From fa58ae1e6a35501f8e8d69a7c5f82f019c95cd0f Mon Sep 17 00:00:00 2001
From: An N Tran <antran@caltech.edu>
Date: Thu, 17 Nov 2022 17:00:46 +0000
Subject: [PATCH] Task 4
---
kernel.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel.c b/kernel.c
index 6224e2f..3e2b33c 100644
--- a/kernel.c
+++ b/kernel.c
@@ -173,7 +173,7 @@ void process_setup(pid_t pid, const char* program_name) {
ptable[pid].regs.reg_rip = pgm.entry();
// allocate and map stack segment
- uintptr_t stack_addr = PROC_START_ADDR + PROC_SIZE * pid - PAGESIZE;
+ uintptr_t stack_addr = MEMSIZE_VIRTUAL - PAGESIZE;
uintptr_t pa = (uintptr_t) kalloc(PAGESIZE);
memory_map(process_pagetable, stack_addr, pa, PTE_PWU);
ptable[pid].regs.reg_rsp = stack_addr + PAGESIZE;
@@ -325,6 +325,7 @@ uintptr_t syscall(regstate* regs) {
int syscall_page_alloc(uintptr_t addr) {
uintptr_t pa = (uintptr_t) kalloc(PAGESIZE);
+ if (pa == 0) return -1;
memory_map(current->pagetable, addr, pa, PTE_PWU);
memset(memory_virtual_to_physical(current->pagetable, addr), 0, PAGESIZE);
return 0;
--
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