Revert x86 sigcontext cleanups (ed596cde) · Commits · 戴 / test

arch/x86/include/asm/sigcontext.h

+3 −3

Original line number	Diff line number	Diff line
		@@ -57,9 +57,9 @@ struct sigcontext {
		unsigned long ip;
		unsigned long flags;
		unsigned short cs;
		unsigned short __pad2; /* Was called gs, but was always zero. */
		unsigned short __pad1; /* Was called fs, but was always zero. */
		unsigned short ss;
		unsigned short gs;
		unsigned short fs;
		unsigned short __pad0;
		unsigned long err;
		unsigned long trapno;
		unsigned long oldmask;

arch/x86/include/uapi/asm/sigcontext.h

+3 −18

Original line number	Diff line number	Diff line
		@@ -177,24 +177,9 @@ struct sigcontext {
		__u64 rip;
		__u64 eflags; /* RFLAGS */
		__u16 cs;

		/*
		* Prior to 2.5.64 ("[PATCH] x86-64 updates for 2.5.64-bk3"),
		* Linux saved and restored fs and gs in these slots. This
		* was counterproductive, as fsbase and gsbase were never
		* saved, so arch_prctl was presumably unreliable.
		*
		* If these slots are ever needed for any other purpose, there
		* is some risk that very old 64-bit binaries could get
		* confused. I doubt that many such binaries still work,
		* though, since the same patch in 2.5.64 also removed the
		* 64-bit set_thread_area syscall, so it appears that there is
		* no TLS API that works in both pre- and post-2.5.64 kernels.
		*/
		__u16 __pad2; /* Was gs. */
		__u16 __pad1; /* Was fs. */

		__u16 ss;
		__u16 gs;
		__u16 fs;
		__u16 __pad0;
		__u64 err;
		__u64 trapno;
		__u64 oldmask;

arch/x86/kernel/signal.c

+11 −15

Original line number	Diff line number	Diff line
		@@ -93,8 +93,15 @@ int restore_sigcontext(struct pt_regs regs, struct sigcontext __user sc)
		COPY(r15);
		#endif /* CONFIG_X86_64 */

		#ifdef CONFIG_X86_32
		COPY_SEG_CPL3(cs);
		COPY_SEG_CPL3(ss);
		#else /* !CONFIG_X86_32 */
		/* Kernel saves and restores only the CS segment register on signals,
		* which is the bare minimum needed to allow mixed 32/64-bit code.
		* App's signal handler can save/restore other segments if needed. */
		COPY_SEG_CPL3(cs);
		#endif /* CONFIG_X86_32 */

		get_user_ex(tmpflags, &sc->flags);
		regs->flags = (regs->flags & ~FIX_EFLAGS) \| (tmpflags & FIX_EFLAGS);
		@@ -154,9 +161,8 @@ int setup_sigcontext(struct sigcontext __user sc, void __user fpstate,
		#else /* !CONFIG_X86_32 */
		put_user_ex(regs->flags, &sc->flags);
		put_user_ex(regs->cs, &sc->cs);
		put_user_ex(0, &sc->__pad2);
		put_user_ex(0, &sc->__pad1);
		put_user_ex(regs->ss, &sc->ss);
		put_user_ex(0, &sc->gs);
		put_user_ex(0, &sc->fs);
		#endif /* CONFIG_X86_32 */

		put_user_ex(fpstate, &sc->fpstate);
		@@ -451,19 +457,9 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,

		regs->sp = (unsigned long)frame;

		/*
		* Set up the CS and SS registers to run signal handlers in
		* 64-bit mode, even if the handler happens to be interrupting
		* 32-bit or 16-bit code.
		*
		* SS is subtle. In 64-bit mode, we don't need any particular
		* SS descriptor, but we do need SS to be valid. It's possible
		* that the old SS is entirely bogus -- this can happen if the
		* signal we're trying to deliver is #GP or #SS caused by a bad
		* SS value.
		*/
		/* Set up the CS register to run signal handlers in 64-bit mode,
		even if the handler happens to be interrupting 32-bit code. */
		regs->cs = __USER_CS;
		regs->ss = __USER_DS;

		return 0;
		}

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