x86_64: further cleanup of 32-bit compat syscall mechanisms

AMD only supports "syscall" from 32-bit compat usermode.
Intel and Centaur(?) only support "sysenter" from 32-bit compat usermode.

Set the X86 feature bits accordingly, and set up the vdso in
accordance with those bits.  On the offchance we run on in a 64-bit
environment which supports neither syscall nor sysenter from 32-bit
mode, then fall back to the int $0x80 vdso.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 8 insertions, 5 deletions

diff --git a/arch/x86/vdso/vdso32.S b/arch/x86/vdso/vdso32.S
index 1e36f72cab86..2ce5f82c333b 100644
--- a/arch/x86/vdso/vdso32.S
+++ b/arch/x86/vdso/vdso32.S
@@ -2,14 +2,17 @@
 
 __INITDATA
 
-        .globl vdso32_default_start, vdso32_default_end
-vdso32_default_start:
-#ifdef CONFIG_X86_32
+        .globl vdso32_int80_start, vdso32_int80_end
+vdso32_int80_start:
         .incbin "arch/x86/vdso/vdso32-int80.so"
-#else
+vdso32_int80_end:
+
+        .globl vdso32_syscall_start, vdso32_syscall_end
+vdso32_syscall_start:
+#ifdef CONFIG_COMPAT
         .incbin "arch/x86/vdso/vdso32-syscall.so"
 #endif
-vdso32_default_end:
+vdso32_syscall_end:
 
         .globl vdso32_sysenter_start, vdso32_sysenter_end
 vdso32_sysenter_start: