LoongArch: Adjust {copy, clear}_user exception handler behavior

The {copy, clear}_user function should returns number of bytes that
could not be {copied, cleared}. So, try to {copy, clear} byte by byte
when ld.{d,w,h} and st.{d,w,h} trapped into an exception.
Reviewed-by: WANG Rui <wangrui@loongson.cn>
Signed-off-by: Weihao Li <liweihao@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/lib/clear_user.S

@@ -11,19 +11,6 @@
 #include <asm/cpu.h>
 #include <asm/regdef.h>
 
-.irp to, 0, 1, 2, 3, 4, 5, 6, 7
-.L_fixup_handle_\to\():
-	sub.d	a0, a2, a0
-	addi.d	a0, a0, (\to) * (-8)
-	jr	ra
-.endr
-
-.irp to, 0, 2, 4
-.L_fixup_handle_s\to\():
-	addi.d	a0, a1, -\to
-	jr	ra
-.endr
-
 SYM_FUNC_START(__clear_user)
 	/*
 	 * Some CPUs support hardware unaligned access
@@ -51,7 +38,7 @@ SYM_FUNC_START(__clear_user_generic)
 2:	move	a0, a1
 	jr	ra
 
-	_asm_extable 1b, .L_fixup_handle_s0
+	_asm_extable 1b, 2b
 SYM_FUNC_END(__clear_user_generic)
 
 /*
@@ -173,33 +160,47 @@ SYM_FUNC_START(__clear_user_fast)
 	jr	ra
 
 	/* fixup and ex_table */
-	_asm_extable 0b, .L_fixup_handle_0
-	_asm_extable 1b, .L_fixup_handle_0
-	_asm_extable 2b, .L_fixup_handle_1
-	_asm_extable 3b, .L_fixup_handle_2
-	_asm_extable 4b, .L_fixup_handle_3
-	_asm_extable 5b, .L_fixup_handle_4
-	_asm_extable 6b, .L_fixup_handle_5
-	_asm_extable 7b, .L_fixup_handle_6
-	_asm_extable 8b, .L_fixup_handle_7
-	_asm_extable 9b, .L_fixup_handle_0
-	_asm_extable 10b, .L_fixup_handle_1
-	_asm_extable 11b, .L_fixup_handle_2
-	_asm_extable 12b, .L_fixup_handle_3
-	_asm_extable 13b, .L_fixup_handle_0
-	_asm_extable 14b, .L_fixup_handle_1
-	_asm_extable 15b, .L_fixup_handle_0
-	_asm_extable 16b, .L_fixup_handle_0
-	_asm_extable 17b, .L_fixup_handle_s0
-	_asm_extable 18b, .L_fixup_handle_s0
-	_asm_extable 19b, .L_fixup_handle_s0
-	_asm_extable 20b, .L_fixup_handle_s2
-	_asm_extable 21b, .L_fixup_handle_s0
-	_asm_extable 22b, .L_fixup_handle_s0
-	_asm_extable 23b, .L_fixup_handle_s4
-	_asm_extable 24b, .L_fixup_handle_s0
-	_asm_extable 25b, .L_fixup_handle_s4
-	_asm_extable 26b, .L_fixup_handle_s0
-	_asm_extable 27b, .L_fixup_handle_s4
-	_asm_extable 28b, .L_fixup_handle_s0
+.Llarge_fixup:
+	sub.d	a1, a2, a0
+
+.Lsmall_fixup:
+29:	st.b	zero, a0, 0
+	addi.d	a0, a0, 1
+	addi.d	a1, a1, -1
+	bgt	a1, zero, 29b
+
+.Lexit:
+	move	a0, a1
+	jr	ra
+
+	_asm_extable 0b, .Lsmall_fixup
+	_asm_extable 1b, .Llarge_fixup
+	_asm_extable 2b, .Llarge_fixup
+	_asm_extable 3b, .Llarge_fixup
+	_asm_extable 4b, .Llarge_fixup
+	_asm_extable 5b, .Llarge_fixup
+	_asm_extable 6b, .Llarge_fixup
+	_asm_extable 7b, .Llarge_fixup
+	_asm_extable 8b, .Llarge_fixup
+	_asm_extable 9b, .Llarge_fixup
+	_asm_extable 10b, .Llarge_fixup
+	_asm_extable 11b, .Llarge_fixup
+	_asm_extable 12b, .Llarge_fixup
+	_asm_extable 13b, .Llarge_fixup
+	_asm_extable 14b, .Llarge_fixup
+	_asm_extable 15b, .Llarge_fixup
+	_asm_extable 16b, .Llarge_fixup
+	_asm_extable 17b, .Lexit
+	_asm_extable 18b, .Lsmall_fixup
+	_asm_extable 19b, .Lsmall_fixup
+	_asm_extable 20b, .Lsmall_fixup
+	_asm_extable 21b, .Lsmall_fixup
+	_asm_extable 22b, .Lsmall_fixup
+	_asm_extable 23b, .Lsmall_fixup
+	_asm_extable 24b, .Lsmall_fixup
+	_asm_extable 25b, .Lsmall_fixup
+	_asm_extable 26b, .Lsmall_fixup
+	_asm_extable 27b, .Lsmall_fixup
+	_asm_extable 28b, .Lsmall_fixup
+	_asm_extable 29b, .Lexit
 SYM_FUNC_END(__clear_user_fast)

arch/loongarch/lib/copy_user.S

@@ -11,19 +11,6 @@
 #include <asm/cpu.h>
 #include <asm/regdef.h>
 
-.irp to, 0, 1, 2, 3, 4, 5, 6, 7
-.L_fixup_handle_\to\():
-	sub.d	a0, a2, a0
-	addi.d	a0, a0, (\to) * (-8)
-	jr	ra
-.endr
-
-.irp to, 0, 2, 4
-.L_fixup_handle_s\to\():
-	addi.d	a0, a2, -\to
-	jr	ra
-.endr
-
 SYM_FUNC_START(__copy_user)
 	/*
 	 * Some CPUs support hardware unaligned access
@@ -54,8 +41,8 @@ SYM_FUNC_START(__copy_user_generic)
 3:	move	a0, a2
 	jr	ra
 
-	_asm_extable 1b, .L_fixup_handle_s0
-	_asm_extable 2b, .L_fixup_handle_s0
+	_asm_extable 1b, 3b
+	_asm_extable 2b, 3b
 SYM_FUNC_END(__copy_user_generic)
 
 /*
@@ -69,10 +56,10 @@ SYM_FUNC_START(__copy_user_fast)
 	sltui	t0, a2, 9
 	bnez	t0, .Lsmall
 
-	add.d	a3, a1, a2
-	add.d	a2, a0, a2
 0:	ld.d	t0, a1, 0
 1:	st.d	t0, a0, 0
+	add.d	a3, a1, a2
+	add.d	a2, a0, a2
 
 	/* align up destination address */
 	andi	t1, a0, 7
@@ -94,7 +81,6 @@ SYM_FUNC_START(__copy_user_fast)
 7:	ld.d	t5, a1, 40
 8:	ld.d	t6, a1, 48
 9:	ld.d	t7, a1, 56
-	addi.d	a1, a1, 64
 10:	st.d	t0, a0, 0
 11:	st.d	t1, a0, 8
 12:	st.d	t2, a0, 16
@@ -103,6 +89,7 @@ SYM_FUNC_START(__copy_user_fast)
 15:	st.d	t5, a0, 40
 16:	st.d	t6, a0, 48
 17:	st.d	t7, a0, 56
+	addi.d	a1, a1, 64
 	addi.d	a0, a0, 64
 	bltu	a1, a4, .Lloop64
 
@@ -114,11 +101,11 @@ SYM_FUNC_START(__copy_user_fast)
 19:	ld.d	t1, a1, 8
 20:	ld.d	t2, a1, 16
 21:	ld.d	t3, a1, 24
-	addi.d	a1, a1, 32
 22:	st.d	t0, a0, 0
 23:	st.d	t1, a0, 8
 24:	st.d	t2, a0, 16
 25:	st.d	t3, a0, 24
+	addi.d	a1, a1, 32
 	addi.d	a0, a0, 32
 
 .Llt32:
@@ -126,9 +113,9 @@ SYM_FUNC_START(__copy_user_fast)
 	bgeu	a1, a4, .Llt16
 26:	ld.d	t0, a1, 0
 27:	ld.d	t1, a1, 8
-	addi.d	a1, a1, 16
 28:	st.d	t0, a0, 0
 29:	st.d	t1, a0, 8
+	addi.d	a1, a1, 16
 	addi.d	a0, a0, 16
 
 .Llt16:
@@ -136,6 +123,7 @@ SYM_FUNC_START(__copy_user_fast)
 	bgeu	a1, a4, .Llt8
 30:	ld.d	t0, a1, 0
 31:	st.d	t0, a0, 0
+	addi.d	a1, a1, 8
 	addi.d	a0, a0, 8
 
 .Llt8:
@@ -214,62 +202,79 @@ SYM_FUNC_START(__copy_user_fast)
 	jr	ra
 
 	/* fixup and ex_table */
-	_asm_extable 0b, .L_fixup_handle_0
-	_asm_extable 1b, .L_fixup_handle_0
-	_asm_extable 2b, .L_fixup_handle_0
-	_asm_extable 3b, .L_fixup_handle_0
-	_asm_extable 4b, .L_fixup_handle_0
-	_asm_extable 5b, .L_fixup_handle_0
-	_asm_extable 6b, .L_fixup_handle_0
-	_asm_extable 7b, .L_fixup_handle_0
-	_asm_extable 8b, .L_fixup_handle_0
-	_asm_extable 9b, .L_fixup_handle_0
-	_asm_extable 10b, .L_fixup_handle_0
-	_asm_extable 11b, .L_fixup_handle_1
-	_asm_extable 12b, .L_fixup_handle_2
-	_asm_extable 13b, .L_fixup_handle_3
-	_asm_extable 14b, .L_fixup_handle_4
-	_asm_extable 15b, .L_fixup_handle_5
-	_asm_extable 16b, .L_fixup_handle_6
-	_asm_extable 17b, .L_fixup_handle_7
-	_asm_extable 18b, .L_fixup_handle_0
-	_asm_extable 19b, .L_fixup_handle_0
-	_asm_extable 20b, .L_fixup_handle_0
-	_asm_extable 21b, .L_fixup_handle_0
-	_asm_extable 22b, .L_fixup_handle_0
-	_asm_extable 23b, .L_fixup_handle_1
-	_asm_extable 24b, .L_fixup_handle_2
-	_asm_extable 25b, .L_fixup_handle_3
-	_asm_extable 26b, .L_fixup_handle_0
-	_asm_extable 27b, .L_fixup_handle_0
-	_asm_extable 28b, .L_fixup_handle_0
-	_asm_extable 29b, .L_fixup_handle_1
-	_asm_extable 30b, .L_fixup_handle_0
-	_asm_extable 31b, .L_fixup_handle_0
-	_asm_extable 32b, .L_fixup_handle_0
-	_asm_extable 33b, .L_fixup_handle_0
-	_asm_extable 34b, .L_fixup_handle_s0
-	_asm_extable 35b, .L_fixup_handle_s0
-	_asm_extable 36b, .L_fixup_handle_s0
-	_asm_extable 37b, .L_fixup_handle_s0
-	_asm_extable 38b, .L_fixup_handle_s0
-	_asm_extable 39b, .L_fixup_handle_s0
-	_asm_extable 40b, .L_fixup_handle_s0
-	_asm_extable 41b, .L_fixup_handle_s2
-	_asm_extable 42b, .L_fixup_handle_s0
-	_asm_extable 43b, .L_fixup_handle_s0
-	_asm_extable 44b, .L_fixup_handle_s0
-	_asm_extable 45b, .L_fixup_handle_s0
-	_asm_extable 46b, .L_fixup_handle_s0
-	_asm_extable 47b, .L_fixup_handle_s4
-	_asm_extable 48b, .L_fixup_handle_s0
-	_asm_extable 49b, .L_fixup_handle_s0
-	_asm_extable 50b, .L_fixup_handle_s0
-	_asm_extable 51b, .L_fixup_handle_s4
-	_asm_extable 52b, .L_fixup_handle_s0
-	_asm_extable 53b, .L_fixup_handle_s0
-	_asm_extable 54b, .L_fixup_handle_s0
-	_asm_extable 55b, .L_fixup_handle_s4
-	_asm_extable 56b, .L_fixup_handle_s0
-	_asm_extable 57b, .L_fixup_handle_s0
+.Llarge_fixup:
+	sub.d	a2, a2, a0
+
+.Lsmall_fixup:
+58:	ld.b	t0, a1, 0
+59:	st.b	t0, a0, 0
+	addi.d	a0, a0, 1
+	addi.d	a1, a1, 1
+	addi.d	a2, a2, -1
+	bgt	a2, zero, 58b
+
+.Lexit:
+	move	a0, a2
+	jr	ra
+
+	_asm_extable 0b, .Lsmall_fixup
+	_asm_extable 1b, .Lsmall_fixup
+	_asm_extable 2b, .Llarge_fixup
+	_asm_extable 3b, .Llarge_fixup
+	_asm_extable 4b, .Llarge_fixup
+	_asm_extable 5b, .Llarge_fixup
+	_asm_extable 6b, .Llarge_fixup
+	_asm_extable 7b, .Llarge_fixup
+	_asm_extable 8b, .Llarge_fixup
+	_asm_extable 9b, .Llarge_fixup
+	_asm_extable 10b, .Llarge_fixup
+	_asm_extable 11b, .Llarge_fixup
+	_asm_extable 12b, .Llarge_fixup
+	_asm_extable 13b, .Llarge_fixup
+	_asm_extable 14b, .Llarge_fixup
+	_asm_extable 15b, .Llarge_fixup
+	_asm_extable 16b, .Llarge_fixup
+	_asm_extable 17b, .Llarge_fixup
+	_asm_extable 18b, .Llarge_fixup
+	_asm_extable 19b, .Llarge_fixup
+	_asm_extable 20b, .Llarge_fixup
+	_asm_extable 21b, .Llarge_fixup
+	_asm_extable 22b, .Llarge_fixup
+	_asm_extable 23b, .Llarge_fixup
+	_asm_extable 24b, .Llarge_fixup
+	_asm_extable 25b, .Llarge_fixup
+	_asm_extable 26b, .Llarge_fixup
+	_asm_extable 27b, .Llarge_fixup
+	_asm_extable 28b, .Llarge_fixup
+	_asm_extable 29b, .Llarge_fixup
+	_asm_extable 30b, .Llarge_fixup
+	_asm_extable 31b, .Llarge_fixup
+	_asm_extable 32b, .Llarge_fixup
+	_asm_extable 33b, .Llarge_fixup
+	_asm_extable 34b, .Lexit
+	_asm_extable 35b, .Lexit
+	_asm_extable 36b, .Lsmall_fixup
+	_asm_extable 37b, .Lsmall_fixup
+	_asm_extable 38b, .Lsmall_fixup
+	_asm_extable 39b, .Lsmall_fixup
+	_asm_extable 40b, .Lsmall_fixup
+	_asm_extable 41b, .Lsmall_fixup
+	_asm_extable 42b, .Lsmall_fixup
+	_asm_extable 43b, .Lsmall_fixup
+	_asm_extable 44b, .Lsmall_fixup
+	_asm_extable 45b, .Lsmall_fixup
+	_asm_extable 46b, .Lsmall_fixup
+	_asm_extable 47b, .Lsmall_fixup
+	_asm_extable 48b, .Lsmall_fixup
+	_asm_extable 49b, .Lsmall_fixup
+	_asm_extable 50b, .Lsmall_fixup
+	_asm_extable 51b, .Lsmall_fixup
+	_asm_extable 52b, .Lsmall_fixup
+	_asm_extable 53b, .Lsmall_fixup
+	_asm_extable 54b, .Lsmall_fixup
+	_asm_extable 55b, .Lsmall_fixup
+	_asm_extable 56b, .Lsmall_fixup
+	_asm_extable 57b, .Lsmall_fixup
+	_asm_extable 58b, .Lexit
+	_asm_extable 59b, .Lexit
 SYM_FUNC_END(__copy_user_fast)