| Message ID | 20200616074934.1600036-7-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | seccomp: Implement constant action bitmaps | expand |
On Tue, Jun 16, 2020 at 12:49 AM Kees Cook <keescook@chromium.org> wrote: > > The seccomp constant action bitmap filter evaluation routine depends > on being able to quickly clear the PTE "accessed" bit for a temporary > allocation. Provide access to the existing CPU-local kernel memory TLB > flushing routines. Can you write a better justification? Also, unless I'm just incompetent this morning, I can't find anyone calling this in the series.
On Tue, Jun 16, 2020 at 09:59:29AM -0700, Andy Lutomirski wrote: > On Tue, Jun 16, 2020 at 12:49 AM Kees Cook <keescook@chromium.org> wrote: > > > > The seccomp constant action bitmap filter evaluation routine depends > > on being able to quickly clear the PTE "accessed" bit for a temporary > > allocation. Provide access to the existing CPU-local kernel memory TLB > > flushing routines. > > Can you write a better justification? Also, unless I'm just Er, dunno? That's the entire reason this series needs it. > incompetent this morning, I can't find anyone calling this in the > series. It's in patch 4, seccomp_update_bitmap(): https://lore.kernel.org/lkml/20200616074934.1600036-5-keescook@chromium.org/
diff --git a/arch/x86/include/asm/tlbflush.h b/arch/x86/include/asm/tlbflush.h index 8c87a2e0b660..ae853e77d6bc 100644 --- a/arch/x86/include/asm/tlbflush.h +++ b/arch/x86/include/asm/tlbflush.h @@ -228,6 +228,8 @@ extern void flush_tlb_all(void); extern void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start, unsigned long end, unsigned int stride_shift, bool freed_tables); +extern void local_flush_tlb_kernel_range(unsigned long start, + unsigned long end); extern void flush_tlb_kernel_range(unsigned long start, unsigned long end); static inline void flush_tlb_page(struct vm_area_struct *vma, unsigned long a) diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 1a3569b43aa5..ffcf2bd0ce1c 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -959,16 +959,22 @@ void flush_tlb_all(void) on_each_cpu(do_flush_tlb_all, NULL, 1); } -static void do_kernel_range_flush(void *info) +void local_flush_tlb_kernel_range(unsigned long start, unsigned long end) { - struct flush_tlb_info *f = info; unsigned long addr; /* flush range by one by one 'invlpg' */ - for (addr = f->start; addr < f->end; addr += PAGE_SIZE) + for (addr = start; addr < end; addr += PAGE_SIZE) flush_tlb_one_kernel(addr); } +static void do_kernel_range_flush(void *info) +{ + struct flush_tlb_info *f = info; + + local_flush_tlb_kernel_range(f->start, f->end); +} + void flush_tlb_kernel_range(unsigned long start, unsigned long end) { /* Balance as user space task's flush, a bit conservative */
The seccomp constant action bitmap filter evaluation routine depends on being able to quickly clear the PTE "accessed" bit for a temporary allocation. Provide access to the existing CPU-local kernel memory TLB flushing routines. Signed-off-by: Kees Cook <keescook@chromium.org> --- arch/x86/include/asm/tlbflush.h | 2 ++ arch/x86/mm/tlb.c | 12 +++++++++--- 2 files changed, 11 insertions(+), 3 deletions(-)