[PATCH 9/9] ARM: add uprobes support
Rabin Vincent
rabin at rab.in
Sun Oct 14 15:23:13 EDT 2012
Add basic uprobes support for ARM.
perf probe --exec and SystemTap's userspace probing work. The ARM
kprobes test code has also been run in a userspace harness to test the
uprobe instruction decoding.
Caveats:
- Thumb is not supported
- XOL abort/trap handling is not implemented
Signed-off-by: Rabin Vincent <rabin at rab.in>
---
arch/arm/Kconfig | 4 +
arch/arm/include/asm/ptrace.h | 6 ++
arch/arm/include/asm/thread_info.h | 5 +-
arch/arm/include/asm/uprobes.h | 34 +++++++
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/signal.c | 4 +
arch/arm/kernel/uprobes.c | 191 ++++++++++++++++++++++++++++++++++++
7 files changed, 244 insertions(+), 1 deletion(-)
create mode 100644 arch/arm/include/asm/uprobes.h
create mode 100644 arch/arm/kernel/uprobes.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 272c3a1..2191b61d 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -168,6 +168,10 @@ config ZONE_DMA
config NEED_DMA_MAP_STATE
def_bool y
+config ARCH_SUPPORTS_UPROBES
+ depends on KPROBES
+ 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 142d6ae..297936a 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -197,6 +197,12 @@ 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 8477b4c..7bedaee 100644
--- a/arch/arm/include/asm/thread_info.h
+++ b/arch/arm/include/asm/thread_info.h
@@ -148,6 +148,7 @@ 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
@@ -160,6 +161,7 @@ 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)
@@ -172,7 +174,8 @@ 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 0000000..fa4b81e
--- /dev/null
+++ b/arch/arm/include/asm/uprobes.h
@@ -0,0 +1,34 @@
+#ifndef _ASM_UPROBES_H
+#define _ASM_UPROBES_H
+
+#include <asm/probes.h>
+
+typedef u32 uprobe_opcode_t;
+
+#define MAX_UINSN_BYTES 4
+#define UPROBE_XOL_SLOT_BYTES 64
+
+#define UPROBE_SWBP_INSN 0x07f001f9
+#define UPROBE_SS_INSN 0x07f001fa
+#define UPROBE_SWBP_INSN_SIZE 4
+
+struct arch_uprobe_task {
+ u32 backup;
+};
+
+struct arch_uprobe {
+ u8 insn[MAX_UINSN_BYTES];
+ uprobe_opcode_t modinsn;
+ 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_specific_insn asi;
+};
+
+#endif
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 5bbec7b..a39f634 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -40,6 +40,7 @@ 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-$(CONFIG_UPROBES) += uprobes.o uprobes-arm.o kprobes-arm.o
obj-$(CONFIG_KPROBES) += kprobes.o kprobes-common.o patch.o
ifdef CONFIG_THUMB2_KERNEL
obj-$(CONFIG_KPROBES) += kprobes-thumb.o
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
index 56f72d2..3b1e88e 100644
--- a/arch/arm/kernel/signal.c
+++ b/arch/arm/kernel/signal.c
@@ -12,6 +12,7 @@
#include <linux/personality.h>
#include <linux/uaccess.h>
#include <linux/tracehook.h>
+#include <linux/uprobes.h>
#include <asm/elf.h>
#include <asm/cacheflush.h>
@@ -655,6 +656,9 @@ 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.c b/arch/arm/kernel/uprobes.c
new file mode 100644
index 0000000..f25a4af
--- /dev/null
+++ b/arch/arm/kernel/uprobes.c
@@ -0,0 +1,191 @@
+/*
+ * 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/sched.h>
+#include <linux/uprobes.h>
+#include <linux/notifier.h>
+#include <linux/kprobes.h>
+
+#include <asm/opcodes.h>
+#include <asm/traps.h>
+
+#include "kprobes.h"
+
+bool is_swbp_insn(uprobe_opcode_t *insn)
+{
+ return (__mem_to_opcode_arm(*insn) & 0x0fffffff) == UPROBE_SWBP_INSN;
+}
+
+bool arch_uprobe_ignore(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ if (!auprobe->asi.insn_check_cc(regs->ARM_cpsr)) {
+ regs->ARM_pc += 4;
+ return true;
+ }
+
+ return false;
+}
+
+bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct kprobe kp;
+
+ if (!auprobe->simulate)
+ return false;
+
+ kp.addr = (void *) regs->ARM_pc;
+ kp.opcode = __mem_to_opcode_arm(*(unsigned int *) auprobe->insn);
+ kp.ainsn.insn_handler = auprobe->asi.insn_handler;
+
+ auprobe->asi.insn_singlestep(&kp, regs);
+
+ return true;
+}
+
+int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
+ unsigned long addr)
+{
+ unsigned int insn;
+ unsigned int bpinsn;
+ enum kprobe_insn ret;
+
+ /* Thumb not yet support */
+ if (addr & 0x3)
+ return -EINVAL;
+
+ insn = __mem_to_opcode_arm(*(unsigned int *)auprobe->insn);
+ auprobe->modinsn = insn;
+
+ ret = arm_kprobe_decode_insn(insn, &auprobe->asi, true);
+ switch (ret) {
+ case INSN_REJECTED:
+ return -EINVAL;
+
+ case INSN_GOOD_NO_SLOT:
+ auprobe->simulate = true;
+ break;
+
+ case INSN_GOOD:
+ default:
+ break;
+ }
+
+ bpinsn = UPROBE_SWBP_INSN;
+ if (insn >= 0xe0000000)
+ bpinsn |= 0xe0000000; /* Unconditional instruction */
+ else
+ bpinsn |= insn & 0xf0000000; /* Copy condition from insn */
+
+ auprobe->bpinsn = bpinsn;
+
+ return 0;
+}
+
+void arch_uprobe_write_opcode(struct arch_uprobe *auprobe, void *vaddr,
+ uprobe_opcode_t opcode)
+{
+ unsigned long *addr = vaddr;
+
+ if (opcode == UPROBE_SWBP_INSN)
+ opcode = __opcode_to_mem_arm(auprobe->bpinsn);
+
+ *addr = opcode;
+}
+
+void arch_uprobe_xol_copy(struct arch_uprobe *auprobe, void *vaddr)
+{
+ unsigned long *addr = vaddr;
+
+ addr[0] = __opcode_to_mem_arm(auprobe->modinsn);
+ addr[1] = __opcode_to_mem_arm(0xe0000000 | UPROBE_SS_INSN);
+}
+
+int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ if (auprobe->prehandler)
+ auprobe->prehandler(auprobe, &utask->autask, regs);
+
+ regs->ARM_pc = utask->xol_vaddr;
+
+ return 0;
+}
+
+int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ regs->ARM_pc = utask->vaddr + 4;
+
+ if (auprobe->posthandler)
+ auprobe->posthandler(auprobe, &utask->autask, regs);
+
+ return 0;
+}
+
+bool arch_uprobe_xol_was_trapped(struct task_struct *t)
+{
+ /* TODO: implement */
+ return false;
+}
+
+void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ /* TODO: implement */
+}
+
+int arch_uprobe_exception_notify(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ return NOTIFY_DONE;
+}
+
+static int uprobe_trap_handler(struct pt_regs *regs, unsigned int instr)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ if ((instr & 0x0fffffff) == UPROBE_SWBP_INSN)
+ uprobe_pre_sstep_notifier(regs);
+ else
+ uprobe_post_sstep_notifier(regs);
+ local_irq_restore(flags);
+
+ return 0;
+}
+
+unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
+{
+ return instruction_pointer(regs);
+}
+
+static struct undef_hook uprobes_arm_break_hook = {
+ .instr_mask = 0x0fffffff,
+ .instr_val = UPROBE_SWBP_INSN,
+ .cpsr_mask = MODE_MASK,
+ .cpsr_val = USR_MODE,
+ .fn = uprobe_trap_handler,
+};
+
+static struct undef_hook uprobes_arm_ss_hook = {
+ .instr_mask = 0x0fffffff,
+ .instr_val = UPROBE_SS_INSN,
+ .cpsr_mask = MODE_MASK,
+ .cpsr_val = USR_MODE,
+ .fn = uprobe_trap_handler,
+};
+
+int arch_uprobes_init(void)
+{
+ register_undef_hook(&uprobes_arm_break_hook);
+ register_undef_hook(&uprobes_arm_ss_hook);
+
+ return 0;
+}
--
1.7.9.5
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