Merge branch 'for-next/extable' into for-next/core

* for-next/extable:
  arm64: vmlinux.lds.S: remove `.fixup` section
  arm64: extable: add load_unaligned_zeropad() handler
  arm64: extable: add a dedicated uaccess handler
  arm64: extable: add `type` and `data` fields
  arm64: extable: use `ex` for `exception_table_entry`
  arm64: extable: make fixup_exception() return bool
  arm64: extable: consolidate definitions
  arm64: gpr-num: support W registers
  arm64: factor out GPR numbering helpers
  arm64: kvm: use kvm_exception_table_entry
  arm64: lib: __arch_copy_to_user(): fold fixups into body
  arm64: lib: __arch_copy_from_user(): fold fixups into body
  arm64: lib: __arch_clear_user(): fold fixups into body

arch/arm64/include/asm/asm-extable.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __ASM_ASM_EXTABLE_H
+#define __ASM_ASM_EXTABLE_H
+
+#define EX_TYPE_NONE			0
+#define EX_TYPE_FIXUP			1
+#define EX_TYPE_BPF			2
+#define EX_TYPE_UACCESS_ERR_ZERO	3
+#define EX_TYPE_LOAD_UNALIGNED_ZEROPAD	4
+
+#ifdef __ASSEMBLY__
+
+#define __ASM_EXTABLE_RAW(insn, fixup, type, data)	\
+	.pushsection	__ex_table, "a";		\
+	.align		2;				\
+	.long		((insn) - .);			\
+	.long		((fixup) - .);			\
+	.short		(type);				\
+	.short		(data);				\
+	.popsection;
+
+/*
+ * Create an exception table entry for `insn`, which will branch to `fixup`
+ * when an unhandled fault is taken.
+ */
+	.macro		_asm_extable, insn, fixup
+	__ASM_EXTABLE_RAW(\insn, \fixup, EX_TYPE_FIXUP, 0)
+	.endm
+
+/*
+ * Create an exception table entry for `insn` if `fixup` is provided. Otherwise
+ * do nothing.
+ */
+	.macro		_cond_extable, insn, fixup
+	.ifnc		\fixup,
+	_asm_extable	\insn, \fixup
+	.endif
+	.endm
+
+#else /* __ASSEMBLY__ */
+
+#include <linux/bits.h>
+#include <linux/stringify.h>
+
+#include <asm/gpr-num.h>
+
+#define __ASM_EXTABLE_RAW(insn, fixup, type, data)	\
+	".pushsection	__ex_table, \"a\"\n"		\
+	".align		2\n"				\
+	".long		((" insn ") - .)\n"		\
+	".long		((" fixup ") - .)\n"		\
+	".short		(" type ")\n"			\
+	".short		(" data ")\n"			\
+	".popsection\n"
+
+#define _ASM_EXTABLE(insn, fixup) \
+	__ASM_EXTABLE_RAW(#insn, #fixup, __stringify(EX_TYPE_FIXUP), "0")
+
+#define EX_DATA_REG_ERR_SHIFT	0
+#define EX_DATA_REG_ERR		GENMASK(4, 0)
+#define EX_DATA_REG_ZERO_SHIFT	5
+#define EX_DATA_REG_ZERO	GENMASK(9, 5)
+
+#define EX_DATA_REG(reg, gpr)						\
+	"((.L__gpr_num_" #gpr ") << " __stringify(EX_DATA_REG_##reg##_SHIFT) ")"
+
+#define _ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, err, zero)		\
+	__DEFINE_ASM_GPR_NUMS						\
+	__ASM_EXTABLE_RAW(#insn, #fixup, 				\
+			  __stringify(EX_TYPE_UACCESS_ERR_ZERO),	\
+			  "("						\
+			    EX_DATA_REG(ERR, err) " | "			\
+			    EX_DATA_REG(ZERO, zero)			\
+			  ")")
+
+#define _ASM_EXTABLE_UACCESS_ERR(insn, fixup, err)			\
+	_ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, err, wzr)
+
+#define EX_DATA_REG_DATA_SHIFT	0
+#define EX_DATA_REG_DATA	GENMASK(4, 0)
+#define EX_DATA_REG_ADDR_SHIFT	5
+#define EX_DATA_REG_ADDR	GENMASK(9, 5)
+
+#define _ASM_EXTABLE_LOAD_UNALIGNED_ZEROPAD(insn, fixup, data, addr)		\
+	__DEFINE_ASM_GPR_NUMS							\
+	__ASM_EXTABLE_RAW(#insn, #fixup,					\
+			  __stringify(EX_TYPE_LOAD_UNALIGNED_ZEROPAD),		\
+			  "("							\
+			    EX_DATA_REG(DATA, data) " | "			\
+			    EX_DATA_REG(ADDR, addr)				\
+			  ")")
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __ASM_ASM_EXTABLE_H */

arch/arm64/include/asm/asm-uaccess.h

@@ -3,10 +3,11 @@
 #define __ASM_ASM_UACCESS_H
 
 #include <asm/alternative-macros.h>
+#include <asm/asm-extable.h>
+#include <asm/assembler.h>
 #include <asm/kernel-pgtable.h>
 #include <asm/mmu.h>
 #include <asm/sysreg.h>
-#include <asm/assembler.h>
 
 /*
  * User access enabling/disabling macros.
@@ -58,6 +59,10 @@ alternative_else_nop_endif
 	.endm
 #endif
 
+#define USER(l, x...)				\
+9999:	x;					\
+	_asm_extable	9999b, l
+
 /*
  * Generate the assembly for LDTR/STTR with exception table entries.
  * This is complicated as there is no post-increment or pair versions of the

arch/arm64/include/asm/assembler.h

@@ -14,9 +14,10 @@
 
 #include <asm-generic/export.h>
 
-#include <asm/asm-offsets.h>
 #include <asm/alternative.h>
 #include <asm/asm-bug.h>
+#include <asm/asm-extable.h>
+#include <asm/asm-offsets.h>
 #include <asm/cpufeature.h>
 #include <asm/cputype.h>
 #include <asm/debug-monitors.h>
@@ -129,32 +130,6 @@ alternative_endif
 	.endr
 	.endm
 
-/*
- * Create an exception table entry for `insn`, which will branch to `fixup`
- * when an unhandled fault is taken.
- */
-	.macro		_asm_extable, insn, fixup
-	.pushsection	__ex_table, "a"
-	.align		3
-	.long		(\insn - .), (\fixup - .)
-	.popsection
-	.endm
-
-/*
- * Create an exception table entry for `insn` if `fixup` is provided. Otherwise
- * do nothing.
- */
-	.macro		_cond_extable, insn, fixup
-	.ifnc		\fixup,
-	_asm_extable	\insn, \fixup
-	.endif
-	.endm
-
-
-#define USER(l, x...)				\
-9999:	x;					\
-	_asm_extable	9999b, l
-
 /*
  * Register aliases.
  */

arch/arm64/include/asm/extable.h

@@ -18,10 +18,21 @@
 struct exception_table_entry
 {
 	int insn, fixup;
+	short type, data;
 };
 
 #define ARCH_HAS_RELATIVE_EXTABLE
 
+#define swap_ex_entry_fixup(a, b, tmp, delta)		\
+do {							\
+	(a)->fixup = (b)->fixup + (delta);		\
+	(b)->fixup = (tmp).fixup - (delta);		\
+	(a)->type = (b)->type;				\
+	(b)->type = (tmp).type;				\
+	(a)->data = (b)->data;				\
+	(b)->data = (tmp).data;				\
+} while (0)
+
 static inline bool in_bpf_jit(struct pt_regs *regs)
 {
 	if (!IS_ENABLED(CONFIG_BPF_JIT))
@@ -32,16 +43,16 @@ static inline bool in_bpf_jit(struct pt_regs *regs)
 }
 
 #ifdef CONFIG_BPF_JIT
-int arm64_bpf_fixup_exception(const struct exception_table_entry *ex,
-			      struct pt_regs *regs);
+bool ex_handler_bpf(const struct exception_table_entry *ex,
+		    struct pt_regs *regs);
 #else /* !CONFIG_BPF_JIT */
 static inline
-int arm64_bpf_fixup_exception(const struct exception_table_entry *ex,
-			      struct pt_regs *regs)
+bool ex_handler_bpf(const struct exception_table_entry *ex,
+		    struct pt_regs *regs)
 {
-	return 0;
+	return false;
 }
 #endif /* !CONFIG_BPF_JIT */
 
-extern int fixup_exception(struct pt_regs *regs);
+bool fixup_exception(struct pt_regs *regs);
 #endif

arch/arm64/include/asm/futex.h

@@ -25,19 +25,14 @@ do {									\
 "	cbz	%w0, 3f\n"						\
 "	sub	%w4, %w4, %w0\n"					\
 "	cbnz	%w4, 1b\n"						\
-"	mov	%w0, %w7\n"						\
+"	mov	%w0, %w6\n"						\
 "3:\n"									\
 "	dmb	ish\n"							\
-"	.pushsection .fixup,\"ax\"\n"					\
-"	.align	2\n"							\
-"4:	mov	%w0, %w6\n"						\
-"	b	3b\n"							\
-"	.popsection\n"							\
-	_ASM_EXTABLE(1b, 4b)						\
-	_ASM_EXTABLE(2b, 4b)						\
+	_ASM_EXTABLE_UACCESS_ERR(1b, 3b, %w0)				\
+	_ASM_EXTABLE_UACCESS_ERR(2b, 3b, %w0)				\
 	: "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp),	\
 	  "+r" (loops)							\
-	: "r" (oparg), "Ir" (-EFAULT), "Ir" (-EAGAIN)			\
+	: "r" (oparg), "Ir" (-EAGAIN)					\
 	: "memory");							\
 	uaccess_disable_privileged();					\
 } while (0)
@@ -105,18 +100,14 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *_uaddr,
 "	cbz	%w3, 3f\n"
 "	sub	%w4, %w4, %w3\n"
 "	cbnz	%w4, 1b\n"
-"	mov	%w0, %w8\n"
+"	mov	%w0, %w7\n"
 "3:\n"
 "	dmb	ish\n"
 "4:\n"
-"	.pushsection .fixup,\"ax\"\n"
-"5:	mov	%w0, %w7\n"
-"	b	4b\n"
-"	.popsection\n"
-	_ASM_EXTABLE(1b, 5b)
-	_ASM_EXTABLE(2b, 5b)
+	_ASM_EXTABLE_UACCESS_ERR(1b, 4b, %w0)
+	_ASM_EXTABLE_UACCESS_ERR(2b, 4b, %w0)
 	: "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp), "+r" (loops)
-	: "r" (oldval), "r" (newval), "Ir" (-EFAULT), "Ir" (-EAGAIN)
+	: "r" (oldval), "r" (newval), "Ir" (-EAGAIN)
 	: "memory");
 	uaccess_disable_privileged();
 

arch/arm64/include/asm/gpr-num.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef __ASM_GPR_NUM_H
+#define __ASM_GPR_NUM_H
+
+#ifdef __ASSEMBLY__
+
+	.irp	num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30
+	.equ	.L__gpr_num_x\num, \num
+	.equ	.L__gpr_num_w\num, \num
+	.endr
+	.equ	.L__gpr_num_xzr, 31
+	.equ	.L__gpr_num_wzr, 31
+
+#else /* __ASSEMBLY__ */
+
+#define __DEFINE_ASM_GPR_NUMS					\
+"	.irp	num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30\n" \
+"	.equ	.L__gpr_num_x\\num, \\num\n"			\
+"	.equ	.L__gpr_num_w\\num, \\num\n"			\
+"	.endr\n"						\
+"	.equ	.L__gpr_num_xzr, 31\n"				\
+"	.equ	.L__gpr_num_wzr, 31\n"
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* __ASM_GPR_NUM_H */

arch/arm64/include/asm/kvm_asm.h

@@ -263,9 +263,10 @@ extern u64 __kvm_get_mdcr_el2(void);
 
 /*
  * KVM extable for unexpected exceptions.
- * In the same format _asm_extable, but output to a different section so that
- * it can be mapped to EL2. The KVM version is not sorted. The caller must
- * ensure:
+ * Create a struct kvm_exception_table_entry output to a section that can be
+ * mapped by EL2. The table is not sorted.
+ *
+ * The caller must ensure:
  * x18 has the hypervisor value to allow any Shadow-Call-Stack instrumented
  * code to write to it, and that SPSR_EL2 and ELR_EL2 are restored by the fixup.
  */

arch/arm64/include/asm/sysreg.h

@@ -13,6 +13,8 @@
 #include <linux/stringify.h>
 #include <linux/kasan-tags.h>
 
+#include <asm/gpr-num.h>
+
 /*
  * ARMv8 ARM reserves the following encoding for system registers:
  * (Ref: ARMv8 ARM, Section: "System instruction class encoding overview",
@@ -1195,17 +1197,12 @@
 
 #ifdef __ASSEMBLY__
 
-	.irp	num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30
-	.equ	.L__reg_num_x\num, \num
-	.endr
-	.equ	.L__reg_num_xzr, 31
-
 	.macro	mrs_s, rt, sreg
-	 __emit_inst(0xd5200000|(\sreg)|(.L__reg_num_\rt))
+	 __emit_inst(0xd5200000|(\sreg)|(.L__gpr_num_\rt))
 	.endm
 
 	.macro	msr_s, sreg, rt
-	__emit_inst(0xd5000000|(\sreg)|(.L__reg_num_\rt))
+	__emit_inst(0xd5000000|(\sreg)|(.L__gpr_num_\rt))
 	.endm
 
 #else
@@ -1214,22 +1211,16 @@
 #include <linux/types.h>
 #include <asm/alternative.h>
 
-#define __DEFINE_MRS_MSR_S_REGNUM				\
-"	.irp	num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30\n" \
-"	.equ	.L__reg_num_x\\num, \\num\n"			\
-"	.endr\n"						\
-"	.equ	.L__reg_num_xzr, 31\n"
-
 #define DEFINE_MRS_S						\
-	__DEFINE_MRS_MSR_S_REGNUM				\
+	__DEFINE_ASM_GPR_NUMS					\
 "	.macro	mrs_s, rt, sreg\n"				\
-	__emit_inst(0xd5200000|(\\sreg)|(.L__reg_num_\\rt))	\
+	__emit_inst(0xd5200000|(\\sreg)|(.L__gpr_num_\\rt))	\
 "	.endm\n"
 
 #define DEFINE_MSR_S						\
-	__DEFINE_MRS_MSR_S_REGNUM				\
+	__DEFINE_ASM_GPR_NUMS					\
 "	.macro	msr_s, sreg, rt\n"				\
-	__emit_inst(0xd5000000|(\\sreg)|(.L__reg_num_\\rt))	\
+	__emit_inst(0xd5000000|(\\sreg)|(.L__gpr_num_\\rt))	\
 "	.endm\n"
 
 #define UNDEFINE_MRS_S						\

arch/arm64/include/asm/uaccess.h

@@ -18,6 +18,7 @@
 #include <linux/kasan-checks.h>
 #include <linux/string.h>
 
+#include <asm/asm-extable.h>
 #include <asm/cpufeature.h>
 #include <asm/mmu.h>
 #include <asm/mte.h>
@@ -70,12 +71,6 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si
 
 #define access_ok(addr, size)	__range_ok(addr, size)
 
-#define _ASM_EXTABLE(from, to)						\
-	"	.pushsection	__ex_table, \"a\"\n"			\
-	"	.align		3\n"					\
-	"	.long		(" #from " - .), (" #to " - .)\n"	\
-	"	.popsection\n"
-
 /*
  * User access enabling/disabling.
  */
@@ -260,15 +255,9 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
 	asm volatile(							\
 	"1:	" load "	" reg "1, [%2]\n"			\
 	"2:\n"								\
-	"	.section .fixup, \"ax\"\n"				\
-	"	.align	2\n"						\
-	"3:	mov	%w0, %3\n"					\
-	"	mov	%1, #0\n"					\
-	"	b	2b\n"						\
-	"	.previous\n"						\
-	_ASM_EXTABLE(1b, 3b)						\
+	_ASM_EXTABLE_UACCESS_ERR_ZERO(1b, 2b, %w0, %w1)			\
 	: "+r" (err), "=&r" (x)						\
-	: "r" (addr), "i" (-EFAULT))
+	: "r" (addr))
 
 #define __raw_get_mem(ldr, x, ptr, err)					\
 do {									\
@@ -337,14 +326,9 @@ do {									\
 	asm volatile(							\
 	"1:	" store "	" reg "1, [%2]\n"			\
 	"2:\n"								\
-	"	.section .fixup,\"ax\"\n"				\
-	"	.align	2\n"						\
-	"3:	mov	%w0, %3\n"					\
-	"	b	2b\n"						\
-	"	.previous\n"						\
-	_ASM_EXTABLE(1b, 3b)						\
+	_ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0)				\
 	: "+r" (err)							\
-	: "r" (x), "r" (addr), "i" (-EFAULT))
+	: "r" (x), "r" (addr))
 
 #define __raw_put_mem(str, x, ptr, err)					\
 do {									\

arch/arm64/include/asm/word-at-a-time.h

@@ -53,29 +53,16 @@ static inline unsigned long find_zero(unsigned long mask)
  */
 static inline unsigned long load_unaligned_zeropad(const void *addr)
 {
-	unsigned long ret, tmp;
+	unsigned long ret;
 
 	__uaccess_enable_tco_async();
 
 	/* Load word from unaligned pointer addr */
 	asm(
-	"1:	ldr	%0, %3\n"
+	"1:	ldr	%0, %2\n"
 	"2:\n"
-	"	.pushsection .fixup,\"ax\"\n"
-	"	.align 2\n"
-	"3:	bic	%1, %2, #0x7\n"
-	"	ldr	%0, [%1]\n"
-	"	and	%1, %2, #0x7\n"
-	"	lsl	%1, %1, #0x3\n"
-#ifndef __AARCH64EB__
-	"	lsr	%0, %0, %1\n"
-#else
-	"	lsl	%0, %0, %1\n"
-#endif
-	"	b	2b\n"
-	"	.popsection\n"
-	_ASM_EXTABLE(1b, 3b)
-	: "=&r" (ret), "=&r" (tmp)
+	_ASM_EXTABLE_LOAD_UNALIGNED_ZEROPAD(1b, 2b, %0, %1)
+	: "=&r" (ret)
 	: "r" (addr), "Q" (*(unsigned long *)addr));
 
 	__uaccess_disable_tco_async();

arch/arm64/kernel/armv8_deprecated.c

@@ -279,7 +279,7 @@ static void __init register_insn_emulation_sysctl(void)
 do {								\
 	uaccess_enable_privileged();				\
 	__asm__ __volatile__(					\
-	"	mov		%w3, %w7\n"			\
+	"	mov		%w3, %w6\n"			\
 	"0:	ldxr"B"		%w2, [%4]\n"			\
 	"1:	stxr"B"		%w0, %w1, [%4]\n"		\
 	"	cbz		%w0, 2f\n"			\
@@ -290,16 +290,10 @@ do {								\
 	"2:\n"							\
 	"	mov		%w1, %w2\n"			\
 	"3:\n"							\
-	"	.pushsection	 .fixup,\"ax\"\n"		\
-	"	.align		2\n"				\
-	"4:	mov		%w0, %w6\n"			\
-	"	b		3b\n"				\
-	"	.popsection"					\
-	_ASM_EXTABLE(0b, 4b)					\
-	_ASM_EXTABLE(1b, 4b)					\
+	_ASM_EXTABLE_UACCESS_ERR(0b, 3b, %w0)			\
+	_ASM_EXTABLE_UACCESS_ERR(1b, 3b, %w0)			\
 	: "=&r" (res), "+r" (data), "=&r" (temp), "=&r" (temp2)	\
 	: "r" ((unsigned long)addr), "i" (-EAGAIN),		\
-	  "i" (-EFAULT),					\
 	  "i" (__SWP_LL_SC_LOOPS)				\
 	: "memory");						\
 	uaccess_disable_privileged();				\

arch/arm64/kernel/traps.c

@@ -527,14 +527,9 @@ NOKPROBE_SYMBOL(do_ptrauth_fault);
 			"1:	" insn ", %1\n"			\
 			"	mov	%w0, #0\n"		\
 			"2:\n"					\
-			"	.pushsection .fixup,\"ax\"\n"	\
-			"	.align	2\n"			\
-			"3:	mov	%w0, %w2\n"		\
-			"	b	2b\n"			\
-			"	.popsection\n"			\
-			_ASM_EXTABLE(1b, 3b)			\
+			_ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0)	\
 			: "=r" (res)				\
-			: "r" (address), "i" (-EFAULT));	\
+			: "r" (address));			\
 		uaccess_ttbr0_disable();			\
 	}
 

arch/arm64/kernel/vmlinux.lds.S

@@ -57,7 +57,7 @@
 #define SBSS_ALIGN			0
 #endif
 
-#define RO_EXCEPTION_TABLE_ALIGN	8
+#define RO_EXCEPTION_TABLE_ALIGN	4
 #define RUNTIME_DISCARD_EXIT
 
 #include <asm-generic/vmlinux.lds.h>
@@ -161,7 +161,6 @@ SECTIONS
 			IDMAP_TEXT
 			HIBERNATE_TEXT
 			TRAMP_TEXT
-			*(.fixup)
 			*(.gnu.warning)
 		. = ALIGN(16);
 		*(.got)			/* Global offset table		*/

arch/arm64/kvm/hyp/include/hyp/switch.h

@@ -30,8 +30,12 @@
 #include <asm/processor.h>
 #include <asm/thread_info.h>
 
-extern struct exception_table_entry __start___kvm_ex_table;
-extern struct exception_table_entry __stop___kvm_ex_table;
+struct kvm_exception_table_entry {
+	int insn, fixup;
+};
+
+extern struct kvm_exception_table_entry __start___kvm_ex_table;
+extern struct kvm_exception_table_entry __stop___kvm_ex_table;
 
 /* Check whether the FP regs were dirtied while in the host-side run loop: */
 static inline bool update_fp_enabled(struct kvm_vcpu *vcpu)
@@ -510,7 +514,7 @@ static inline void __kvm_unexpected_el2_exception(void)
 {
 	extern char __guest_exit_panic[];
 	unsigned long addr, fixup;
-	struct exception_table_entry *entry, *end;
+	struct kvm_exception_table_entry *entry, *end;
 	unsigned long elr_el2 = read_sysreg(elr_el2);
 
 	entry = &__start___kvm_ex_table;

arch/arm64/lib/clear_user.S

@@ -4,7 +4,7 @@
  */
 
 #include <linux/linkage.h>
-#include <asm/assembler.h>
+#include <asm/asm-uaccess.h>
 
 	.text
 
@@ -45,13 +45,11 @@ USER(9f, sttrh	wzr, [x0])
 USER(7f, sttrb	wzr, [x2, #-1])
 5:	mov	x0, #0
 	ret
-SYM_FUNC_END(__arch_clear_user)
-EXPORT_SYMBOL(__arch_clear_user)
 
-	.section .fixup,"ax"
-	.align	2
+	// Exception fixups
 7:	sub	x0, x2, #5	// Adjust for faulting on the final byte...
 8:	add	x0, x0, #4	// ...or the second word of the 4-7 byte case
 9:	sub	x0, x2, x0
 	ret
-	.previous
+SYM_FUNC_END(__arch_clear_user)
+EXPORT_SYMBOL(__arch_clear_user)

arch/arm64/lib/copy_from_user.S

@@ -60,11 +60,8 @@ SYM_FUNC_START(__arch_copy_from_user)
 #include "copy_template.S"
 	mov	x0, #0				// Nothing to copy
 	ret
-SYM_FUNC_END(__arch_copy_from_user)
-EXPORT_SYMBOL(__arch_copy_from_user)
 
-	.section .fixup,"ax"
-	.align	2
+	// Exception fixups
 9997:	cmp	dst, dstin
 	b.ne	9998f
 	// Before being absolutely sure we couldn't copy anything, try harder
@@ -72,4 +69,5 @@ USER(9998f, ldtrb tmp1w, [srcin])
 	strb	tmp1w, [dst], #1
 9998:	sub	x0, end, dst			// bytes not copied
 	ret
-	.previous
+SYM_FUNC_END(__arch_copy_from_user)
+EXPORT_SYMBOL(__arch_copy_from_user)

arch/arm64/lib/copy_to_user.S

@@ -59,11 +59,8 @@ SYM_FUNC_START(__arch_copy_to_user)
 #include "copy_template.S"
 	mov	x0, #0
 	ret
-SYM_FUNC_END(__arch_copy_to_user)
-EXPORT_SYMBOL(__arch_copy_to_user)
 
-	.section .fixup,"ax"
-	.align	2
+	// Exception fixups
 9997:	cmp	dst, dstin
 	b.ne	9998f
 	// Before being absolutely sure we couldn't copy anything, try harder
@@ -72,4 +69,5 @@ USER(9998f, sttrb tmp1w, [dst])
 	add	dst, dst, #1
 9998:	sub	x0, end, dst			// bytes not copied
 	ret
-	.previous
+SYM_FUNC_END(__arch_copy_to_user)
+EXPORT_SYMBOL(__arch_copy_to_user)

arch/arm64/mm/extable.c

@@ -3,20 +3,87 @@
  * Based on arch/arm/mm/extable.c
  */
 
+#include <linux/bitfield.h>
 #include <linux/extable.h>
 #include <linux/uaccess.h>
 
-int fixup_exception(struct pt_regs *regs)
+#include <asm/asm-extable.h>
+#include <asm/ptrace.h>
+
+typedef bool (*ex_handler_t)(const struct exception_table_entry *,
+			     struct pt_regs *);
+
+static inline unsigned long
+get_ex_fixup(const struct exception_table_entry *ex)
+{
+	return ((unsigned long)&ex->fixup + ex->fixup);
+}
+
+static bool ex_handler_fixup(const struct exception_table_entry *ex,
+			     struct pt_regs *regs)
+{
+	regs->pc = get_ex_fixup(ex);
+	return true;
+}
+
+static bool ex_handler_uaccess_err_zero(const struct exception_table_entry *ex,
+					struct pt_regs *regs)
+{
+	int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
+	int reg_zero = FIELD_GET(EX_DATA_REG_ZERO, ex->data);
+
+	pt_regs_write_reg(regs, reg_err, -EFAULT);
+	pt_regs_write_reg(regs, reg_zero, 0);
+
+	regs->pc = get_ex_fixup(ex);
+	return true;
+}
+
+static bool
+ex_handler_load_unaligned_zeropad(const struct exception_table_entry *ex,
+				  struct pt_regs *regs)
+{
+	int reg_data = FIELD_GET(EX_DATA_REG_DATA, ex->type);
+	int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->type);
+	unsigned long data, addr, offset;
+
+	addr = pt_regs_read_reg(regs, reg_addr);
+
+	offset = addr & 0x7UL;
+	addr &= ~0x7UL;
+
+	data = *(unsigned long*)addr;
+
+#ifndef __AARCH64EB__
+	data >>= 8 * offset;
+#else
+	data <<= 8 * offset;
+#endif
+
+	pt_regs_write_reg(regs, reg_data, data);
+
+	regs->pc = get_ex_fixup(ex);
+	return true;
+}
+
+bool fixup_exception(struct pt_regs *regs)
 {
-	const struct exception_table_entry *fixup;
+	const struct exception_table_entry *ex;
 
-	fixup = search_exception_tables(instruction_pointer(regs));
-	if (!fixup)
-		return 0;
+	ex = search_exception_tables(instruction_pointer(regs));
+	if (!ex)
+		return false;
 
-	if (in_bpf_jit(regs))
-		return arm64_bpf_fixup_exception(fixup, regs);
+	switch (ex->type) {
+	case EX_TYPE_FIXUP:
+		return ex_handler_fixup(ex, regs);
+	case EX_TYPE_BPF:
+		return ex_handler_bpf(ex, regs);
+	case EX_TYPE_UACCESS_ERR_ZERO:
+		return ex_handler_uaccess_err_zero(ex, regs);
+	case EX_TYPE_LOAD_UNALIGNED_ZEROPAD:
+		return ex_handler_load_unaligned_zeropad(ex, regs);
+	}
 
-	regs->pc = (unsigned long)&fixup->fixup + fixup->fixup;
-	return 1;
+	BUG();
 }

arch/arm64/net/bpf_jit_comp.c

@@ -13,6 +13,7 @@
 #include <linux/printk.h>
 #include <linux/slab.h>
 
+#include <asm/asm-extable.h>
 #include <asm/byteorder.h>
 #include <asm/cacheflush.h>
 #include <asm/debug-monitors.h>
@@ -358,15 +359,15 @@ static void build_epilogue(struct jit_ctx *ctx)
 #define BPF_FIXUP_OFFSET_MASK	GENMASK(26, 0)
 #define BPF_FIXUP_REG_MASK	GENMASK(31, 27)
 
-int arm64_bpf_fixup_exception(const struct exception_table_entry *ex,
-			      struct pt_regs *regs)
+bool ex_handler_bpf(const struct exception_table_entry *ex,
+		    struct pt_regs *regs)
 {
 	off_t offset = FIELD_GET(BPF_FIXUP_OFFSET_MASK, ex->fixup);
 	int dst_reg = FIELD_GET(BPF_FIXUP_REG_MASK, ex->fixup);
 
 	regs->regs[dst_reg] = 0;
 	regs->pc = (unsigned long)&ex->fixup - offset;
-	return 1;
+	return true;
 }
 
 /* For accesses to BTF pointers, add an entry to the exception table */
@@ -412,6 +413,8 @@ static int add_exception_handler(const struct bpf_insn *insn,
 	ex->fixup = FIELD_PREP(BPF_FIXUP_OFFSET_MASK, offset) |
 		    FIELD_PREP(BPF_FIXUP_REG_MASK, dst_reg);
 
+	ex->type = EX_TYPE_BPF;
+
 	ctx->exentry_idx++;
 	return 0;
 }

scripts/sorttable.c

@@ -231,6 +231,34 @@ static void sort_relative_table(char *extab_image, int image_size)
 	}
 }
 
+static void arm64_sort_relative_table(char *extab_image, int image_size)
+{
+	int i = 0;
+
+	while (i < image_size) {
+		uint32_t *loc = (uint32_t *)(extab_image + i);
+
+		w(r(loc) + i, loc);
+		w(r(loc + 1) + i + 4, loc + 1);
+		/* Don't touch the fixup type or data */
+
+		i += sizeof(uint32_t) * 3;
+	}
+
+	qsort(extab_image, image_size / 12, 12, compare_relative_table);
+
+	i = 0;
+	while (i < image_size) {
+		uint32_t *loc = (uint32_t *)(extab_image + i);
+
+		w(r(loc) - i, loc);
+		w(r(loc + 1) - (i + 4), loc + 1);
+		/* Don't touch the fixup type or data */
+
+		i += sizeof(uint32_t) * 3;
+	}
+}
+
 static void x86_sort_relative_table(char *extab_image, int image_size)
 {
 	int i = 0;
@@ -343,6 +371,8 @@ static int do_file(char const *const fname, void *addr)
 		custom_sort = s390_sort_relative_table;
 		break;
 	case EM_AARCH64:
+		custom_sort = arm64_sort_relative_table;
+		break;
 	case EM_PARISC:
 	case EM_PPC:
 	case EM_PPC64: