From 3ae36655b97a03fa1decf72f04078ef945647c1a Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Wed, 10 Aug 2011 11:15:32 -0400 Subject: x86-64: Rework vsyscall emulation and add vsyscall= parameter There are three choices: vsyscall=native: Vsyscalls are native code that issues the corresponding syscalls. vsyscall=emulate (default): Vsyscalls are emulated by instruction fault traps, tested in the bad_area path. The actual contents of the vsyscall page is the same as the vsyscall=native case except that it's marked NX. This way programs that make assumptions about what the code in the page does will not be confused when they read that code. vsyscall=none: Trying to execute a vsyscall will segfault. Signed-off-by: Andy Lutomirski Link: http://lkml.kernel.org/r/8449fb3abf89851fd6b2260972666a6f82542284.1312988155.git.luto@mit.edu Signed-off-by: H. Peter Anvin --- arch/x86/mm/fault.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'arch/x86/mm/fault.c') diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index c1d018238f32..e58935c25b94 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -720,6 +720,18 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, if (is_errata100(regs, address)) return; +#ifdef CONFIG_X86_64 + /* + * Instruction fetch faults in the vsyscall page might need + * emulation. + */ + if (unlikely((error_code & PF_INSTR) && + ((address & ~0xfff) == VSYSCALL_START))) { + if (emulate_vsyscall(regs, address)) + return; + } +#endif + if (unlikely(show_unhandled_signals)) show_signal_msg(regs, error_code, address, tsk); -- cgit v1.2.3