[PATCH v1 1/2] arm64: kprobes: implement optprobes

[PATCH v1 1/2] arm64: kprobes: implement optprobes

[Janet Liu]

From: Janet Liu <janet.liu@unisoc.com>

Limitations:
  -only support 17(4096/240) kprobes
   240 is from optprobe_template_end - optprobe_template_entry
   4096 is from optinsn_slot reserve space size
  -only support steppable insn to be probed

This patch replaced the probed instruction with a 'b' instruction,
 unconditionally branch to a buffer. The buffer contains instructions
to create an pt_regs on stack, and then calls optimized_callback() which
call the pre_handle(). After the executing kprobe handler, run the
replaced instrunction, and branch to PC that probed instruction.

The range of 'b' instruction is +/-128MB, alloc page from buddy is
probable out of this +/-128MB range, so the buffer is allocated from
a reserved area. For simple, only 4K is reserved. Futher patch can make
optimization.

Signed-off-by: Janet Liu <janet.liu@unisoc.com>
---
 arch/arm64/Kconfig                            |   1 +
 arch/arm64/include/asm/probes.h               |  23 +++
 arch/arm64/kernel/probes/Makefile             |   1 +
 arch/arm64/kernel/probes/base_regs.h          |  76 ++++++++
 arch/arm64/kernel/probes/kprobes_trampoline.S |  55 +-----
 arch/arm64/kernel/probes/opt.c                | 247 ++++++++++++++++++++++++++
 arch/arm64/kernel/probes/opt_head.S           |  40 +++++
 7 files changed, 389 insertions(+), 54 deletions(-)
 create mode 100644 arch/arm64/kernel/probes/base_regs.h
 create mode 100644 arch/arm64/kernel/probes/opt.c
 create mode 100644 arch/arm64/kernel/probes/opt_head.S

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 5c7ae4c..ab07251 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -199,6 +199,7 @@ config ARM64
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES
+	select HAVE_OPTPROBES
 	select HAVE_KRETPROBES
 	select HAVE_GENERIC_VDSO
 	select IOMMU_DMA if IOMMU_SUPPORT
diff --git a/arch/arm64/include/asm/probes.h b/arch/arm64/include/asm/probes.h
index 0069467..3114881 100644
--- a/arch/arm64/include/asm/probes.h
+++ b/arch/arm64/include/asm/probes.h
@@ -25,6 +25,29 @@ struct arch_probe_insn {
 struct arch_specific_insn {
 	struct arch_probe_insn api;
 };
+
+/* optinsn template addresses */
+extern __visible kprobe_opcode_t optinsn_slot;
+extern __visible kprobe_opcode_t optprobe_template_entry;
+extern __visible kprobe_opcode_t optprobe_template_val;
+extern __visible kprobe_opcode_t optprobe_template_call;
+extern __visible kprobe_opcode_t optprobe_template_end;
+extern __visible kprobe_opcode_t optprobe_template_restore_orig_insn;
+extern __visible kprobe_opcode_t optprobe_template_restore_end;
+
+#define MAX_OPTIMIZED_LENGTH    4
+#define MAX_OPTINSN_SIZE                                \
+	((kprobe_opcode_t *)&optprobe_template_end -        \
+	(kprobe_opcode_t *)&optprobe_template_entry)
+
+
+struct arch_optimized_insn {
+	/* copy of the original instructions */
+	kprobe_opcode_t copied_insn[AARCH64_INSN_SIZE];
+	/* detour code buffer */
+	kprobe_opcode_t *insn;
+};
+
 #endif
 
 #endif
diff --git a/arch/arm64/kernel/probes/Makefile b/arch/arm64/kernel/probes/Makefile
index 8e4be92..c77c92a 100644
--- a/arch/arm64/kernel/probes/Makefile
+++ b/arch/arm64/kernel/probes/Makefile
@@ -2,5 +2,6 @@
 obj-$(CONFIG_KPROBES)		+= kprobes.o decode-insn.o	\
 				   kprobes_trampoline.o		\
 				   simulate-insn.o
+obj-$(CONFIG_OPTPROBES) 	+= opt.o opt_head.o
 obj-$(CONFIG_UPROBES)		+= uprobes.o decode-insn.o	\
 				   simulate-insn.o
diff --git a/arch/arm64/kernel/probes/base_regs.h b/arch/arm64/kernel/probes/base_regs.h
new file mode 100644
index 0000000..45565dc
--- /dev/null
+++ b/arch/arm64/kernel/probes/base_regs.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+//
+// Copyright (C) 2021, Unisoc Inc.
+// Author: Janet Liu <janet.liu@unisoc.com>
+
+#include <asm/asm-offsets.h>
+
+	.macro  save_all_base_regs
+
+	sub     sp, sp, #(PT_REGS_SIZE + 16)
+
+	stp x0, x1, [sp, #S_X0]
+	stp x2, x3, [sp, #S_X2]
+	stp x4, x5, [sp, #S_X4]
+	stp x6, x7, [sp, #S_X6]
+	stp x8, x9, [sp, #S_X8]
+	stp x10, x11, [sp, #S_X10]
+	stp x12, x13, [sp, #S_X12]
+	stp x14, x15, [sp, #S_X14]
+	stp x16, x17, [sp, #S_X16]
+	stp x18, x19, [sp, #S_X18]
+	stp x20, x21, [sp, #S_X20]
+	stp x22, x23, [sp, #S_X22]
+	stp x24, x25, [sp, #S_X24]
+	stp x26, x27, [sp, #S_X26]
+	stp x28, x29, [sp, #S_X28]
+	add x0, sp, #(PT_REGS_SIZE + 16)
+	stp lr, x0, [sp, #S_LR]
+
+	stp x29, x30, [sp, #PT_REGS_SIZE]
+	add x29, sp, #PT_REGS_SIZE
+	stp x29, x30, [sp, #S_STACKFRAME]
+	add x29, sp, #S_STACKFRAME
+
+	/*
+	 * Construct a useful saved PSTATE
+	 */
+	mrs x0, nzcv
+	mrs x1, daif
+	orr x0, x0, x1
+	mrs x1, CurrentEL
+	orr x0, x0, x1
+	mrs x1, SPSel
+	orr x0, x0, x1
+	stp xzr, x0, [sp, #S_PC]
+	.endm
+
+	.macro  restore_all_base_regs trampoline = 0
+	.if trampoline == 0
+	ldr x0, [sp, #S_PSTATE]
+	and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT)
+	msr nzcv, x0
+	.endif
+
+	ldp x0, x1, [sp, #S_X0]
+	ldp x2, x3, [sp, #S_X2]
+	ldp x4, x5, [sp, #S_X4]
+	ldp x6, x7, [sp, #S_X6]
+	ldp x8, x9, [sp, #S_X8]
+	ldp x10, x11, [sp, #S_X10]
+	ldp x12, x13, [sp, #S_X12]
+	ldp x14, x15, [sp, #S_X14]
+	ldp x16, x17, [sp, #S_X16]
+	ldp x18, x19, [sp, #S_X18]
+	ldp x20, x21, [sp, #S_X20]
+	ldp x22, x23, [sp, #S_X22]
+	ldp x24, x25, [sp, #S_X24]
+	ldp x26, x27, [sp, #S_X26]
+	ldp x28, x29, [sp, #S_X28]
+
+	.if \trampoline == 1
+	ldr lr, [sp, #S_LR]
+	.endif
+
+	add     sp, sp, #(PT_REGS_SIZE + 16)
+	.endm
diff --git a/arch/arm64/kernel/probes/kprobes_trampoline.S b/arch/arm64/kernel/probes/kprobes_trampoline.S
index 288a84e2..cdc874f 100644
--- a/arch/arm64/kernel/probes/kprobes_trampoline.S
+++ b/arch/arm64/kernel/probes/kprobes_trampoline.S
@@ -6,63 +6,11 @@
 #include <linux/linkage.h>
 #include <asm/asm-offsets.h>
 #include <asm/assembler.h>
+#include "base_regs.h"
 
 	.text
 
-	.macro	save_all_base_regs
-	stp x0, x1, [sp, #S_X0]
-	stp x2, x3, [sp, #S_X2]
-	stp x4, x5, [sp, #S_X4]
-	stp x6, x7, [sp, #S_X6]
-	stp x8, x9, [sp, #S_X8]
-	stp x10, x11, [sp, #S_X10]
-	stp x12, x13, [sp, #S_X12]
-	stp x14, x15, [sp, #S_X14]
-	stp x16, x17, [sp, #S_X16]
-	stp x18, x19, [sp, #S_X18]
-	stp x20, x21, [sp, #S_X20]
-	stp x22, x23, [sp, #S_X22]
-	stp x24, x25, [sp, #S_X24]
-	stp x26, x27, [sp, #S_X26]
-	stp x28, x29, [sp, #S_X28]
-	add x0, sp, #PT_REGS_SIZE
-	stp lr, x0, [sp, #S_LR]
-	/*
-	 * Construct a useful saved PSTATE
-	 */
-	mrs x0, nzcv
-	mrs x1, daif
-	orr x0, x0, x1
-	mrs x1, CurrentEL
-	orr x0, x0, x1
-	mrs x1, SPSel
-	orr x0, x0, x1
-	stp xzr, x0, [sp, #S_PC]
-	.endm
-
-	.macro	restore_all_base_regs
-	ldr x0, [sp, #S_PSTATE]
-	and x0, x0, #(PSR_N_BIT | PSR_Z_BIT | PSR_C_BIT | PSR_V_BIT)
-	msr nzcv, x0
-	ldp x0, x1, [sp, #S_X0]
-	ldp x2, x3, [sp, #S_X2]
-	ldp x4, x5, [sp, #S_X4]
-	ldp x6, x7, [sp, #S_X6]
-	ldp x8, x9, [sp, #S_X8]
-	ldp x10, x11, [sp, #S_X10]
-	ldp x12, x13, [sp, #S_X12]
-	ldp x14, x15, [sp, #S_X14]
-	ldp x16, x17, [sp, #S_X16]
-	ldp x18, x19, [sp, #S_X18]
-	ldp x20, x21, [sp, #S_X20]
-	ldp x22, x23, [sp, #S_X22]
-	ldp x24, x25, [sp, #S_X24]
-	ldp x26, x27, [sp, #S_X26]
-	ldp x28, x29, [sp, #S_X28]
-	.endm
-
 SYM_CODE_START(kretprobe_trampoline)
-	sub sp, sp, #PT_REGS_SIZE
 
 	save_all_base_regs
 
@@ -76,7 +24,6 @@ SYM_CODE_START(kretprobe_trampoline)
 
 	restore_all_base_regs
 
-	add sp, sp, #PT_REGS_SIZE
 	ret
 
 SYM_CODE_END(kretprobe_trampoline)
diff --git a/arch/arm64/kernel/probes/opt.c b/arch/arm64/kernel/probes/opt.c
new file mode 100644
index 0000000..b1f8f0d
--- /dev/null
+++ b/arch/arm64/kernel/probes/opt.c
@@ -0,0 +1,247 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Kernel Probes Jump Optimization (Optprobes)
+//
+// Copyright (C) 2021, Unisoc Inc.
+// Author: Janet Liu <janet.liu@unisoc.com>
+#include <linux/kprobes.h>
+#include <linux/jump_label.h>
+#include <linux/slab.h>
+#include <asm/patching.h>
+#include <asm/ptrace.h>
+#include <asm/kprobes.h>
+#include <asm/cacheflush.h>
+#include <asm/insn.h>
+
+#define TMPL_VAL_IDX \
+	((kprobe_opcode_t *)&optprobe_template_val - (kprobe_opcode_t *)&optprobe_template_entry)
+#define TMPL_CALL_IDX \
+	((kprobe_opcode_t *)&optprobe_template_call - (kprobe_opcode_t *)&optprobe_template_entry)
+#define TMPL_END_IDX \
+	((kprobe_opcode_t *)&optprobe_template_end - (kprobe_opcode_t *)&optprobe_template_entry)
+#define TMPL_RESTORE_ORIGN_INSN \
+	((kprobe_opcode_t *)&optprobe_template_restore_orig_insn \
+	- (kprobe_opcode_t *)&optprobe_template_entry)
+#define TMPL_RESTORE_END \
+	((kprobe_opcode_t *)&optprobe_template_restore_end \
+	- (kprobe_opcode_t *)&optprobe_template_entry)
+
+
+static bool optinsn_page_in_use;
+
+void *alloc_optinsn_page(void)
+{
+	if (optinsn_page_in_use)
+		return NULL;
+	optinsn_page_in_use = true;
+	return &optinsn_slot;
+}
+
+void free_optinsn_page(void *page __maybe_unused)
+{
+	optinsn_page_in_use = false;
+}
+
+int arch_prepared_optinsn(struct arch_optimized_insn *optinsn)
+{
+	return optinsn->insn != NULL;
+}
+
+/*
+ * In ARM64 ISA, kprobe opt always replace one instruction (4 bytes
+ * aligned and 4 bytes long). It is impossible to encounter another
+ * kprobe in the address range. So always return 0.
+ */
+int arch_check_optimized_kprobe(struct optimized_kprobe *op)
+{
+	return 0;
+}
+
+/* only optimize steppable insn */
+static int can_optimize(struct kprobe *kp)
+{
+	if (!kp->ainsn.api.insn)
+		return 0;
+	return 1;
+}
+
+/* Free optimized instruction slot */
+static void
+__arch_remove_optimized_kprobe(struct optimized_kprobe *op, int dirty)
+{
+	if (op->optinsn.insn) {
+		free_optinsn_slot(op->optinsn.insn, dirty);
+		op->optinsn.insn = NULL;
+	}
+}
+
+extern void kprobe_handler(struct pt_regs *regs);
+
+static void
+optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs)
+{
+	unsigned long flags;
+	struct kprobe_ctlblk *kcb;
+
+	if (kprobe_disabled(&op->kp))
+		return;
+
+	/* Save skipped registers */
+	regs->pc = (unsigned long)op->kp.addr;
+	regs->orig_x0 = ~0UL;
+	regs->stackframe[1] = (unsigned long)op->kp.addr + 4;
+
+	local_irq_save(flags);
+	kcb = get_kprobe_ctlblk();
+
+	if (kprobe_running()) {
+		kprobes_inc_nmissed_count(&op->kp);
+	} else {
+		__this_cpu_write(current_kprobe, &op->kp);
+		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+		opt_pre_handler(&op->kp, regs);
+		__this_cpu_write(current_kprobe, NULL);
+	}
+
+	local_irq_restore(flags);
+}
+NOKPROBE_SYMBOL(optimized_callback)
+
+int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *orig)
+{
+	kprobe_opcode_t *code;
+	void **addrs;
+	long offset;
+	kprobe_opcode_t final_branch;
+	u32 insns[8];
+	int i;
+
+	if (!can_optimize(orig))
+		return -EILSEQ;
+
+	/* Allocate instruction slot */
+	code = get_optinsn_slot();
+	if (!code)
+		return -ENOMEM;
+
+	/* use a 'b' instruction to branch to optinsn.insn.
+	 * according armv8 manual, branch range is +/-128MB,
+	 * is encoded as "imm26" times 4.
+	 *   31  30      26
+	 *  +---+-----------+----------------+
+	 *  | 0 | 0 0 1 0 1 |      imm26     |
+	 *  +---+-----------+----------------+
+	 */
+	offset = (long)code - (long)orig->addr;
+
+	if (offset > 0x7ffffffL || offset < -0x8000000 || offset & 0x3) {
+
+		free_optinsn_slot(code, 0);
+		return -ERANGE;
+	}
+
+	addrs = kmalloc(MAX_OPTINSN_SIZE * sizeof(kprobe_opcode_t *), GFP_KERNEL);
+	for (i = 0; i < MAX_OPTINSN_SIZE; i++)
+		addrs[i] = &code[i];
+
+	/* Copy arch-dep-instance from template. */
+	aarch64_insn_patch_text(addrs,
+				(kprobe_opcode_t *)&optprobe_template_entry,
+				TMPL_RESTORE_ORIGN_INSN);
+
+	/* Set probe information */
+	*(unsigned long *)&insns[TMPL_VAL_IDX-TMPL_RESTORE_ORIGN_INSN] = (unsigned long)op;
+
+
+	/* Set probe function call */
+	*(unsigned long *)&insns[TMPL_CALL_IDX-TMPL_RESTORE_ORIGN_INSN] = (unsigned long)optimized_callback;
+
+	final_branch = aarch64_insn_gen_branch_imm((unsigned long)(&code[TMPL_RESTORE_END]),
+						   (unsigned long)(op->kp.addr) + 4,
+						   AARCH64_INSN_BRANCH_NOLINK);
+
+	/* The original probed instruction */
+	if (orig->ainsn.api.insn)
+		insns[0] = orig->opcode;
+	else
+		insns[0] = 0xd503201f; /*nop*/
+
+	/* Jump back to next instruction */
+	insns[1] = final_branch;
+
+	aarch64_insn_patch_text(addrs + TMPL_RESTORE_ORIGN_INSN,
+				insns,
+				TMPL_END_IDX - TMPL_RESTORE_ORIGN_INSN);
+
+	flush_icache_range((unsigned long)code, (unsigned long)(&code[TMPL_END_IDX]));
+
+	/* Set op->optinsn.insn means prepared. */
+	op->optinsn.insn = code;
+
+	kfree(addrs);
+
+	return 0;
+}
+
+void __kprobes arch_optimize_kprobes(struct list_head *oplist)
+{
+	struct optimized_kprobe *op, *tmp;
+
+	list_for_each_entry_safe(op, tmp, oplist, list) {
+		unsigned long insn;
+		void *addrs[] = {0};
+		u32 insns[] = {0};
+
+		WARN_ON(kprobe_disabled(&op->kp));
+
+		/*
+		 * Backup instructions which will be replaced
+		 * by jump address
+		 */
+		memcpy(op->optinsn.copied_insn, op->kp.addr,
+				AARCH64_INSN_SIZE);
+
+		insn = aarch64_insn_gen_branch_imm((unsigned long)op->kp.addr,
+						   (unsigned long)op->optinsn.insn,
+						   AARCH64_INSN_BRANCH_NOLINK);
+
+		insns[0] = insn;
+		addrs[0] = op->kp.addr;
+
+		aarch64_insn_patch_text(addrs, insns, 1);
+
+		list_del_init(&op->list);
+	}
+}
+
+void arch_unoptimize_kprobe(struct optimized_kprobe *op)
+{
+	arch_arm_kprobe(&op->kp);
+}
+
+/*
+ * Recover original instructions and breakpoints from relative jumps.
+ * Caller must call with locking kprobe_mutex.
+ */
+void arch_unoptimize_kprobes(struct list_head *oplist,
+			    struct list_head *done_list)
+{
+	struct optimized_kprobe *op, *tmp;
+
+	list_for_each_entry_safe(op, tmp, oplist, list) {
+		arch_unoptimize_kprobe(op);
+		list_move(&op->list, done_list);
+	}
+}
+
+int arch_within_optimized_kprobe(struct optimized_kprobe *op,
+				unsigned long addr)
+{
+	return ((unsigned long)op->kp.addr <= addr &&
+		(unsigned long)op->kp.addr + AARCH64_INSN_SIZE > addr);
+}
+
+void arch_remove_optimized_kprobe(struct optimized_kprobe *op)
+{
+	__arch_remove_optimized_kprobe(op, 1);
+}
diff --git a/arch/arm64/kernel/probes/opt_head.S b/arch/arm64/kernel/probes/opt_head.S
new file mode 100644
index 0000000..0b437c3
--- /dev/null
+++ b/arch/arm64/kernel/probes/opt_head.S
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0-only
+ * Copyright 2021 Unisoc Inc.
+ */
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+#include <asm/assembler.h>
+#include "base_regs.h"
+	.align 2
+	.global optinsn_slot
+	optinsn_slot:
+	.space  4096
+	.global optprobe_template_entry
+	optprobe_template_entry:
+
+	save_all_base_regs
+
+	mov	x1, sp
+	ldr	x0, 1f
+	ldr	x2, 2f
+	blr	x2
+	nop
+
+	restore_all_base_regs 1
+
+	.global optprobe_template_restore_orig_insn
+	optprobe_template_restore_orig_insn:
+	nop
+	.global optprobe_template_restore_end
+	optprobe_template_restore_end:
+	nop
+	.align 3
+	.global optprobe_template_val
+	optprobe_template_val:
+1:	.space 8
+	.global optprobe_template_call
+	optprobe_template_call:
+2:	.space 8
+	.global optprobe_template_end
+	optprobe_template_end:
+
-- 
1.9.1


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[PATCH v1 2/2] arm64: kprobes: add support for KPROBES_ON_FTRACE

[Janet Liu]

From: Janet Liu <janet.liu@unisoc.com>

This patch allow kprobes on ftrace call sites. This optimization
avoids use of a trap with regular kprobes.

This depends on HAVE_DYNAMIC_FTRACE_WITH_REGS which depends on
"patchable-function-entry" options which is only implemented with newer
toolchains.

Signed-off-by: Janet Liu <janet.liu@unisoc.com>
---
 arch/arm64/Kconfig                 |  1 +
 arch/arm64/kernel/probes/Makefile  |  1 +
 arch/arm64/kernel/probes/ftrace.c  | 73 ++++++++++++++++++++++++++++++++++++++
 arch/arm64/kernel/probes/kprobes.c | 27 ++++++++++++++
 4 files changed, 102 insertions(+)
 create mode 100644 arch/arm64/kernel/probes/ftrace.c

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index ab07251..c3fd0dd 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -200,6 +200,7 @@ config ARM64
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES
 	select HAVE_OPTPROBES
+	select HAVE_KPROBES_ON_FTRACE
 	select HAVE_KRETPROBES
 	select HAVE_GENERIC_VDSO
 	select IOMMU_DMA if IOMMU_SUPPORT
diff --git a/arch/arm64/kernel/probes/Makefile b/arch/arm64/kernel/probes/Makefile
index c77c92a..d9b204f 100644
--- a/arch/arm64/kernel/probes/Makefile
+++ b/arch/arm64/kernel/probes/Makefile
@@ -3,5 +3,6 @@ obj-$(CONFIG_KPROBES)		+= kprobes.o decode-insn.o	\
 				   kprobes_trampoline.o		\
 				   simulate-insn.o
 obj-$(CONFIG_OPTPROBES) 	+= opt.o opt_head.o
+obj-$(CONFIG_KPROBES_ON_FTRACE) += ftrace.o
 obj-$(CONFIG_UPROBES)		+= uprobes.o decode-insn.o	\
 				   simulate-insn.o
diff --git a/arch/arm64/kernel/probes/ftrace.c b/arch/arm64/kernel/probes/ftrace.c
new file mode 100644
index 0000000..46ea92e
--- /dev/null
+++ b/arch/arm64/kernel/probes/ftrace.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Dynamic Ftrace based Kprobes Optimization
+//
+// Copyright (C) 2021, Unisoc Inc.
+// Author: Janet Liu <janet.liu@unisoc.com>
+#include <linux/kprobes.h>
+#include <linux/ptrace.h>
+#include <linux/hardirq.h>
+#include <linux/preempt.h>
+#include <linux/ftrace.h>
+
+
+/* Ftrace callback handler for kprobes*/
+void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
+			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
+{
+	struct kprobe *p;
+	struct kprobe_ctlblk *kcb;
+	struct pt_regs *regs = ftrace_get_regs(fregs);
+	int bit;
+
+	bit = ftrace_test_recursion_trylock(ip, parent_ip);
+	if (bit < 0)
+		return;
+
+	preempt_disable_notrace();
+	p = get_kprobe((kprobe_opcode_t *)ip);
+	if (unlikely(!p) || kprobe_disabled(p))
+		goto end;
+
+	kcb = get_kprobe_ctlblk();
+	if (kprobe_running()) {
+		kprobes_inc_nmissed_count(p);
+	} else {
+		unsigned long orig_ip = instruction_pointer(regs);
+
+		instruction_pointer_set(regs, ip);
+
+		__this_cpu_write(current_kprobe, p);
+		kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+		if (!p->pre_handler || !p->pre_handler(p, regs)) {
+			/*
+			 *Emulate singlestep (and also recover regs->pc)
+			 *as if there is a nop
+			 */
+			instruction_pointer_set(regs,
+					(unsigned long)p->addr + MCOUNT_INSN_SIZE);
+			if (unlikely(p->post_handler)) {
+				kcb->kprobe_status = KPROBE_HIT_SSDONE;
+				p->post_handler(p, regs, 0);
+			}
+			instruction_pointer_set(regs, orig_ip);
+		}
+
+		/*
+		 * If pre_handler returns !0,it changes regs->pc. We have to
+		 * skip emulating post_handler.
+		 */
+		__this_cpu_write(current_kprobe, NULL);
+	}
+end:
+	preempt_enable_notrace();
+	ftrace_test_recursion_unlock(bit);
+}
+NOKPROBE_SYMBOL(kprobe_ftrace_handler);
+
+int arch_prepare_kprobe_ftrace(struct kprobe *p)
+{
+	p->ainsn.api.insn = NULL;
+	p->ainsn.api.restore = 0;
+	return 0;
+}
diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
index 6dbcc89..3d371d3 100644
--- a/arch/arm64/kernel/probes/kprobes.c
+++ b/arch/arm64/kernel/probes/kprobes.c
@@ -417,6 +417,33 @@ int __kprobes arch_trampoline_kprobe(struct kprobe *p)
 	return 0;
 }
 
+kprobe_opcode_t __kprobes *kprobe_lookup_name(const char *name, unsigned int offset)
+{
+	kprobe_opcode_t *addr;
+
+	addr = (kprobe_opcode_t *)kallsyms_lookup_name(name);
+#ifdef CONFIG_KPROBES_ON_FTRACE
+	if (addr && !offset) {
+		unsigned long faddr;
+
+		faddr = ftrace_location_range((unsigned long)addr,
+					      (unsigned long)addr + 8);
+		if (faddr)
+			addr = (kprobe_opcode_t *)faddr;
+	}
+#endif
+	return addr;
+}
+
+bool __kprobes arch_kprobe_on_func_entry(unsigned long offset)
+{
+#ifdef CONFIG_KPROBES_ON_FTRACE
+	return offset <= 8;
+#else
+	return !offset;
+#endif
+}
+
 int __init arch_init_kprobes(void)
 {
 	register_kernel_break_hook(&kprobes_break_hook);
-- 
1.9.1


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Re: [PATCH v1 1/2] arm64: kprobes: implement optprobes

[kernel test robot]

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Hi Janet,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on arm64/for-next/core]
[also build test ERROR on v5.15-rc7]
[cannot apply to next-20211029]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Janet-Liu/arm64-kprobes-implement-optprobes/20211029-203008
base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
config: arm64-randconfig-r013-20211028 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 5db7568a6a1fcb408eb8988abdaff2a225a8eb72)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install arm64 cross compiling tool for clang build
        # apt-get install binutils-aarch64-linux-gnu
        # https://github.com/0day-ci/linux/commit/de1ae53eec913c9f0e37aff234c567ee7d2f8582
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Janet-Liu/arm64-kprobes-implement-optprobes/20211029-203008
        git checkout de1ae53eec913c9f0e37aff234c567ee7d2f8582
        # save the attached .config to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> <instantiation>:1:5: error: expected absolute expression
   .if trampoline == 0
       ^
   arch/arm64/kernel/probes/kprobes_trampoline.S:25:2: note: while in macro instantiation
    restore_all_base_regs
    ^
--
>> <instantiation>:1:5: error: expected absolute expression
   .if trampoline == 0
       ^
   arch/arm64/kernel/probes/opt_head.S:23:2: note: while in macro instantiation
    restore_all_base_regs 1
    ^

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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