Imbus/xv6-riscv-kernel
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exec compiles but argstr() doesn't work yet

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This commit is contained in:
Robert Morris 2019-05-31 12:43:20 -04:00
parent 5d34fa2a48
commit 7fd1f1eb0a
8 changed files with 207 additions and 69 deletions
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56
proc.c
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@ -94,18 +94,7 @@ found:
}
// An empty user page table.
p->pagetable = uvmcreate();
// map the trampoline code (for system call return)
// at the highest user virtual address.
// only the supervisor uses it, on the way
// to/from user space, so not PTE_U.
mappages(p->pagetable, TRAMPOLINE, PGSIZE,
(uint64)trampstart, PTE_R | PTE_X);
// map the trapframe, for trampoline.S.
mappages(p->pagetable, (TRAMPOLINE - PGSIZE), PGSIZE,
(uint64)(p->tf), PTE_R | PTE_W);
p->pagetable = proc_pagetable(p);
// Set up new context to start executing at forkret,
// which returns to user space.
@ -116,6 +105,45 @@ found:
return p;
}
// Create a page table for a given process,
// with no users pages, but with trampoline pages.
// Called both when creating a process, and
// by exec() when building tentative new memory image,
// which might fail.
pagetable_t
proc_pagetable(struct proc *p)
{
pagetable_t pagetable;
// An empty user page table.
pagetable = uvmcreate();
// map the trampoline code (for system call return)
// at the highest user virtual address.
// only the supervisor uses it, on the way
// to/from user space, so not PTE_U.
mappages(pagetable, TRAMPOLINE, PGSIZE,
(uint64)trampstart, PTE_R | PTE_X);
// map the trapframe, for trampoline.S.
mappages(pagetable, (TRAMPOLINE - PGSIZE), PGSIZE,
(uint64)(p->tf), PTE_R | PTE_W);
return pagetable;
}
// Free a process's page table, and free the
// physical memory the page table refers to.
// Called both when a process exits and from
// exec() if it fails.
void
proc_freepagetable(pagetable_t pagetable, uint64 sz)
{
unmappages(pagetable, TRAMPOLINE, PGSIZE, 0);
unmappages(pagetable, TRAMPOLINE-PGSIZE, PGSIZE, 0);
uvmfree(pagetable, sz);
}
// a user program that calls exec("/init")
// od -t xC initcode
unsigned char initcode[] = {
@ -295,9 +323,7 @@ wait(void)
np->kstack = 0;
kfree((void*)np->tf);
np->tf = 0;
unmappages(np->pagetable, TRAMPOLINE, PGSIZE, 0);
unmappages(np->pagetable, TRAMPOLINE-PGSIZE, PGSIZE, 0);
uvmfree(np->pagetable, np->sz);
proc_freepagetable(np->pagetable, np->sz);
np->pagetable = 0;
np->pid = 0;
np->parent = 0;