diff options
| author | Joerg Roedel <jroedel@suse.de> | 2018-07-18 11:41:03 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-07-20 01:11:44 +0200 |
| commit | f94560cd6b5117f8913f4c42f4d9a405c26ddc1c (patch) | |
| tree | 3b23e49c0b0d61a40d12c169086e71d44915a611 /arch/x86/mm | |
| parent | 2c1b9fbe83412598d2dccdd448147336b085e0c6 (diff) | |
x86/mm/pti: Clone CPU_ENTRY_AREA on PMD level on x86_32
Cloning on the P4D level would clone the complete kernel address space into
the user-space page-tables for PAE kernels. Cloning on PMD level is fine
for PAE and legacy paging.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Pavel Machek <pavel@ucw.cz>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1531906876-13451-27-git-send-email-joro@8bytes.org
Diffstat (limited to 'arch/x86/mm')
| -rw-r--r-- | arch/x86/mm/pti.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 79217868dd13..a594e3b6401a 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -348,6 +348,7 @@ pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear) } } +#ifdef CONFIG_X86_64 /* * Clone a single p4d (i.e. a top-level entry on 4-level systems and a * next-level entry on 5-level systems. @@ -371,6 +372,25 @@ static void __init pti_clone_user_shared(void) pti_clone_p4d(CPU_ENTRY_AREA_BASE); } +#else /* CONFIG_X86_64 */ + +/* + * On 32 bit PAE systems with 1GB of Kernel address space there is only + * one pgd/p4d for the whole kernel. Cloning that would map the whole + * address space into the user page-tables, making PTI useless. So clone + * the page-table on the PMD level to prevent that. + */ +static void __init pti_clone_user_shared(void) +{ + unsigned long start, end; + + start = CPU_ENTRY_AREA_BASE; + end = start + (PAGE_SIZE * CPU_ENTRY_AREA_PAGES); + + pti_clone_pmds(start, end, 0); +} +#endif /* CONFIG_X86_64 */ + /* * Clone the ESPFIX P4D into the user space visible page table */ |