Merge branch master from git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

Pick up the spectre documentation so the Grand Schemozzle can be added.

1 files changed, 83 insertions, 75 deletions

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index b043c754d978..be9ca198c581 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -8,7 +8,7 @@
  *
  * entry.S contains the system-call and fault low-level handling routines.
  *
- * Some of this is documented in Documentation/x86/entry_64.txt
+ * Some of this is documented in Documentation/x86/entry_64.rst
  *
  * A note on terminology:
  * - iret frame:	Architecture defined interrupt frame from SS to RIP
@@ -866,18 +866,84 @@ apicinterrupt IRQ_WORK_VECTOR			irq_work_interrupt		smp_irq_work_interrupt
  */
 #define CPU_TSS_IST(x) PER_CPU_VAR(cpu_tss_rw) + (TSS_ist + (x) * 8)
 
+.macro idtentry_part do_sym, has_error_code:req, read_cr2:req, paranoid:req, shift_ist=-1, ist_offset=0
+
+	.if \paranoid
+	call	paranoid_entry
+	/* returned flag: ebx=0: need swapgs on exit, ebx=1: don't need it */
+	.else
+	call	error_entry
+	.endif
+	UNWIND_HINT_REGS
+
+	.if \read_cr2
+	/*
+	 * Store CR2 early so subsequent faults cannot clobber it. Use R12 as
+	 * intermediate storage as RDX can be clobbered in enter_from_user_mode().
+	 * GET_CR2_INTO can clobber RAX.
+	 */
+	GET_CR2_INTO(%r12);
+	.endif
+
+	.if \shift_ist != -1
+	TRACE_IRQS_OFF_DEBUG			/* reload IDT in case of recursion */
+	.else
+	TRACE_IRQS_OFF
+	.endif
+
+	.if \paranoid == 0
+	testb	$3, CS(%rsp)
+	jz	.Lfrom_kernel_no_context_tracking_\@
+	CALL_enter_from_user_mode
+.Lfrom_kernel_no_context_tracking_\@:
+	.endif
+
+	movq	%rsp, %rdi			/* pt_regs pointer */
+
+	.if \has_error_code
+	movq	ORIG_RAX(%rsp), %rsi		/* get error code */
+	movq	$-1, ORIG_RAX(%rsp)		/* no syscall to restart */
+	.else
+	xorl	%esi, %esi			/* no error code */
+	.endif
+
+	.if \shift_ist != -1
+	subq	$\ist_offset, CPU_TSS_IST(\shift_ist)
+	.endif
+
+	.if \read_cr2
+	movq	%r12, %rdx			/* Move CR2 into 3rd argument */
+	.endif
+
+	call	\do_sym
+
+	.if \shift_ist != -1
+	addq	$\ist_offset, CPU_TSS_IST(\shift_ist)
+	.endif
+
+	.if \paranoid
+	/* this procedure expect "no swapgs" flag in ebx */
+	jmp	paranoid_exit
+	.else
+	jmp	error_exit
+	.endif
+
+.endm
+
 /**
  * idtentry - Generate an IDT entry stub
  * @sym:		Name of the generated entry point
- * @do_sym: 		C function to be called
- * @has_error_code: 	True if this IDT vector has an error code on the stack
- * @paranoid: 		non-zero means that this vector may be invoked from
+ * @do_sym:		C function to be called
+ * @has_error_code:	True if this IDT vector has an error code on the stack
+ * @paranoid:		non-zero means that this vector may be invoked from
  *			kernel mode with user GSBASE and/or user CR3.
  *			2 is special -- see below.
  * @shift_ist:		Set to an IST index if entries from kernel mode should
- *             		decrement the IST stack so that nested entries get a
+ *			decrement the IST stack so that nested entries get a
  *			fresh stack.  (This is for #DB, which has a nasty habit
- *             		of recursing.)
+ *			of recursing.)
+ * @create_gap:		create a 6-word stack gap when coming from kernel mode.
+ * @read_cr2:		load CR2 into the 3rd argument; done before calling any C code
  *
  * idtentry generates an IDT stub that sets up a usable kernel context,
  * creates struct pt_regs, and calls @do_sym.  The stub has the following
@@ -902,15 +968,19 @@ apicinterrupt IRQ_WORK_VECTOR			irq_work_interrupt		smp_irq_work_interrupt
  * @paranoid == 2 is special: the stub will never switch stacks.  This is for
  * #DF: if the thread stack is somehow unusable, we'll still get a useful OOPS.
  */
-.macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1 ist_offset=0 create_gap=0
+.macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1 ist_offset=0 create_gap=0 read_cr2=0
 ENTRY(\sym)
 	UNWIND_HINT_IRET_REGS offset=\has_error_code*8
 
 	/* Sanity check */
-	.if \shift_ist != -1 && \paranoid == 0
+	.if \shift_ist != -1 && \paranoid != 1
 	.error "using shift_ist requires paranoid=1"
 	.endif
 
+	.if \create_gap && \paranoid
+	.error "using create_gap requires paranoid=0"
+	.endif
+
 	ASM_CLAC
 
 	.if \has_error_code == 0
@@ -936,47 +1006,7 @@ ENTRY(\sym)
 .Lfrom_usermode_no_gap_\@:
 	.endif
 
-	.if \paranoid
-	call	paranoid_entry
-	.else
-	call	error_entry
-	.endif
-	UNWIND_HINT_REGS
-	/* returned flag: ebx=0: need swapgs on exit, ebx=1: don't need it */
-
-	.if \paranoid
-	.if \shift_ist != -1
-	TRACE_IRQS_OFF_DEBUG			/* reload IDT in case of recursion */
-	.else
-	TRACE_IRQS_OFF
-	.endif
-	.endif
-
-	movq	%rsp, %rdi			/* pt_regs pointer */
-
-	.if \has_error_code
-	movq	ORIG_RAX(%rsp), %rsi		/* get error code */
-	movq	$-1, ORIG_RAX(%rsp)		/* no syscall to restart */
-	.else
-	xorl	%esi, %esi			/* no error code */
-	.endif
-
-	.if \shift_ist != -1
-	subq	$\ist_offset, CPU_TSS_IST(\shift_ist)
-	.endif
-
-	call	\do_sym
-
-	.if \shift_ist != -1
-	addq	$\ist_offset, CPU_TSS_IST(\shift_ist)
-	.endif
-
-	/* these procedures expect "no swapgs" flag in ebx */
-	.if \paranoid
-	jmp	paranoid_exit
-	.else
-	jmp	error_exit
-	.endif
+	idtentry_part \do_sym, \has_error_code, \read_cr2, \paranoid, \shift_ist, \ist_offset
 
 	.if \paranoid == 1
 	/*
@@ -985,21 +1015,9 @@ ENTRY(\sym)
 	 * run in real process context if user_mode(regs).
 	 */
 .Lfrom_usermode_switch_stack_\@:
-	call	error_entry
-
-	movq	%rsp, %rdi			/* pt_regs pointer */
-
-	.if \has_error_code
-	movq	ORIG_RAX(%rsp), %rsi		/* get error code */
-	movq	$-1, ORIG_RAX(%rsp)		/* no syscall to restart */
-	.else
-	xorl	%esi, %esi			/* no error code */
+	idtentry_part \do_sym, \has_error_code, \read_cr2, paranoid=0
 	.endif
 
-	call	\do_sym
-
-	jmp	error_exit
-	.endif
 _ASM_NOKPROBE(\sym)
 END(\sym)
 .endm
@@ -1009,7 +1027,7 @@ idtentry overflow			do_overflow			has_error_code=0
 idtentry bounds				do_bounds			has_error_code=0
 idtentry invalid_op			do_invalid_op			has_error_code=0
 idtentry device_not_available		do_device_not_available		has_error_code=0
-idtentry double_fault			do_double_fault			has_error_code=1 paranoid=2
+idtentry double_fault			do_double_fault			has_error_code=1 paranoid=2 read_cr2=1
 idtentry coprocessor_segment_overrun	do_coprocessor_segment_overrun	has_error_code=0
 idtentry invalid_TSS			do_invalid_TSS			has_error_code=1
 idtentry segment_not_present		do_segment_not_present		has_error_code=1
@@ -1178,14 +1196,13 @@ idtentry stack_segment		do_stack_segment	has_error_code=1
 #ifdef CONFIG_XEN_PV
 idtentry xennmi			do_nmi			has_error_code=0
 idtentry xendebug		do_debug		has_error_code=0
-idtentry xenint3		do_int3			has_error_code=0
 #endif
 
 idtentry general_protection	do_general_protection	has_error_code=1
-idtentry page_fault		do_page_fault		has_error_code=1
+idtentry page_fault		do_page_fault		has_error_code=1	read_cr2=1
 
 #ifdef CONFIG_KVM_GUEST
-idtentry async_page_fault	do_async_page_fault	has_error_code=1
+idtentry async_page_fault	do_async_page_fault	has_error_code=1	read_cr2=1
 #endif
 
 #ifdef CONFIG_X86_MCE
@@ -1292,20 +1309,11 @@ ENTRY(error_entry)
 	movq	%rax, %rsp			/* switch stack */
 	ENCODE_FRAME_POINTER
 	pushq	%r12
-
-	/*
-	 * We need to tell lockdep that IRQs are off.  We can't do this until
-	 * we fix gsbase, and we should do it before enter_from_user_mode
-	 * (which can take locks).
-	 */
-	TRACE_IRQS_OFF
-	CALL_enter_from_user_mode
 	ret
 
 .Lerror_entry_done_lfence:
 	FENCE_SWAPGS_KERNEL_ENTRY
 .Lerror_entry_done:
-	TRACE_IRQS_OFF
 	ret
 
 	/*