arm64: kernel: Add support for User Access Override

'User Access Override' is a new ARMv8.2 feature which allows the
unprivileged load and store instructions to be overridden to behave in
the normal way.

This patch converts {get,put}_user() and friends to use ldtr*/sttr*
instructions - so that they can only access EL0 memory, then enables
UAO when fs==KERNEL_DS so that these functions can access kernel memory.

This allows user space's read/write permissions to be checked against the
page tables, instead of testing addr<USER_DS, then using the kernel's
read/write permissions.

Signed-off-by: James Morse <james.morse@arm.com>
[catalin.marinas@arm.com: move uao_thread_switch() above dsb()]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

4 files changed, 20 insertions, 20 deletions

diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S
index a9723c71c52b..3f950b677c07 100644
--- a/arch/arm64/lib/clear_user.S
+++ b/arch/arm64/lib/clear_user.S
@@ -39,20 +39,20 @@ ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_HAS_PAN, \
 	subs	x1, x1, #8
 	b.mi	2f
 1:
-USER(9f, str	xzr, [x0], #8	)
+uao_user_alternative 9f, str, sttr, xzr, x0, 8
 	subs	x1, x1, #8
 	b.pl	1b
 2:	adds	x1, x1, #4
 	b.mi	3f
-USER(9f, str	wzr, [x0], #4	)
+uao_user_alternative 9f, str, sttr, wzr, x0, 4
 	sub	x1, x1, #4
 3:	adds	x1, x1, #2
 	b.mi	4f
-USER(9f, strh	wzr, [x0], #2	)
+uao_user_alternative 9f, strh, sttrh, wzr, x0, 2
 	sub	x1, x1, #2
 4:	adds	x1, x1, #1
 	b.mi	5f
-USER(9f, strb	wzr, [x0]	)
+uao_user_alternative 9f, strb, sttrb, wzr, x0, 0
 5:	mov	x0, #0
 ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_HAS_PAN, \
 	    CONFIG_ARM64_PAN)
diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
index 4699cd74f87e..1d982d64f1a7 100644
--- a/arch/arm64/lib/copy_from_user.S
+++ b/arch/arm64/lib/copy_from_user.S
@@ -34,7 +34,7 @@
  */
 
 	.macro ldrb1 ptr, regB, val
-	USER(9998f, ldrb  \ptr, [\regB], \val)
+	uao_user_alternative 9998f, ldrb, ldtrb, \ptr, \regB, \val
 	.endm
 
 	.macro strb1 ptr, regB, val
@@ -42,7 +42,7 @@
 	.endm
 
 	.macro ldrh1 ptr, regB, val
-	USER(9998f, ldrh  \ptr, [\regB], \val)
+	uao_user_alternative 9998f, ldrh, ldtrh, \ptr, \regB, \val
 	.endm
 
 	.macro strh1 ptr, regB, val
@@ -50,7 +50,7 @@
 	.endm
 
 	.macro ldr1 ptr, regB, val
-	USER(9998f, ldr \ptr, [\regB], \val)
+	uao_user_alternative 9998f, ldr, ldtr, \ptr, \regB, \val
 	.endm
 
 	.macro str1 ptr, regB, val
@@ -58,7 +58,7 @@
 	.endm
 
 	.macro ldp1 ptr, regB, regC, val
-	USER(9998f, ldp \ptr, \regB, [\regC], \val)
+	uao_ldp 9998f, \ptr, \regB, \regC, \val
 	.endm
 
 	.macro stp1 ptr, regB, regC, val
diff --git a/arch/arm64/lib/copy_in_user.S b/arch/arm64/lib/copy_in_user.S
index 81c8fc93c100..feaad1520dc1 100644
--- a/arch/arm64/lib/copy_in_user.S
+++ b/arch/arm64/lib/copy_in_user.S
@@ -35,35 +35,35 @@
  *	x0 - bytes not copied
  */
 	.macro ldrb1 ptr, regB, val
-	USER(9998f, ldrb  \ptr, [\regB], \val)
+	uao_user_alternative 9998f, ldrb, ldtrb, \ptr, \regB, \val
 	.endm
 
 	.macro strb1 ptr, regB, val
-	USER(9998f, strb \ptr, [\regB], \val)
+	uao_user_alternative 9998f, strb, sttrb, \ptr, \regB, \val
 	.endm
 
 	.macro ldrh1 ptr, regB, val
-	USER(9998f, ldrh  \ptr, [\regB], \val)
+	uao_user_alternative 9998f, ldrh, ldtrh, \ptr, \regB, \val
 	.endm
 
 	.macro strh1 ptr, regB, val
-	USER(9998f, strh \ptr, [\regB], \val)
+	uao_user_alternative 9998f, strh, sttrh, \ptr, \regB, \val
 	.endm
 
 	.macro ldr1 ptr, regB, val
-	USER(9998f, ldr \ptr, [\regB], \val)
+	uao_user_alternative 9998f, ldr, ldtr, \ptr, \regB, \val
 	.endm
 
 	.macro str1 ptr, regB, val
-	USER(9998f, str \ptr, [\regB], \val)
+	uao_user_alternative 9998f, str, sttr, \ptr, \regB, \val
 	.endm
 
 	.macro ldp1 ptr, regB, regC, val
-	USER(9998f, ldp \ptr, \regB, [\regC], \val)
+	uao_ldp 9998f, \ptr, \regB, \regC, \val
 	.endm
 
 	.macro stp1 ptr, regB, regC, val
-	USER(9998f, stp \ptr, \regB, [\regC], \val)
+	uao_stp 9998f, \ptr, \regB, \regC, \val
 	.endm
 
 end	.req	x5
diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S
index 7512bbbc07ac..2dae2cd2c481 100644
--- a/arch/arm64/lib/copy_to_user.S
+++ b/arch/arm64/lib/copy_to_user.S
@@ -37,7 +37,7 @@
 	.endm
 
 	.macro strb1 ptr, regB, val
-	USER(9998f, strb \ptr, [\regB], \val)
+	uao_user_alternative 9998f, strb, sttrb, \ptr, \regB, \val
 	.endm
 
 	.macro ldrh1 ptr, regB, val
@@ -45,7 +45,7 @@
 	.endm
 
 	.macro strh1 ptr, regB, val
-	USER(9998f, strh \ptr, [\regB], \val)
+	uao_user_alternative 9998f, strh, sttrh, \ptr, \regB, \val
 	.endm
 
 	.macro ldr1 ptr, regB, val
@@ -53,7 +53,7 @@
 	.endm
 
 	.macro str1 ptr, regB, val
-	USER(9998f, str \ptr, [\regB], \val)
+	uao_user_alternative 9998f, str, sttr, \ptr, \regB, \val
 	.endm
 
 	.macro ldp1 ptr, regB, regC, val
@@ -61,7 +61,7 @@
 	.endm
 
 	.macro stp1 ptr, regB, regC, val
-	USER(9998f, stp \ptr, \regB, [\regC], \val)
+	uao_stp 9998f, \ptr, \regB, \regC, \val
 	.endm
 
 end	.req	x5