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x86/mm: Add vsyscall address helper

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We will shortly be using this check in two locations.  Put it in
a helper before we do so.

Let's also insert PAGE_MASK instead of the open-coded ~0xfff.
It is easier to read and also more obviously correct considering
the implicit type conversion that has to happen when it is not
an implicit 'unsigned long'.

Cc: x86@kernel.org
Cc: Jann Horn <jannh@google.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180928160228.C593509B@viggo.jf.intel.com
This commit is contained in:
Dave Hansen 2018-09-28 09:02:28 -07:00 committed by Peter Zijlstra
parent 88259744e2
commit 02e983b760
1 changed files with 10 additions and 1 deletions
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11
arch/x86/mm/fault.c
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@ -840,6 +840,15 @@ show_signal_msg(struct pt_regs *regs, unsigned long error_code,
show_opcodes(regs, loglvl);
}
/*
* The (legacy) vsyscall page is the long page in the kernel portion
* of the address space that has user-accessible permissions.
*/
static bool is_vsyscall_vaddr(unsigned long vaddr)
{
return (vaddr & PAGE_MASK) == VSYSCALL_ADDR;
}
static void
__bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
unsigned long address, u32 *pkey, int si_code)
@ -869,7 +878,7 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code,
* emulation.
*/
if (unlikely((error_code & X86_PF_INSTR) &&
((address & ~0xfff) == VSYSCALL_ADDR))) {
is_vsyscall_vaddr(address))) {
if (emulate_vsyscall(regs, address))
return;
}