[PATCH 4.14 012/146] x86/mm/pti: Populate user PGD

Greg Kroah-Hartman
2018-01-01T14:39:17Z

From: Dave Hansen <dave.hansen@linux.intel.com>

commit fc2fbc8512ed08d1de7720936fd7d2e4ce02c3a2 upstream.

In clone_pgd_range() copy the init user PGDs which cover the kernel half of
the address space, so a process has all the required kernel mappings
visible.

[ tglx: Split out from the big kaiser dump and folded Andys simplification ]

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/include/asm/pgtable.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -1125,7 +1125,14 @@ static inline int pud_write(pud_t pud)
*/
static inline void clone_pgd_range(pgd_t *dst, pgd_t *src, int count)
{
- memcpy(dst, src, count * sizeof(pgd_t));
+ memcpy(dst, src, count * sizeof(pgd_t));
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+ if (!static_cpu_has(X86_FEATURE_PTI))
+ return;
+ /* Clone the user space pgd as well */
+ memcpy(kernel_to_user_pgdp(dst), kernel_to_user_pgdp(src),
+ count * sizeof(pgd_t));
+#endif
}

#define PTE_SHIFT ilog2(PTRS_PER_PTE)