ARM: uaccess: consolidate uaccess asm to asm/uaccess-asm.h

Consolidate the user access assembly code to asm/uaccess-asm.h.  This
moves the csdb, check_uaccess, uaccess_mask_range_ptr, uaccess_enable,
uaccess_disable, uaccess_save, uaccess_restore macros, and creates two
new ones for exception entry and exit - uaccess_entry and uaccess_exit.

This makes the uaccess_save and uaccess_restore macros private to
asm/uaccess-asm.h.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

arch/arm/include/asm/assembler.h

@@ -18,11 +18,11 @@
 #endif
 
 #include <asm/ptrace.h>
-#include <asm/domain.h>
 #include <asm/opcodes-virt.h>
 #include <asm/asm-offsets.h>
 #include <asm/page.h>
 #include <asm/thread_info.h>
+#include <asm/uaccess-asm.h>
 
 #define IOMEM(x)	(x)
 
@@ -446,79 +446,6 @@ THUMB(	orr	\reg , \reg , #PSR_T_BIT	)
 	.size \name , . - \name
 	.endm
 
-	.macro	csdb
-#ifdef CONFIG_THUMB2_KERNEL
-	.inst.w	0xf3af8014
-#else
-	.inst	0xe320f014
-#endif
-	.endm
-
-	.macro check_uaccess, addr:req, size:req, limit:req, tmp:req, bad:req
-#ifndef CONFIG_CPU_USE_DOMAINS
-	adds	\tmp, \addr, #\size - 1
-	sbcscc	\tmp, \tmp, \limit
-	bcs	\bad
-#ifdef CONFIG_CPU_SPECTRE
-	movcs	\addr, #0
-	csdb
-#endif
-#endif
-	.endm
-
-	.macro uaccess_mask_range_ptr, addr:req, size:req, limit:req, tmp:req
-#ifdef CONFIG_CPU_SPECTRE
-	sub	\tmp, \limit, #1
-	subs	\tmp, \tmp, \addr	@ tmp = limit - 1 - addr
-	addhs	\tmp, \tmp, #1		@ if (tmp >= 0) {
-	subshs	\tmp, \tmp, \size	@ tmp = limit - (addr + size) }
-	movlo	\addr, #0		@ if (tmp < 0) addr = NULL
-	csdb
-#endif
-	.endm
-
-	.macro	uaccess_disable, tmp, isb=1
-#ifdef CONFIG_CPU_SW_DOMAIN_PAN
-	/*
-	 * Whenever we re-enter userspace, the domains should always be
-	 * set appropriately.
-	 */
-	mov	\tmp, #DACR_UACCESS_DISABLE
-	mcr	p15, 0, \tmp, c3, c0, 0		@ Set domain register
-	.if	\isb
-	instr_sync
-	.endif
-#endif
-	.endm
-
-	.macro	uaccess_enable, tmp, isb=1
-#ifdef CONFIG_CPU_SW_DOMAIN_PAN
-	/*
-	 * Whenever we re-enter userspace, the domains should always be
-	 * set appropriately.
-	 */
-	mov	\tmp, #DACR_UACCESS_ENABLE
-	mcr	p15, 0, \tmp, c3, c0, 0
-	.if	\isb
-	instr_sync
-	.endif
-#endif
-	.endm
-
-	.macro	uaccess_save, tmp
-#ifdef CONFIG_CPU_SW_DOMAIN_PAN
-	mrc	p15, 0, \tmp, c3, c0, 0
-	str	\tmp, [sp, #SVC_DACR]
-#endif
-	.endm
-
-	.macro	uaccess_restore
-#ifdef CONFIG_CPU_SW_DOMAIN_PAN
-	ldr	r0, [sp, #SVC_DACR]
-	mcr	p15, 0, r0, c3, c0, 0
-#endif
-	.endm
-
 	.irp	c,,eq,ne,cs,cc,mi,pl,vs,vc,hi,ls,ge,lt,gt,le,hs,lo
 	.macro	ret\c, reg
 #if __LINUX_ARM_ARCH__ < 6

arch/arm/include/asm/uaccess-asm.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __ASM_UACCESS_ASM_H__
+#define __ASM_UACCESS_ASM_H__
+
+#include <asm/asm-offsets.h>
+#include <asm/domain.h>
+#include <asm/memory.h>
+#include <asm/thread_info.h>
+
+	.macro	csdb
+#ifdef CONFIG_THUMB2_KERNEL
+	.inst.w	0xf3af8014
+#else
+	.inst	0xe320f014
+#endif
+	.endm
+
+	.macro check_uaccess, addr:req, size:req, limit:req, tmp:req, bad:req
+#ifndef CONFIG_CPU_USE_DOMAINS
+	adds	\tmp, \addr, #\size - 1
+	sbcscc	\tmp, \tmp, \limit
+	bcs	\bad
+#ifdef CONFIG_CPU_SPECTRE
+	movcs	\addr, #0
+	csdb
+#endif
+#endif
+	.endm
+
+	.macro uaccess_mask_range_ptr, addr:req, size:req, limit:req, tmp:req
+#ifdef CONFIG_CPU_SPECTRE
+	sub	\tmp, \limit, #1
+	subs	\tmp, \tmp, \addr	@ tmp = limit - 1 - addr
+	addhs	\tmp, \tmp, #1		@ if (tmp >= 0) {
+	subshs	\tmp, \tmp, \size	@ tmp = limit - (addr + size) }
+	movlo	\addr, #0		@ if (tmp < 0) addr = NULL
+	csdb
+#endif
+	.endm
+
+	.macro	uaccess_disable, tmp, isb=1
+#ifdef CONFIG_CPU_SW_DOMAIN_PAN
+	/*
+	 * Whenever we re-enter userspace, the domains should always be
+	 * set appropriately.
+	 */
+	mov	\tmp, #DACR_UACCESS_DISABLE
+	mcr	p15, 0, \tmp, c3, c0, 0		@ Set domain register
+	.if	\isb
+	instr_sync
+	.endif
+#endif
+	.endm
+
+	.macro	uaccess_enable, tmp, isb=1
+#ifdef CONFIG_CPU_SW_DOMAIN_PAN
+	/*
+	 * Whenever we re-enter userspace, the domains should always be
+	 * set appropriately.
+	 */
+	mov	\tmp, #DACR_UACCESS_ENABLE
+	mcr	p15, 0, \tmp, c3, c0, 0
+	.if	\isb
+	instr_sync
+	.endif
+#endif
+	.endm
+
+	.macro	uaccess_save, tmp
+#ifdef CONFIG_CPU_SW_DOMAIN_PAN
+	mrc	p15, 0, \tmp, c3, c0, 0
+	str	\tmp, [sp, #SVC_DACR]
+#endif
+	.endm
+
+	.macro	uaccess_restore
+#ifdef CONFIG_CPU_SW_DOMAIN_PAN
+	ldr	r0, [sp, #SVC_DACR]
+	mcr	p15, 0, r0, c3, c0, 0
+#endif
+	.endm
+
+	/*
+	 * Save the address limit on entry to a privileged exception and
+	 * if using PAN, save and disable usermode access.
+	 */
+	.macro	uaccess_entry, tsk, tmp0, tmp1, tmp2, disable
+	ldr	\tmp0, [\tsk, #TI_ADDR_LIMIT]
+	mov	\tmp1, #TASK_SIZE
+	str	\tmp1, [\tsk, #TI_ADDR_LIMIT]
+	str	\tmp0, [sp, #SVC_ADDR_LIMIT]
+	uaccess_save \tmp0
+	.if \disable
+	uaccess_disable \tmp0
+	.endif
+	.endm
+
+	/* Restore the user access state previously saved by uaccess_entry */
+	.macro	uaccess_exit, tsk, tmp0, tmp1
+	ldr	\tmp1, [sp, #SVC_ADDR_LIMIT]
+	uaccess_restore
+	str	\tmp1, [\tsk, #TI_ADDR_LIMIT]
+	.endm
+
+#endif /* __ASM_UACCESS_ASM_H__ */

arch/arm/kernel/entry-armv.S

@@ -27,6 +27,7 @@
 #include <asm/unistd.h>
 #include <asm/tls.h>
 #include <asm/system_info.h>
+#include <asm/uaccess-asm.h>
 
 #include "entry-header.S"
 #include <asm/entry-macro-multi.S>
@@ -179,15 +180,7 @@ ENDPROC(__und_invalid)
 	stmia	r7, {r2 - r6}
 
 	get_thread_info tsk
-	ldr	r0, [tsk, #TI_ADDR_LIMIT]
-	mov	r1, #TASK_SIZE
-	str	r1, [tsk, #TI_ADDR_LIMIT]
-	str	r0, [sp, #SVC_ADDR_LIMIT]
-
-	uaccess_save r0
-	.if \uaccess
-	uaccess_disable r0
-	.endif
+	uaccess_entry tsk, r0, r1, r2, \uaccess
 
 	.if \trace
 #ifdef CONFIG_TRACE_IRQFLAGS

arch/arm/kernel/entry-header.S

@@ -6,6 +6,7 @@
 #include <asm/asm-offsets.h>
 #include <asm/errno.h>
 #include <asm/thread_info.h>
+#include <asm/uaccess-asm.h>
 #include <asm/v7m.h>
 
 @ Bad Abort numbers
@@ -217,9 +218,7 @@
 	blne	trace_hardirqs_off
 #endif
 	.endif
-	ldr	r1, [sp, #SVC_ADDR_LIMIT]
-	uaccess_restore
-	str	r1, [tsk, #TI_ADDR_LIMIT]
+	uaccess_exit tsk, r0, r1
 
 #ifndef CONFIG_THUMB2_KERNEL
 	@ ARM mode SVC restore
@@ -263,9 +262,7 @@
 	@ on the stack remains correct).
 	@
 	.macro  svc_exit_via_fiq
-	ldr	r1, [sp, #SVC_ADDR_LIMIT]
-	uaccess_restore
-	str	r1, [tsk, #TI_ADDR_LIMIT]
+	uaccess_exit tsk, r0, r1
 #ifndef CONFIG_THUMB2_KERNEL
 	@ ARM mode restore
 	mov	r0, sp