diff options
Diffstat (limited to 'drivers/lguest/core.c')
| -rw-r--r-- | drivers/lguest/core.c | 33 |
1 files changed, 22 insertions, 11 deletions
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c index 7743d73..5eea435 100644 --- a/drivers/lguest/core.c +++ b/drivers/lguest/core.c @@ -1,8 +1,6 @@ /*P:400 This contains run_guest() which actually calls into the Host<->Guest * Switcher and analyzes the return, such as determining if the Guest wants the - * Host to do something. This file also contains useful helper routines, and a - * couple of non-obvious setup and teardown pieces which were implemented after - * days of debugging pain. :*/ + * Host to do something. This file also contains useful helper routines. :*/ #include <linux/module.h> #include <linux/stringify.h> #include <linux/stddef.h> @@ -49,8 +47,8 @@ static __init int map_switcher(void) * easy. */ - /* We allocate an array of "struct page"s. map_vm_area() wants the - * pages in this form, rather than just an array of pointers. */ + /* We allocate an array of struct page pointers. map_vm_area() wants + * this, rather than just an array of pages. */ switcher_page = kmalloc(sizeof(switcher_page[0])*TOTAL_SWITCHER_PAGES, GFP_KERNEL); if (!switcher_page) { @@ -69,11 +67,22 @@ static __init int map_switcher(void) switcher_page[i] = virt_to_page(addr); } + /* First we check that the Switcher won't overlap the fixmap area at + * the top of memory. It's currently nowhere near, but it could have + * very strange effects if it ever happened. */ + if (SWITCHER_ADDR + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){ + err = -ENOMEM; + printk("lguest: mapping switcher would thwack fixmap\n"); + goto free_pages; + } + /* Now we reserve the "virtual memory area" we want: 0xFFC00000 * (SWITCHER_ADDR). We might not get it in theory, but in practice - * it's worked so far. */ + * it's worked so far. The end address needs +1 because __get_vm_area + * allocates an extra guard page, so we need space for that. */ switcher_vma = __get_vm_area(TOTAL_SWITCHER_PAGES * PAGE_SIZE, - VM_ALLOC, SWITCHER_ADDR, VMALLOC_END); + VM_ALLOC, SWITCHER_ADDR, SWITCHER_ADDR + + (TOTAL_SWITCHER_PAGES+1) * PAGE_SIZE); if (!switcher_vma) { err = -ENOMEM; printk("lguest: could not map switcher pages high\n"); @@ -161,7 +170,7 @@ void __lgread(struct lg_cpu *cpu, void *b, unsigned long addr, unsigned bytes) } } -/* This is the write (copy into guest) version. */ +/* This is the write (copy into Guest) version. */ void __lgwrite(struct lg_cpu *cpu, unsigned long addr, const void *b, unsigned bytes) { @@ -198,9 +207,9 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user) if (cpu->break_out) return -EAGAIN; - /* Check if there are any interrupts which can be delivered - * now: if so, this sets up the hander to be executed when we - * next run the Guest. */ + /* Check if there are any interrupts which can be delivered now: + * if so, this sets up the hander to be executed when we next + * run the Guest. */ maybe_do_interrupt(cpu); /* All long-lived kernel loops need to check with this horrible @@ -235,8 +244,10 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user) lguest_arch_handle_trap(cpu); } + /* Special case: Guest is 'dead' but wants a reboot. */ if (cpu->lg->dead == ERR_PTR(-ERESTART)) return -ERESTART; + /* The Guest is dead => "No such file or directory" */ return -ENOENT; } |