* Re: [PATCH 1/2] vmalloc: New flag for flush before releasing pages [not found] ` <20181128000754.18056-2-rick.p.edgecombe@intel.com> @ 2018-12-04 0:04 ` Edgecombe, Rick P 2018-12-04 0:04 ` Edgecombe, Rick P 0 siblings, 1 reply; 2+ messages in thread From: Edgecombe, Rick P @ 2018-12-04 0:04 UTC (permalink / raw) To: linux-arch@vger.kernel.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Dock, Deneen T, daniel@iogearbox.net, rostedt@goodmis.org, ast@kernel.org, jeyu@kernel.org, linux-mm@kvack.org, jannh@google.com, ard.biesheuvel@linaro.org, kristen@linux.intel.com, akpm@linux-foundation.org, will.deacon@arm.com, mingo@redhat.com, luto@kernel.org, kernel-hardening@lists.openwall.com It looks like this new flag is in linux-next now. As I am reading it, these architectures have a module_alloc that uses some sort of executable flag and are not using the default module_alloc which is already covered, and so may need it plugged in: arm arm64 parisc s390 unicore32 Thanks, Rick On Tue, 2018-11-27 at 16:07 -0800, Rick Edgecombe wrote: > Since vfree will lazily flush the TLB, but not lazily free the underlying > pages, > it often leaves stale TLB entries to freed pages that could get re-used. This > is > undesirable for cases where the memory being freed has special permissions > such > as executable. > > Having callers flush the TLB after calling vfree still leaves a window where > the pages are freed, but the TLB entry remains. Also the entire operation can > be > deferred if the vfree is called from an interrupt and so a TLB flush after > calling vfree would miss the entire operation. So in order to support this use > case, a new flag VM_IMMEDIATE_UNMAP is added, that will cause the free > operation > to take place like this: > 1. Unmap > 2. Flush TLB/Unmap aliases > 3. Free pages > In the deferred case these steps are all done by the work queue. > > This implementation derives from two sketches from Dave Hansen and > Andy Lutomirski. > > Suggested-by: Dave Hansen <dave.hansen@intel.com> > Suggested-by: Andy Lutomirski <luto@kernel.org> > Suggested-by: Will Deacon <will.deacon@arm.com> > Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> > --- > include/linux/vmalloc.h | 1 + > mm/vmalloc.c | 13 +++++++++++-- > 2 files changed, 12 insertions(+), 2 deletions(-) > > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h > index 398e9c95cd61..cca6b6b83cf0 100644 > --- a/include/linux/vmalloc.h > +++ b/include/linux/vmalloc.h > @@ -21,6 +21,7 @@ struct notifier_block; /* in notifier.h */ > #define VM_UNINITIALIZED 0x00000020 /* vm_struct is not fully > initialized */ > #define VM_NO_GUARD 0x00000040 /* don't add guard page */ > #define VM_KASAN 0x00000080 /* has allocated kasan shadow > memory */ > +#define VM_IMMEDIATE_UNMAP 0x00000200 /* flush before releasing > pages */ > /* bits [20..32] reserved for arch specific ioremap internals */ > > /* > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 97d4b25d0373..68766651b5a7 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -1516,6 +1516,14 @@ static void __vunmap(const void *addr, int > deallocate_pages) > debug_check_no_obj_freed(area->addr, get_vm_area_size(area)); > > remove_vm_area(addr); > + > + /* > + * Need to flush the TLB before freeing pages in the case of this flag. > + * As long as that's happening, unmap aliases. > + */ > + if (area->flags & VM_IMMEDIATE_UNMAP) > + vm_unmap_aliases(); > + > if (deallocate_pages) { > int i; > > @@ -1925,8 +1933,9 @@ EXPORT_SYMBOL(vzalloc_node); > > void *vmalloc_exec(unsigned long size) > { > - return __vmalloc_node(size, 1, GFP_KERNEL, PAGE_KERNEL_EXEC, > - NUMA_NO_NODE, __builtin_return_address(0)); > + return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END, > + GFP_KERNEL, PAGE_KERNEL_EXEC, VM_IMMEDIATE_UNMAP, > + NUMA_NO_NODE, __builtin_return_address(0)); > } > > #if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32) ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH 1/2] vmalloc: New flag for flush before releasing pages 2018-12-04 0:04 ` [PATCH 1/2] vmalloc: New flag for flush before releasing pages Edgecombe, Rick P @ 2018-12-04 0:04 ` Edgecombe, Rick P 0 siblings, 0 replies; 2+ messages in thread From: Edgecombe, Rick P @ 2018-12-04 0:04 UTC (permalink / raw) To: linux-arch@vger.kernel.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Dock, Deneen T, daniel@iogearbox.net, rostedt@goodmis.org, ast@kernel.org, jeyu@kernel.org, linux-mm@kvack.org, jannh@google.com, ard.biesheuvel@linaro.org, kristen@linux.intel.com, akpm@linux-foundation.org, will.deacon@arm.com, mingo@redhat.com, luto@kernel.org, kernel-hardening@lists.openwall.com, Hansen, Dave, mhiramat@kernel.org, naveen.n.rao@linux.vnet.ibm.com, davem@davemloft.net, Keshavamurthy, Anil S It looks like this new flag is in linux-next now. As I am reading it, these architectures have a module_alloc that uses some sort of executable flag and are not using the default module_alloc which is already covered, and so may need it plugged in: arm arm64 parisc s390 unicore32 Thanks, Rick On Tue, 2018-11-27 at 16:07 -0800, Rick Edgecombe wrote: > Since vfree will lazily flush the TLB, but not lazily free the underlying > pages, > it often leaves stale TLB entries to freed pages that could get re-used. This > is > undesirable for cases where the memory being freed has special permissions > such > as executable. > > Having callers flush the TLB after calling vfree still leaves a window where > the pages are freed, but the TLB entry remains. Also the entire operation can > be > deferred if the vfree is called from an interrupt and so a TLB flush after > calling vfree would miss the entire operation. So in order to support this use > case, a new flag VM_IMMEDIATE_UNMAP is added, that will cause the free > operation > to take place like this: > 1. Unmap > 2. Flush TLB/Unmap aliases > 3. Free pages > In the deferred case these steps are all done by the work queue. > > This implementation derives from two sketches from Dave Hansen and > Andy Lutomirski. > > Suggested-by: Dave Hansen <dave.hansen@intel.com> > Suggested-by: Andy Lutomirski <luto@kernel.org> > Suggested-by: Will Deacon <will.deacon@arm.com> > Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> > --- > include/linux/vmalloc.h | 1 + > mm/vmalloc.c | 13 +++++++++++-- > 2 files changed, 12 insertions(+), 2 deletions(-) > > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h > index 398e9c95cd61..cca6b6b83cf0 100644 > --- a/include/linux/vmalloc.h > +++ b/include/linux/vmalloc.h > @@ -21,6 +21,7 @@ struct notifier_block; /* in notifier.h */ > #define VM_UNINITIALIZED 0x00000020 /* vm_struct is not fully > initialized */ > #define VM_NO_GUARD 0x00000040 /* don't add guard page */ > #define VM_KASAN 0x00000080 /* has allocated kasan shadow > memory */ > +#define VM_IMMEDIATE_UNMAP 0x00000200 /* flush before releasing > pages */ > /* bits [20..32] reserved for arch specific ioremap internals */ > > /* > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 97d4b25d0373..68766651b5a7 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -1516,6 +1516,14 @@ static void __vunmap(const void *addr, int > deallocate_pages) > debug_check_no_obj_freed(area->addr, get_vm_area_size(area)); > > remove_vm_area(addr); > + > + /* > + * Need to flush the TLB before freeing pages in the case of this flag. > + * As long as that's happening, unmap aliases. > + */ > + if (area->flags & VM_IMMEDIATE_UNMAP) > + vm_unmap_aliases(); > + > if (deallocate_pages) { > int i; > > @@ -1925,8 +1933,9 @@ EXPORT_SYMBOL(vzalloc_node); > > void *vmalloc_exec(unsigned long size) > { > - return __vmalloc_node(size, 1, GFP_KERNEL, PAGE_KERNEL_EXEC, > - NUMA_NO_NODE, __builtin_return_address(0)); > + return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END, > + GFP_KERNEL, PAGE_KERNEL_EXEC, VM_IMMEDIATE_UNMAP, > + NUMA_NO_NODE, __builtin_return_address(0)); > } > > #if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32) ^ permalink raw reply [flat|nested] 2+ messages in thread
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2018-12-04 0:04 ` [PATCH 1/2] vmalloc: New flag for flush before releasing pages Edgecombe, Rick P
2018-12-04 0:04 ` Edgecombe, Rick P
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