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

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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: Andy Lutomirski <luto@amacapital.net>
Reviewed-by: Josh 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: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Andy Lutomirski 2014-10-29 14:33:45 -07:00 committed by Thomas Gleixner
parent e76b027e64
commit 87983c66bc
1 changed files with 9 additions and 5 deletions
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14
arch/x86/kernel/vsyscall_64.c
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@ -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);
__set_fixmap(VSYSCALL_PAGE, physaddr_vsyscall,
vsyscall_mode == NATIVE
? PAGE_KERNEL_VSYSCALL
: PAGE_KERNEL_VVAR);
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);
}