arm64: Add uprobe support

This patch adds support for uprobe on ARM64 architecture.

Unit tests for following have been done so far and they have been found
working
    1. Step-able instructions, like sub, ldr, add etc.
    2. Simulation-able like ret, cbnz, cbz etc.
    3. uretprobe
    4. Reject-able instructions like sev, wfe etc.
    5. trapped and abort xol path
    6. probe at unaligned user address.
    7. longjump test cases

Currently it does not support aarch32 instruction probing.

Signed-off-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

5 files changed, 52 insertions, 1 deletions

diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
index 2e5fb976a572..e9f64ecb75ce 100644
--- a/arch/arm64/include/asm/cacheflush.h
+++ b/arch/arm64/include/asm/cacheflush.h
@@ -71,6 +71,7 @@ extern void __flush_dcache_area(void *addr, size_t len);
 extern void __clean_dcache_area_poc(void *addr, size_t len);
 extern void __clean_dcache_area_pou(void *addr, size_t len);
 extern long __flush_cache_user_range(unsigned long start, unsigned long end);
+extern void sync_icache_aliases(void *kaddr, unsigned long len);
 
 static inline void flush_cache_mm(struct mm_struct *mm)
 {
diff --git a/arch/arm64/include/asm/debug-monitors.h b/arch/arm64/include/asm/debug-monitors.h
index b71420a12f26..a44cf5225429 100644
--- a/arch/arm64/include/asm/debug-monitors.h
+++ b/arch/arm64/include/asm/debug-monitors.h
@@ -68,6 +68,9 @@
 #define BRK64_ESR_MASK		0xFFFF
 #define BRK64_ESR_KPROBES	0x0004
 #define BRK64_OPCODE_KPROBES	(AARCH64_BREAK_MON | (BRK64_ESR_KPROBES << 5))
+/* uprobes BRK opcodes with ESR encoding  */
+#define BRK64_ESR_UPROBES	0x0005
+#define BRK64_OPCODE_UPROBES	(AARCH64_BREAK_MON | (BRK64_ESR_UPROBES << 5))
 
 /* AArch32 */
 #define DBG_ESR_EVT_BKPT	0x4
diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index ada08b5b036d..513daf050e84 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -217,6 +217,14 @@ int valid_user_regs(struct user_pt_regs *regs, struct task_struct *task);
 
 #include <asm-generic/ptrace.h>
 
+#define procedure_link_pointer(regs)	((regs)->regs[30])
+
+static inline void procedure_link_pointer_set(struct pt_regs *regs,
+					   unsigned long val)
+{
+	procedure_link_pointer(regs) = val;
+}
+
 #undef profile_pc
 extern unsigned long profile_pc(struct pt_regs *regs);
 
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index e9ea5a6bd449..f6859831462e 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -112,6 +112,7 @@ static inline struct thread_info *current_thread_info(void)
 #define TIF_NEED_RESCHED	1
 #define TIF_NOTIFY_RESUME	2	/* callback before returning to user */
 #define TIF_FOREIGN_FPSTATE	3	/* CPU's FP state is not current's */
+#define TIF_UPROBE		4	/* uprobe breakpoint or singlestep */
 #define TIF_NOHZ		7
 #define TIF_SYSCALL_TRACE	8
 #define TIF_SYSCALL_AUDIT	9
@@ -132,10 +133,12 @@ static inline struct thread_info *current_thread_info(void)
 #define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SYSCALL_TRACEPOINT	(1 << TIF_SYSCALL_TRACEPOINT)
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
+#define _TIF_UPROBE		(1 << TIF_UPROBE)
 #define _TIF_32BIT		(1 << TIF_32BIT)
 
 #define _TIF_WORK_MASK		(_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
-				 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE)
+				 _TIF_NOTIFY_RESUME | _TIF_FOREIGN_FPSTATE | \
+				 _TIF_UPROBE)
 
 #define _TIF_SYSCALL_WORK	(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
 				 _TIF_SYSCALL_TRACEPOINT | _TIF_SECCOMP | \
diff --git a/arch/arm64/include/asm/uprobes.h b/arch/arm64/include/asm/uprobes.h
new file mode 100644
index 000000000000..8d004073d0e8
--- /dev/null
+++ b/arch/arm64/include/asm/uprobes.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2014-2016 Pratyush Anand <panand@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _ASM_UPROBES_H
+#define _ASM_UPROBES_H
+
+#include <asm/debug-monitors.h>
+#include <asm/insn.h>
+#include <asm/probes.h>
+
+#define MAX_UINSN_BYTES		AARCH64_INSN_SIZE
+
+#define UPROBE_SWBP_INSN	BRK64_OPCODE_UPROBES
+#define UPROBE_SWBP_INSN_SIZE	AARCH64_INSN_SIZE
+#define UPROBE_XOL_SLOT_BYTES	MAX_UINSN_BYTES
+
+typedef u32 uprobe_opcode_t;
+
+struct arch_uprobe_task {
+};
+
+struct arch_uprobe {
+	union {
+		u8 insn[MAX_UINSN_BYTES];
+		u8 ixol[MAX_UINSN_BYTES];
+	};
+	struct arch_probe_insn api;
+	bool simulate;
+};
+
+#endif