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| author | Dave Hansen <dave.hansen@linux.intel.com> | 2018-04-06 22:55:07 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2018-04-09 18:27:33 +0200 |
| commit | 6baf4bec02dbc41645c3a5130ee15a8e1d62b80f (patch) | |
| tree | 8ebd462bb7ebff7d7db72e28a0bc8a405f2e1c1c /arch/x86/kernel/espfix_64.c | |
| parent | x86/mm: Introduce "default" kernel PTE mask (diff) | |
| download | linux-6baf4bec02dbc41645c3a5130ee15a8e1d62b80f.tar.xz linux-6baf4bec02dbc41645c3a5130ee15a8e1d62b80f.zip | |
x86/espfix: Document use of _PAGE_GLOBAL
The "normal" kernel page table creation mechanisms using
PAGE_KERNEL_* page protections will never set _PAGE_GLOBAL with PTI.
The few places in the kernel that always want _PAGE_GLOBAL must
avoid using PAGE_KERNEL_*.
Document that we want it here and its use is not accidental.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180406205507.BCF4D4F0@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/espfix_64.c')
| -rw-r--r-- | arch/x86/kernel/espfix_64.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/kernel/espfix_64.c b/arch/x86/kernel/espfix_64.c index e5ec3cafa72e..aebd0d5bc086 100644 --- a/arch/x86/kernel/espfix_64.c +++ b/arch/x86/kernel/espfix_64.c @@ -195,6 +195,10 @@ void init_espfix_ap(int cpu) pte_p = pte_offset_kernel(&pmd, addr); stack_page = page_address(alloc_pages_node(node, GFP_KERNEL, 0)); + /* + * __PAGE_KERNEL_* includes _PAGE_GLOBAL, which we want since + * this is mapped to userspace. + */ pte = __pte(__pa(stack_page) | ((__PAGE_KERNEL_RO | _PAGE_ENC) & ptemask)); for (n = 0; n < ESPFIX_PTE_CLONES; n++) set_pte(&pte_p[n*PTE_STRIDE], pte); |