From: Karol Herbst kherbst@redhat.com
[ Upstream commit 6d60ce384d1d5ca32b595244db4077a419acc687 ]
If something calls ioremap() with an address not aligned to PAGE_SIZE, the returned address might be not aligned as well. This led to a probe registered on exactly the returned address, but the entire page was armed for mmiotracing.
On calling iounmap() the address passed to unregister_kmmio_probe() was PAGE_SIZE aligned by the caller leading to a complete freeze of the machine.
We should always page align addresses while (un)registerung mappings, because the mmiotracer works on top of pages, not mappings. We still keep track of the probes based on their real addresses and lengths though, because the mmiotrace still needs to know what are mapped memory regions.
Also move the call to mmiotrace_iounmap() prior page aligning the address, so that all probes are unregistered properly, otherwise the kernel ends up failing memory allocations randomly after disabling the mmiotracer.
Tested-by: Lyude lyude@redhat.com Signed-off-by: Karol Herbst kherbst@redhat.com Acked-by: Pekka Paalanen ppaalanen@gmail.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Steven Rostedt rostedt@goodmis.org Cc: Thomas Gleixner tglx@linutronix.de Cc: nouveau@lists.freedesktop.org Link: http://lkml.kernel.org/r/20171127075139.4928-1-kherbst@redhat.com Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/x86/mm/ioremap.c | 4 ++-- arch/x86/mm/kmmio.c | 12 +++++++----- 2 files changed, 9 insertions(+), 7 deletions(-)
diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index 7aaa2635862d..ecae9ac216fa 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -347,11 +347,11 @@ void iounmap(volatile void __iomem *addr) (void __force *)addr < phys_to_virt(ISA_END_ADDRESS)) return;
+ mmiotrace_iounmap(addr); + addr = (volatile void __iomem *) (PAGE_MASK & (unsigned long __force)addr);
- mmiotrace_iounmap(addr); - /* Use the vm area unlocked, assuming the caller ensures there isn't another iounmap for the same address in parallel. Reuse of the virtual address is prevented by diff --git a/arch/x86/mm/kmmio.c b/arch/x86/mm/kmmio.c index afc47f5c9531..cadb82be5f36 100644 --- a/arch/x86/mm/kmmio.c +++ b/arch/x86/mm/kmmio.c @@ -434,17 +434,18 @@ int register_kmmio_probe(struct kmmio_probe *p) unsigned long flags; int ret = 0; unsigned long size = 0; + unsigned long addr = p->addr & PAGE_MASK; const unsigned long size_lim = p->len + (p->addr & ~PAGE_MASK); unsigned int l; pte_t *pte;
spin_lock_irqsave(&kmmio_lock, flags); - if (get_kmmio_probe(p->addr)) { + if (get_kmmio_probe(addr)) { ret = -EEXIST; goto out; }
- pte = lookup_address(p->addr, &l); + pte = lookup_address(addr, &l); if (!pte) { ret = -EINVAL; goto out; @@ -453,7 +454,7 @@ int register_kmmio_probe(struct kmmio_probe *p) kmmio_count++; list_add_rcu(&p->list, &kmmio_probes); while (size < size_lim) { - if (add_kmmio_fault_page(p->addr + size)) + if (add_kmmio_fault_page(addr + size)) pr_err("Unable to set page fault.\n"); size += page_level_size(l); } @@ -527,19 +528,20 @@ void unregister_kmmio_probe(struct kmmio_probe *p) { unsigned long flags; unsigned long size = 0; + unsigned long addr = p->addr & PAGE_MASK; const unsigned long size_lim = p->len + (p->addr & ~PAGE_MASK); struct kmmio_fault_page *release_list = NULL; struct kmmio_delayed_release *drelease; unsigned int l; pte_t *pte;
- pte = lookup_address(p->addr, &l); + pte = lookup_address(addr, &l); if (!pte) return;
spin_lock_irqsave(&kmmio_lock, flags); while (size < size_lim) { - release_kmmio_fault_page(p->addr + size, &release_list); + release_kmmio_fault_page(addr + size, &release_list); size += page_level_size(l); } list_del_rcu(&p->list);