iguard unlocks and releases IP upon destruction
}
}
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