Revert "x86/signal/64: Re-add support for SS in the 64-bit signal context"

[android-x86/kernel.git] / arch / x86 / include / uapi / asm / ucontext.h

diff --git a/arch/x86/include/uapi/asm/ucontext.h b/arch/x86/include/uapi/asm/ucontext.h
index e3d1ec9..b7c29c8 100644 (file)
--- a/arch/x86/include/uapi/asm/ucontext.h
+++ b/arch/x86/include/uapi/asm/ucontext.h
@@ -1,54 +1,11 @@
 #ifndef _ASM_X86_UCONTEXT_H
 #define _ASM_X86_UCONTEXT_H
 
-/*
- * Indicates the presence of extended state information in the memory
- * layout pointed by the fpstate pointer in the ucontext's sigcontext
- * struct (uc_mcontext).
- */
-#define UC_FP_XSTATE   0x1
-
-#ifdef __x86_64__
-/*
- * UC_SIGCONTEXT_SS will be set when delivering 64-bit or x32 signals on
- * kernels that save SS in the sigcontext.  All kernels that set
- * UC_SIGCONTEXT_SS will correctly restore at least the low 32 bits of esp
- * regardless of SS (i.e. they implement espfix).
- *
- * Kernels that set UC_SIGCONTEXT_SS will also set UC_STRICT_RESTORE_SS
- * when delivering a signal that came from 64-bit code.
- *
- * Sigreturn restores SS as follows:
- *
- * if (saved SS is valid || UC_STRICT_RESTORE_SS is set ||
- *     saved CS is not 64-bit)
- *         new SS = saved SS  (will fail IRET and signal if invalid)
- * else
- *         new SS = a flat 32-bit data segment
- *
- * This behavior serves three purposes:
- *
- * - Legacy programs that construct a 64-bit sigcontext from scratch
- *   with zero or garbage in the SS slot (e.g. old CRIU) and call
- *   sigreturn will still work.
- *
- * - Old DOSEMU versions sometimes catch a signal from a segmented
- *   context, delete the old SS segment (with modify_ldt), and change
- *   the saved CS to a 64-bit segment.  These DOSEMU versions expect
- *   sigreturn to send them back to 64-bit mode without killing them,
- *   despite the fact that the SS selector when the signal was raised is
- *   no longer valid.  UC_STRICT_RESTORE_SS will be clear, so the kernel
- *   will fix up SS for these DOSEMU versions.
- *
- * - Old and new programs that catch a signal and return without
- *   modifying the saved context will end up in exactly the state they
- *   started in, even if they were running in a segmented context when
- *   the signal was raised..  Old kernels would lose track of the
- *   previous SS value.
- */
-#define UC_SIGCONTEXT_SS       0x2
-#define UC_STRICT_RESTORE_SS   0x4
-#endif
+#define UC_FP_XSTATE   0x1     /* indicates the presence of extended state
+                                * information in the memory layout pointed
+                                * by the fpstate pointer in the ucontext's
+                                * sigcontext struct (uc_mcontext).
+                                */
 
 #include <asm-generic/ucontext.h>