Commit dc4fac84 authored May 10, 2016 by Andy Lutomirski Committed by Ingo Molnar May 20, 2016

x86/mm: Switch from TASK_SIZE to TASK_SIZE_MAX in the page fault code



x86's page fault handlers had two TASK_SIZE uses that should have
been TASK_SIZE_MAX.  I don't think that either one had a visible
effect, but this makes the code clearer and should save a few bytes
of text.

(And I eventually want to eradicate TASK_SIZE.  This will help.)

Reported-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ruslan Kabatsayev <b7.10110111@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1242fb23b0d05c3069dbf5758ac55d26bc114bef.1462914565.git.luto@kernel.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent d696ca01

arch/x86/mm/fault.c

+8 −3

Original line number	Diff line number	Diff line
		@@ -292,7 +292,7 @@ void vmalloc_sync_all(void)
		return;

		for (address = VMALLOC_START & PMD_MASK;
		address >= TASK_SIZE && address < FIXADDR_TOP;
		address >= TASK_SIZE_MAX && address < FIXADDR_TOP;
		address += PMD_SIZE) {
		struct page *page;

		@@ -854,8 +854,13 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
		return;
		}
		#endif
		/* Kernel addresses are always protection faults: */
		if (address >= TASK_SIZE)

		/*
		* To avoid leaking information about the kernel page table
		* layout, pretend that user-mode accesses to kernel addresses
		* are always protection faults.
		*/
		if (address >= TASK_SIZE_MAX)
		error_code \|= PF_PROT;

		if (likely(show_unhandled_signals))

Admin message