Commit-ID: 02e983b760c0d4183c28d625a3c99016e2cd8a7f Gitweb: https://git.kernel.org/tip/02e983b760c0d4183c28d625a3c99016e2cd8a7f Author: Dave Hansen <[email protected]> AuthorDate: Fri, 28 Sep 2018 09:02:28 -0700 Committer: Peter Zijlstra <[email protected]> CommitDate: Tue, 9 Oct 2018 16:51:16 +0200
x86/mm: Add vsyscall address helper 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: [email protected] Cc: Jann Horn <[email protected]> Cc: Sean Christopherson <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Andy Lutomirski <[email protected]> Signed-off-by: Dave Hansen <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Link: http://lkml.kernel.org/r/[email protected] --- arch/x86/mm/fault.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 57b074b02ebb..7a627ac3a0d2 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -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; }
