| Message ID | 20200225073731.465270-6-avagin@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: add the time namespace support | expand |
On 2/25/20 7:37 AM, Andrei Vagin wrote: > Forbid splitting VVAR VMA resulting in a stricter ABI and reducing the > amount of corner-cases to consider while working further on VDSO time > namespace support. > > As the offset from timens to VVAR page is computed compile-time, the pages > in VVAR should stay together and not being partically mremap()'ed. > > Signed-off-by: Andrei Vagin <avagin@gmail.com> Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> > --- > arch/arm64/kernel/vdso.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c > index fb32c6f76078..c003f7ee383a 100644 > --- a/arch/arm64/kernel/vdso.c > +++ b/arch/arm64/kernel/vdso.c > @@ -235,6 +235,17 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, > return vmf_insert_pfn(vma, vmf->address, pfn); > } > > +static int vvar_mremap(const struct vm_special_mapping *sm, > + struct vm_area_struct *new_vma) > +{ > + unsigned long new_size = new_vma->vm_end - new_vma->vm_start; > + > + if (new_size != VVAR_NR_PAGES * PAGE_SIZE) > + return -EINVAL; > + > + return 0; > +} > + > static int __setup_additional_pages(enum arch_vdso_type arch_index, > struct mm_struct *mm, > struct linux_binprm *bprm, > @@ -315,6 +326,7 @@ static struct vm_special_mapping aarch32_vdso_spec[C_PAGES] = { > { > .name = "[vvar]", > .fault = vvar_fault, > + .mremap = vvar_mremap, > }, > { > .name = "[vdso]", > @@ -497,6 +509,7 @@ static struct vm_special_mapping vdso_spec[A_PAGES] __ro_after_init = { > { > .name = "[vvar]", > .fault = vvar_fault, > + .mremap = vvar_mremap, > }, > { > .name = "[vdso]", >
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index fb32c6f76078..c003f7ee383a 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -235,6 +235,17 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, return vmf_insert_pfn(vma, vmf->address, pfn); } +static int vvar_mremap(const struct vm_special_mapping *sm, + struct vm_area_struct *new_vma) +{ + unsigned long new_size = new_vma->vm_end - new_vma->vm_start; + + if (new_size != VVAR_NR_PAGES * PAGE_SIZE) + return -EINVAL; + + return 0; +} + static int __setup_additional_pages(enum arch_vdso_type arch_index, struct mm_struct *mm, struct linux_binprm *bprm, @@ -315,6 +326,7 @@ static struct vm_special_mapping aarch32_vdso_spec[C_PAGES] = { { .name = "[vvar]", .fault = vvar_fault, + .mremap = vvar_mremap, }, { .name = "[vdso]", @@ -497,6 +509,7 @@ static struct vm_special_mapping vdso_spec[A_PAGES] __ro_after_init = { { .name = "[vvar]", .fault = vvar_fault, + .mremap = vvar_mremap, }, { .name = "[vdso]",
Forbid splitting VVAR VMA resulting in a stricter ABI and reducing the amount of corner-cases to consider while working further on VDSO time namespace support. As the offset from timens to VVAR page is computed compile-time, the pages in VVAR should stay together and not being partically mremap()'ed. Signed-off-by: Andrei Vagin <avagin@gmail.com> --- arch/arm64/kernel/vdso.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)