Merge tag 'loongarch-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson

Pull LoongArch updates from Huacai Chen:

 - Switch to relative exception tables

 - Add unaligned access support

 - Add alternative runtime patching mechanism

 - Add FDT booting support from efi system table

 - Add suspend/hibernation (ACPI S3/S4) support

 - Add basic STACKPROTECTOR support

 - Add ftrace (function tracer) support

 - Update the default config file

* tag 'loongarch-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson: (24 commits)
  LoongArch: Update Loongson-3 default config file
  LoongArch: modules/ftrace: Initialize PLT at load time
  LoongArch/ftrace: Add HAVE_FUNCTION_GRAPH_RET_ADDR_PTR support
  LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_ARGS support
  LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_REGS support
  LoongArch/ftrace: Add dynamic function graph tracer support
  LoongArch/ftrace: Add dynamic function tracer support
  LoongArch/ftrace: Add recordmcount support
  LoongArch/ftrace: Add basic support
  LoongArch: module: Use got/plt section indices for relocations
  LoongArch: Add basic STACKPROTECTOR support
  LoongArch: Add hibernation (ACPI S4) support
  LoongArch: Add suspend (ACPI S3) support
  LoongArch: Add processing ISA Node in DeviceTree
  LoongArch: Add FDT booting support from efi system table
  LoongArch: Use alternative to optimize libraries
  LoongArch: Add alternative runtime patching mechanism
  LoongArch: Add unaligned access support
  LoongArch: BPF: Add BPF exception tables
  LoongArch: Remove the .fixup section usage
  ...

72 files changed, 3645 insertions, 187 deletions

diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 659d7bc47d7b..46e3d62c0eea 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -436,8 +436,8 @@ ignore-unaligned-usertrap
 
 On architectures where unaligned accesses cause traps, and where this
 feature is supported (``CONFIG_SYSCTL_ARCH_UNALIGN_NO_WARN``;
-currently, ``arc`` and ``ia64``), controls whether all unaligned traps
-are logged.
+currently, ``arc``, ``ia64`` and ``loongarch``), controls whether all
+unaligned traps are logged.
 
 = =============================================================
 0 Log all unaligned accesses.
@@ -1492,8 +1492,8 @@ unaligned-trap
 
 On architectures where unaligned accesses cause traps, and where this
 feature is supported (``CONFIG_SYSCTL_ARCH_UNALIGN_ALLOW``; currently,
-``arc`` and ``parisc``), controls whether unaligned traps are caught
-and emulated (instead of failing).
+``arc``, ``parisc`` and ``loongarch``), controls whether unaligned traps
+are caught and emulated (instead of failing).
 
 = ========================================================
 0 Do not emulate unaligned accesses.
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index a508813d5ea2..9cc8b84f7eb0 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -58,6 +58,7 @@ config LOONGARCH
 	select ARCH_WANTS_NO_INSTR
 	select BUILDTIME_TABLE_SORT
 	select COMMON_CLK
+	select CPU_PM
 	select EFI
 	select GENERIC_CLOCKEVENTS
 	select GENERIC_CMOS_UPDATE
@@ -86,11 +87,18 @@ config LOONGARCH
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select HAVE_ASM_MODVERSIONS
 	select HAVE_CONTEXT_TRACKING_USER
+	select HAVE_C_RECORDMCOUNT
 	select HAVE_DEBUG_STACKOVERFLOW
 	select HAVE_DMA_CONTIGUOUS
+	select HAVE_DYNAMIC_FTRACE
+	select HAVE_DYNAMIC_FTRACE_WITH_ARGS
+	select HAVE_DYNAMIC_FTRACE_WITH_REGS
 	select HAVE_EBPF_JIT
 	select HAVE_EXIT_THREAD
 	select HAVE_FAST_GUP
+	select HAVE_FTRACE_MCOUNT_RECORD
+	select HAVE_FUNCTION_GRAPH_TRACER
+	select HAVE_FUNCTION_TRACER
 	select HAVE_GENERIC_VDSO
 	select HAVE_IOREMAP_PROT
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
@@ -104,6 +112,7 @@ config LOONGARCH
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_RSEQ
 	select HAVE_SETUP_PER_CPU_AREA if NUMA
+	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_TIF_NOHZ
 	select HAVE_VIRT_CPU_ACCOUNTING_GEN if !SMP
@@ -113,6 +122,8 @@ config LOONGARCH
 	select MODULES_USE_ELF_RELA if MODULES
 	select NEED_PER_CPU_EMBED_FIRST_CHUNK
 	select NEED_PER_CPU_PAGE_FIRST_CHUNK
+	select OF
+	select OF_EARLY_FLATTREE
 	select PCI
 	select PCI_DOMAINS_GENERIC
 	select PCI_ECAM if ACPI
@@ -123,6 +134,8 @@ config LOONGARCH
 	select RTC_LIB
 	select SMP
 	select SPARSE_IRQ
+	select SYSCTL_ARCH_UNALIGN_ALLOW
+	select SYSCTL_ARCH_UNALIGN_NO_WARN
 	select SYSCTL_EXCEPTION_TRACE
 	select SWIOTLB
 	select TRACE_IRQFLAGS_SUPPORT
@@ -516,6 +529,13 @@ config ARCH_MMAP_RND_BITS_MAX
 
 menu "Power management options"
 
+config ARCH_SUSPEND_POSSIBLE
+	def_bool y
+
+config ARCH_HIBERNATION_POSSIBLE
+	def_bool y
+
+source "kernel/power/Kconfig"
 source "drivers/acpi/Kconfig"
 
 endmenu
diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
index 01b57b726322..4402387d2755 100644
--- a/arch/loongarch/Makefile
+++ b/arch/loongarch/Makefile
@@ -25,6 +25,11 @@ endif
 32bit-emul		= elf32loongarch
 64bit-emul		= elf64loongarch
 
+ifdef CONFIG_DYNAMIC_FTRACE
+KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
+CC_FLAGS_FTRACE := -fpatchable-function-entry=2
+endif
+
 ifdef CONFIG_64BIT
 tool-archpref		= $(64bit-tool-archpref)
 UTS_MACHINE		:= loongarch64
@@ -104,6 +109,9 @@ endif
 libs-y += arch/loongarch/lib/
 libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
 
+# suspend and hibernation support
+drivers-$(CONFIG_PM)	+= arch/loongarch/power/
+
 ifeq ($(KBUILD_EXTMOD),)
 prepare: vdso_prepare
 vdso_prepare: prepare0
diff --git a/arch/loongarch/configs/loongson3_defconfig b/arch/loongarch/configs/loongson3_defconfig
index 3540e9c0a631..eb84cae642e5 100644
--- a/arch/loongarch/configs/loongson3_defconfig
+++ b/arch/loongarch/configs/loongson3_defconfig
@@ -34,12 +34,13 @@ CONFIG_SYSFS_DEPRECATED=y
 CONFIG_RELAY=y
 CONFIG_BLK_DEV_INITRD=y
 CONFIG_EXPERT=y
-CONFIG_USERFAULTFD=y
+CONFIG_KALLSYMS_ALL=y
 CONFIG_PERF_EVENTS=y
-# CONFIG_COMPAT_BRK is not set
 CONFIG_LOONGARCH=y
 CONFIG_64BIT=y
 CONFIG_MACH_LOONGSON64=y
+CONFIG_PAGE_SIZE_16KB=y
+CONFIG_HZ_250=y
 CONFIG_DMI=y
 CONFIG_EFI=y
 CONFIG_SMP=y
@@ -47,14 +48,14 @@ CONFIG_HOTPLUG_CPU=y
 CONFIG_NR_CPUS=64
 CONFIG_NUMA=y
 CONFIG_KEXEC=y
-CONFIG_PAGE_SIZE_16KB=y
-CONFIG_HZ_250=y
+CONFIG_SUSPEND=y
+CONFIG_HIBERNATION=y
 CONFIG_ACPI=y
 CONFIG_ACPI_SPCR_TABLE=y
-CONFIG_ACPI_HOTPLUG_CPU=y
 CONFIG_ACPI_TAD=y
 CONFIG_ACPI_DOCK=y
 CONFIG_ACPI_IPMI=m
+CONFIG_ACPI_HOTPLUG_CPU=y
 CONFIG_ACPI_PCI_SLOT=y
 CONFIG_ACPI_HOTPLUG_MEMORY=y
 CONFIG_EFI_ZBOOT=y
@@ -73,17 +74,19 @@ CONFIG_UNIXWARE_DISKLABEL=y
 CONFIG_IOSCHED_BFQ=y
 CONFIG_BFQ_GROUP_IOSCHED=y
 CONFIG_BINFMT_MISC=m
-CONFIG_MEMORY_HOTPLUG=y
-CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y
-CONFIG_MEMORY_HOTREMOVE=y
-CONFIG_KSM=y
-CONFIG_TRANSPARENT_HUGEPAGE=y
+CONFIG_ZPOOL=y
 CONFIG_ZSWAP=y
 CONFIG_ZSWAP_COMPRESSOR_DEFAULT_ZSTD=y
-CONFIG_ZPOOL=y
 CONFIG_ZBUD=y
 CONFIG_Z3FOLD=y
 CONFIG_ZSMALLOC=m
+# CONFIG_COMPAT_BRK is not set
+CONFIG_MEMORY_HOTPLUG=y
+CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE=y
+CONFIG_MEMORY_HOTREMOVE=y
+CONFIG_KSM=y
+CONFIG_TRANSPARENT_HUGEPAGE=y
+CONFIG_USERFAULTFD=y
 CONFIG_NET=y
 CONFIG_PACKET=y
 CONFIG_UNIX=y
@@ -118,7 +121,6 @@ CONFIG_NETFILTER=y
 CONFIG_BRIDGE_NETFILTER=m
 CONFIG_NETFILTER_NETLINK_LOG=m
 CONFIG_NF_CONNTRACK=m
-CONFIG_NF_LOG_NETDEV=m
 CONFIG_NF_CONNTRACK_AMANDA=m
 CONFIG_NF_CONNTRACK_FTP=m
 CONFIG_NF_CONNTRACK_NETBIOS_NS=m
@@ -416,6 +418,7 @@ CONFIG_SCSI_VIRTIO=m
 CONFIG_ATA=y
 CONFIG_SATA_AHCI=y
 CONFIG_SATA_AHCI_PLATFORM=y
+CONFIG_AHCI_DWC=y
 CONFIG_PATA_ATIIXP=y
 CONFIG_PATA_PCMCIA=m
 CONFIG_MD=y
@@ -469,13 +472,11 @@ CONFIG_VIRTIO_NET=m
 # CONFIG_NET_VENDOR_ARC is not set
 # CONFIG_NET_VENDOR_ATHEROS is not set
 CONFIG_BNX2=y
-# CONFIG_NET_VENDOR_BROCADE is not set
 # CONFIG_NET_VENDOR_CAVIUM is not set
 CONFIG_CHELSIO_T1=m
 CONFIG_CHELSIO_T1_1G=y
 CONFIG_CHELSIO_T3=m
 CONFIG_CHELSIO_T4=m
-# CONFIG_NET_VENDOR_CIRRUS is not set
 # CONFIG_NET_VENDOR_CISCO is not set
 # CONFIG_NET_VENDOR_DEC is not set
 # CONFIG_NET_VENDOR_DLINK is not set
@@ -496,6 +497,7 @@ CONFIG_IXGBE=y
 # CONFIG_NET_VENDOR_NVIDIA is not set
 # CONFIG_NET_VENDOR_OKI is not set
 # CONFIG_NET_VENDOR_QLOGIC is not set
+# CONFIG_NET_VENDOR_BROCADE is not set
 # CONFIG_NET_VENDOR_QUALCOMM is not set
 # CONFIG_NET_VENDOR_RDC is not set
 CONFIG_8139CP=m
@@ -505,9 +507,9 @@ CONFIG_R8169=y
 # CONFIG_NET_VENDOR_ROCKER is not set
 # CONFIG_NET_VENDOR_SAMSUNG is not set
 # CONFIG_NET_VENDOR_SEEQ is not set
-# CONFIG_NET_VENDOR_SOLARFLARE is not set
 # CONFIG_NET_VENDOR_SILAN is not set
 # CONFIG_NET_VENDOR_SIS is not set
+# CONFIG_NET_VENDOR_SOLARFLARE is not set
 # CONFIG_NET_VENDOR_SMSC is not set
 CONFIG_STMMAC_ETH=y
 # CONFIG_NET_VENDOR_SUN is not set
@@ -588,6 +590,7 @@ CONFIG_SERIAL_8250_EXTENDED=y
 CONFIG_SERIAL_8250_MANY_PORTS=y
 CONFIG_SERIAL_8250_SHARE_IRQ=y
 CONFIG_SERIAL_8250_RSA=y
+CONFIG_SERIAL_OF_PLATFORM=y
 CONFIG_SERIAL_NONSTANDARD=y
 CONFIG_PRINTER=m
 CONFIG_VIRTIO_CONSOLE=y
@@ -602,6 +605,11 @@ CONFIG_I2C_GPIO=y
 CONFIG_SPI=y
 CONFIG_GPIO_SYSFS=y
 CONFIG_GPIO_LOONGSON=y
+CONFIG_POWER_RESET=y
+CONFIG_POWER_RESET_RESTART=y
+CONFIG_POWER_RESET_SYSCON=y
+CONFIG_POWER_RESET_SYSCON_POWEROFF=y
+CONFIG_SYSCON_REBOOT_MODE=y
 CONFIG_SENSORS_LM75=m
 CONFIG_SENSORS_LM93=m
 CONFIG_SENSORS_W83795=m
@@ -609,16 +617,16 @@ CONFIG_SENSORS_W83627HF=m
 CONFIG_RC_CORE=m
 CONFIG_LIRC=y
 CONFIG_RC_DECODERS=y
+CONFIG_IR_IMON_DECODER=m
+CONFIG_IR_JVC_DECODER=m
+CONFIG_IR_MCE_KBD_DECODER=m
 CONFIG_IR_NEC_DECODER=m
 CONFIG_IR_RC5_DECODER=m
 CONFIG_IR_RC6_DECODER=m
-CONFIG_IR_JVC_DECODER=m
-CONFIG_IR_SONY_DECODER=m
 CONFIG_IR_SANYO_DECODER=m
 CONFIG_IR_SHARP_DECODER=m
-CONFIG_IR_MCE_KBD_DECODER=m
+CONFIG_IR_SONY_DECODER=m
 CONFIG_IR_XMP_DECODER=m
-CONFIG_IR_IMON_DECODER=m
 CONFIG_MEDIA_SUPPORT=m
 CONFIG_MEDIA_USB_SUPPORT=y
 CONFIG_USB_VIDEO_CLASS=m
@@ -638,6 +646,7 @@ CONFIG_DRM_VIRTIO_GPU=m
 CONFIG_FB=y
 CONFIG_FB_EFI=y
 CONFIG_FB_RADEON=y
+CONFIG_LCD_CLASS_DEVICE=y
 CONFIG_LCD_PLATFORM=m
 # CONFIG_VGA_CONSOLE is not set
 CONFIG_FRAMEBUFFER_CONSOLE=y
@@ -647,7 +656,6 @@ CONFIG_SOUND=y
 CONFIG_SND=y
 CONFIG_SND_SEQUENCER=m
 CONFIG_SND_SEQ_DUMMY=m
-# CONFIG_SND_ISA is not set
 CONFIG_SND_BT87X=m
 CONFIG_SND_BT87X_OVERCLOCK=y
 CONFIG_SND_HDA_INTEL=y
@@ -818,10 +826,6 @@ CONFIG_CRYPTO_USER=m
 # CONFIG_CRYPTO_MANAGER_DISABLE_TESTS is not set
 CONFIG_CRYPTO_PCRYPT=m
 CONFIG_CRYPTO_CRYPTD=m
-CONFIG_CRYPTO_CHACHA20POLY1305=m
-CONFIG_CRYPTO_HMAC=y
-CONFIG_CRYPTO_VMAC=m
-CONFIG_CRYPTO_WP512=m
 CONFIG_CRYPTO_ANUBIS=m
 CONFIG_CRYPTO_BLOWFISH=m
 CONFIG_CRYPTO_CAST5=m
@@ -831,6 +835,9 @@ CONFIG_CRYPTO_SEED=m
 CONFIG_CRYPTO_SERPENT=m
 CONFIG_CRYPTO_TEA=m
 CONFIG_CRYPTO_TWOFISH=m
+CONFIG_CRYPTO_CHACHA20POLY1305=m
+CONFIG_CRYPTO_VMAC=m
+CONFIG_CRYPTO_WP512=m
 CONFIG_CRYPTO_DEFLATE=m
 CONFIG_CRYPTO_LZO=m
 CONFIG_CRYPTO_842=m
@@ -844,6 +851,7 @@ CONFIG_CRYPTO_DEV_VIRTIO=m
 CONFIG_PRINTK_TIME=y
 CONFIG_STRIP_ASM_SYMS=y
 CONFIG_MAGIC_SYSRQ=y
+CONFIG_DEBUG_FS=y
 # CONFIG_SCHED_DEBUG is not set
 CONFIG_SCHEDSTATS=y
 # CONFIG_DEBUG_PREEMPT is not set
diff --git a/arch/loongarch/include/asm/acpi.h b/arch/loongarch/include/asm/acpi.h
index 825c2519b9d1..4198753aa1d0 100644
--- a/arch/loongarch/include/asm/acpi.h
+++ b/arch/loongarch/include/asm/acpi.h
@@ -35,4 +35,14 @@ extern struct list_head acpi_wakeup_device_list;
 
 #define ACPI_TABLE_UPGRADE_MAX_PHYS ARCH_LOW_ADDRESS_LIMIT
 
+extern int loongarch_acpi_suspend(void);
+extern int (*acpi_suspend_lowlevel)(void);
+extern void loongarch_suspend_enter(void);
+
+static inline unsigned long acpi_get_wakeup_address(void)
+{
+	extern void loongarch_wakeup_start(void);
+	return (unsigned long)loongarch_wakeup_start;
+}
+
 #endif /* _ASM_LOONGARCH_ACPI_H */
diff --git a/arch/loongarch/include/asm/alternative-asm.h b/arch/loongarch/include/asm/alternative-asm.h
new file mode 100644
index 000000000000..ff3d10ac393f
--- /dev/null
+++ b/arch/loongarch/include/asm/alternative-asm.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ALTERNATIVE_ASM_H
+#define _ASM_ALTERNATIVE_ASM_H
+
+#ifdef __ASSEMBLY__
+
+#include <asm/asm.h>
+
+/*
+ * Issue one struct alt_instr descriptor entry (need to put it into
+ * the section .altinstructions, see below). This entry contains
+ * enough information for the alternatives patching code to patch an
+ * instruction. See apply_alternatives().
+ */
+.macro altinstruction_entry orig alt feature orig_len alt_len
+	.long \orig - .
+	.long \alt - .
+	.short \feature
+	.byte \orig_len
+	.byte \alt_len
+.endm
+
+/*
+ * Define an alternative between two instructions. If @feature is
+ * present, early code in apply_alternatives() replaces @oldinstr with
+ * @newinstr. ".fill" directive takes care of proper instruction padding
+ * in case @newinstr is longer than @oldinstr.
+ */
+.macro ALTERNATIVE oldinstr, newinstr, feature
+140 :
+	\oldinstr
+141 :
+	.fill - (((144f-143f)-(141b-140b)) > 0) * ((144f-143f)-(141b-140b)) / 4, 4, 0x03400000
+142 :
+
+	.pushsection .altinstructions, "a"
+	altinstruction_entry 140b, 143f, \feature, 142b-140b, 144f-143f
+	.popsection
+
+	.subsection 1
+143 :
+	\newinstr
+144 :
+	.previous
+.endm
+
+#define old_len			(141b-140b)
+#define new_len1		(144f-143f)
+#define new_len2		(145f-144f)
+
+#define alt_max_short(a, b)	((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))
+
+/*
+ * Same as ALTERNATIVE macro above but for two alternatives. If CPU
+ * has @feature1, it replaces @oldinstr with @newinstr1. If CPU has
+ * @feature2, it replaces @oldinstr with @feature2.
+ */
+.macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2
+140 :
+	\oldinstr
+141 :
+	.fill - ((alt_max_short(new_len1, new_len2) - (old_len)) > 0) * \
+		(alt_max_short(new_len1, new_len2) - (old_len)) / 4, 4, 0x03400000
+142 :
+
+	.pushsection .altinstructions, "a"
+	altinstruction_entry 140b, 143f, \feature1, 142b-140b, 144f-143f, 142b-141b
+	altinstruction_entry 140b, 144f, \feature2, 142b-140b, 145f-144f, 142b-141b
+	.popsection
+
+	.subsection 1
+143 :
+	\newinstr1
+144 :
+	\newinstr2
+145 :
+	.previous
+.endm
+
+#endif  /*  __ASSEMBLY__  */
+
+#endif /* _ASM_ALTERNATIVE_ASM_H */
diff --git a/arch/loongarch/include/asm/alternative.h b/arch/loongarch/include/asm/alternative.h
new file mode 100644
index 000000000000..cee7b29785ab
--- /dev/null
+++ b/arch/loongarch/include/asm/alternative.h
@@ -0,0 +1,111 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ALTERNATIVE_H
+#define _ASM_ALTERNATIVE_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+#include <linux/stddef.h>
+#include <linux/stringify.h>
+#include <asm/asm.h>
+
+struct alt_instr {
+	s32 instr_offset;	/* offset to original instruction */
+	s32 replace_offset;	/* offset to replacement instruction */
+	u16 feature;		/* feature bit set for replacement */
+	u8  instrlen;		/* length of original instruction */
+	u8  replacementlen;	/* length of new instruction */
+} __packed;
+
+/*
+ * Debug flag that can be tested to see whether alternative
+ * instructions were patched in already:
+ */
+extern int alternatives_patched;
+extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
+
+extern void alternative_instructions(void);
+extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
+
+#define b_replacement(num)	"664"#num
+#define e_replacement(num)	"665"#num
+
+#define alt_end_marker		"663"
+#define alt_slen		"662b-661b"
+#define alt_total_slen		alt_end_marker"b-661b"
+#define alt_rlen(num)		e_replacement(num)"f-"b_replacement(num)"f"
+
+#define __OLDINSTR(oldinstr, num)					\
+	"661:\n\t" oldinstr "\n662:\n"					\
+	".fill -(((" alt_rlen(num) ")-(" alt_slen ")) > 0) * "		\
+		"((" alt_rlen(num) ")-(" alt_slen ")) / 4, 4, 0x03400000\n"
+
+#define OLDINSTR(oldinstr, num)						\
+	__OLDINSTR(oldinstr, num)					\
+	alt_end_marker ":\n"
+
+#define alt_max_short(a, b)	"((" a ") ^ (((" a ") ^ (" b ")) & -(-((" a ") < (" b ")))))"
+
+/*
+ * Pad the second replacement altern