| Message ID | alpine.LRH.2.02.2009161451140.21915@file01.intranet.prod.int.rdu2.redhat.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | a1cd6c2ae47ee10ff21e62475685d5b399e2ed4a |
| Headers | show |
| Series | pmem: fix __copy_user_flushcache | expand |
On Wed, Sep 16, 2020 at 11:57 AM Mikulas Patocka <mpatocka@redhat.com> wrote: > > > > On Wed, 16 Sep 2020, Dan Williams wrote: > > > On Wed, Sep 16, 2020 at 10:24 AM Mikulas Patocka <mpatocka@redhat.com> wrote: > > > > > > > > > > > > On Wed, 16 Sep 2020, Dan Williams wrote: > > > > > > > On Wed, Sep 16, 2020 at 3:57 AM Mikulas Patocka <mpatocka@redhat.com> wrote: > > > > > > > > > > > > > > > > > > > > I'm submitting this patch that adds the required exports (so that we could > > > > > use __copy_from_user_flushcache on x86, arm64 and powerpc). Please, queue > > > > > it for the next merge window. > > > > > > > > Why? This should go with the first user, and it's not clear that it > > > > needs to be relative to the current dax_operations export scheme. > > > > > > Before nvfs gets included in the kernel, I need to distribute it as a > > > module. So, it would make my maintenance easier. But if you don't want to > > > export it now, no problem, I can just copy __copy_user_flushcache from the > > > kernel to the module. > > > > That sounds a better plan than exporting symbols with no in-kernel consumer. > > BTW, this function is buggy. Here I'm submitting the patch. > > > > From: Mikulas Patocka <mpatocka@redhat.com> > > If we copy less than 8 bytes and if the destination crosses a cache line, > __copy_user_flushcache would invalidate only the first cache line. This > patch makes it invalidate the second cache line as well. Good catch. > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > Cc: stable@vger.kernel.org > > --- > arch/x86/lib/usercopy_64.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > Index: linux-2.6/arch/x86/lib/usercopy_64.c > =================================================================== > --- linux-2.6.orig/arch/x86/lib/usercopy_64.c 2020-09-05 10:01:27.000000000 +0200 > +++ linux-2.6/arch/x86/lib/usercopy_64.c 2020-09-16 20:48:31.000000000 +0200 > @@ -120,7 +120,7 @@ long __copy_user_flushcache(void *dst, c > */ > if (size < 8) { > if (!IS_ALIGNED(dest, 4) || size != 4) > - clean_cache_range(dst, 1); > + clean_cache_range(dst, size); > } else { > if (!IS_ALIGNED(dest, 8)) { > dest = ALIGN(dest, boot_cpu_data.x86_clflush_size); > You can add: Fixes: 0aed55af8834 ("x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations") Reviewed-by: Dan Williams <dan.j.wiilliams@intel.com>
Index: linux-2.6/arch/x86/lib/usercopy_64.c =================================================================== --- linux-2.6.orig/arch/x86/lib/usercopy_64.c 2020-09-05 10:01:27.000000000 +0200 +++ linux-2.6/arch/x86/lib/usercopy_64.c 2020-09-16 20:48:31.000000000 +0200 @@ -120,7 +120,7 @@ long __copy_user_flushcache(void *dst, c */ if (size < 8) { if (!IS_ALIGNED(dest, 4) || size != 4) - clean_cache_range(dst, 1); + clean_cache_range(dst, size); } else { if (!IS_ALIGNED(dest, 8)) { dest = ALIGN(dest, boot_cpu_data.x86_clflush_size);