ARM: add uprobes support

Using Rabin Vincent's ARM uprobes patches as a base, enable uprobes
support on ARM.

Caveats:

 - Thumb is not supported

Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: David A. Long <dave.long@linaro.org>

9 files changed, 542 insertions, 1 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index e25419817791..4d05bb93714a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -207,6 +207,9 @@ config ZONE_DMA
 config NEED_DMA_MAP_STATE
        def_bool y
 
+config ARCH_SUPPORTS_UPROBES
+        def_bool y
+
 config ARCH_HAS_DMA_SET_COHERENT_MASK
         bool
 
diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 04c99f36ff7f..ee688b0a13c3 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -80,6 +80,12 @@ static inline long regs_return_value(struct pt_regs *regs)
 
 #define instruction_pointer(regs)       (regs)->ARM_pc
 
+static inline void instruction_pointer_set(struct pt_regs *regs,
+                                           unsigned long val)
+{
+        instruction_pointer(regs) = val;
+}
+
 #ifdef CONFIG_SMP
 extern unsigned long profile_pc(struct pt_regs *regs);
 #else
diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
index 71a06b293489..f989d7c22dc5 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -153,6 +153,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,
 #define TIF_SIGPENDING          0
 #define TIF_NEED_RESCHED        1
 #define TIF_NOTIFY_RESUME       2       /* callback before returning to user */
+#define TIF_UPROBE              7
 #define TIF_SYSCALL_TRACE       8
 #define TIF_SYSCALL_AUDIT       9
 #define TIF_SYSCALL_TRACEPOINT  10
@@ -165,6 +166,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,
 #define _TIF_SIGPENDING         (1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED       (1 << TIF_NEED_RESCHED)
 #define _TIF_NOTIFY_RESUME      (1 << TIF_NOTIFY_RESUME)
+#define _TIF_UPROBE             (1 << TIF_UPROBE)
 #define _TIF_SYSCALL_TRACE      (1 << TIF_SYSCALL_TRACE)
 #define _TIF_SYSCALL_AUDIT      (1 << TIF_SYSCALL_AUDIT)
 #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
@@ -178,7 +180,8 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *,
 /*
  * Change these and you break ASM code in entry-common.S
  */
-#define _TIF_WORK_MASK          (_TIF_NEED_RESCHED | _TIF_SIGPENDING | _TIF_NOTIFY_RESUME)
+#define _TIF_WORK_MASK          (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
+                                 _TIF_NOTIFY_RESUME | _TIF_UPROBE)
 
 #endif /* __KERNEL__ */
 #endif /* __ASM_ARM_THREAD_INFO_H */
diff --git a/arch/arm/include/asm/uprobes.h b/arch/arm/include/asm/uprobes.h
new file mode 100644
index 000000000000..9472c20b7d49
--- /dev/null
+++ b/arch/arm/include/asm/uprobes.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2012 Rabin Vincent <rabin at rab.in>
+ *
+ * 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/probes.h>
+#include <asm/opcodes.h>
+
+typedef u32 uprobe_opcode_t;
+
+#define MAX_UINSN_BYTES         4
+#define UPROBE_XOL_SLOT_BYTES   64
+
+#define UPROBE_SWBP_ARM_INSN    0xe7f001f9
+#define UPROBE_SS_ARM_INSN      0xe7f001fa
+#define UPROBE_SWBP_INSN        __opcode_to_mem_arm(UPROBE_SWBP_ARM_INSN)
+#define UPROBE_SWBP_INSN_SIZE   4
+
+struct arch_uprobe_task {
+        u32 backup;
+        unsigned long   saved_trap_no;
+};
+
+struct arch_uprobe {
+        u8 insn[MAX_UINSN_BYTES];
+        unsigned long ixol[2];
+        uprobe_opcode_t bpinsn;
+        bool simulate;
+        u32 pcreg;
+        void (*prehandler)(struct arch_uprobe *auprobe,
+                           struct arch_uprobe_task *autask,
+                           struct pt_regs *regs);
+        void (*posthandler)(struct arch_uprobe *auprobe,
+                            struct arch_uprobe_task *autask,
+                            struct pt_regs *regs);
+        struct arch_probes_insn asi;
+};
+
+#endif
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index bb739f28dd80..a766bcbaf8ad 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_DYNAMIC_FTRACE)	+= ftrace.o insn.o
 obj-$(CONFIG_FUNCTION_GRAPH_TRACER)     += ftrace.o insn.o
 obj-$(CONFIG_JUMP_LABEL)        += jump_label.o insn.o patch.o
 obj-$(CONFIG_KEXEC)             += machine_kexec.o relocate_kernel.o
+obj-$(CONFIG_UPROBES)           += probes.o probes-arm.o uprobes.o uprobes-arm.o
 obj-$(CONFIG_KPROBES)           += probes.o kprobes.o kprobes-common.o patch.o
 ifdef CONFIG_THUMB2_KERNEL
 obj-$(CONFIG_KPROBES)           += kprobes-thumb.o probes-thumb.o
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 04d63880037f..bd1983437205 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -13,6 +13,7 @@
 #include <linux/personality.h>
 #include <linux/uaccess.h>
 #include <linux/tracehook.h>
+#include <linux/uprobes.h>
 
 #include <asm/elf.h>
 #include <asm/cacheflush.h>
@@ -590,6 +591,9 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
                                         return restart;
                                 }
                                 syscall = 0;
+                        } else if (thread_flags & _TIF_UPROBE) {
+                                clear_thread_flag(TIF_UPROBE);
+                                uprobe_notify_resume(regs);
                         } else {
                                 clear_thread_flag(TIF_NOTIFY_RESUME);
                                 tracehook_notify_resume(regs);
diff --git a/arch/arm/kernel/uprobes-arm.c b/arch/arm/kernel/uprobes-arm.c
new file mode 100644
index 000000000000..d3b655ff17da
--- /dev/null
+++ b/arch/arm/kernel/uprobes-arm.c
@@ -0,0 +1,234 @@
+/*
+ * Copyright (C) 2012 Rabin Vincent <rabin at rab.in>
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/stddef.h>
+#include <linux/wait.h>
+#include <linux/uprobes.h>
+#include <linux/module.h>
+
+#include "probes.h"
+#include "probes-arm.h"
+#include "uprobes.h"
+
+static int uprobes_substitute_pc(unsigned long *pinsn, u32 oregs)
+{
+        probes_opcode_t insn = __mem_to_opcode_arm(*pinsn);
+        probes_opcode_t temp;
+        probes_opcode_t mask;
+        int freereg;
+        u32 free = 0xffff;
+        u32 regs;