From: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
To: "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Dock, Deneen T" <deneen.t.dock@intel.com>,
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<kernel-hardening@lists.openwall.com>,
"Hansen, Dave" <dave.hansen@intel.com>,
"mhiramat@kernel.org" <mhiramat@kernel.org>,
"naveen.n.rao@linux.vnet.ibm.com"
<naveen.n.rao@linux.vnet.ibm.com>,
"davem@davemloft.net" <davem@davemloft.net>,
"Keshavamurthy, Anil S" <anil.s.keshavamurthy@intel.com>
Subject: Re: [PATCH 1/2] vmalloc: New flag for flush before releasing pages
Date: Tue, 4 Dec 2018 00:04:21 +0000 [thread overview]
Message-ID: <f00a7c0b99cb3dae3f42e144c0532a6a299c06a0.camel@intel.com> (raw)
In-Reply-To: <20181128000754.18056-2-rick.p.edgecombe@intel.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)
next prev parent reply other threads:[~2018-12-04 0:04 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-28 0:07 [PATCH 0/2] Don’t leave executable TLB entries to freed pages Rick Edgecombe
2018-11-28 0:07 ` [PATCH 1/2] vmalloc: New flag for flush before releasing pages Rick Edgecombe
2018-12-04 0:04 ` Edgecombe, Rick P [this message]
2018-12-04 1:43 ` Nadav Amit
2018-12-04 16:03 ` Will Deacon
2018-12-04 20:02 ` Edgecombe, Rick P
2018-12-04 20:09 ` Andy Lutomirski
2018-12-04 23:52 ` Edgecombe, Rick P
2018-12-05 1:57 ` Andy Lutomirski
2018-12-05 11:41 ` Will Deacon
2018-12-05 23:16 ` Andy Lutomirski
2018-12-06 7:29 ` Ard Biesheuvel
2018-12-06 11:10 ` Will Deacon
2018-12-06 18:53 ` Andy Lutomirski
2018-12-06 19:01 ` Tycho Andersen
2018-12-06 19:19 ` Andy Lutomirski
2018-12-06 19:39 ` Nadav Amit
2018-12-06 20:17 ` Andy Lutomirski
2018-12-06 23:08 ` Nadav Amit
2018-12-07 3:06 ` Edgecombe, Rick P
2018-12-06 20:19 ` Edgecombe, Rick P
2018-12-06 20:26 ` Andy Lutomirski
2018-12-06 19:04 ` Ard Biesheuvel
2018-12-06 19:20 ` Andy Lutomirski
2018-12-06 19:23 ` Ard Biesheuvel
2018-12-06 19:31 ` Will Deacon
2018-12-06 19:36 ` Ard Biesheuvel
2018-12-04 20:36 ` Nadav Amit
[not found] ` <e70c618d10ddbb834b7a3bbdd6e2bebed0f8719d.camel@intel.com>
2018-12-05 0:01 ` Nadav Amit
2018-12-05 0:29 ` Edgecombe, Rick P
2018-12-05 0:53 ` Nadav Amit
2018-12-05 1:45 ` Edgecombe, Rick P
2018-12-05 2:09 ` Nadav Amit
2018-12-04 18:56 ` Andy Lutomirski
2018-12-04 19:44 ` Nadav Amit
2018-12-04 19:48 ` Andy Lutomirski
2018-12-04 22:48 ` Nadav Amit
2018-12-04 23:27 ` Andy Lutomirski
2018-12-04 23:34 ` Nadav Amit
2018-12-05 1:09 ` Edgecombe, Rick P
2018-12-05 1:45 ` Nadav Amit
2018-11-28 0:07 ` [PATCH 2/2] x86/modules: Make x86 allocs to flush when free Rick Edgecombe
2018-11-28 23:11 ` Andrew Morton
2018-11-29 0:02 ` Edgecombe, Rick P
2018-11-29 1:40 ` Andy Lutomirski
2018-11-29 6:14 ` Edgecombe, Rick P
2018-11-28 1:06 ` [PATCH 0/2] Don’t leave executable TLB entries to freed pages Nadav Amit
2018-11-28 1:21 ` Nadav Amit
2018-11-28 9:57 ` Will Deacon
2018-11-28 18:29 ` Nadav Amit
2018-11-29 14:06 ` Masami Hiramatsu
2018-11-29 18:49 ` Edgecombe, Rick P
2018-11-29 23:19 ` Masami Hiramatsu
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