Revert "MFC r322762, r322799, r322832, r322833:"

This reverts commit 2589da26b930eaf9441b6bf27c0f410062adf507.

1 files changed, 13 insertions, 54 deletions

diff --git a/sys/amd64/amd64/exception.S b/sys/amd64/amd64/exception.S
index c288f3d..2c2b99b 100644
--- a/sys/amd64/amd64/exception.S
+++ b/sys/amd64/amd64/exception.S
@@ -187,13 +187,12 @@ alltraps_testi:
 	jz	alltraps_pushregs_no_rdi
 	sti
 alltraps_pushregs_no_rdi:
-	movq	%rdx,TF_RDX(%rsp)
-	movq	%rax,TF_RAX(%rsp)
-alltraps_pushregs_no_rax:
 	movq	%rsi,TF_RSI(%rsp)
+	movq	%rdx,TF_RDX(%rsp)
 	movq	%rcx,TF_RCX(%rsp)
 	movq	%r8,TF_R8(%rsp)
 	movq	%r9,TF_R9(%rsp)
+	movq	%rax,TF_RAX(%rsp)
 	movq	%rbx,TF_RBX(%rsp)
 	movq	%rbp,TF_RBP(%rsp)
 	movq	%r10,TF_R10(%rsp)
@@ -327,44 +326,22 @@ IDTVEC(prot)
 prot_addrf:
 	movq	$0,TF_ADDR(%rsp)
 	movq	%rdi,TF_RDI(%rsp)	/* free up a GP register */
-	movq	%rax,TF_RAX(%rsp)
-	movq	%rdx,TF_RDX(%rsp)
-	movw	%fs,TF_FS(%rsp)
-	movw	%gs,TF_GS(%rsp)
 	leaq	doreti_iret(%rip),%rdi
 	cmpq	%rdi,TF_RIP(%rsp)
-	je	5f			/* kernel but with user gsbase!! */
+	je	1f			/* kernel but with user gsbase!! */
 	testb	$SEL_RPL_MASK,TF_CS(%rsp) /* Did we come from kernel? */
-	jz	6f			/* already running with kernel GS.base */
-	testb	$CPUID_STDEXT_FSGSBASE,cpu_stdext_feature(%rip)
-	jz	2f
-	cmpw	$KUF32SEL,TF_FS(%rsp)
-	jne	1f
-	rdfsbaseq %rax
-1:	cmpw	$KUG32SEL,TF_GS(%rsp)
-	jne	2f
-	rdgsbaseq %rdx
-2:	swapgs
-	movq	PCPU(CURPCB),%rdi
-	testb	$CPUID_STDEXT_FSGSBASE,cpu_stdext_feature(%rip)
-	jz	4f
-	cmpw	$KUF32SEL,TF_FS(%rsp)
-	jne	3f
-	movq	%rax,PCB_FSBASE(%rdi)
-3:	cmpw	$KUG32SEL,TF_GS(%rsp)
-	jne	4f
-	movq	%rdx,PCB_GSBASE(%rdi)
-4:	orl	$PCB_FULL_IRET,PCB_FLAGS(%rdi)	/* always full iret from GPF */
+	jz	2f			/* already running with kernel GS.base */
+1:	swapgs
+2:	movq	PCPU(CURPCB),%rdi
+	orl	$PCB_FULL_IRET,PCB_FLAGS(%rdi)	/* always full iret from GPF */
+	movw	%fs,TF_FS(%rsp)
+	movw	%gs,TF_GS(%rsp)
 	movw	%es,TF_ES(%rsp)
 	movw	%ds,TF_DS(%rsp)
 	testl	$PSL_I,TF_RFLAGS(%rsp)
-	jz	alltraps_pushregs_no_rax
+	jz	alltraps_pushregs_no_rdi
 	sti
-	jmp	alltraps_pushregs_no_rax
-
-5:	swapgs
-6:	movq	PCPU(CURPCB),%rdi
-	jmp	4b
+	jmp	alltraps_pushregs_no_rdi
 
 /*
  * Fast syscall entry point.  We enter here with just our new %cs/%ss set,
@@ -372,8 +349,8 @@ prot_addrf:
  * pointer.  We have to juggle a few things around to find our stack etc.
  * swapgs gives us access to our PCPU space only.
  *
- * We do not support invoking this from a custom segment registers,
- * esp. %cs, %ss, %fs, %gs, e.g. using entries from an LDT.
+ * We do not support invoking this from a custom %cs or %ss (e.g. using
+ * entries from an LDT).
  */
 IDTVEC(fast_syscall)
 	swapgs
@@ -526,23 +503,6 @@ IDTVEC(nmi)
 nmi_fromuserspace:
 	incl	%ebx
 	swapgs
-	testb	$CPUID_STDEXT_FSGSBASE,cpu_stdext_feature(%rip)
-	jz	2f
-	movq	PCPU(CURPCB),%rdi
-	testq	%rdi,%rdi
-	jz	2f
-	cmpw	$KUF32SEL,TF_FS(%rsp)
-	jne	1f
-	rdfsbaseq %rax
-	movq	%rax,PCB_FSBASE(%rdi)
-1:	cmpw	$KUG32SEL,TF_GS(%rsp)
-	jne	2f
-	movl	$MSR_KGSBASE,%ecx
-	rdmsr
-	shlq	$32,%rdx
-	orq	%rdx,%rax
-	movq	%rax,PCB_GSBASE(%rdi)
-2:
 /* Note: this label is also used by ddb and gdb: */
 nmi_calltrap:
 	FAKE_MCOUNT(TF_RIP(%rsp))
@@ -745,7 +705,6 @@ doreti_exit:
 	jz	ld_regs
 	testl	$PCB_FULL_IRET,PCB_FLAGS(%r8)
 	jz	ld_regs
-	andl	$~PCB_FULL_IRET,PCB_FLAGS(%r8)
 	testl	$TF_HASSEGS,TF_FLAGS(%rsp)
 	je	set_segs