s390: move expoline assembler macros to a header

BugLink: https://bugs.launchpad.net/bugs/1775477

[ Upstream commit 6dd85fbb ]

To be able to use the expoline branches in different assembler
files move the associated macros from entry.S to a new header
nospec-insn.h.

While we are at it make the macros a bit nicer to use.

Cc: stable@vger.kernel.org # 4.16
Fixes: f19fbd5e ("s390: introduce execute-trampolines for branches")
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

arch/s390/include/asm/nospec-insn.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_S390_NOSPEC_ASM_H
+#define _ASM_S390_NOSPEC_ASM_H
+
+#ifdef __ASSEMBLY__
+
+#ifdef CONFIG_EXPOLINE
+
+/*
+ * The expoline macros are used to create thunks in the same format
+ * as gcc generates them. The 'comdat' section flag makes sure that
+ * the various thunks are merged into a single copy.
+ */
+	.macro __THUNK_PROLOG_NAME name
+	.pushsection .text.\name,"axG",@progbits,\name,comdat
+	.globl \name
+	.hidden \name
+	.type \name,@function
+\name:
+	.cfi_startproc
+	.endm
+
+	.macro __THUNK_EPILOG
+	.cfi_endproc
+	.popsection
+	.endm
+
+	.macro __THUNK_PROLOG_BR r1,r2
+	__THUNK_PROLOG_NAME __s390x_indirect_jump_r\r2\()use_r\r1
+	.endm
+
+	.macro __THUNK_BR r1,r2
+	jg	__s390x_indirect_jump_r\r2\()use_r\r1
+	.endm
+
+	.macro __THUNK_BRASL r1,r2,r3
+	brasl	\r1,__s390x_indirect_jump_r\r3\()use_r\r2
+	.endm
+
+	.macro	__DECODE_RR expand,reg,ruse
+	.set __decode_fail,1
+	.irp r1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
+	.ifc \reg,%r\r1
+	.irp r2,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
+	.ifc \ruse,%r\r2
+	\expand \r1,\r2
+	.set __decode_fail,0
+	.endif
+	.endr
+	.endif
+	.endr
+	.if __decode_fail == 1
+	.error "__DECODE_RR failed"
+	.endif
+	.endm
+
+	.macro	__DECODE_RRR expand,rsave,rtarget,ruse
+	.set __decode_fail,1
+	.irp r1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
+	.ifc \rsave,%r\r1
+	.irp r2,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
+	.ifc \rtarget,%r\r2
+	.irp r3,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
+	.ifc \ruse,%r\r3
+	\expand \r1,\r2,\r3
+	.set __decode_fail,0
+	.endif
+	.endr
+	.endif
+	.endr
+	.endif
+	.endr
+	.if __decode_fail == 1
+	.error "__DECODE_RRR failed"
+	.endif
+	.endm
+
+	.macro __THUNK_EX_BR reg,ruse
+#ifdef CONFIG_HAVE_MARCH_Z10_FEATURES
+	exrl	0,555f
+	j	.
+#else
+	larl	\ruse,555f
+	ex	0,0(\ruse)
+	j	.
+#endif
+555:	br	\reg
+	.endm
+
+	.macro GEN_BR_THUNK reg,ruse=%r1
+	__DECODE_RR __THUNK_PROLOG_BR,\reg,\ruse
+	__THUNK_EX_BR \reg,\ruse
+	__THUNK_EPILOG
+	.endm
+
+	.macro BR_EX reg,ruse=%r1
+557:	__DECODE_RR __THUNK_BR,\reg,\ruse
+	.pushsection .s390_indirect_branches,"a",@progbits
+	.long	557b-.
+	.popsection
+	.endm
+
+	.macro BASR_EX rsave,rtarget,ruse=%r1
+559:	__DECODE_RRR __THUNK_BRASL,\rsave,\rtarget,\ruse
+	.pushsection .s390_indirect_branches,"a",@progbits
+	.long	559b-.
+	.popsection
+	.endm
+
+#else
+	.macro GEN_BR_THUNK reg,ruse=%r1
+	.endm
+
+	 .macro BR_EX reg,ruse=%r1
+	br	\reg
+	.endm
+
+	.macro BASR_EX rsave,rtarget,ruse=%r1
+	basr	\rsave,\rtarget
+	.endm
+#endif
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_S390_NOSPEC_ASM_H */

arch/s390/kernel/entry.S

@@ -23,6 +23,7 @@
 #include <asm/vx-insn.h>
 #include <asm/setup.h>
 #include <asm/nmi.h>
+#include <asm/nospec-insn.h>
 
 __PT_R0      =	__PT_GPRS
 __PT_R1      =	__PT_GPRS + 8
@@ -225,74 +226,16 @@ _PIF_WORK	= (_PIF_PER_TRAP)
 	.popsection
 	.endm
 
-#ifdef CONFIG_EXPOLINE
-
-	.macro GEN_BR_THUNK name,reg,tmp
-	.section .text.\name,"axG",@progbits,\name,comdat
-	.globl \name
-	.hidden \name
-	.type \name,@function
-\name:
-	.cfi_startproc
-#ifdef CONFIG_HAVE_MARCH_Z10_FEATURES
-	exrl	0,0f
-#else
-	larl	\tmp,0f
-	ex	0,0(\tmp)
-#endif
-	j	.
-0:	br	\reg
-	.cfi_endproc
-	.endm
-
-	GEN_BR_THUNK __s390x_indirect_jump_r1use_r9,%r9,%r1
-	GEN_BR_THUNK __s390x_indirect_jump_r1use_r14,%r14,%r1
-	GEN_BR_THUNK __s390x_indirect_jump_r11use_r14,%r14,%r11
-
-	.macro BASR_R14_R9
-0:	brasl	%r14,__s390x_indirect_jump_r1use_r9
-	.pushsection .s390_indirect_branches,"a",@progbits
-	.long	0b-.
-	.popsection
-	.endm
-
-	.macro BR_R1USE_R14
-0:	jg	__s390x_indirect_jump_r1use_r14
-	.pushsection .s390_indirect_branches,"a",@progbits
-	.long	0b-.
-	.popsection
-	.endm
-
-	.macro BR_R11USE_R14
-0:	jg	__s390x_indirect_jump_r11use_r14
-	.pushsection .s390_indirect_branches,"a",@progbits
-	.long	0b-.
-	.popsection
-	.endm
-
-#else	/* CONFIG_EXPOLINE */
-
-	.macro BASR_R14_R9
-	basr	%r14,%r9
-	.endm
-
-	.macro BR_R1USE_R14
-	br	%r14
-	.endm
-
-	.macro BR_R11USE_R14
-	br	%r14
-	.endm
-
-#endif /* CONFIG_EXPOLINE */
-
+	GEN_BR_THUNK %r9
+	GEN_BR_THUNK %r14
+	GEN_BR_THUNK %r14,%r11
 
 	.section .kprobes.text, "ax"
 
 ENTRY(__bpon)
 	.globl __bpon
 	BPON
-	BR_R1USE_R14
+	BR_EX	%r14
 
 /*
  * Scheduler resume function, called by switch_to
@@ -322,7 +265,7 @@ ENTRY(__switch_to)
 	TSTMSK	__LC_MACHINE_FLAGS,MACHINE_FLAG_LPP
 	jz	0f
 	.insn	s,0xb2800000,__LC_LPP		# set program parameter
-0:	BR_R1USE_R14
+0:	BR_EX	%r14
 
 .L__critical_start:
 
@@ -388,7 +331,7 @@ sie_exit:
 	xgr	%r5,%r5
 	lmg	%r6,%r14,__SF_GPRS(%r15)	# restore kernel registers
 	lg	%r2,__SF_EMPTY+16(%r15)		# return exit reason code
-	BR_R1USE_R14
+	BR_EX	%r14
 .Lsie_fault:
 	lghi	%r14,-EFAULT
 	stg	%r14,__SF_EMPTY+16(%r15)	# set exit reason code
@@ -445,7 +388,7 @@ ENTRY(system_call)
 	lgf	%r9,0(%r8,%r10)			# get system call add.
 	TSTMSK	__TI_flags(%r12),_TIF_TRACE
 	jnz	.Lsysc_tracesys
-	BASR_R14_R9				# call sys_xxxx
+	BASR_EX	%r14,%r9			# call sys_xxxx
 	stg	%r2,__PT_R2(%r11)		# store return value
 
 .Lsysc_return:
@@ -585,7 +528,7 @@ ENTRY(system_call)
 	lmg	%r3,%r7,__PT_R3(%r11)
 	stg	%r7,STACK_FRAME_OVERHEAD(%r15)
 	lg	%r2,__PT_ORIG_GPR2(%r11)
-	BASR_R14_R9			# call sys_xxx
+	BASR_EX	%r14,%r9		# call sys_xxx
 	stg	%r2,__PT_R2(%r11)	# store return value
 .Lsysc_tracenogo:
 	TSTMSK	__TI_flags(%r12),_TIF_TRACE
@@ -609,7 +552,7 @@ ENTRY(ret_from_fork)
 	lmg	%r9,%r10,__PT_R9(%r11)	# load gprs
 ENTRY(kernel_thread_starter)
 	la	%r2,0(%r10)
-	BASR_R14_R9
+	BASR_EX	%r14,%r9
 	j	.Lsysc_tracenogo
 
 /*
@@ -685,7 +628,7 @@ ENTRY(pgm_check_handler)
 	je	.Lpgm_return
 	lgf	%r9,0(%r10,%r1)		# load address of handler routine
 	lgr	%r2,%r11		# pass pointer to pt_regs
-	BASR_R14_R9			# branch to interrupt-handler
+	BASR_EX	%r14,%r9		# branch to interrupt-handler
 .Lpgm_return:
 	LOCKDEP_SYS_EXIT
 	tm	__PT_PSW+1(%r11),0x01	# returning to user ?
@@ -962,7 +905,7 @@ ENTRY(psw_idle)
 	stpt	__TIMER_IDLE_ENTER(%r2)
 .Lpsw_idle_lpsw:
 	lpswe	__SF_EMPTY(%r15)
-	BR_R1USE_R14
+	BR_EX	%r14
 .Lpsw_idle_end:
 
 /*
@@ -1007,7 +950,7 @@ ENTRY(save_fpu_regs)
 .Lsave_fpu_regs_done:
 	oi	__LC_CPU_FLAGS+7,_CIF_FPU
 .Lsave_fpu_regs_exit:
-	BR_R1USE_R14
+	BR_EX	%r14
 .Lsave_fpu_regs_end:
 
 /*
@@ -1054,7 +997,7 @@ load_fpu_regs:
 .Lload_fpu_regs_done:
 	ni	__LC_CPU_FLAGS+7,255-_CIF_FPU
 .Lload_fpu_regs_exit:
-	BR_R1USE_R14
+	BR_EX	%r14
 .Lload_fpu_regs_end:
 
 .L__critical_end:
@@ -1227,7 +1170,7 @@ cleanup_critical:
 	jl	0f
 	clg	%r9,BASED(.Lcleanup_table+104)	# .Lload_fpu_regs_end
 	jl	.Lcleanup_load_fpu_regs
-0:	BR_R11USE_R14
+0:	BR_EX	%r14
 
 	.align	8
 .Lcleanup_table:
@@ -1257,7 +1200,7 @@ cleanup_critical:
 	ni	__SIE_PROG0C+3(%r9),0xfe	# no longer in SIE
 	lctlg	%c1,%c1,__LC_USER_ASCE		# load primary asce
 	larl	%r9,sie_exit			# skip forward to sie_exit
-	BR_R11USE_R14
+	BR_EX	%r14
 #endif
 
 .Lcleanup_system_call:
@@ -1315,7 +1258,7 @@ cleanup_critical:
 	stg	%r15,56(%r11)		# r15 stack pointer
 	# set new psw address and exit
 	larl	%r9,.Lsysc_do_svc
-	BR_R11USE_R14
+	BR_EX	%r14,%r11
 .Lcleanup_system_call_insn:
 	.quad	system_call
 	.quad	.Lsysc_stmg
@@ -1325,7 +1268,7 @@ cleanup_critical:
 
 .Lcleanup_sysc_tif:
 	larl	%r9,.Lsysc_tif
-	BR_R11USE_R14
+	BR_EX	%r14,%r11
 
 .Lcleanup_sysc_restore:
 	# check if stpt has been executed
@@ -1342,14 +1285,14 @@ cleanup_critical:
 	mvc	0(64,%r11),__PT_R8(%r9)
 	lmg	%r0,%r7,__PT_R0(%r9)
 1:	lmg	%r8,%r9,__LC_RETURN_PSW
-	BR_R11USE_R14
+	BR_EX	%r14,%r11
 .Lcleanup_sysc_restore_insn:
 	.quad	.Lsysc_exit_timer
 	.quad	.Lsysc_done - 4
 
 .Lcleanup_io_tif:
 	larl	%r9,.Lio_tif
-	BR_R11USE_R14
+	BR_EX	%r14,%r11
 
 .Lcleanup_io_restore:
 	# check if stpt has been executed
@@ -1363,7 +1306,7 @@ cleanup_critical:
 	mvc	0(64,%r11),__PT_R8(%r9)
 	lmg	%r0,%r7,__PT_R0(%r9)
 1:	lmg	%r8,%r9,__LC_RETURN_PSW
-	BR_R11USE_R14
+	BR_EX	%r14,%r11
 .Lcleanup_io_restore_insn:
 	.quad	.Lio_exit_timer
 	.quad	.Lio_done - 4
@@ -1415,17 +1358,17 @@ cleanup_critical:
 	# prepare return psw
 	nihh	%r8,0xfcfd		# clear irq & wait state bits
 	lg	%r9,48(%r11)		# return from psw_idle
-	BR_R11USE_R14
+	BR_EX	%r14,%r11
 .Lcleanup_idle_insn:
 	.quad	.Lpsw_idle_lpsw
 
 .Lcleanup_save_fpu_regs:
 	larl	%r9,save_fpu_regs
-	BR_R11USE_R14
+	BR_EX	%r14,%r11
 
 .Lcleanup_load_fpu_regs:
 	larl	%r9,load_fpu_regs
-	BR_R11USE_R14
+	BR_EX	%r14,%r11
 
 /*
  * Integer constants