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/kernel/vsyscall_emu_64.S | 36 +++++++++++++++++++++++------------- 1 file changed, 23 insertions(+), 13 deletions(-) (limited to 'arch/x86/kernel/vsyscall_emu_64.S') diff --git a/arch/x86/kernel/vsyscall_emu_64.S b/arch/x86/kernel/vsyscall_emu_64.S index ffa845eae5ca..c9596a9af159 100644 --- a/arch/x86/kernel/vsyscall_emu_64.S +++ b/arch/x86/kernel/vsyscall_emu_64.S @@ -7,21 +7,31 @@ */ #include + #include +#include +#include + +__PAGE_ALIGNED_DATA + .globl __vsyscall_page + .balign PAGE_SIZE, 0xcc + .type __vsyscall_page, @object +__vsyscall_page: + + mov $__NR_gettimeofday, %rax + syscall + ret -/* The unused parts of the page are filled with 0xcc by the linker script. */ + .balign 1024, 0xcc + mov $__NR_time, %rax + syscall + ret -.section .vsyscall_0, "a" -ENTRY(vsyscall_0) - int $VSYSCALL_EMU_VECTOR -END(vsyscall_0) + .balign 1024, 0xcc + mov $__NR_getcpu, %rax + syscall + ret -.section .vsyscall_1, "a" -ENTRY(vsyscall_1) - int $VSYSCALL_EMU_VECTOR -END(vsyscall_1) + .balign 4096, 0xcc -.section .vsyscall_2, "a" -ENTRY(vsyscall_2) - int $VSYSCALL_EMU_VECTOR -END(vsyscall_2) + .size __vsyscall_page, 4096 -- cgit v1.2.3