Commit 87983c66 authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Thomas Gleixner
Browse files

x86_64, vsyscall: Turn vsyscalls all the way off when vsyscall==none 



I see no point in having an unusable read-only page sitting at
0xffffffffff600000 when vsyscall=none. Instead, skip mapping it and
remove it from /proc/PID/maps.

I kept the ratelimited warning when programs try to use a vsyscall
in this mode, since it may help admins avoid confusion.

Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Link: http://lkml.kernel.org/r/0dddbadc1d4e3bfbaf887938ff42afc97a7cc1f2.1414618407.git.luto@amacapital.net


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent e76b027e

arch/x86/kernel/vsyscall_64.c

+9 −5
Original line number Diff line number Diff line
@@ -307,6 +307,8 @@ struct vm_area_struct *get_gate_vma(struct mm_struct *mm) 
	if (!mm || mm->context.ia32_compat)

		return NULL;

#endif

	if (vsyscall_mode == NONE)

		return NULL;

	return &gate_vma;

}
@@ -327,7 +329,7 @@ int in_gate_area(struct mm_struct *mm, unsigned long addr) 
 */

int in_gate_area_no_mm(unsigned long addr)

{

	return (addr & PAGE_MASK) == VSYSCALL_ADDR;

	return vsyscall_mode != NONE && (addr & PAGE_MASK) == VSYSCALL_ADDR;

}



void __init map_vsyscall(void)
@@ -335,10 +337,12 @@ void __init map_vsyscall(void) 
	extern char __vsyscall_page;

	unsigned long physaddr_vsyscall = __pa_symbol(&__vsyscall_page);



	if (vsyscall_mode != NONE)

		__set_fixmap(VSYSCALL_PAGE, physaddr_vsyscall,

			     vsyscall_mode == NATIVE

			     ? PAGE_KERNEL_VSYSCALL

			     : PAGE_KERNEL_VVAR);



	BUILD_BUG_ON((unsigned long)__fix_to_virt(VSYSCALL_PAGE) !=

		     (unsigned long)VSYSCALL_ADDR);

}