On Mon, Aug 12, 2013 at 2:57 PM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > On Thu, 8 Aug 2013 18:51:20 +0400 Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote: > >> On Wed, Aug 07, 2013 at 01:28:12PM -0700, Andrew Morton wrote: >> > >> > Good god. >> > >> > I wonder if these can be turned into out-of-line functions in some form >> > which humans can understand. >> > >> > or >> > >> > #define pte_to_pgoff(pte) >> > frob(pte, PTE_FILE_SHIFT1, PTE_FILE_BITS1) + >> > frob(PTE_FILE_SHIFT2, PTE_FILE_BITS2) + >> > frob(PTE_FILE_SHIFT3, PTE_FILE_BITS3) + >> > frob(PTE_FILE_SHIFT4, PTE_FILE_BITS1 + PTE_FILE_BITS2 + PTE_FILE_BITS3) >> >> Hi, here is what I ended up with. Please take a look (I decided to post >> patch in the thread since it's related to the context of the mails). > > You could have #undefed _mfrob and __frob after using them, but whatever. > > I saved this patch to wave at the x86 guys for 3.12. I plan to merge > mm-save-soft-dirty-bits-on-file-pages.patch for 3.11. > >> Guys, is there a reason for "if _PAGE_BIT_FILE < _PAGE_BIT_PROTNONE" >> test present in this pgtable-2level.h file at all? I can't imagine >> where it can be false on x86. > > I doubt if "Guys" read this. x86 maintainers cc'ed. > > > > > > From: Cyrill Gorcunov <gorcunov@xxxxxxxxx> > Subject: arch/x86/include/asm/pgtable-2level.h: clean up pte_to_pgoff and pgoff_to_pte helpers > > Andrew asked if there a way to make pte_to_pgoff and pgoff_to_pte macro > helpers somehow more readable. > > With this patch it should be more understandable what is happening with > bits when they come to and from pte entry. > > Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxx> > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > --- > > arch/x86/include/asm/pgtable-2level.h | 82 ++++++++++++------------ > 1 file changed, 41 insertions(+), 41 deletions(-) > > diff -puN arch/x86/include/asm/pgtable-2level.h~arch-x86-include-asm-pgtable-2levelh-clean-up-pte_to_pgoff-and-pgoff_to_pte-helpers arch/x86/include/asm/pgtable-2level.h > --- a/arch/x86/include/asm/pgtable-2level.h~arch-x86-include-asm-pgtable-2levelh-clean-up-pte_to_pgoff-and-pgoff_to_pte-helpers > +++ a/arch/x86/include/asm/pgtable-2level.h > @@ -55,6 +55,9 @@ static inline pmd_t native_pmdp_get_and_ > #define native_pmdp_get_and_clear(xp) native_local_pmdp_get_and_clear(xp) > #endif > > +#define _mfrob(v,r,m,l) ((((v) >> (r)) & (m)) << (l)) > +#define __frob(v,r,l) (((v) >> (r)) << (l)) > + > #ifdef CONFIG_MEM_SOFT_DIRTY > If I'm understanding this right, the idea is to take the bits in the range a..b of v and stick them at c..d, where a-b == c-d. Would it make sense to change this to look something like #define __frob(v, inmsb, inlsb, outlsb) ((v >> inlsb) & ((1<<(inmsb - inlsb + 1)-1) << outlsb) For extra fun, there could be an __unfrob macro that takes the same inmsg, inlsb, outlsb parameters but undoes it so that it's (more) clear that the operations that are supposed to be inverses are indeed inverses. --Andy -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>