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Subject[PATCH v2 23/31] arm64: Debugging support
Date
From: Will Deacon <will.deacon@arm.com>

This patch adds ptrace, debug monitors and hardware breakpoints support.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---
arch/arm64/include/asm/debug-monitors.h | 88 +++
arch/arm64/include/asm/hw_breakpoint.h | 137 +++++
arch/arm64/kernel/debug-monitors.c | 288 ++++++++++
arch/arm64/kernel/hw_breakpoint.c | 880 +++++++++++++++++++++++++++++++
arch/arm64/kernel/ptrace.c | 834 +++++++++++++++++++++++++++++
5 files changed, 2227 insertions(+), 0 deletions(-)
create mode 100644 arch/arm64/include/asm/debug-monitors.h
create mode 100644 arch/arm64/include/asm/hw_breakpoint.h
create mode 100644 arch/arm64/kernel/debug-monitors.c
create mode 100644 arch/arm64/kernel/hw_breakpoint.c
create mode 100644 arch/arm64/kernel/ptrace.c
diff --git a/arch/arm64/include/asm/debug-monitors.h b/arch/arm64/include/asm/debug-monitors.h
new file mode 100644
index 0000000..7eaa0b3
--- /dev/null
+++ b/arch/arm64/include/asm/debug-monitors.h
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_DEBUG_MONITORS_H
+#define __ASM_DEBUG_MONITORS_H
+
+#ifdef __KERNEL__
+
+#define DBG_ESR_EVT(x) (((x) >> 27) & 0x7)
+
+/* AArch64 */
+#define DBG_ESR_EVT_HWBP 0x0
+#define DBG_ESR_EVT_HWSS 0x1
+#define DBG_ESR_EVT_HWWP 0x2
+#define DBG_ESR_EVT_BRK 0x6
+
+enum debug_el {
+ DBG_ACTIVE_EL0 = 0,
+ DBG_ACTIVE_EL1,
+};
+
+/* AArch32 */
+#define DBG_ESR_EVT_BKPT 0x4
+#define DBG_ESR_EVT_VECC 0x5
+
+#define AARCH32_BREAK_ARM 0x07f001f0
+#define AARCH32_BREAK_THUMB 0xde01
+#define AARCH32_BREAK_THUMB2_LO 0xf7f0
+#define AARCH32_BREAK_THUMB2_HI 0xa000
+
+#ifndef __ASSEMBLY__
+struct task_struct;
+
+#define local_dbg_save(flags) \
+ do { \
+ typecheck(unsigned long, flags); \
+ asm volatile( \
+ "mrs %0, daif // local_dbg_save\n" \
+ "msr daifset, #8" \
+ : "=r" (flags) : : "memory"); \
+ } while (0)
+
+#define local_dbg_restore(flags) \
+ do { \
+ typecheck(unsigned long, flags); \
+ asm volatile( \
+ "msr daif, %0 // local_dbg_restore\n" \
+ : : "r" (flags) : "memory"); \
+ } while (0)
+
+#define DBG_ARCH_ID_RESERVED 0 /* In case of ptrace ABI updates. */
+
+u8 debug_monitors_arch(void);
+
+void enable_debug_monitors(enum debug_el el);
+void disable_debug_monitors(enum debug_el el);
+
+void user_rewind_single_step(struct task_struct *task);
+void user_fastforward_single_step(struct task_struct *task);
+
+void kernel_enable_single_step(struct pt_regs *regs);
+void kernel_disable_single_step(void);
+int kernel_active_single_step(void);
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+int reinstall_suspended_bps(struct pt_regs *regs);
+#else
+static inline int reinstall_suspended_bps(struct pt_regs *regs)
+{
+ return -ENODEV;
+}
+#endif
+
+#endif /* __ASSEMBLY */
+#endif /* __KERNEL__ */
+#endif /* __ASM_DEBUG_MONITORS_H */
diff --git a/arch/arm64/include/asm/hw_breakpoint.h b/arch/arm64/include/asm/hw_breakpoint.h
new file mode 100644
index 0000000..d064047
--- /dev/null
+++ b/arch/arm64/include/asm/hw_breakpoint.h
@@ -0,0 +1,137 @@
+/*
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_HW_BREAKPOINT_H
+#define __ASM_HW_BREAKPOINT_H
+
+#ifdef __KERNEL__
+
+struct arch_hw_breakpoint_ctrl {
+ u32 __reserved : 19,
+ len : 8,
+ type : 2,
+ privilege : 2,
+ enabled : 1;
+};
+
+struct arch_hw_breakpoint {
+ u64 address;
+ u64 trigger;
+ struct arch_hw_breakpoint_ctrl ctrl;
+};
+
+static inline u32 encode_ctrl_reg(struct arch_hw_breakpoint_ctrl ctrl)
+{
+ return (ctrl.len << 5) | (ctrl.type << 3) | (ctrl.privilege << 1) |
+ ctrl.enabled;
+}
+
+static inline void decode_ctrl_reg(u32 reg,
+ struct arch_hw_breakpoint_ctrl *ctrl)
+{
+ ctrl->enabled = reg & 0x1;
+ reg >>= 1;
+ ctrl->privilege = reg & 0x3;
+ reg >>= 2;
+ ctrl->type = reg & 0x3;
+ reg >>= 2;
+ ctrl->len = reg & 0xff;
+}
+
+/* Breakpoint */
+#define ARM_BREAKPOINT_EXECUTE 0
+
+/* Watchpoints */
+#define ARM_BREAKPOINT_LOAD 1
+#define ARM_BREAKPOINT_STORE 2
+#define AARCH64_ESR_ACCESS_MASK (1 << 6)
+
+/* Privilege Levels */
+#define AARCH64_BREAKPOINT_EL1 1
+#define AARCH64_BREAKPOINT_EL0 2
+
+/* Lengths */
+#define ARM_BREAKPOINT_LEN_1 0x1
+#define ARM_BREAKPOINT_LEN_2 0x3
+#define ARM_BREAKPOINT_LEN_4 0xf
+#define ARM_BREAKPOINT_LEN_8 0xff
+
+/* Kernel stepping */
+#define ARM_KERNEL_STEP_NONE 0
+#define ARM_KERNEL_STEP_ACTIVE 1
+#define ARM_KERNEL_STEP_SUSPEND 2
+
+/*
+ * Limits.
+ * Changing these will require modifications to the register accessors.
+ */
+#define ARM_MAX_BRP 16
+#define ARM_MAX_WRP 16
+#define ARM_MAX_HBP_SLOTS (ARM_MAX_BRP + ARM_MAX_WRP)
+
+/* Virtual debug register bases. */
+#define AARCH64_DBG_REG_BVR 0
+#define AARCH64_DBG_REG_BCR (AARCH64_DBG_REG_BVR + ARM_MAX_BRP)
+#define AARCH64_DBG_REG_WVR (AARCH64_DBG_REG_BCR + ARM_MAX_BRP)
+#define AARCH64_DBG_REG_WCR (AARCH64_DBG_REG_WVR + ARM_MAX_WRP)
+
+/* Debug register names. */
+#define AARCH64_DBG_REG_NAME_BVR "bvr"
+#define AARCH64_DBG_REG_NAME_BCR "bcr"
+#define AARCH64_DBG_REG_NAME_WVR "wvr"
+#define AARCH64_DBG_REG_NAME_WCR "wcr"
+
+/* Accessor macros for the debug registers. */
+#define AARCH64_DBG_READ(N, REG, VAL) do {\
+ asm volatile("mrs %0, dbg" REG #N "_el1" : "=r" (VAL));\
+} while (0)
+
+#define AARCH64_DBG_WRITE(N, REG, VAL) do {\
+ asm volatile("msr dbg" REG #N "_el1, %0" :: "r" (VAL));\
+} while (0)
+
+struct task_struct;
+struct notifier_block;
+struct perf_event;
+struct pmu;
+
+extern int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
+ int *gen_len, int *gen_type);
+extern int arch_check_bp_in_kernelspace(struct perf_event *bp);
+extern int arch_validate_hwbkpt_settings(struct perf_event *bp);
+extern int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
+ unsigned long val, void *data);
+
+extern int arch_install_hw_breakpoint(struct perf_event *bp);
+extern void arch_uninstall_hw_breakpoint(struct perf_event *bp);
+extern void hw_breakpoint_pmu_read(struct perf_event *bp);
+extern int hw_breakpoint_slots(int type);
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+extern void hw_breakpoint_thread_switch(struct task_struct *next);
+extern void ptrace_hw_copy_thread(struct task_struct *task);
+#else
+static inline void hw_breakpoint_thread_switch(struct task_struct *next)
+{
+}
+static inline void ptrace_hw_copy_thread(struct task_struct *task)
+{
+}
+#endif
+
+extern struct pmu perf_ops_bp;
+
+#endif /* __KERNEL__ */
+#endif /* __ASM_BREAKPOINT_H */
diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
new file mode 100644
index 0000000..0c3ba9f
--- /dev/null
+++ b/arch/arm64/kernel/debug-monitors.c
@@ -0,0 +1,288 @@
+/*
+ * ARMv8 single-step debug support and mdscr context switching.
+ *
+ * Copyright (C) 2012 ARM Limited
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ */
+
+#include <linux/cpu.h>
+#include <linux/debugfs.h>
+#include <linux/hardirq.h>
+#include <linux/init.h>
+#include <linux/ptrace.h>
+#include <linux/stat.h>
+
+#include <asm/debug-monitors.h>
+#include <asm/local.h>
+#include <asm/cputype.h>
+#include <asm/system_misc.h>
+
+/* Low-level stepping controls. */
+#define DBG_MDSCR_SS (1 << 0)
+#define DBG_SPSR_SS (1 << 21)
+
+/* MDSCR_EL1 enabling bits */
+#define DBG_MDSCR_KDE (1 << 13)
+#define DBG_MDSCR_MDE (1 << 15)
+#define DBG_MDSCR_MASK ~(DBG_MDSCR_KDE | DBG_MDSCR_MDE)
+
+/* Determine debug architecture. */
+u8 debug_monitors_arch(void)
+{
+ return read_cpuid(ID_AA64DFR0_EL1) & 0xf;
+}
+
+/*
+ * MDSCR access routines.
+ */
+static void mdscr_write(u32 mdscr)
+{
+ unsigned long flags;
+ local_dbg_save(flags);
+ asm volatile("msr mdscr_el1, %0" :: "r" (mdscr));
+ local_dbg_restore(flags);
+}
+
+static u32 mdscr_read(void)
+{
+ u32 mdscr;
+ asm volatile("mrs %0, mdscr_el1" : "=r" (mdscr));
+ return mdscr;
+}
+
+/*
+ * Allow root to disable self-hosted debug from userspace.
+ * This is useful if you want to connect an external JTAG debugger.
+ */
+static u32 debug_enabled = 1;
+
+static int create_debug_debugfs_entry(void)
+{
+ debugfs_create_bool("debug_enabled", 0644, NULL, &debug_enabled);
+ return 0;
+}
+fs_initcall(create_debug_debugfs_entry);
+
+static int __init early_debug_disable(char *buf)
+{
+ debug_enabled = 0;
+ return 0;
+}
+
+early_param("nodebugmon", early_debug_disable);
+
+/*
+ * Keep track of debug users on each core.
+ * The ref counts are per-cpu so we use a local_t type.
+ */
+static DEFINE_PER_CPU(local_t, mde_ref_count);
+static DEFINE_PER_CPU(local_t, kde_ref_count);
+
+void enable_debug_monitors(enum debug_el el)
+{
+ u32 mdscr, enable = 0;
+
+ WARN_ON(preemptible());
+
+ if (local_inc_return(&__get_cpu_var(mde_ref_count)) == 1)
+ enable = DBG_MDSCR_MDE;
+
+ if (el == DBG_ACTIVE_EL1 &&
+ local_inc_return(&__get_cpu_var(kde_ref_count)) == 1)
+ enable |= DBG_MDSCR_KDE;
+
+ if (enable && debug_enabled) {
+ mdscr = mdscr_read();
+ mdscr |= enable;
+ mdscr_write(mdscr);
+ }
+}
+
+void disable_debug_monitors(enum debug_el el)
+{
+ u32 mdscr, disable = 0;
+
+ WARN_ON(preemptible());
+
+ if (local_dec_and_test(&__get_cpu_var(mde_ref_count)))
+ disable = ~DBG_MDSCR_MDE;
+
+ if (el == DBG_ACTIVE_EL1 &&
+ local_dec_and_test(&__get_cpu_var(kde_ref_count)))
+ disable &= ~DBG_MDSCR_KDE;
+
+ if (disable) {
+ mdscr = mdscr_read();
+ mdscr &= disable;
+ mdscr_write(mdscr);
+ }
+}
+
+/*
+ * OS lock clearing.
+ */
+static void clear_os_lock(void *unused)
+{
+ asm volatile("msr mdscr_el1, %0" : : "r" (0));
+ isb();
+ asm volatile("msr oslar_el1, %0" : : "r" (0));
+ isb();
+}
+
+static int __cpuinit os_lock_notify(struct notifier_block *self,
+ unsigned long action, void *data)
+{
+ int cpu = (unsigned long)data;
+ if (action == CPU_ONLINE)
+ smp_call_function_single(cpu, clear_os_lock, NULL, 1);
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata os_lock_nb = {
+ .notifier_call = os_lock_notify,
+};
+
+static int __cpuinit debug_monitors_init(void)
+{
+ /* Clear the OS lock. */
+ smp_call_function(clear_os_lock, NULL, 1);
+ clear_os_lock(NULL);
+
+ /* Register hotplug handler. */
+ register_cpu_notifier(&os_lock_nb);
+ return 0;
+}
+postcore_initcall(debug_monitors_init);
+
+/*
+ * Single step API and exception handling.
+ */
+static void set_regs_spsr_ss(struct pt_regs *regs)
+{
+ unsigned long spsr;
+
+ spsr = regs->pstate;
+ spsr &= ~DBG_SPSR_SS;
+ spsr |= DBG_SPSR_SS;
+ regs->pstate = spsr;
+}
+
+static void clear_regs_spsr_ss(struct pt_regs *regs)
+{
+ unsigned long spsr;
+
+ spsr = regs->pstate;
+ spsr &= ~DBG_SPSR_SS;
+ regs->pstate = spsr;
+}
+
+static int single_step_handler(unsigned long addr, unsigned int esr,
+ struct pt_regs *regs)
+{
+ siginfo_t info;
+
+ /*
+ * If we are stepping a pending breakpoint, call the hw_breakpoint
+ * handler first.
+ */
+ if (!reinstall_suspended_bps(regs))
+ return 0;
+
+ if (user_mode(regs)) {
+ info.si_signo = SIGTRAP;
+ info.si_errno = 0;
+ info.si_code = TRAP_HWBKPT;
+ info.si_addr = (void __user *)instruction_pointer(regs);
+ force_sig_info(SIGTRAP, &info, current);
+
+ /*
+ * ptrace will disable single step unless explicitly
+ * asked to re-enable it. For other clients, it makes
+ * sense to leave it enabled (i.e. rewind the controls
+ * to the active-not-pending state).
+ */
+ user_rewind_single_step(current);
+ } else {
+ /* TODO: route to KGDB */
+ pr_warning("Unexpected kernel single-step exception at EL1\n");
+ /*
+ * Re-enable stepping since we know that we will be
+ * returning to regs.
+ */
+ set_regs_spsr_ss(regs);
+ }
+
+ return 0;
+}
+
+static int __init single_step_init(void)
+{
+ hook_debug_fault_code(DBG_ESR_EVT_HWSS, single_step_handler, SIGTRAP,
+ TRAP_HWBKPT, "single-step handler");
+ return 0;
+}
+arch_initcall(single_step_init);
+
+/* Re-enable single step for syscall restarting. */
+void user_rewind_single_step(struct task_struct *task)
+{
+ /*
+ * If single step is active for this thread, then set SPSR.SS
+ * to 1 to avoid returning to the active-pending state.
+ */
+ if (test_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP))
+ set_regs_spsr_ss(task_pt_regs(task));
+}
+
+void user_fastforward_single_step(struct task_struct *task)
+{
+ if (test_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP))
+ clear_regs_spsr_ss(task_pt_regs(task));
+}
+
+/* Kernel API */
+void kernel_enable_single_step(struct pt_regs *regs)
+{
+ WARN_ON(!irqs_disabled());
+ set_regs_spsr_ss(regs);
+ mdscr_write(mdscr_read() | DBG_MDSCR_SS);
+ enable_debug_monitors(DBG_ACTIVE_EL1);
+}
+
+void kernel_disable_single_step(void)
+{
+ WARN_ON(!irqs_disabled());
+ mdscr_write(mdscr_read() & ~DBG_MDSCR_SS);
+ disable_debug_monitors(DBG_ACTIVE_EL1);
+}
+
+int kernel_active_single_step(void)
+{
+ WARN_ON(!irqs_disabled());
+ return mdscr_read() & DBG_MDSCR_SS;
+}
+
+/* ptrace API */
+void user_enable_single_step(struct task_struct *task)
+{
+ set_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP);
+ set_regs_spsr_ss(task_pt_regs(task));
+}
+
+void user_disable_single_step(struct task_struct *task)
+{
+ clear_ti_thread_flag(task_thread_info(task), TIF_SINGLESTEP);
+}
diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c
new file mode 100644
index 0000000..5ab825c
--- /dev/null
+++ b/arch/arm64/kernel/hw_breakpoint.c
@@ -0,0 +1,880 @@
+/*
+ * HW_breakpoint: a unified kernel/user-space hardware breakpoint facility,
+ * using the CPU's debug registers.
+ *
+ * Copyright (C) 2012 ARM Limited
+ * Author: Will Deacon <will.deacon@arm.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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define pr_fmt(fmt) "hw-breakpoint: " fmt
+
+#include <linux/errno.h>
+#include <linux/hw_breakpoint.h>
+#include <linux/perf_event.h>
+#include <linux/ptrace.h>
+#include <linux/smp.h>
+
+#include <asm/compat.h>
+#include <asm/current.h>
+#include <asm/debug-monitors.h>
+#include <asm/hw_breakpoint.h>
+#include <asm/kdebug.h>
+#include <asm/traps.h>
+#include <asm/cputype.h>
+#include <asm/system_misc.h>
+
+/* Breakpoint currently in use for each BRP. */
+static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[ARM_MAX_BRP]);
+
+/* Watchpoint currently in use for each WRP. */
+static DEFINE_PER_CPU(struct perf_event *, wp_on_reg[ARM_MAX_WRP]);
+
+/* Currently stepping a per-CPU kernel breakpoint. */
+static DEFINE_PER_CPU(int, stepping_kernel_bp);
+
+/* Number of BRP/WRP registers on this CPU. */
+static int core_num_brps;
+static int core_num_wrps;
+
+/* Determine number of BRP registers available. */
+static int get_num_brps(void)
+{
+ return ((read_cpuid(ID_AA64DFR0_EL1) >> 12) & 0xf) + 1;
+}
+
+/* Determine number of WRP registers available. */
+static int get_num_wrps(void)
+{
+ return ((read_cpuid(ID_AA64DFR0_EL1) >> 20) & 0xf) + 1;
+}
+
+int hw_breakpoint_slots(int type)
+{
+ /*
+ * We can be called early, so don't rely on
+ * our static variables being initialised.
+ */
+ switch (type) {
+ case TYPE_INST:
+ return get_num_brps();
+ case TYPE_DATA:
+ return get_num_wrps();
+ default:
+ pr_warning("unknown slot type: %d\n", type);
+ return 0;
+ }
+}
+
+#define READ_WB_REG_CASE(OFF, N, REG, VAL) \
+ case (OFF + N): \
+ AARCH64_DBG_READ(N, REG, VAL); \
+ break
+
+#define WRITE_WB_REG_CASE(OFF, N, REG, VAL) \
+ case (OFF + N): \
+ AARCH64_DBG_WRITE(N, REG, VAL); \
+ break
+
+#define GEN_READ_WB_REG_CASES(OFF, REG, VAL) \
+ READ_WB_REG_CASE(OFF, 0, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 1, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 2, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 3, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 4, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 5, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 6, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 7, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 8, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 9, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 10, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 11, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 12, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 13, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 14, REG, VAL); \
+ READ_WB_REG_CASE(OFF, 15, REG, VAL)
+
+#define GEN_WRITE_WB_REG_CASES(OFF, REG, VAL) \
+ WRITE_WB_REG_CASE(OFF, 0, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 1, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 2, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 3, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 4, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 5, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 6, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 7, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 8, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 9, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 10, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 11, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 12, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 13, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 14, REG, VAL); \
+ WRITE_WB_REG_CASE(OFF, 15, REG, VAL)
+
+static u64 read_wb_reg(int reg, int n)
+{
+ u64 val = 0;
+
+ switch (reg + n) {
+ GEN_READ_WB_REG_CASES(AARCH64_DBG_REG_BVR, AARCH64_DBG_REG_NAME_BVR, val);
+ GEN_READ_WB_REG_CASES(AARCH64_DBG_REG_BCR, AARCH64_DBG_REG_NAME_BCR, val);
+ GEN_READ_WB_REG_CASES(AARCH64_DBG_REG_WVR, AARCH64_DBG_REG_NAME_WVR, val);
+ GEN_READ_WB_REG_CASES(AARCH64_DBG_REG_WCR, AARCH64_DBG_REG_NAME_WCR, val);
+ default:
+ pr_warning("attempt to read from unknown breakpoint register %d\n", n);
+ }
+
+ return val;
+}
+
+static void write_wb_reg(int reg, int n, u64 val)
+{
+ switch (reg + n) {
+ GEN_WRITE_WB_REG_CASES(AARCH64_DBG_REG_BVR, AARCH64_DBG_REG_NAME_BVR, val);
+ GEN_WRITE_WB_REG_CASES(AARCH64_DBG_REG_BCR, AARCH64_DBG_REG_NAME_BCR, val);
+ GEN_WRITE_WB_REG_CASES(AARCH64_DBG_REG_WVR, AARCH64_DBG_REG_NAME_WVR, val);
+ GEN_WRITE_WB_REG_CASES(AARCH64_DBG_REG_WCR, AARCH64_DBG_REG_NAME_WCR, val);
+ default:
+ pr_warning("attempt to write to unknown breakpoint register %d\n", n);
+ }
+ isb();
+}
+
+/*
+ * Convert a breakpoint privilege level to the corresponding exception
+ * level.
+ */
+static enum debug_el debug_exception_level(int privilege)
+{
+ switch (privilege) {
+ case AARCH64_BREAKPOINT_EL0:
+ return DBG_ACTIVE_EL0;
+ case AARCH64_BREAKPOINT_EL1:
+ return DBG_ACTIVE_EL1;
+ default:
+ pr_warning("invalid breakpoint privilege level %d\n", privilege);
+ return -EINVAL;
+ }
+}
+
+/*
+ * Install a perf counter breakpoint.
+ */
+int arch_install_hw_breakpoint(struct perf_event *bp)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ struct perf_event **slot, **slots;
+ struct debug_info *debug_info = &current->thread.debug;
+ int i, max_slots, ctrl_reg, val_reg, reg_enable;
+ u32 ctrl;
+
+ if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
+ /* Breakpoint */
+ ctrl_reg = AARCH64_DBG_REG_BCR;
+ val_reg = AARCH64_DBG_REG_BVR;
+ slots = __get_cpu_var(bp_on_reg);
+ max_slots = core_num_brps;
+ reg_enable = !debug_info->bps_disabled;
+ } else {
+ /* Watchpoint */
+ ctrl_reg = AARCH64_DBG_REG_WCR;
+ val_reg = AARCH64_DBG_REG_WVR;
+ slots = __get_cpu_var(wp_on_reg);
+ max_slots = core_num_wrps;
+ reg_enable = !debug_info->wps_disabled;
+ }
+
+ for (i = 0; i < max_slots; ++i) {
+ slot = &slots[i];
+
+ if (!*slot) {
+ *slot = bp;
+ break;
+ }
+ }
+
+ if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot"))
+ return -ENOSPC;
+
+ /* Ensure debug monitors are enabled at the correct exception level. */
+ enable_debug_monitors(debug_exception_level(info->ctrl.privilege));
+
+ /* Setup the address register. */
+ write_wb_reg(val_reg, i, info->address);
+
+ /* Setup the control register. */
+ ctrl = encode_ctrl_reg(info->ctrl);
+ write_wb_reg(ctrl_reg, i, reg_enable ? ctrl | 0x1 : ctrl & ~0x1);
+
+ return 0;
+}
+
+void arch_uninstall_hw_breakpoint(struct perf_event *bp)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ struct perf_event **slot, **slots;
+ int i, max_slots, base;
+
+ if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
+ /* Breakpoint */
+ base = AARCH64_DBG_REG_BCR;
+ slots = __get_cpu_var(bp_on_reg);
+ max_slots = core_num_brps;
+ } else {
+ /* Watchpoint */
+ base = AARCH64_DBG_REG_WCR;
+ slots = __get_cpu_var(wp_on_reg);
+ max_slots = core_num_wrps;
+ }
+
+ /* Remove the breakpoint. */
+ for (i = 0; i < max_slots; ++i) {
+ slot = &slots[i];
+
+ if (*slot == bp) {
+ *slot = NULL;
+ break;
+ }
+ }
+
+ if (WARN_ONCE(i == max_slots, "Can't find any breakpoint slot"))
+ return;
+
+ /* Reset the control register. */
+ write_wb_reg(base, i, 0);
+
+ /* Release the debug monitors for the correct exception level. */
+ disable_debug_monitors(debug_exception_level(info->ctrl.privilege));
+}
+
+static int get_hbp_len(u8 hbp_len)
+{
+ unsigned int len_in_bytes = 0;
+
+ switch (hbp_len) {
+ case ARM_BREAKPOINT_LEN_1:
+ len_in_bytes = 1;
+ break;
+ case ARM_BREAKPOINT_LEN_2:
+ len_in_bytes = 2;
+ break;
+ case ARM_BREAKPOINT_LEN_4:
+ len_in_bytes = 4;
+ break;
+ case ARM_BREAKPOINT_LEN_8:
+ len_in_bytes = 8;
+ break;
+ }
+
+ return len_in_bytes;
+}
+
+/*
+ * Check whether bp virtual address is in kernel space.
+ */
+int arch_check_bp_in_kernelspace(struct perf_event *bp)
+{
+ unsigned int len;
+ unsigned long va;
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+
+ va = info->address;
+ len = get_hbp_len(info->ctrl.len);
+
+ return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
+}
+
+/*
+ * Extract generic type and length encodings from an arch_hw_breakpoint_ctrl.
+ * Hopefully this will disappear when ptrace can bypass the conversion
+ * to generic breakpoint descriptions.
+ */
+int arch_bp_generic_fields(struct arch_hw_breakpoint_ctrl ctrl,
+ int *gen_len, int *gen_type)
+{
+ /* Type */
+ switch (ctrl.type) {
+ case ARM_BREAKPOINT_EXECUTE:
+ *gen_type = HW_BREAKPOINT_X;
+ break;
+ case ARM_BREAKPOINT_LOAD:
+ *gen_type = HW_BREAKPOINT_R;
+ break;
+ case ARM_BREAKPOINT_STORE:
+ *gen_type = HW_BREAKPOINT_W;
+ break;
+ case ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE:
+ *gen_type = HW_BREAKPOINT_RW;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /* Len */
+ switch (ctrl.len) {
+ case ARM_BREAKPOINT_LEN_1:
+ *gen_len = HW_BREAKPOINT_LEN_1;
+ break;
+ case ARM_BREAKPOINT_LEN_2:
+ *gen_len = HW_BREAKPOINT_LEN_2;
+ break;
+ case ARM_BREAKPOINT_LEN_4:
+ *gen_len = HW_BREAKPOINT_LEN_4;
+ break;
+ case ARM_BREAKPOINT_LEN_8:
+ *gen_len = HW_BREAKPOINT_LEN_8;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/*
+ * Construct an arch_hw_breakpoint from a perf_event.
+ */
+static int arch_build_bp_info(struct perf_event *bp)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+
+ /* Type */
+ switch (bp->attr.bp_type) {
+ case HW_BREAKPOINT_X:
+ info->ctrl.type = ARM_BREAKPOINT_EXECUTE;
+ break;
+ case HW_BREAKPOINT_R:
+ info->ctrl.type = ARM_BREAKPOINT_LOAD;
+ break;
+ case HW_BREAKPOINT_W:
+ info->ctrl.type = ARM_BREAKPOINT_STORE;
+ break;
+ case HW_BREAKPOINT_RW:
+ info->ctrl.type = ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /* Len */
+ switch (bp->attr.bp_len) {
+ case HW_BREAKPOINT_LEN_1:
+ info->ctrl.len = ARM_BREAKPOINT_LEN_1;
+ break;
+ case HW_BREAKPOINT_LEN_2:
+ info->ctrl.len = ARM_BREAKPOINT_LEN_2;
+ break;
+ case HW_BREAKPOINT_LEN_4:
+ info->ctrl.len = ARM_BREAKPOINT_LEN_4;
+ break;
+ case HW_BREAKPOINT_LEN_8:
+ info->ctrl.len = ARM_BREAKPOINT_LEN_8;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /*
+ * On AArch64, we only permit breakpoints of length 4, whereas
+ * AArch32 also requires breakpoints of length 2 for Thumb.
+ * Watchpoints can be of length 1, 2, 4 or 8 bytes.
+ */
+ if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
+ if (is_compat_task()) {
+ if (info->ctrl.len != ARM_BREAKPOINT_LEN_2 &&
+ info->ctrl.len != ARM_BREAKPOINT_LEN_4)
+ return -EINVAL;
+ } else if (info->ctrl.len != ARM_BREAKPOINT_LEN_4) {
+ /*
+ * FIXME: Some tools (I'm looking at you perf) assume
+ * that breakpoints should be sizeof(long). This
+ * is nonsense. For now, we fix up the parameter
+ * but we should probably return -EINVAL instead.
+ */
+ info->ctrl.len = ARM_BREAKPOINT_LEN_4;
+ }
+ }
+
+ /* Address */
+ info->address = bp->attr.bp_addr;
+
+ /*
+ * Privilege
+ * Note that we disallow combined EL0/EL1 breakpoints because
+ * that would complicate the stepping code.
+ */
+ if (arch_check_bp_in_kernelspace(bp))
+ info->ctrl.privilege = AARCH64_BREAKPOINT_EL1;
+ else
+ info->ctrl.privilege = AARCH64_BREAKPOINT_EL0;
+
+ /* Enabled? */
+ info->ctrl.enabled = !bp->attr.disabled;
+
+ return 0;
+}
+
+/*
+ * Validate the arch-specific HW Breakpoint register settings.
+ */
+int arch_validate_hwbkpt_settings(struct perf_event *bp)
+{
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
+ int ret;
+ u64 alignment_mask, offset;
+
+ /* Build the arch_hw_breakpoint. */
+ ret = arch_build_bp_info(bp);
+ if (ret)
+ return ret;
+
+ /*
+ * Check address alignment.
+ * We don't do any clever alignment correction for watchpoints
+ * because using 64-bit unaligned addresses is deprecated for
+ * AArch64.
+ *
+ * AArch32 tasks expect some simple alignment fixups, so emulate
+ * that here.
+ */
+ if (is_compat_task()) {
+ if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
+ alignment_mask = 0x7;
+ else
+ alignment_mask = 0x3;
+ offset = info->address & alignment_mask;
+ switch (offset) {
+ case 0:
+ /* Aligned */
+ break;
+ case 1:
+ /* Allow single byte watchpoint. */
+ if (info->ctrl.len == ARM_BREAKPOINT_LEN_1)
+ break;
+ case 2:
+ /* Allow halfword watchpoints and breakpoints. */
+ if (info->ctrl.len == ARM_BREAKPOINT_LEN_2)
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ info->address &= ~alignment_mask;
+ info->ctrl.len <<= offset;
+ } else {
+ if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE)
+ alignment_mask = 0x3;
+ else
+ alignment_mask = 0x7;
+ if (info->address & alignment_mask)
+ return -EINVAL;
+ }
+
+ /*
+ * Disallow per-task kernel breakpoints since these would
+ * complicate the stepping code.
+ */
+ if (info->ctrl.privilege == AARCH64_BREAKPOINT_EL1 && bp->hw.bp_target)
+ return -EINVAL;
+
+ return 0;
+}
+
+/*
+ * Enable/disable all of the breakpoints active at the specified
+ * exception level at the register level.
+ * This is used when single-stepping after a breakpoint exception.
+ */
+static void toggle_bp_registers(int reg, enum debug_el el, int enable)
+{
+ int i, max_slots, privilege;
+ u32 ctrl;
+ struct perf_event **slots;
+
+ switch (reg) {
+ case AARCH64_DBG_REG_BCR:
+ slots = __get_cpu_var(bp_on_reg);
+ max_slots = core_num_brps;
+ break;
+ case AARCH64_DBG_REG_WCR:
+ slots = __get_cpu_var(wp_on_reg);
+ max_slots = core_num_wrps;
+ break;
+ default:
+ return;
+ }
+
+ for (i = 0; i < max_slots; ++i) {
+ if (!slots[i])
+ continue;
+
+ privilege = counter_arch_bp(slots[i])->ctrl.privilege;
+ if (debug_exception_level(privilege) != el)
+ continue;
+
+ ctrl = read_wb_reg(reg, i);
+ if (enable)
+ ctrl |= 0x1;
+ else
+ ctrl &= ~0x1;
+ write_wb_reg(reg, i, ctrl);
+ }
+}
+
+/*
+ * Debug exception handlers.
+ */
+static int breakpoint_handler(unsigned long unused, unsigned int esr,
+ struct pt_regs *regs)
+{
+ int i, step = 0, *kernel_step;
+ u32 ctrl_reg;
+ u64 addr, val;
+ struct perf_event *bp, **slots;
+ struct debug_info *debug_info;
+ struct arch_hw_breakpoint_ctrl ctrl;
+
+ slots = (struct perf_event **)__get_cpu_var(bp_on_reg);
+ addr = instruction_pointer(regs);
+ debug_info = &current->thread.debug;
+
+ for (i = 0; i < core_num_brps; ++i) {
+ rcu_read_lock();
+
+ bp = slots[i];
+
+ if (bp == NULL)
+ goto unlock;
+
+ /* Check if the breakpoint value matches. */
+ val = read_wb_reg(AARCH64_DBG_REG_BVR, i);
+ if (val != (addr & ~0x3))
+ goto unlock;
+
+ /* Possible match, check the byte address select to confirm. */
+ ctrl_reg = read_wb_reg(AARCH64_DBG_REG_BCR, i);
+ decode_ctrl_reg(ctrl_reg, &ctrl);
+ if (!((1 << (addr & 0x3)) & ctrl.len))
+ goto unlock;
+
+ counter_arch_bp(bp)->trigger = addr;
+ perf_bp_event(bp, regs);
+
+ /* Do we need to handle the stepping? */
+ if (!bp->overflow_handler)
+ step = 1;
+unlock:
+ rcu_read_unlock();
+ }
+
+ if (!step)
+ return 0;
+
+ if (user_mode(regs)) {
+ debug_info->bps_disabled = 1;
+ toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL0, 0);
+
+ /* If we're already stepping a watchpoint, just return. */
+ if (debug_info->wps_disabled)
+ return 0;
+
+ if (test_thread_flag(TIF_SINGLESTEP))
+ debug_info->suspended_step = 1;
+ else
+ user_enable_single_step(current);
+ } else {
+ toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL1, 0);
+ kernel_step = &__get_cpu_var(stepping_kernel_bp);
+
+ if (*kernel_step != ARM_KERNEL_STEP_NONE)
+ return 0;
+
+ if (kernel_active_single_step()) {
+ *kernel_step = ARM_KERNEL_STEP_SUSPEND;
+ } else {
+ *kernel_step = ARM_KERNEL_STEP_ACTIVE;
+ kernel_enable_single_step(regs);
+ }
+ }
+
+ return 0;
+}
+
+static int watchpoint_handler(unsigned long addr, unsigned int esr,
+ struct pt_regs *regs)
+{
+ int i, step = 0, *kernel_step, access;
+ u32 ctrl_reg;
+ u64 val, alignment_mask;
+ struct perf_event *wp, **slots;
+ struct debug_info *debug_info;
+ struct arch_hw_breakpoint *info;
+ struct arch_hw_breakpoint_ctrl ctrl;
+
+ slots = (struct perf_event **)__get_cpu_var(wp_on_reg);
+ debug_info = &current->thread.debug;
+
+ for (i = 0; i < core_num_wrps; ++i) {
+ rcu_read_lock();
+
+ wp = slots[i];
+
+ if (wp == NULL)
+ goto unlock;
+
+ info = counter_arch_bp(wp);
+ /* AArch32 watchpoints are either 4 or 8 bytes aligned. */
+ if (is_compat_task()) {
+ if (info->ctrl.len == ARM_BREAKPOINT_LEN_8)
+ alignment_mask = 0x7;
+ else
+ alignment_mask = 0x3;
+ } else {
+ alignment_mask = 0x7;
+ }
+
+ /* Check if the watchpoint value matches. */
+ val = read_wb_reg(AARCH64_DBG_REG_WVR, i);
+ if (val != (addr & ~alignment_mask))
+ goto unlock;
+
+ /* Possible match, check the byte address select to confirm. */
+ ctrl_reg = read_wb_reg(AARCH64_DBG_REG_WCR, i);
+ decode_ctrl_reg(ctrl_reg, &ctrl);
+ if (!((1 << (addr & alignment_mask)) & ctrl.len))
+ goto unlock;
+
+ /*
+ * Check that the access type matches.
+ * 0 => load, otherwise => store
+ */
+ access = (esr & AARCH64_ESR_ACCESS_MASK) ? HW_BREAKPOINT_W :
+ HW_BREAKPOINT_R;
+ if (!(access & hw_breakpoint_type(wp)))
+ goto unlock;
+
+ info->trigger = addr;
+ perf_bp_event(wp, regs);
+
+ /* Do we need to handle the stepping? */
+ if (!wp->overflow_handler)
+ step = 1;
+
+unlock:
+ rcu_read_unlock();
+ }
+
+ if (!step)
+ return 0;
+
+ /*
+ * We always disable EL0 watchpoints because the kernel can
+ * cause these to fire via an unprivileged access.
+ */
+ toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL0, 0);
+
+ if (user_mode(regs)) {
+ debug_info->wps_disabled = 1;
+
+ /* If we're already stepping a breakpoint, just return. */
+ if (debug_info->bps_disabled)
+ return 0;
+
+ if (test_thread_flag(TIF_SINGLESTEP))
+ debug_info->suspended_step = 1;
+ else
+ user_enable_single_step(current);
+ } else {
+ toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL1, 0);
+ kernel_step = &__get_cpu_var(stepping_kernel_bp);
+
+ if (*kernel_step != ARM_KERNEL_STEP_NONE)
+ return 0;
+
+ if (kernel_active_single_step()) {
+ *kernel_step = ARM_KERNEL_STEP_SUSPEND;
+ } else {
+ *kernel_step = ARM_KERNEL_STEP_ACTIVE;
+ kernel_enable_single_step(regs);
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * Handle single-step exception.
+ */
+int reinstall_suspended_bps(struct pt_regs *regs)
+{
+ struct debug_info *debug_info = &current->thread.debug;
+ int handled_exception = 0, *kernel_step;
+
+ kernel_step = &__get_cpu_var(stepping_kernel_bp);
+
+ /*
+ * Called from single-step exception handler.
+ * Return 0 if execution can resume, 1 if a SIGTRAP should be
+ * reported.
+ */
+ if (user_mode(regs)) {
+ if (debug_info->bps_disabled) {
+ debug_info->bps_disabled = 0;
+ toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL0, 1);
+ handled_exception = 1;
+ }
+
+ if (debug_info->wps_disabled) {
+ debug_info->wps_disabled = 0;
+ toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL0, 1);
+ handled_exception = 1;
+ }
+
+ if (handled_exception) {
+ if (debug_info->suspended_step) {
+ debug_info->suspended_step = 0;
+ /* Allow exception handling to fall-through. */
+ handled_exception = 0;
+ } else {
+ user_disable_single_step(current);
+ }
+ }
+ } else if (*kernel_step != ARM_KERNEL_STEP_NONE) {
+ toggle_bp_registers(AARCH64_DBG_REG_BCR, DBG_ACTIVE_EL1, 1);
+ toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL1, 1);
+
+ if (!debug_info->wps_disabled)
+ toggle_bp_registers(AARCH64_DBG_REG_WCR, DBG_ACTIVE_EL0, 1);
+
+ if (*kernel_step != ARM_KERNEL_STEP_SUSPEND) {
+ kernel_disable_single_step();
+ handled_exception = 1;
+ } else {
+ handled_exception = 0;
+ }
+
+ *kernel_step = ARM_KERNEL_STEP_NONE;
+ }
+
+ return !handled_exception;
+}
+
+/*
+ * Context-switcher for restoring suspended breakpoints.
+ */
+void hw_breakpoint_thread_switch(struct task_struct *next)
+{
+ /*
+ * current next
+ * disabled: 0 0 => The usual case, NOTIFY_DONE
+ * 0 1 => Disable the registers
+ * 1 0 => Enable the registers
+ * 1 1 => NOTIFY_DONE. per-task bps will
+ * get taken care of by perf.
+ */
+
+ struct debug_info *current_debug_info, *next_debug_info;
+
+ current_debug_info = &current->thread.debug;
+ next_debug_info = &next->thread.debug;
+
+ /* Update breakpoints. */
+ if (current_debug_info->bps_disabled != next_debug_info->bps_disabled)
+ toggle_bp_registers(AARCH64_DBG_REG_BCR,
+ DBG_ACTIVE_EL0,
+ !next_debug_info->bps_disabled);
+
+ /* Update watchpoints. */
+ if (current_debug_info->wps_disabled != next_debug_info->wps_disabled)
+ toggle_bp_registers(AARCH64_DBG_REG_WCR,
+ DBG_ACTIVE_EL0,
+ !next_debug_info->wps_disabled);
+}
+
+/*
+ * CPU initialisation.
+ */
+static void reset_ctrl_regs(void *unused)
+{
+ int i;
+
+ for (i = 0; i < core_num_brps; ++i) {
+ write_wb_reg(AARCH64_DBG_REG_BCR, i, 0UL);
+ write_wb_reg(AARCH64_DBG_REG_BVR, i, 0UL);
+ }
+
+ for (i = 0; i < core_num_wrps; ++i) {
+ write_wb_reg(AARCH64_DBG_REG_WCR, i, 0UL);
+ write_wb_reg(AARCH64_DBG_REG_WVR, i, 0UL);
+ }
+}
+
+static int __cpuinit hw_breakpoint_reset_notify(struct notifier_block *self,
+ unsigned long action,
+ void *hcpu)
+{
+ int cpu = (long)hcpu;
+ if (action == CPU_ONLINE)
+ smp_call_function_single(cpu, reset_ctrl_regs, NULL, 1);
+ return NOTIFY_OK;
+}
+
+static struct notifier_block __cpuinitdata hw_breakpoint_reset_nb = {
+ .notifier_call = hw_breakpoint_reset_notify,
+};
+
+/*
+ * One-time initialisation.
+ */
+static int __init arch_hw_breakpoint_init(void)
+{
+ core_num_brps = get_num_brps();
+ core_num_wrps = get_num_wrps();
+
+ pr_info("found %d breakpoint and %d watchpoint registers.\n",
+ core_num_brps, core_num_wrps);
+
+ /*
+ * Reset the breakpoint resources. We assume that a halting
+ * debugger will leave the world in a nice state for us.
+ */
+ smp_call_function(reset_ctrl_regs, NULL, 1);
+ reset_ctrl_regs(NULL);
+
+ /* Register debug fault handlers. */
+ hook_debug_fault_code(DBG_ESR_EVT_HWBP, breakpoint_handler, SIGTRAP,
+ TRAP_HWBKPT, "hw-breakpoint handler");
+ hook_debug_fault_code(DBG_ESR_EVT_HWWP, watchpoint_handler, SIGTRAP,
+ TRAP_HWBKPT, "hw-watchpoint handler");
+
+ /* Register hotplug notifier. */
+ register_cpu_notifier(&hw_breakpoint_reset_nb);
+
+ return 0;
+}
+arch_initcall(arch_hw_breakpoint_init);
+
+void hw_breakpoint_pmu_read(struct perf_event *bp)
+{
+}
+
+/*
+ * Dummy function to register with die_notifier.
+ */
+int hw_breakpoint_exceptions_notify(struct notifier_block *unused,
+ unsigned long val, void *data)
+{
+ return NOTIFY_DONE;
+}
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
new file mode 100644
index 0000000..816b1b5
--- /dev/null
+++ b/arch/arm64/kernel/ptrace.c
@@ -0,0 +1,834 @@
+/*
+ * Based on arch/arm/kernel/ptrace.c
+ *
+ * By Ross Biro 1/23/92
+ * edited by Linus Torvalds
+ * ARM modifications Copyright (C) 2000 Russell King
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/ptrace.h>
+#include <linux/user.h>
+#include <linux/security.h>
+#include <linux/init.h>
+#include <linux/signal.h>
+#include <linux/uaccess.h>
+#include <linux/perf_event.h>
+#include <linux/hw_breakpoint.h>
+#include <linux/regset.h>
+#include <linux/tracehook.h>
+#include <linux/elf.h>
+
+#include <asm/compat.h>
+#include <asm/debug-monitors.h>
+#include <asm/pgtable.h>
+#include <asm/traps.h>
+#include <asm/system_misc.h>
+
+/*
+ * TODO: does not yet catch signals sent when the child dies.
+ * in exit.c or in signal.c.
+ */
+
+/*
+ * Called by kernel/ptrace.c when detaching..
+ */
+void ptrace_disable(struct task_struct *child)
+{
+}
+
+/*
+ * Handle hitting a breakpoint.
+ */
+static int ptrace_break(struct pt_regs *regs)
+{
+ siginfo_t info;
+
+ info.si_signo = SIGTRAP;
+ info.si_errno = 0;
+ info.si_code = TRAP_BRKPT;
+ info.si_addr = (void __user *)instruction_pointer(regs);
+
+ force_sig_info(SIGTRAP, &info, current);
+ return 0;
+}
+
+static int arm64_break_trap(unsigned long addr, unsigned int esr,
+ struct pt_regs *regs)
+{
+ return ptrace_break(regs);
+}
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+/*
+ * Convert a virtual register number into an index for a thread_info
+ * breakpoint array. Breakpoints are identified using positive numbers
+ * whilst watchpoints are negative. The registers are laid out as pairs
+ * of (address, control), each pair mapping to a unique hw_breakpoint struct.
+ * Register 0 is reserved for describing resource information.
+ */
+static int ptrace_hbp_num_to_idx(long num)
+{
+ if (num < 0)
+ num = (ARM_MAX_BRP << 1) - num;
+ return (num - 1) >> 1;
+}
+
+/*
+ * Returns the virtual register number for the address of the
+ * breakpoint at index idx.
+ */
+static long ptrace_hbp_idx_to_num(int idx)
+{
+ long mid = ARM_MAX_BRP << 1;
+ long num = (idx << 1) + 1;
+ return num > mid ? mid - num : num;
+}
+
+/*
+ * Handle hitting a HW-breakpoint.
+ */
+static void ptrace_hbptriggered(struct perf_event *bp,
+ struct perf_sample_data *data,
+ struct pt_regs *regs)
+{
+ struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);
+ long num;
+ int i;
+ siginfo_t info;
+
+ for (i = 0; i < ARM_MAX_HBP_SLOTS; ++i)
+ if (current->thread.debug.hbp[i] == bp)
+ break;
+
+ num = (i == ARM_MAX_HBP_SLOTS) ? 0 : ptrace_hbp_idx_to_num(i);
+
+ info.si_signo = SIGTRAP;
+ info.si_errno = (int)num;
+ info.si_code = TRAP_HWBKPT;
+ info.si_addr = (void __user *)(bkpt->trigger);
+
+ force_sig_info(SIGTRAP, &info, current);
+}
+
+/*
+ * Unregister breakpoints from this task and reset the pointers in
+ * the thread_struct.
+ */
+void flush_ptrace_hw_breakpoint(struct task_struct *tsk)
+{
+ int i;
+ struct thread_struct *t = &tsk->thread;
+
+ for (i = 0; i < ARM_MAX_HBP_SLOTS; i++) {
+ if (t->debug.hbp[i]) {
+ unregister_hw_breakpoint(t->debug.hbp[i]);
+ t->debug.hbp[i] = NULL;
+ }
+ }
+}
+
+void ptrace_hw_copy_thread(struct task_struct *task)
+{
+ memset(&task->thread.debug, 0, sizeof(struct debug_info));
+}
+
+static u32 ptrace_get_hbp_resource_info(void)
+{
+ u8 num_brps, num_wrps, debug_arch, wp_len;
+ u32 reg = 0;
+
+ num_brps = hw_breakpoint_slots(TYPE_INST);
+ num_wrps = hw_breakpoint_slots(TYPE_DATA);
+
+ debug_arch = debug_monitors_arch();
+ wp_len = 8; /* Reserved on AArch64 */
+ reg |= debug_arch;
+ reg <<= 8;
+ reg |= wp_len;
+ reg <<= 8;
+ reg |= num_wrps;
+ reg <<= 8;
+ reg |= num_brps;
+
+ return reg;
+}
+
+static struct perf_event *ptrace_hbp_create(struct task_struct *tsk, int type)
+{
+ struct perf_event_attr attr;
+
+ ptrace_breakpoint_init(&attr);
+
+ /*
+ * Initialise fields to sane defaults
+ * (i.e. values that will pass validation).
+ */
+ attr.bp_addr = 0;
+ attr.bp_len = HW_BREAKPOINT_LEN_4;
+ attr.bp_type = type;
+ attr.disabled = 1;
+
+ return register_user_hw_breakpoint(&attr, ptrace_hbptriggered, NULL,
+ tsk);
+}
+
+static int ptrace_gethbpregs(struct task_struct *tsk, long num,
+ unsigned long __user *data)
+{
+ u64 addr_reg;
+ u32 ctrl_reg;
+ int idx, ret = 0;
+ struct perf_event *bp;
+ struct arch_hw_breakpoint_ctrl arch_ctrl;
+
+ if (num == 0) {
+ ctrl_reg = ptrace_get_hbp_resource_info();
+ if (put_user(ctrl_reg, (u32 __user *)data))
+ ret = -EFAULT;
+ } else {
+ idx = ptrace_hbp_num_to_idx(num);
+ if (idx < 0 || idx >= ARM_MAX_HBP_SLOTS)
+ return -EINVAL;
+
+ bp = tsk->thread.debug.hbp[idx];
+ arch_ctrl = counter_arch_bp(bp)->ctrl;
+
+ if (is_compat_task()) {
+ /*
+ * Fix up the len because we may have adjusted
+ * it to compensate for an unaligned address.
+ */
+ while (!(arch_ctrl.len & 0x1))
+ arch_ctrl.len >>= 1;
+ }
+
+ if (num & 0x1) {
+ addr_reg = bp ? bp->attr.bp_addr : 0;
+ if (put_user(addr_reg, data))
+ ret = -EFAULT;
+ } else {
+ ctrl_reg = bp ? encode_ctrl_reg(arch_ctrl) : 0;
+ if (put_user(ctrl_reg, (u32 __user *)data))
+ ret = -EFAULT;
+ }
+ }
+
+ return ret;
+}
+
+static int ptrace_sethbpregs(struct task_struct *tsk, long num,
+ unsigned long __user *data)
+{
+ int idx, gen_len, gen_type, implied_type, ret;
+ u64 user_addr;
+ u32 user_ctrl;
+ struct perf_event *bp;
+ struct arch_hw_breakpoint_ctrl ctrl;
+ struct perf_event_attr attr;
+
+ if (num == 0)
+ return 0;
+ else if (num < 0)
+ implied_type = HW_BREAKPOINT_RW;
+ else
+ implied_type = HW_BREAKPOINT_X;
+
+ idx = ptrace_hbp_num_to_idx(num);
+ if (idx < 0 || idx >= ARM_MAX_HBP_SLOTS)
+ return -EFAULT;
+
+ bp = tsk->thread.debug.hbp[idx];
+ if (!bp) {
+ bp = ptrace_hbp_create(tsk, implied_type);
+ if (IS_ERR(bp))
+ return PTR_ERR(bp);
+ tsk->thread.debug.hbp[idx] = bp;
+ }
+
+ attr = bp->attr;
+
+ if (num & 0x1) {
+ /* Address */
+ if (get_user(user_addr, data))
+ return -EFAULT;
+ attr.bp_addr = user_addr;
+ } else {
+ /* Control */
+ if (get_user(user_ctrl, (u32 __user *)data))
+ return -EFAULT;
+ decode_ctrl_reg(user_ctrl, &ctrl);
+ ret = arch_bp_generic_fields(ctrl, &gen_len, &gen_type);
+ if (ret)
+ return ret;
+
+ if ((gen_type & implied_type) != gen_type)
+ return -EINVAL;
+
+ attr.bp_len = gen_len;
+ attr.bp_type = gen_type;
+ attr.disabled = !ctrl.enabled;
+ }
+
+ return modify_user_hw_breakpoint(bp, &attr);
+}
+#endif /* CONFIG_HAVE_HW_BREAKPOINT */
+
+static int gpr_get(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ void *kbuf, void __user *ubuf)
+{
+ struct user_pt_regs *uregs = &task_pt_regs(target)->user_regs;
+ return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0, -1);
+}
+
+static int gpr_set(struct task_struct *target, const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ const void *kbuf, const void __user *ubuf)
+{
+ int ret;
+ struct user_pt_regs newregs;
+
+ ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &newregs, 0, -1);
+ if (ret)
+ return ret;
+
+ if (!valid_user_regs(&newregs))
+ return -EINVAL;
+
+ task_pt_regs(target)->user_regs = newregs;
+ return 0;
+}
+
+/*
+ * TODO: update fp accessors for lazy context switching (sync/flush hwstate)
+ */
+static int fpr_get(struct task_struct *target, const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ void *kbuf, void __user *ubuf)
+{
+ struct user_fpsimd_state *uregs;
+ uregs = &target->thread.fpsimd_state.user_fpsimd;
+ return user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0, -1);
+}
+
+static int fpr_set(struct task_struct *target, const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ const void *kbuf, const void __user *ubuf)
+{
+ int ret;
+ struct user_fpsimd_state newstate;
+
+ ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &newstate, 0, -1);
+ if (ret)
+ return ret;
+
+ target->thread.fpsimd_state.user_fpsimd = newstate;
+ return ret;
+}
+
+enum aarch64_regset {
+ REGSET_GPR,
+ REGSET_FPR,
+};
+
+static const struct user_regset aarch64_regsets[] = {
+ [REGSET_GPR] = {
+ .core_note_type = NT_PRSTATUS,
+ .n = sizeof(struct user_pt_regs) / sizeof(u64),
+ .size = sizeof(u64),
+ .align = sizeof(u64),
+ .get = gpr_get,
+ .set = gpr_set
+ },
+ [REGSET_FPR] = {
+ .core_note_type = NT_PRFPREG,
+ .n = sizeof(struct user_fpsimd_state) / sizeof(u32),
+ /*
+ * We pretend we have 32-bit registers because the fpsr and
+ * fpcr are 32-bits wide.
+ */
+ .size = sizeof(u32),
+ .align = sizeof(u32),
+ .get = fpr_get,
+ .set = fpr_set
+ },
+};
+
+static const struct user_regset_view user_aarch64_view = {
+ .name = "aarch64", .e_machine = EM_AARCH64,
+ .regsets = aarch64_regsets, .n = ARRAY_SIZE(aarch64_regsets)
+};
+
+#ifdef CONFIG_AARCH32_EMULATION
+enum compat_regset {
+ REGSET_COMPAT_GPR,
+ REGSET_COMPAT_VFP,
+};
+
+static int compat_gpr_get(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ void *kbuf, void __user *ubuf)
+{
+ int ret = 0;
+ unsigned int i, start, num_regs;
+
+ /* Calculate the number of AArch32 registers contained in count */
+ num_regs = count / regset->size;
+
+ /* Convert pos into an register number */
+ start = pos / regset->size;
+
+ if (start + num_regs > regset->n)
+ return -EIO;
+
+ for (i = 0; i < num_regs; ++i) {
+ unsigned int idx = start + i;
+ void *reg;
+
+ switch (idx) {
+ case 15:
+ reg = (void *)&task_pt_regs(target)->pc;
+ break;
+ case 16:
+ reg = (void *)&task_pt_regs(target)->pstate;
+ break;
+ case 17:
+ reg = (void *)&task_pt_regs(target)->orig_x0;
+ break;
+ default:
+ reg = (void *)&task_pt_regs(target)->regs[idx];
+ }
+
+ ret = copy_to_user(ubuf, reg, sizeof(compat_ulong_t));
+
+ if (ret)
+ break;
+ else
+ ubuf += sizeof(compat_ulong_t);
+ }
+
+ return ret;
+}
+
+static int compat_gpr_set(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ const void *kbuf, const void __user *ubuf)
+{
+ struct pt_regs newregs;
+ int ret = 0;
+ unsigned int i, start, num_regs;
+
+ /* Calculate the number of AArch32 registers contained in count */
+ num_regs = count / regset->size;
+
+ /* Convert pos into an register number */
+ start = pos / regset->size;
+
+ if (start + num_regs > regset->n)
+ return -EIO;
+
+ newregs = *task_pt_regs(target);
+
+ for (i = 0; i < num_regs; ++i) {
+ unsigned int idx = start + i;
+ void *reg;
+
+ switch (idx) {
+ case 15:
+ reg = (void *)&newregs.pc;
+ break;
+ case 16:
+ reg = (void *)&newregs.pstate;
+ break;
+ case 17:
+ reg = (void *)&newregs.orig_x0;
+ break;
+ default:
+ reg = (void *)&newregs.regs[idx];
+ }
+
+ ret = copy_from_user(reg, ubuf, sizeof(compat_ulong_t));
+
+ if (ret)
+ goto out;
+ else
+ ubuf += sizeof(compat_ulong_t);
+ }
+
+ if (valid_user_regs(&newregs.user_regs))
+ *task_pt_regs(target) = newregs;
+ else
+ ret = -EINVAL;
+
+out:
+ return ret;
+}
+
+static int compat_vfp_get(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ void *kbuf, void __user *ubuf)
+{
+ struct user_fpsimd_state *uregs;
+ compat_ulong_t fpscr;
+ int ret;
+
+ uregs = &target->thread.fpsimd_state.user_fpsimd;
+
+ /*
+ * The VFP registers are packed into the fpsimd_state, so they all sit
+ * nicely together for us. We just need to create the fpscr separately.
+ */
+ ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, uregs, 0,
+ VFP_STATE_SIZE - sizeof(compat_ulong_t));
+
+ if (count && !ret) {
+ fpscr = (uregs->fpsr & VFP_FPSCR_STAT_MASK) |
+ (uregs->fpcr & VFP_FPSCR_CTRL_MASK);
+ ret = put_user(fpscr, (compat_ulong_t *)ubuf);
+ }
+
+ return ret;
+}
+
+static int compat_vfp_set(struct task_struct *target,
+ const struct user_regset *regset,
+ unsigned int pos, unsigned int count,
+ const void *kbuf, const void __user *ubuf)
+{
+ struct user_fpsimd_state *uregs;
+ compat_ulong_t fpscr;
+ int ret;
+
+ if (pos + count > VFP_STATE_SIZE)
+ return -EIO;
+
+ uregs = &target->thread.fpsimd_state.user_fpsimd;
+
+ ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, uregs, 0,
+ VFP_STATE_SIZE - sizeof(compat_ulong_t));
+
+ if (count && !ret) {
+ ret = get_user(fpscr, (compat_ulong_t *)ubuf);
+ uregs->fpsr = fpscr & VFP_FPSCR_STAT_MASK;
+ uregs->fpcr = fpscr & VFP_FPSCR_CTRL_MASK;
+ }
+
+ return ret;
+}
+
+static const struct user_regset aarch32_regsets[] = {
+ [REGSET_COMPAT_GPR] = {
+ .core_note_type = NT_PRSTATUS,
+ .n = COMPAT_ELF_NGREG,
+ .size = sizeof(compat_elf_greg_t),
+ .align = sizeof(compat_elf_greg_t),
+ .get = compat_gpr_get,
+ .set = compat_gpr_set
+ },
+ [REGSET_COMPAT_VFP] = {
+ .core_note_type = NT_ARM_VFP,
+ .n = VFP_STATE_SIZE / sizeof(compat_ulong_t),
+ .size = sizeof(compat_ulong_t),
+ .align = sizeof(compat_ulong_t),
+ .get = compat_vfp_get,
+ .set = compat_vfp_set
+ },
+};
+
+static const struct user_regset_view user_aarch32_view = {
+ .name = "aarch32", .e_machine = EM_ARM,
+ .regsets = aarch32_regsets, .n = ARRAY_SIZE(aarch32_regsets)
+};
+#endif /* CONFIG_AARCH32_EMULATION */
+
+const struct user_regset_view *task_user_regset_view(struct task_struct *task)
+{
+#ifdef CONFIG_AARCH32_EMULATION
+ if (test_tsk_thread_flag(task, TIF_32BIT))
+ return &user_aarch32_view;
+#endif
+ return &user_aarch64_view;
+}
+
+long arch_ptrace(struct task_struct *child, long request,
+ unsigned long addr, unsigned long data)
+{
+ int ret;
+ unsigned long *datap = (unsigned long __user *)data;
+
+ switch (request) {
+ case PTRACE_GET_THREAD_AREA:
+ ret = put_user(child->thread.tp_value, datap);
+ break;
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+ case PTRACE_GETHBPREGS:
+ ret = ptrace_gethbpregs(child, addr, datap);
+ break;
+
+ case PTRACE_SETHBPREGS:
+ ret = ptrace_sethbpregs(child, addr, datap);
+ break;
+#endif
+
+ default:
+ ret = ptrace_request(child, request, addr, data);
+ break;
+ }
+
+ return ret;
+}
+
+#ifdef CONFIG_AARCH32_EMULATION
+
+#include <linux/compat.h>
+
+int aarch32_break_trap(struct pt_regs *regs)
+{
+ unsigned int instr;
+ bool bp = false;
+ void __user *pc = (void __user *)instruction_pointer(regs);
+
+ if (compat_thumb_mode(regs)) {
+ /* get 16-bit Thumb instruction */
+ get_user(instr, (u16 __user *)pc);
+ if (instr == AARCH32_BREAK_THUMB2_LO) {
+ /* get second half of 32-bit Thumb-2 instruction */
+ get_user(instr, (u16 __user *)(pc + 2));
+ bp = instr == AARCH32_BREAK_THUMB2_HI;
+ } else {
+ bp = instr == AARCH32_BREAK_THUMB;
+ }
+ } else {
+ /* 32-bit ARM instruction */
+ get_user(instr, (u32 __user *)pc);
+ bp = (instr & ~0xf0000000) == AARCH32_BREAK_ARM;
+ }
+
+ if (bp)
+ return ptrace_break(regs);
+ return 1;
+}
+
+static int compat_ptrace_read_user(struct task_struct *tsk, compat_ulong_t off,
+ compat_ulong_t __user *ret)
+{
+ compat_ulong_t tmp;
+
+ if (off & 3)
+ return -EIO;
+
+ if (off == PT_TEXT_ADDR)
+ tmp = tsk->mm->start_code;
+ else if (off == PT_DATA_ADDR)
+ tmp = tsk->mm->start_data;
+ else if (off == PT_TEXT_END_ADDR)
+ tmp = tsk->mm->end_code;
+ else if (off < sizeof(compat_elf_gregset_t))
+ return copy_regset_to_user(tsk, &user_aarch32_view,
+ REGSET_COMPAT_GPR, off,
+ sizeof(compat_ulong_t), ret);
+ else if (off >= COMPAT_USER_SZ)
+ return -EIO;
+ else
+ tmp = 0;
+
+ return put_user(tmp, ret);
+}
+
+static int compat_ptrace_write_user(struct task_struct *tsk, compat_ulong_t off,
+ compat_ulong_t val)
+{
+ int ret;
+
+ if (off & 3 || off >= COMPAT_USER_SZ)
+ return -EIO;
+
+ if (off >= sizeof(compat_elf_gregset_t))
+ return 0;
+
+ ret = copy_regset_from_user(tsk, &user_aarch32_view,
+ REGSET_COMPAT_GPR, off,
+ sizeof(compat_ulong_t),
+ &val);
+ return ret;
+}
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+static int compat_ptrace_gethbpregs(struct task_struct *tsk, compat_long_t num,
+ compat_ulong_t __user *data)
+{
+ int ret;
+ unsigned long kdata;
+
+ mm_segment_t old_fs = get_fs();
+ set_fs(KERNEL_DS);
+ ret = ptrace_gethbpregs(tsk, (long)num, &kdata);
+ set_fs(old_fs);
+
+ if (!ret)
+ ret = put_user(kdata, data);
+
+ return ret;
+}
+
+static int compat_ptrace_sethbpregs(struct task_struct *tsk, compat_long_t num,
+ compat_ulong_t __user *data)
+{
+ int ret;
+ unsigned long kdata = 0;
+ mm_segment_t old_fs = get_fs();
+
+ ret = get_user(kdata, data);
+
+ if (!ret) {
+ set_fs(KERNEL_DS);
+ ret = ptrace_sethbpregs(tsk, (long)num, &kdata);
+ set_fs(old_fs);
+ }
+
+ return ret;
+}
+#endif /* CONFIG_HAVE_HW_BREAKPOINT */
+
+long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
+ compat_ulong_t caddr, compat_ulong_t cdata)
+{
+ unsigned long addr = caddr;
+ unsigned long data = cdata;
+ void __user *datap = compat_ptr(data);
+ int ret;
+
+ switch (request) {
+ case PTRACE_PEEKUSR:
+ ret = compat_ptrace_read_user(child, addr, datap);
+ break;
+
+ case PTRACE_POKEUSR:
+ ret = compat_ptrace_write_user(child, addr, data);
+ break;
+
+ case PTRACE_GETREGS:
+ ret = copy_regset_to_user(child,
+ &user_aarch32_view,
+ REGSET_COMPAT_GPR,
+ 0, sizeof(compat_elf_gregset_t),
+ datap);
+ break;
+
+ case PTRACE_SETREGS:
+ ret = copy_regset_from_user(child,
+ &user_aarch32_view,
+ REGSET_COMPAT_GPR,
+ 0, sizeof(compat_elf_gregset_t),
+ datap);
+ break;
+
+ case PTRACE_GET_THREAD_AREA:
+ ret = put_user((compat_ulong_t)child->thread.tp_value,
+ (compat_ulong_t __user *)datap);
+ break;
+
+ case PTRACE_SET_SYSCALL:
+ task_pt_regs(child)->syscallno = data;
+ ret = 0;
+ break;
+
+ case COMPAT_PTRACE_GETVFPREGS:
+ ret = copy_regset_to_user(child,
+ &user_aarch32_view,
+ REGSET_COMPAT_VFP,
+ 0, VFP_STATE_SIZE,
+ datap);
+ break;
+
+ case COMPAT_PTRACE_SETVFPREGS:
+ ret = copy_regset_from_user(child,
+ &user_aarch32_view,
+ REGSET_COMPAT_VFP,
+ 0, VFP_STATE_SIZE,
+ datap);
+ break;
+
+#ifdef CONFIG_HAVE_HW_BREAKPOINT
+ case PTRACE_GETHBPREGS:
+ ret = compat_ptrace_gethbpregs(child, addr, datap);
+ break;
+
+ case PTRACE_SETHBPREGS:
+ ret = compat_ptrace_sethbpregs(child, addr, datap);
+ break;
+#endif
+
+ default:
+ ret = compat_ptrace_request(child, request, addr,
+ data);
+ break;
+ }
+
+ return ret;
+}
+#endif /* CONFIG_AARCH32_EMULATION */
+
+static int __init ptrace_break_init(void)
+{
+ hook_debug_fault_code(DBG_ESR_EVT_BRK, arm64_break_trap, SIGTRAP,
+ TRAP_BRKPT, "ptrace BRK handler");
+ return 0;
+}
+core_initcall(ptrace_break_init);
+
+
+asmlinkage int syscall_trace(int dir, struct pt_regs *regs)
+{
+ unsigned long saved_reg;
+
+ if (!test_thread_flag(TIF_SYSCALL_TRACE))
+ return regs->syscallno;
+
+ if (test_thread_flag(TIF_32BIT)) {
+ /* AArch32 uses ip (r12) for scratch */
+ saved_reg = regs->regs[12];
+ regs->regs[12] = dir;
+ } else {
+ /*
+ * Save X7. X7 is used to denote syscall entry/exit:
+ * X7 = 0 -> entry, = 1 -> exit
+ */
+ saved_reg = regs->regs[7];
+ regs->regs[7] = dir;
+ }
+
+ if (dir)
+ tracehook_report_syscall_exit(regs, 0);
+ else if (tracehook_report_syscall_entry(regs))
+ regs->syscallno = ~0UL;
+
+ if (test_thread_flag(TIF_32BIT))
+ regs->regs[12] = saved_reg;
+ else
+ regs->regs[7] = saved_reg;
+
+ return regs->syscallno;
+}


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