Make sure the tlb doesn't have an outdated mem pointer

emu/tlb.c

@@ -1,7 +1,9 @@
 #include "emu/cpu.h"
 #include "emu/tlb.h"
 
-void tlb_init(struct tlb *tlb, struct mem *mem) {
+void tlb_refresh(struct tlb *tlb, struct mem *mem) {
+    if (tlb->mem == mem && tlb->mem_changes == mem->changes)
+        return;
     tlb->mem = mem;
     tlb->dirty_page = TLB_PAGE_EMPTY;
     tlb->mem_changes = mem->changes;

emu/tlb.h

@@ -22,7 +22,7 @@ struct tlb {
 #define TLB_INDEX(addr) (((addr >> PAGE_BITS) & (TLB_SIZE - 1)) ^ (addr >> (PAGE_BITS + TLB_BITS)))
 #define TLB_PAGE(addr) (addr & 0xfffff000)
 #define TLB_PAGE_EMPTY 1
-void tlb_init(struct tlb *tlb, struct mem *mem);
+void tlb_refresh(struct tlb *tlb, struct mem *mem);
 void tlb_free(struct tlb *tlb);
 void tlb_flush(struct tlb *tlb);
 void *tlb_handle_miss(struct tlb *tlb, addr_t addr, int type);

jit/jit.c

@@ -240,8 +240,8 @@ static int cpu_single_step(struct cpu_state *cpu, struct tlb *tlb) {
 
 int cpu_run_to_interrupt(struct cpu_state *cpu, struct tlb *tlb) {
     read_wrlock(&cpu->mem->lock);
-    if (cpu->mem->changes != tlb->mem_changes)
-        tlb_init(tlb, cpu->mem);
+    printk("%d cpu run with mem %p %d, tlb->mem %p %d\n", current->pid, cpu->mem, cpu->mem->changes, tlb->mem, tlb->mem_changes);
+    tlb_refresh(tlb, cpu->mem);
     int interrupt = (cpu->tf ? cpu_single_step : cpu_step_to_interrupt)(cpu, tlb);
     cpu->trapno = interrupt;
     read_wrunlock(&cpu->mem->lock);

kernel/exec.c

@@ -197,8 +197,10 @@ static int elf_exec(struct fd *fd, const char *file, struct exec_args argv, stru
     // from this point on, if any error occurs the process will have to be
     // killed before it even starts. please don't be too sad about it, it's
     // just a process.
+    struct mm *old_mm = current->mm;
     mm_release(current->mm);
     task_set_mm(current, mm_new());
+    printk("%d replacing %p with %p\n", current->pid, &old_mm->mem, &current->mm->mem);
     write_wrlock(&current->mem->lock);
 
     current->mm->exefile = fd_retain(fd);

kernel/task.c

@@ -95,7 +95,7 @@ void task_destroy(struct task *task) {
 void task_run_current() {
     struct cpu_state *cpu = &current->cpu;
     struct tlb tlb;
-    tlb_init(&tlb, current->mem);
+    tlb_refresh(&tlb, current->mem);
     while (true) {
         int interrupt = cpu_run_to_interrupt(cpu, &tlb);
         handle_interrupt(interrupt);

tools/ptraceomatic.c

@@ -484,7 +484,7 @@ int main(int argc, char *const argv[]) {
     struct cpu_state *cpu = &current->cpu;
     cpu->tf = true;
     struct tlb tlb;
-    tlb_init(&tlb, cpu->mem);
+    tlb_refresh(&tlb, cpu->mem);
     int undefined_flags = 2;
     struct cpu_state old_cpu = *cpu;
     int i = 0;

tools/unicornomatic.c

@@ -489,7 +489,7 @@ int main(int argc, char *const argv[]) {
 
     struct cpu_state *cpu = &current->cpu;
     struct tlb tlb;
-    tlb_init(&tlb, cpu->mem);
+    tlb_refresh(&tlb, cpu->mem);
     int undefined_flags = 0;
     struct cpu_state old_cpu = *cpu;
     while (true) {