1 files changed, 117 insertions, 0 deletions
diff --git a/arch/arm/include/asm/uaccess-asm.h b/arch/arm/include/asm/uaccess-asm.h
new file mode 100644
index 000000000..907571fd0
--- /dev/null
+++ b/arch/arm/include/asm/uaccess-asm.h
@@ -0,0 +1,117 @@
+/* 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
+
+#if defined(CONFIG_CPU_SW_DOMAIN_PAN) || defined(CONFIG_CPU_USE_DOMAINS)
+#define DACR(x...)	x
+#else
+#define DACR(x...)
+#endif
+
+	/*
+	 * Save the address limit on entry to a privileged exception.
+	 *
+	 * If we are using the DACR for kernel access by the user accessors
+	 * (CONFIG_CPU_USE_DOMAINS=y), always reset the DACR kernel domain
+	 * back to client mode, whether or not \disable is set.
+	 *
+	 * If we are using SW PAN, set the DACR user domain to no access
+	 * if \disable is set.
+	 */
+	.macro	uaccess_entry, tsk, tmp0, tmp1, tmp2, disable
+	ldr	\tmp1, [\tsk, #TI_ADDR_LIMIT]
+	mov	\tmp2, #TASK_SIZE
+	str	\tmp2, [\tsk, #TI_ADDR_LIMIT]
+ DACR(	mrc	p15, 0, \tmp0, c3, c0, 0)
+ DACR(	str	\tmp0, [sp, #SVC_DACR])
+	str	\tmp1, [sp, #SVC_ADDR_LIMIT]
+	.if \disable && IS_ENABLED(CONFIG_CPU_SW_DOMAIN_PAN)
+	/* kernel=client, user=no access */
+	mov	\tmp2, #DACR_UACCESS_DISABLE
+	mcr	p15, 0, \tmp2, c3, c0, 0
+	instr_sync
+	.elseif IS_ENABLED(CONFIG_CPU_USE_DOMAINS)
+	/* kernel=client */
+	bic	\tmp2, \tmp0, #domain_mask(DOMAIN_KERNEL)
+	orr	\tmp2, \tmp2, #domain_val(DOMAIN_KERNEL, DOMAIN_CLIENT)
+	mcr	p15, 0, \tmp2, c3, c0, 0
+	instr_sync
+	.endif
+	.endm
+
+	/* Restore the user access state previously saved by uaccess_entry */
+	.macro	uaccess_exit, tsk, tmp0, tmp1
+	ldr	\tmp1, [sp, #SVC_ADDR_LIMIT]
+ DACR(	ldr	\tmp0, [sp, #SVC_DACR])
+	str	\tmp1, [\tsk, #TI_ADDR_LIMIT]
+ DACR(	mcr	p15, 0, \tmp0, c3, c0, 0)
+	.endm
+
+#undef DACR
+
+#endif /* __ASM_UACCESS_ASM_H__ */