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Peter Anvin" , linux-arm-kernel@lists.infradead.org, Linux Kernel Mailing List , Mark Rutland , "Liang, Kan" , Andrew Morton Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Steven Price =E6=96=BC 2019=E5=B9=B410=E6=9C=8819=E6= =97=A5 =E9=80=B1=E5=85=AD =E4=B8=8B=E5=8D=884:12=E5=AF=AB=E9=81=93=EF=BC=9A > > It is useful to be able to skip parts of the page table tree even when > walking without VMAs. Add test_p?d callbacks similar to test_walk but > which are called just before a table at that level is walked. If the > callback returns non-zero then the entire table is skipped. > > Signed-off-by: Steven Price > --- > include/linux/pagewalk.h | 11 +++++++++++ > mm/pagewalk.c | 24 ++++++++++++++++++++++++ > 2 files changed, 35 insertions(+) > > diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h > index 12004b097eae..df424197a25a 100644 > --- a/include/linux/pagewalk.h > +++ b/include/linux/pagewalk.h > @@ -24,6 +24,11 @@ struct mm_walk; > * "do page table walk over the current vma", return= ing > * a negative value means "abort current page table = walk > * right now" and returning 1 means "skip the curren= t vma" > + * @test_pmd: similar to test_walk(), but called for every pmd. > + * @test_pud: similar to test_walk(), but called for every pud. > + * @test_p4d: similar to test_walk(), but called for every p4d. > + * Returning 0 means walk this part of the page tabl= es, > + * returning 1 means to skip this range. > * > * p?d_entry callbacks are called even if those levels are folded on a > * particular architecture/configuration. > @@ -46,6 +51,12 @@ struct mm_walk_ops { > struct mm_walk *walk); > int (*test_walk)(unsigned long addr, unsigned long next, > struct mm_walk *walk); > + int (*test_pmd)(unsigned long addr, unsigned long next, > + pmd_t *pmd_start, struct mm_walk *walk); > + int (*test_pud)(unsigned long addr, unsigned long next, > + pud_t *pud_start, struct mm_walk *walk); > + int (*test_p4d)(unsigned long addr, unsigned long next, > + p4d_t *p4d_start, struct mm_walk *walk); > }; > > /** > diff --git a/mm/pagewalk.c b/mm/pagewalk.c > index 4139e9163aee..43acffefd43f 100644 > --- a/mm/pagewalk.c > +++ b/mm/pagewalk.c > @@ -34,6 +34,14 @@ static int walk_pmd_range(pud_t *pud, unsigned long ad= dr, unsigned long end, > const struct mm_walk_ops *ops =3D walk->ops; > int err =3D 0; > > + if (ops->test_pmd) { > + err =3D ops->test_pmd(addr, end, pmd_offset(pud, 0UL), wa= lk); > + if (err < 0) > + return err; > + if (err > 0) > + return 0; > + } > + > pmd =3D pmd_offset(pud, addr); > do { > again: > @@ -85,6 +93,14 @@ static int walk_pud_range(p4d_t *p4d, unsigned long ad= dr, unsigned long end, > const struct mm_walk_ops *ops =3D walk->ops; > int err =3D 0; > > + if (ops->test_pud) { > + err =3D ops->test_pud(addr, end, pud_offset(p4d, 0UL), wa= lk); > + if (err < 0) > + return err; > + if (err > 0) > + return 0; > + } > + > pud =3D pud_offset(p4d, addr); > do { > again: > @@ -128,6 +144,14 @@ static int walk_p4d_range(pgd_t *pgd, unsigned long = addr, unsigned long end, > const struct mm_walk_ops *ops =3D walk->ops; > int err =3D 0; > > + if (ops->test_p4d) { > + err =3D ops->test_p4d(addr, end, p4d_offset(pgd, 0UL), wa= lk); > + if (err < 0) > + return err; > + if (err > 0) > + return 0; > + } > + > p4d =3D p4d_offset(pgd, addr); > do { > next =3D p4d_addr_end(addr, end); > -- > 2.20.1 > It's good to me. Tested-by: Zong Li