From 283d5ab4c964ab525e45fcade06d6fd7e977c43e Mon Sep 17 00:00:00 2001 From: Mole Shang <135e2@135e2.dev> Date: Thu, 18 Jan 2024 17:35:27 +0800 Subject: lab syscall: finish Conflicts: kernel/syscall.c kernel/syscall.h user/user.h user/usys.pl --- kernel/kalloc.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'kernel/kalloc.c') diff --git a/kernel/kalloc.c b/kernel/kalloc.c index 0699e7e..c2fdb86 100644 --- a/kernel/kalloc.c +++ b/kernel/kalloc.c @@ -80,3 +80,17 @@ kalloc(void) memset((char*)r, 5, PGSIZE); // fill with junk return (void*)r; } + +int +get_freemem(void) +{ + int n; + struct run *r; + + acquire(&kmem.lock); + for (n = 0, r = kmem.freelist; r; r = r->next) + n++; + release(&kmem.lock); + + return n * PGSIZE; +} -- cgit v1.2.3 From 4a6593f1a6f666c618d303a4858c4c6d31b41c63 Mon Sep 17 00:00:00 2001 From: Mole Shang <135e2@135e2.dev> Date: Sun, 11 Feb 2024 17:51:28 +0800 Subject: lab cow: finish --- kernel/kalloc.c | 43 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 42 insertions(+), 1 deletion(-) (limited to 'kernel/kalloc.c') diff --git a/kernel/kalloc.c b/kernel/kalloc.c index c2fdb86..581f0f6 100644 --- a/kernel/kalloc.c +++ b/kernel/kalloc.c @@ -23,10 +23,41 @@ struct { struct run *freelist; } kmem; +int phypg_refcnt[PHYSTOP/PGSIZE]; + +// Increase the refcnt +int +refcnt_inc(uint64 pa) +{ + acquire(&kmem.lock); + int *prefcnt = &phypg_refcnt[pa/PGSIZE]; + if(pa > PHYSTOP || *prefcnt < 1) + panic("increase refcnt"); + (*prefcnt)++; + release(&kmem.lock); + return *prefcnt; +} + +// Decrease the refcnt +int +refcnt_dec(uint64 pa) +{ + acquire(&kmem.lock); + int *prefcnt = &phypg_refcnt[pa/PGSIZE]; + if(pa > PHYSTOP || *prefcnt < 1) + panic("decrease refcnt"); + (*prefcnt)--; + release(&kmem.lock); + return *prefcnt; +} + void kinit() { initlock(&kmem.lock, "kmem"); + // init all refcnt to 1, which would later be freed to 0 by kfree() + for(uint64 p = PGROUNDUP((uint64)end); p + PGSIZE <= PHYSTOP; p += PGSIZE) + phypg_refcnt[p/PGSIZE] = 1; freerange(end, (void*)PHYSTOP); } @@ -51,6 +82,12 @@ kfree(void *pa) if(((uint64)pa % PGSIZE) != 0 || (char*)pa < end || (uint64)pa >= PHYSTOP) panic("kfree"); + refcnt_dec((uint64)pa); + + if(phypg_refcnt[(uint64)pa/PGSIZE] > 0) + // We still have refs to this phy page, do not actually free it + return; + // Fill with junk to catch dangling refs. memset(pa, 1, PGSIZE); @@ -72,8 +109,12 @@ kalloc(void) acquire(&kmem.lock); r = kmem.freelist; - if(r) + if(r){ + if(phypg_refcnt[(uint64)r/PGSIZE]) + panic("kalloc: invalid refcnt"); + phypg_refcnt[(uint64)r/PGSIZE] = 1; kmem.freelist = r->next; + } release(&kmem.lock); if(r) -- cgit v1.2.3